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1
Li, Peng Hui, und Rong Ye Li. „The Kinematic Analysis of the Walking Mechanism Based on the Leg-Wheel Mobile Robot“. Advanced Materials Research 694-697 (Mai 2013): 1700–1704. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.1700.
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In the studying and designing process for the robotic walking system, a theoretical analysis and simulation on the kinematic characteristics of the walking mechanism of the robot is done. From our experiments, the characteristic curves of velocity and acceleration of the drop-foot point are obtained. The walking mechanism is stable in the translation cycle, which contributes to the stability of the robot motion, while the robot still can move at a certain speed. The stress of the walking mechanism is complicated in the step cycle, because both the velocity and acceleration get a certain amount of mutation.
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Godoy, Jorge Curiel, Ignacio Juárez Campos, Lucia Márquez Pérez und Leonardo Romero Muñoz. „Nonanthropomorphic exoskeleton with legs based on eight-bar linkages“. International Journal of Advanced Robotic Systems 15, Nr. 1 (01.01.2018): 172988141875577. http://dx.doi.org/10.1177/1729881418755770.
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This article presents the principles upon which a new nonanthropomorphic biped exoskeleton was designed, whose legs are based on an eight-bar mechanism. The main function of the exoskeleton is to assist people who have difficulty walking. Every leg is based on the planar Peaucellier–Lipkin mechanism, which is a one degree of freedom linkage. To be used as a robotic leg, the Peaucellier–Lipkin mechanism was modified by including two more degrees of freedom, as well as by the addition of a mechanical system based on toothed pulleys and timing belts that provides balance and stability to the user. The use of the Peaucellier–Lipkin mechanism, its transformation from one to three degrees of freedom, and the incorporation of the stability system are the main innovations and contributions of this novel nonanthropomorphic exoskeleton. Its mobility and performance are also presented herein, through forward and inverse kinematics, together with its application in carrying out the translation movement of the robotic foot along paths with the imposition of motion laws based on polynomial functions of time.
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Beira, R., L. Santos-Carreras, G. Rognini, H. Bleuler und R. Clavel. „Dionis: A Novel Remote-Center-of-Motion Parallel Manipulator for Minimally Invasive Surgery“. Applied Bionics and Biomechanics 8, Nr. 2 (2011): 191–208. http://dx.doi.org/10.1155/2011/973097.
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The large volume and reduced dexterity of current surgical robotic systems are factors that restrict their effective performance. To improve the usefulness of surgical robots in minimally invasive surgery (MIS), a compact and accurate positioning mechanism, namedDionis, is proposed in this paper. This spatial hybrid mechanism based on a novel parallel kinematics is able to provide three rotations and one translation for single port procedures. The corresponding axes intersect at a remote center of rotation (RCM) that is the MIS entry port. Another important feature of the proposed positioning manipulator is that it can be placed below the operating table plane, allowing a quick and direct access to the patient, without removing the robotic system. This, besides saving precious space in the operating room, may improve safety over existing solutions. The conceptual design of Dionis is presented in this paper. Solutions for the inverse and direct kinematics are developed, as well as the analytical workspace and singularity analysis. Due to its unique design and kinematics, the proposed mechanism is highly compact, stiff and its dexterity fullfils the workspace specifications for MIS procedures.
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Choi, Jueun, Sangeun Park, Young-Hak Kim, Youngjin Moon und Jaesoon Choi. „A Vascular Intervention Assist Device Using Bi-Motional Roller Cartridge Structure and Clinical Evaluation“. Biosensors 11, Nr. 9 (10.09.2021): 329. http://dx.doi.org/10.3390/bios11090329.
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Conventional vascular intervention procedures present issues including X-ray exposure during operation, and an experience-dependent success rate and clinical outcome. This paper presents a novel robotic system using modularized bi-motional roller cartridge assemblies for robotic vascular interventions, specifically percutaneous coronary interventions (PCIs). The patient-side robot manipulates instruments such as the guiding catheter, guidewire, balloon/stent catheter, and diagnostic sensor catheter via commands from the user interface device, which is controlled by the physician. The proposed roller cartridge assembly can accommodate instruments of various sizes with an active clamping mechanism, and implements simultaneous translation and rotation motions. It also implements force feedback in the physician-side system, to effectively monitor the patient-side system’s status. The positioning accuracy and precision in using the robotic system showed satisfactory performance in a phantom-based test. It was also confirmed, through animal experiments and a pilot clinical trial, that the system demonstrates feasibility for clinical use.
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Zhou, Chunlin, Huifeng Wu, Xiang Xu, Yong Liu, Qi Zhu und Shuwen Pan. „Development and control of a robotic arm for percutaneous surgery“. Assembly Automation 37, Nr. 3 (07.08.2017): 314–21. http://dx.doi.org/10.1108/aa-12-2016-179.
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Purpose The purpose of this paper is to propose a robotic system for percutaneous surgery. The key component in the system, a robotic arm that can manipulate a puncture needle is presented. The mechanical design, the motion control and the force control method of the robotic arm are discussed in the paper. Design/methodology/approach The arm with an arc mechanism placed on a 3D Cartesian stage is developed as a puncture needle manipulator to locate the position of the needle tip, tune the needle’s posture and actuate the puncture motion under the visual guidance of two orthogonal X-ray images of a patient by a surgeon. A focusing method by using two laser spots is proposed to automatically move the needle tip to a surgery entry point on the skin. A dynamics model is developed to control the position of the needle mechanism and an explicit force control strategy is utilized to perform the needle insertion. Findings With the surgical system, a surgeon can easily perform puncture operation by taking two orthogonal real-time X-ray images as a visual feedback and accurately navigating the needle insertion. The laser-guided focusing method is efficient in placement of the needle tip. The explicit force control strategy is proved to be effective for holding constant and stable puncture force in experiments. Originality/value The robotic arm has an advantage in easy redirection of the needle because the rotation and the translation are decoupled in the mechanism. By adopting simple laser pens and a well-developed kinematics model, the system can handle the entry point, locating task automatically. The focusing method and the force control method proposed in the paper are useful for the present system and could be intuitive for similar surgical robots.
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Palpacelli, Matteo, Luca Carbonari, Giacomo Palmieri und Massimo Callegari. „Design of a Lockable Spherical Joint for a Reconfigurable 3-URU Parallel Platform“. Robotics 7, Nr. 3 (02.08.2018): 42. http://dx.doi.org/10.3390/robotics7030042.
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This article deals with the functional and preliminary design of a reconfigurable joint for robotic applications. Such mechanism is a key element for a class of lower mobility parallel manipulators, allowing a local reconfiguration of the kinematic chain that enables a change in platform’s mobility. The mechanism can be integrated in the kinematic structure of a 3-URU manipulator, which shall accordingly gain the ability to change mobility from pure translation to pure rotation. As a matter of fact, special kinematics conditions must be met for the accomplishment of this task. Such peculiar requirements are described and properly exploited for the design of an effective reconfigurable mechanism. A detailed description of the joint operational principle is provided, also showing how to design it when is physically located at the fixed base of the manipulator.
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Kim, In, Kotaro Tadano, Takahiro Kanno und Kenji Kawashima. „Implementing pseudo haptic feedback in a semi-isometric master interface for robotic surgery“. International Journal of Advanced Robotic Systems 14, Nr. 5 (01.09.2017): 172988141773388. http://dx.doi.org/10.1177/1729881417733885.
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We have developed a master interface that uses an isometric velocity control technique for translation and an anisometric position control technique for rotation. Using the developed interface, the operator can concentrate on the slave side and control the robot without repositioning required in conventional master arm due to the workspace limitation. However, it cannot display haptic to the operator for the translation directions with the manipulator. In this article, we propose a method to feedback the external force on the slave side to the master manipulator without using actuators or link mechanism but using a pseudo haptic effect. A flexible wrist joint with a spring is used at the tip of the slave forceps to enhance visual effect. The spring stiffness is pneumatically controlled. At the same time, we change the reference velocity of the slave according to the external force applied to the slave manipulator. The changed velocity caused by the external force restrains the slave motion. Using both the visual feedback and the motion restrain, the master–slave system is able to display force to the operator as pseudo haptic feedback without actuators. Experiments of pulling suture threads are executed using the developed master–slave surgical robot. It is confirmed that the master–slave system with pseudo haptic feedback can decrease the variance of force.
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Higuchi, Mineo. „Development of a Human Symbiotic Assist Arm “PAS-Arm” (Basic Concept and Mechanism)“. Journal of Robotics and Mechatronics 24, Nr. 3 (20.06.2012): 458–63. http://dx.doi.org/10.20965/jrm.2012.p0458.
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We describe a new robotic assist device: a passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator, handling a shared payload. PAS-Arms are physically passive. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces, which constrain and guide the motion of the payload within a shared workspace. PAS-Arms have three joints and a three dimensional workspace, but possesses only a two degrees of freedom, due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. The combination of CVTs and differential gears places one mechanical constraint on three angular velocities of the joints. PAS-Arms have no joint actuators and no force sensors. Thus they are potentially well suited to safety and low cost. This paper proposes a basic concept of PAS-Arms and explains a principle and a construction of PAS-Arms. We discuss the relation of PAS-Arms to conventionally actuated robots and another type of assist arms. We also describe range of transmission ratio of CVTs.11. This paper is the full translation from the transactions of JSME, Series C, Vol.73, No.730, 2007.
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Saunders, Ben, Necati Cihan Camgoz und Richard Bowden. „Continuous 3D Multi-Channel Sign Language Production via Progressive Transformers and Mixture Density Networks“. International Journal of Computer Vision 129, Nr. 7 (07.05.2021): 2113–35. http://dx.doi.org/10.1007/s11263-021-01457-9.
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AbstractSign languages are multi-channel visual languages, where signers use a continuous 3D space to communicate. Sign language production (SLP), the automatic translation from spoken to sign languages, must embody both the continuous articulation and full morphology of sign to be truly understandable by the Deaf community. Previous deep learning-based SLP works have produced only a concatenation of isolated signs focusing primarily on the manual features, leading to a robotic and non-expressive production. In this work, we propose a novel Progressive Transformer architecture, the first SLP model to translate from spoken language sentences to continuous 3D multi-channel sign pose sequences in an end-to-end manner. Our transformer network architecture introduces a counter decoding that enables variable length continuous sequence generation by tracking the production progress over time and predicting the end of sequence. We present extensive data augmentation techniques to reduce prediction drift, alongside an adversarial training regime and a mixture density network (MDN) formulation to produce realistic and expressive sign pose sequences. We propose a back translation evaluation mechanism for SLP, presenting benchmark quantitative results on the challenging PHOENIX14T dataset and setting baselines for future research. We further provide a user evaluation of our SLP model, to understand the Deaf reception of our sign pose productions.
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Higuchi, Mineo. „Development of a Human Symbiotic Assist Arm “PAS-Arm” (Design of Mechanism · CVT and Experimental System)“. Journal of Robotics and Mechatronics 25, Nr. 1 (20.02.2013): 211–19. http://dx.doi.org/10.20965/jrm.2013.p0211.
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We describe a new robotic assist device: a passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator, handling a shared payload. PAS-Arms are physically passive. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces, which constrain and guide the motion of the payload within a shared workspace. PAS-Arms have three joints and a three-dimensional workspace, but possess only a two degrees of freedom, due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. We have developed an experimental system of the PAS-Arm. In this paper, we describe kinematic specification of the experimental system. We discuss the differential relation of transmission ratios created by the CVTs. We conducted the relationship between transmission ratio resolutions of the CVTs and resolutions of normal vector of the virtual guiding surface, and the relationship between angular velocities of PAS-Arm’s joints and time derivative of the transmission ratios. Assuming that the Euclidean norm of the angular velocities is constant, maximum time derivative of transmission ratios is in proportion to link lengths of the PAS-Arm. We also describe the design of the CVT for use in the experimental system.1 1. This paper is the full translation from the transactions of JSME, Series C, Vol.75, No.749, pp. 104-112, 2009.
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Higuchi, Mineo, und Tsukasa Ogasawara. „Development of a Human Symbiotic Assist Arm “PAS-Arm” (Experimental System and Creation of Virtual Guiding Surfaces)“. Journal of Robotics and Mechatronics 25, Nr. 2 (20.04.2013): 285–93. http://dx.doi.org/10.20965/jrm.2013.p0285.
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We describe a new robotic assist device: the passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator. PASArms are physically passive. The force to manipulate the arm end must be provided by the operator. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces that constrain and guide the motion of the operator. PAS-Arms have three joints and a three dimensional workspace, but possess only two degrees of freedom due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. In this paper, we first discuss the manipulability ellipsoid for the PAS-Arm. The major axis of the ellipsoid is the direction in which the arm end may be easily manipulated, and vice versa. We have developed an experimental system for the PAS-Arm. The CVTs of the experimental system may not adjust the transmission ratio to zero. Second, we describe an algorithm to address that problem. Finally, we present initial experiments that verify the PAS-Arm mechanism. The experimental results successfully produced virtual guiding surfaces.1 1. This paper is the full translation from the transactions of JSME, Series C, Vol.76, No.763, pp. 611-618, 2010.
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Yigit, Cihat Bora, und Pinar Boyraz. „Design and Modelling of a Cable-Driven Parallel-Series Hybrid Variable Stiffness Joint Mechanism for Robotics“. Mechanical Sciences 8, Nr. 1 (22.03.2017): 65–77. http://dx.doi.org/10.5194/ms-8-65-2017.
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Abstract. The robotics, particularly the humanoid research field, needs new mechanisms to meet the criteria enforced by compliance, workspace requirements, motion profile characteristics and variable stiffness using lightweight but robust designs. The mechanism proposed herein is a solution to this problem by a parallel-series hybrid mechanism. The parallel term comes from two cable-driven plates supported by a compression spring in between. Furthermore, there is a two-part concentric shaft, passing through both plates connected by a universal joint. Because of the kinematic constraints of the universal joint, the mechanism can be considered as a serial chain. The mechanism has 4 degrees of freedom (DOF) which are pitch, roll, yaw motions and translational movement in z axis for stiffness adjustment. The kinematic model is obtained to define the workspace. The helical spring is analysed by using Castigliano's Theorem and the behaviour of bending and compression characteristics are presented which are validated by using finite element analysis (FEA). Hence, the dynamic model of the mechanism is derived depending on the spring reaction forces and moments. The motion experiments are performed to validate both kinematic and dynamic models. As a result, the proposed mechanism has a potential use in robotics especially in humanoid robot joints, considering the requirements of this robotic field.
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Zhang, Ziwei, und Guoying Meng. „Design and analysis of a six degrees of freedom serial–parallel robotic mechanism with multi-degree of freedom legs“. International Journal of Advanced Robotic Systems 15, Nr. 6 (01.11.2018): 172988141881264. http://dx.doi.org/10.1177/1729881418812643.
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A novel mobile serial–parallel mechanism with legs for in-pipe use is proposed. The mobile robotic mechanism is composed of two identical three-universal joint–prismatic joint–universal joint parallel mechanisms connected in series and two gripping modules. The proposed parallel mechanism has two rotational freedoms and one translational freedom. In addition, the parallel mechanism can achieve continuous and equivalent rotation. The singularities of the parallel mechanism are analyzed. The overall serial–parallel mechanism has six degrees of freedom, and each gripping module has four degrees of freedom. Each parallel mechanism in the waist module is driven by three servo-electric cylinders and each leg mechanism in the gripping modules is controlled by a linear actuator. The robotic mechanism can perform peristaltic movement and turning in space. The robotic mechanism possesses a simple structure and high flexibility, along with the merits of serial–parallel mechanism. In this article, analytic models for the kinematics and dynamics of the robotic mechanism are derived. Additionally, numerical examples are given, and their solutions are validated based on results obtained by SimMechanics and Adams.
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Yamaguchi, Kent T., Edward C. Cheung, Keith L. Markolf, Daniel V. Boguszewski, Justin Mathew, Christopher J. Lama, David R. McAllister und Frank A. Petrigliano. „Effects of Anterior Closing Wedge Tibial Osteotomy on Anterior Cruciate Ligament Force and Knee Kinematics“. American Journal of Sports Medicine 46, Nr. 2 (03.11.2017): 370–77. http://dx.doi.org/10.1177/0363546517736767.
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Background: A certain percentage of patients undergoing anterior cruciate ligament (ACL) reconstruction will experience graft failure, and there is mounting evidence that an increased posterior tibial slope (PTS) may be a predisposing factor. Theoretically, under tibiofemoral compression force (TFC), a reduced PTS would induce less anterior tibial translation (ATT) and lower ACL force. Hypothesis: Ten-degree anterior closing wedge osteotomy of the proximal tibia will significantly reduce ACL force and alter knee kinematics during robotic testing. Study Design: Controlled laboratory study. Methods: Eleven fresh-frozen human knees were instrumented with a load cell that measured ACL force as the knee was flexing continuously from 0° to 50° under 200-N TFC as our initial testing condition, followed by the addition of the following tibial loads: 45-N anterior force (AF), 5-N·m valgus moment (VM), 2-N·m internal torque (IT), and all loads combined. ACL force and knee kinematics were recorded before and after osteotomy. Results: Osteotomy produced significant changes in the tibiofemoral position at full extension (as defined by a 2-N·m knee extension moment). This resulted in apparent knee hyperextension (9.4° ± 1.9°), posterior tibial translation (7.9 mm ± 1.6 mm), internal tibial rotation (3.2° ± 2.3°), and valgus tibial rotation (3.2° ± 1.5°). During straight knee flexion with TFC alone, osteotomy reduced ACL force to 0 N beyond 5° of flexion, and ATT was reduced between 0° and 45° ( P < .05). With TFC + AF, ACL force was reduced beyond 5° of flexion, and ATT was reduced between 5° and 45° ( P < .05). With TFC + VM, ACL force was less than 10 N beyond 5° of flexion, and ATT was reduced at all flexion angles ( P < .05). Under the loading conditions TFC + IT and TFC + IT + AF + VM, osteotomy did not significantly change ACL force or ATT at any flexion angle. Conclusion: In general, osteotomy lowered ACL force and reduced ATT when IT was not present. The benefits of osteotomy were negated when IT was included possibly because the dominant mechanism of ACL force generation was cruciate impingement from internal winding and not ATT. Clinical Relevance: PTS-reducing osteotomy significantly decreased ACL force and reduced ATT for knee loads that did not include IT.
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Filippov, Gleb S., Konstantin A. Shalyukhin, Gagik V. Rashoyan, Viktor A. Glazunov, Sergey A. Skvortsov und Alexandr K. Aleshin. „PARALLEL MANIPULATOR MECHANISM FOR USE IN ROBOTIC SURGERY“. Technologies & Quality 51, Nr. 1 (29.04.2021): 46–51. http://dx.doi.org/10.34216/2587-6147-2021-1-51-46-51.
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The article examines the mechanisms of parallel and parallel-sequential structure, including specific translational-guides, flat, spherical mechanisms of a parallel structure with three degrees of freedom, modifications of Delta robots from various manufacturers. The most famous studies of robots of parallel-serial structure are presented. Mazor Renaissance and Mazor X robotic systems for robotic assistance during spinal surgery are examined. The method of synthesis of mechanisms of parallel-serial structure with five degrees of freedom is briefly presented. Examples of synthesised schemes of mechanisms and three-dimensional schemes, synthesised using in the computer-aided design system Compass 3D, are given. A diagram of a mechanism of a parallel-sequential structure with five degrees of freedom for robotic assistance during minimally invasive operations, which can be used as an alternative to the da Vinci Surgical System Platform, is examined. An example of modelling the solution of the inverse problem of positions, direct and inverse problems of velocities and direct and inverse dynamic problems in the Mathcad system, the result of modelling the motion of the output link in various initial conditions is given. The results of experimental studies using a prototype mechanism are shown.
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Zhang, Dan, und Bin Wei. „Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism“. Measurement Science Review 17, Nr. 2 (01.04.2017): 83–92. http://dx.doi.org/10.1515/msr-2017-0011.
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Abstract The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism are studied and optimized. The stiffness of the robotic system in every single moveable direction is measured and analyzed, and it is observed that in the case where one tries to make the x and y translational stiffness larger, the z directional stiffness will be reduced, i.e. the x and y translational stiffness contradicts with the one in z direction. Subsequently, the objective functions for the summation of the x and y translational stiffness and z directional stiffness are established and they are being optimized simultaneously. However, we later found that these two objectives are not in the same scale; a normalization of the objectives is thus taken into consideration. Meanwhile, the robotic system’s workspace is studied and optimized. Through comparing the stiffness landscape and the workspace volume landscape, it is also observed that the z translational stiffness shows the same changing tendency with the workspace volume’s changing tendency while the x and y translational stiffness shows the opposite changing tendency compared to the workspace volume’s. Via employing the Pareto front theory and differential evolution, the summation of the x and y translational stiffness and the volume of the workspace are being simultaneously optimized. Finally, the mechanism is employed to synthesize an exercise-walking machine for stroke patients.
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Nguyen, Tong Thien, Hieu Thi Hong Le und Hien Thi Ngoc Nguyen. „2-D AERODYNAMIC MODEL OF INSECT FLYING MECHANISM FOR ROBOTIC APPLICATION“. Science and Technology Development Journal 12, Nr. 14 (15.08.2009): 95–107. http://dx.doi.org/10.32508/stdj.v12i14.2344.
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Two-dimensional aerodynamic models of unsteady flapping wing motions are analyzed with focus on advanced rotation and the wing's rotation axis to explain the force peak at the end of each half stroke. In this model, the translational velocity of the wing along the stroke plane is constant for most of the time except near end and the beginning of each stroke where it slows down to zero and then speeds up again for the next stroke. The flapping wing motions with various combination of controlled translational and rotational velocity of the wings along horizontal or inclined stroke planes with straight-line trajectory are investigated numerically through two-dimensional Navier-Stokes solutions. CFD programs based on Finite Volume Method are used to simulate the flow around a thin airfoil in combined translational and rotational motions. The simulation provides the flow patterns, pressure fields from which the aerodynamic forces and moments are obtained.
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Enescu, Monica Loredana, und Cătălin Alexandru. „Modeling and Simulation of A 6 Dof Robot“. Advanced Materials Research 463-464 (Februar 2012): 1116–19. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.1116.
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The purpose of this paper is to model and simulate a 6 DOF robotic system with revolute joints. This is in order to optimize the motion law which results in uniform coating deposited by spray pyrolysis. The structure and the complexity of the robotic system are determined by the necessary movements in the spray pyrolysis process. The nozzle (end-effector of the robot manipulator) has two translations, in longitudinal and transversal direction relative to the surface deposition. The mechanical model of the robot mechanism was developed by using the MBS (Multi Body Systems) environment ADAMS of MSC Software.
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Xie, Fugui, Xin-Jun Liu und Tiemin Li. „Type Synthesis and Typical Application of 1T2R-Type Parallel Robotic Mechanisms“. Mathematical Problems in Engineering 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/206181.
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This paper focuses on the 1T2R-type (T: translational DOF; R: rotational DOF) parallel robotic mechanisms (PKMs) and discusses their type synthesis and typical application in five-axis machine tools. Based on Grassmann line geometry and atlas method, a systematic method dealing with the type synthesis of lower mobility PKMs is introduced. The Blanding rules and generalized Blanding rules, which are the criterions in realizing the mutual conversion between the freedom-space atlas and the constraint-space atlas, are summarized and discussed in detail. Thereafter, the entire procedure of the type synthesis is presented, and the type synthesis of 1T2R PKMs is carried out. Based on the synthesis results, a five-axis hybrid mechanism is proposed and a machine tool is developed consequently. The type synthesis method presented in this paper is intuitive and concise and can be used in the type synthesis of other lower mobility PKMs.
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Fujie, Hiromichi, Takeshi Sekito und Akiyuki Orita. „A Novel Robotic System for Joint Biomechanical Tests: Application to the Human Knee Joint“. Journal of Biomechanical Engineering 126, Nr. 1 (01.02.2004): 54–61. http://dx.doi.org/10.1115/1.1644567.
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The objectives of the work reported in this article were to develop a novel 6-degree-of-freedom (DOF) robotic system for knee joint biomechanics, to complete a hybrid force-position control scheme, to evaluate the system performance, and to demonstrate a combined loading test. The manipulator of the system utilizes two mechanisms; the upper mechanism has two translational axes and three rotational axes while the lower mechanism has only a single translational axis. All axes were driven with AC servo-motors. This unique configuration results in a simple kinematic description of manipulator motion. Jacobian transformation was used to calculate both the displacement and force/moment, which allowed for a hybrid control of the displacement of, and force/moment applied to, the human knee joint. The control and data acquisition were performed on a personal computer in the C-language programming environment with a multi-tasking operating system. Preliminary tests revealed that the clamp-to-clamp compliance of the system was smaller in the vertical (Z) and longitudinal (Y) directions (0.001 mm/N) than in lateral (X) direction (0.003 mm/N). The displacement error under the application of 500 N of load was smallest in the vertical direction (0.001±0.003 mm (mean±SD), and largest in the lateral direction (0.084±0.027 mm). Using this test system, it was possible to simulate multiple loading conditions in a human knee joint in which a cyclic anterior force was applied together with a coupled, joint compressive force, while allowing natural knee motion. The developed system seems to be a useful tool for studies of knee joint biomechanics.
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Chen, Z. H., Y. B. Zhang und K. M. Wang. „Design and Analysis of a Novel Planar Translational Parallel Robotic Mechanism with Three Limbs“. IOP Conference Series: Materials Science and Engineering 646 (17.10.2019): 012004. http://dx.doi.org/10.1088/1757-899x/646/1/012004.
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Guo, Lei, Zeyu Wang, Yuan Song, Xianjie Shan und Dongming Gan. „Structural optimization of a new type of lever-assisted gear reducer based on a genetic algorithm“. Mechanical Sciences 12, Nr. 1 (26.03.2021): 333–43. http://dx.doi.org/10.5194/ms-12-333-2021.
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Abstract. Gear reducers are critical for speed and torque transmissions between motors and manipulators. With the development of robotic research, many new requirements, such as low speed and heavy load, have been proposed for the design of gear reducers used in the joints. To meet these challenges, here, we present the design of a new gear reducer based on a spherical motion sub-lever drive mechanism. Our lever-based gear reducer can transmit the speed and torque from the input shaft to the output shaft through a fixed-axis gear train transmission, lever transmission, and internal translational gear transmission. Compared with traditional gear reducers, our lever-based reducer has stronger load capacities and is suitable for low-speed and heavy-load scenarios. The design parameters of the lever drive mechanism were optimized via finite element analysis and a genetic algorithm, and the assembly of the lever drive mechanism was further simplified. We found the dimensions of the lever are critical for improving the overall performance of this reducer. In addition, the transmission ability of this reducer was demonstrated by a physical prototype. This reducer will find many applications in robotic joints, cranes, and mine hoists.
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Srivastava, MV Padma. „Restorative Therapies after Stroke: Drugs, Devices and Robotics“. Annals of the National Academy of Medical Sciences (India) 53, Nr. 01 (Januar 2017): 051–65. http://dx.doi.org/10.1055/s-0040-1712745.
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ABSTRACTRestorative therapies aim to improve outcome and function by promoting plasticity within a therapeutic time window between days to weeks to years. In this article, the mechanisms by which cell-based, pharmacological and robotic treatments stimulate endogenous brain remodelling after stroke, particularly neurogenesis, axonal plasticity and white-matter integrity are described with a brief outline of the potential of neuroimaging (fMRI) techniques. Stem cells aid stroke recovery via mechanisms depending on the type of cells used. Transplanted embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and neural stem cells (NSCs) can replace the missing brain cells in the Infarcted area, while adult stem cells, such as mesenchymal stem cells or multipotent stromal cells (MSCs) and MNCs, provide trophic support to enhance self-repair systems such as endogenous neurogenesis. Most preclinical studies of stem cell therapy for stroke have emphasized the need to enhance self-repair systems rather than to replace lost cells, regardless of the type of cells used. Noninvasive brain stimulation (NIBS) provides a valuable tool for interventional neurophysiology by modulating brain activity in a specific distributed, cortico-subcortical network. The two most commonly used techniques for noninvasive brain stimulation are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). The article also discusses the potential role and current evidence for the use of pharmacological therapy, robotics and specific forms of physiotherapy regimes in optimizing stroke recovery. Neurorestoration is a concept that has been proven emphatically in several experimental models and clinical studies of stroke. Elucidating the underlying mechanisms of cell-based, pharmacological and rehabilitative therapies is of primary interest and crucial for translation of treatments to clinical use. The knowledge must provide an impetus for the development of superior, advanced and cost effective neuro restorative interventions that will enhance stroke recovery.
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Afschrift, Maarten, Friedl De Groote und Ilse Jonkers. „Similar sensorimotor transformations control balance during standing and walking“. PLOS Computational Biology 17, Nr. 6 (25.06.2021): e1008369. http://dx.doi.org/10.1371/journal.pcbi.1008369.
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Standing and walking balance control in humans relies on the transformation of sensory information to motor commands that drive muscles. Here, we evaluated whether sensorimotor transformations underlying walking balance control can be described by task-level center of mass kinematics feedback similar to standing balance control. We found that delayed linear feedback of center of mass position and velocity, but not delayed linear feedback from ankle angles and angular velocities, can explain reactive ankle muscle activity and joint moments in response to perturbations of walking across protocols (discrete and continuous platform translations and discrete pelvis pushes). Feedback gains were modulated during the gait cycle and decreased with walking speed. Our results thus suggest that similar task-level variables, i.e. center of mass position and velocity, are controlled across standing and walking but that feedback gains are modulated during gait to accommodate changes in body configuration during the gait cycle and in stability with walking speed. These findings have important implications for modelling the neuromechanics of human balance control and for biomimetic control of wearable robotic devices. The feedback mechanisms we identified can be used to extend the current neuromechanical models that lack balance control mechanisms for the ankle joint. When using these models in the control of wearable robotic devices, we believe that this will facilitate shared control of balance between the user and the robotic device.
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Chung, Y. S., M. Griffis und J. Duffy. „Repeatable Joint Displacement Generation for Redundant Robotic Systems“. Journal of Mechanical Design 116, Nr. 1 (01.03.1994): 11–16. http://dx.doi.org/10.1115/1.2919335.
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This paper presents a novel, practical, and theoretically sound kinematic control strategy for serial redundant manipulators. This strategy yields repeatability in the joint space of a serial redundant manipulator whose end effector undergoes some general cyclic type motion. This is accomplished by deriving a new inverse kinematic equation that is based on springs being theoretically or conceptually located in the joints of the manipulator (torsional springs for revolute joints, translational springs for prismatic joints). Previous researchers have also derived an inverse kinematic equation for serial redundant manipulators. However, to the authors’ knowledge, the new strategy is the first to include the free angles of torsional springs and the free lengths of translational springs. This is important because it ensures the repeatability in the joint space of a serial redundant manipulator whose end effector undergoes a cyclic type motion. Numerical verification for repeatability is done in terms of Lie bracket condition. Choices for the free angle and torsional stiffness of a joint (or the free length and translational stiffness) are made based upon the mechanical limits of the joint.
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Zhou, Dongbo, Kotaro Tadano und Daisuke Haraguchi. „Motion Control and External Force Estimation of a Pneumatically Driven Multi-DOF Robotic Forceps“. Applied Sciences 10, Nr. 11 (26.05.2020): 3679. http://dx.doi.org/10.3390/app10113679.
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Robotic forceps with a rigid-link joint mechanism is orthodox for current robotic-assisted surgery systems. However, external force estimation without force sensors during operations is difficult for such electrically driven forceps. This work introduces a pneumatically driven multi-DOF (DOF: degree of freedom) forceps using a rigid-link mechanism with less interference of the wire drive between joints and realizes external force estimation by utilizing high back-drivability of pneumatic cylinders. We developed a position controller with dynamic compensation of the mechanical friction, in which the rotational angles of the three movable joints of the forceps are independently controlled. Moreover, we designed an external force observer in the position controller by applying the disturbance observer scheme. The results of the performance evaluation experiments are as follows. First, in the joint position control experiments, smooth and stable controllability is confirmed for sinusoidal reference inputs with the mean absolute errors of less than 2°. The resolution of the joint position control is approximately 1° for the response of step increasing reference inputs, which is acceptable for laparoscopic surgery. Second, the external force observer can correctly estimate the translational and the grasping forces with less than 20% errors of the maximum output forces. The practical sensitivities of the external force estimation are better than 0.5 N for translational forces and 0.2 N for grasping forces. The achieved performance of the developed forceps can be applicable for interactive force control in some particular surgical tasks such as suturing, ligation, organ traction and exclusion.
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Nagai, Takashi, Hiroshi Yokoi und Yukinori Kakazu. „SMA-Net: A Deformable Morphology Robot Using Shape Memory Alloy“. Journal of Robotics and Mechatronics 14, Nr. 3 (20.06.2002): 290–97. http://dx.doi.org/10.20965/jrm.2002.p0290.
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Deformation of morphology is one goal of advanced robotics design research. This study started from a project of the development of a morph-functional machine, where the developmental study of a deformable robot which can behave like an ameba, is one of the main topics. This paper proposes the prototype design of a deformable morphology robot based on the lattice structure of elastic elements, shape memory alloy springs. The proposed structure of SMA-Net has both passively deformable functionality and active deformability. The functions of deformability of SMA-Net give new concepts of robotics design. However, it becomes difficult to control overall behavior because of the large degrees of freedom of the structure, external force comes into passive deformation and it makes change of physical property of motion control, and the relation between elements of robot yield nonlinear dynamics. Therefore, as first step for control, we investigated the movement mechanism of the robot. The proposed control method is periodic ON/OFF control, system parameters of SMA-Net are explored to find the resonance phase of the whole structure. Experiments show basic deformations of SMA-Net and the motion of translation and rotation.
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Staicu, Stefan. „Recursive modelling in dynamics of Delta parallel robot“. Robotica 27, Nr. 2 (März 2009): 199–207. http://dx.doi.org/10.1017/s0263574708004451.
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SUMMARYRecursive matrix relations in kinematics and dynamics of a Delta parallel robot having three revolute actuators are established in this paper. The prototype of the manipulator is a three degrees-of-freedom space mechanism, which consists of a system of parallel closed kinematical chains connecting to the moving platform. Knowing the translation motion of the platform, we develop first the inverse kinematics problem and determine the position, velocity and acceleration of each robot's element. Further, the inverse dynamic problem is solved using an approach based on the fundamental principle of virtual work. Finally, a comparative study on time-history evolution of the torques of the three actuators is analysed.
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Yan, Liang, Lei Zhang, Nan Yao, Zong Xia Jiao, I. Ming Chen und Chin Yin Chen. „Design and Analysis of Tubular Linear Machines with Dual Halbach Arrays“. Applied Mechanics and Materials 284-287 (Januar 2013): 667–71. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.667.
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Linear machines are widely employed in robotics, transportation and manufacturing industries because complex rotation-to-translation conversion mechanism is no longer required. This paper proposed a novel tubular linear machine with dual permanent magnet (PM) Halbach arrays to achieve high force output performance. Based on Lorentz force law, the magnetic force output and force ripple for three-phase winding linear machine is formulated in analytical way. By taking advantage of the analytical models, the force output is simulated with respect to the motion of the mover. Numerical result is then obtained to validate the analytical force models. In addition, based on the technology of non-dimensionalization, the mathematical force models are employed to analyze the influence among the structure parameters on the force output and force ripple for design purpose of the tubular linear machines. The study in this paper could contribute to the design analysis and optimization of electromagnetic linear machines with similar poles patterns.
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Xiong, Shaoping, Gabriel Wilfong und John Lumkes. „Development of a novel high-speed actuation mechanism using a magneto-rheological fluid clutch and its application to a fluid control valve“. Journal of Intelligent Material Systems and Structures 30, Nr. 16 (28.07.2019): 2502–16. http://dx.doi.org/10.1177/1045389x19862368.
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In many dynamic systems, such as vehicles, engine air and fuel control systems, fluid power systems, industrial robotics, and testing machines, high-speed actuators are necessary to achieve efficient system operation and high bandwidth performance. This article introduces a new actuation mechanism to enable high-speed actuation. The premise for this actuation mechanism is to momentarily couple a moving component (kinetic energy source) with translational components, which is enabled by a coupling/clutch system. The kinetic energy source (flywheel, electric motor, pump or motor shaft, etc.) is intermittently clutched and declutched to produce linear motion. This article presents such an energy coupler actuator using a magneto-rheological fluid clutch, initially focused on an application for high-speed valve actuation. A multi-physics coupled model was developed to evaluate the proposed energy coupler actuator performance. Simulations were conducted to optimize the energy coupler actuator design parameters. A prototype of the magneto-rheological fluid energy coupler actuator based on the optimal design solution was fabricated and experimentally tested, which achieved 1.6-mm stroke in 4.7 ms.
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Minsch, Niklas, Matthias Müller, Thomas Gereke, Andreas Nocke und Chokri Cherif. „3D truss structures with coreless 3D filament winding technology“. Journal of Composite Materials 53, Nr. 15 (19.12.2018): 2077–89. http://dx.doi.org/10.1177/0021998318820583.
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A coreless manufacturing process for generic 3D rigid frame topologies will be introduced in this paper. The aim is to extend the field of filament winding from mainly 2D-shells and some exceptional cases of 3D rigid frames. This manufacturing process employs a coreless translation cross-winding method in order to continuously deposit a roving around deflection points in space. On this basis, a design methodology is being created and deductively verified by designing a beam for a three-point bending load case. The composite beam is designed on a macro level simulation approach to match the stiffness of a reference aluminum profile, which is commonly employed as structural component for robotic gripper systems in automotive assemblies. The performance of the beams is subsequently compared by three-point bending experiments. This demonstrates that the composite beam offers equivalent stiffness and strength properties with a weight-reduction potential of nearly 50% for bending loads.
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Matsusaka, Yosuke, Hiroyuki Fujii und Isao Hara. „An Extensible Dialogue Script for a Robot Based on Unification of State-Transition Models“. Journal of Robotics 2010 (2010): 1–14. http://dx.doi.org/10.1155/2010/301923.
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We propose extension-by-unification method to improve reusability of the dialogue components in the development of communication function of the robot. Compared to previous extension-by-connection method used in behavior-based communication robot developments, the extension-by-unification method has the ability to decompose the script into components. The decomposed components can be recomposed to build a new application easily. In this paper, first we, explain a reformulation we have applied to the conventional state-transition model. Second, we explain a set of algorithms to decompose, recompose, and detect the conflict of each component. Third, we explain a dialogue engine and a script management server we have developed. The script management server has a function to propose reusable components to the developer in real time by implementing the conflict detection algorithm. The dialogue engine SEAT (Speech Event-Action Translator) has flexible adapter mechanism to enable quick integration to robotic systems. We have confirmed that by the application of three robots, development efficiency has improved by 30%.
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Chen, S. F., J. H. Oliver und D. Fernandez-Baca. „A Fast Algorithm for Planning Collision-Free Paths With Rotations“. Journal of Mechanical Design 120, Nr. 1 (01.03.1998): 52–57. http://dx.doi.org/10.1115/1.2826676.
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Motion planning is a major problem in robotics. The objective is to plan a collision-free path for a robot moving through a workspace populated with obstacles. In this paper, we present a fast and practical algorithm for moving a convex polygonal robot among a set of polygonal obstacles with translations and rotations. The running time is O(c((n + k)N + n log n)), where c is a parameter controlling the precision of the results, n is the total number of obstacle vertices, k is the number of intersections of configuration space obstacles, and N is the number of obstacles, decomposed into convex objects. This work builds upon the slabbing method proposed by Ahrikencheikh et al. [2], which finds an optimal motion for a point among a set of nonoverlapping obstacles. Here, we extend the slabbing method to the motion planning of a convex polygonal robot with translations and rotations, which also allows overlapping configuration space obstacles. This algorithm has been fully implemented and the experimental results show that it is more robust and faster than other approaches.
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Eliseev, S. V., A. S. Mironov und Quang Truc Vuong. „Dynamic damping under introduction of additional couplings and external actions“. Vestnik of Don State Technical University 19, Nr. 1 (01.04.2019): 38–44. http://dx.doi.org/10.23947/1992-5980-2019-19-1-38-44.
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Introduction.The dynamic interaction features in mechanical oscillating systems, whose structure includes additional couplings, are considered. In practice, such cases occur when using various optional mechanisms and motion translation devices under the formation of technical objects. The study objective is to develop a method for constructing mathematical models in the problems of dynamics of the mechanical oscillating systems with optional devices and features in the system of external disturbing factors.Materials and Methods. The techniques used to study properties of the systems and the dynamic effects are based on the ideas of structural mathematical modeling. It is believed that the mechanical oscillating system, considered as a design model of a technical object, can be compared to the dynamically equivalent automatic control system. The mathematical apparatus of the automatic control theory is used.Research Results.A method for constructing mathematical models is developed. The essential analytical relations for plotting oscillating systems are obtained, which enable to form a methodological basis for the integral estimation and comparative analysis of the initial system properties in various dynamic states. Dynamic properties of the two-degree-offreedom systems within the framework of the computer simulation are investigated. The implementability of dynamic oscillation damping mode simultaneously in two coordinates with the joint action of two in-phase kinematic perturbations in the mechanical oscillating systems is shown.Discussion and Conclusions.The possibilities of new dynamic effects, which are associated with the change in the system structure under certain forms of dynamic interactions, are noted. The study is of interest to experts in machine dynamics, robotics, mechatronics, nano and mesomechanics.
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Le, Anh Vu, Rizuwana Parween, Rajesh Elara Mohan, Nguyen Huu Khanh Nhan und Raihan Enjikalayil Abdulkader. „Optimization Complete Area Coverage by Reconfigurable hTrihex Tiling Robot“. Sensors 20, Nr. 11 (03.06.2020): 3170. http://dx.doi.org/10.3390/s20113170.
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Completed area coverage planning (CACP) plays an essential role in various fields of robotics, such as area exploration, search, rescue, security, cleaning, and maintenance. Tiling robots with the ability to change their shape is a feasible solution to enhance the ability to cover predefined map areas with flexible sizes and to access the narrow space constraints. By dividing the map into sub-areas with the same size as the changeable robot shapes, the robot can plan the optimal movement to predetermined locations, transform its morphologies to cover the specific area, and ensure that the map is completely covered. The optimal navigation planning problem, including the least changing shape, shortest travel distance, and the lowest travel time while ensuring complete coverage of the map area, are solved in this paper. To this end, we propose the CACP framework for a tiling robot called hTrihex with three honeycomb shape modules. The robot can shift its shape into three different morphologies ensuring coverage of the map with a predetermined size. However, the ability to change shape also raises the complexity issues of the moving mechanisms. Therefore, the process of optimizing trajectories of the complete coverage is modeled according to the Traveling Salesman Problem (TSP) problem and solved by evolutionary approaches Genetic Algorithm (GA) and Ant Colony Optimization (ACO). Hence, the costweight to clear a pair of waypoints in the TSP is defined as the required energy shift the robot between the two locations. This energy corresponds to the three operating processes of the hTrihex robot: transformation, translation, and orientation correction. The CACP framework is verified both in the simulation environment and in the real environment. From the experimental results, proposed CACP capable of generating the Pareto-optimal outcome that navigates the robot from the goal to destination in various workspaces, and the algorithm could be adopted to other tiling robot platforms with multiple configurations.
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Ito, Koji, Yoji Yamada, Tadashi Onishi, Shiro Oda, Susumu Hara und Shogo Okamoto. „2A1-A04 Proposal of A Test Method Using A Lower-Limb Dummy for Human Wearable Robot Safety : 1^ Report: Proposal of A Lower-Limb Dummy with A Mechanism of 1 Translation Motion in Conjunction with Knee-Joint Rotation(Robotics with Safety and Reliability)“. Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2011 (2011): _2A1—A04_1—_2A1—A04_4. http://dx.doi.org/10.1299/jsmermd.2011._2a1-a04_1.
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Yoshida, Sho, Takahiro Kanno und Kenji Kawashima. „Surgical Robot With Variable Remote Center of Motion Mechanism Using Flexible Structure“. Journal of Mechanisms and Robotics 10, Nr. 3 (05.04.2018). http://dx.doi.org/10.1115/1.4039396.
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Remote center of motion (RCM) mechanisms are often used in surgical robots for laparoscopic surgery. In this paper, a RCM mechanism for holding a robotic forceps that facilitates adjustment using a flexible structure is proposed. The flexible structure is designed and manufactured with polypropylene-like resin material using a three-dimensional (3D) printer. Super elastic NI-Ti rods are inserted in the structure to have elasticity for bending and have rigidity for twisting. The structure achieves pitch motion around the remote center with two pneumatic cylinders. One cylinder drives the position and the other cylinder controls the bending radius of the structure. Therefore, the location of the remote center can be variable. This allows easier adjustment of the remote center before or during operation. The holder robot including the mechanism has four degrees-of-freedom (DOFs) in total, consisting of the pitch, a rotation around yaw axis, a translation in the direction of forceps insertion and a rotation of the forceps. Pneumatic rotary actuators are used for rotations and a cylinder is used for the translational motion. The model of the flexible structure is derived experimentally to design a controller for the pitch motion. A pneumatically driven robotic forceps is mounted on the holder to construct a master–slave control system. Experimental results show that the proposed control law achieves the desired rotational pitch motion. We compare the holder with a rigid link RCM holder and confirm the robustness of the proposed holder for variable remote center. Finally, the effectiveness of the system is confirmed with suturing tasks using a phantom tissue.
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Zhang, Xiaoli, und Carl A. Nelson. „Kinematic Analysis and Optimization of a Novel Robot for Surgical Tool Manipulation“. Journal of Medical Devices 2, Nr. 2 (14.05.2008). http://dx.doi.org/10.1115/1.2918740.
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The size and limited dexterity of current surgical robotic systems are factors that limit their usefulness. To improve the level of assimilation of surgical robots in minimally invasive surgery (MIS), a compact, lightweight surgical robotic positioning mechanism with four degrees of freedom (DOFs) (three rotational DOFs and one translation DOF) is proposed in this paper. This spatial mechanism based on a bevel-gear wrist is remotely driven with three rotation axes intersecting at a remote rotation center (the MIS entry port). Forward and inverse kinematics are derived, and these are used for optimizing the mechanism structure given workspace requirements. By evaluating different spherical geared configurations with various link angles and pitch angles, an optimal design is achieved, which performs surgical tool positioning throughout the desired kinematic workspace while occupying a small space bounded by a hemisphere of radius 13.7cm. This optimized workspace conservatively accounts for collision avoidance between the patient and robot or internally between the robot links. This resultant mechanism is highly compact and yet has the dexterity to cover the extended workspace typically required in telesurgery. It can also be used for tool tracking and skills assessment. Due to the linear nature of the gearing relationships, it may also be well suited for implementing force feedback for telesurgery.
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Li, Jianmin, Yuan Xing, Ke Liang und Shuxin Wang. „Kinematic Design of a Novel Spatial Remote Center-of-Motion Mechanism for Minimally Invasive Surgical Robot“. Journal of Medical Devices 9, Nr. 1 (01.03.2015). http://dx.doi.org/10.1115/1.4028651.
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To deliver more value to the healthcare industry, a specialized surgical robot is needed in the minimally invasive surgery (MIS) field. To fill this need, a compact hybrid robotic wrist with four degrees of freedom (DOFs) is developed for assisting physicians to perform MIS. The main body of the wrist is a 2DOF parallel mechanism with a remote center-of-motion (RCM), which is located outside the mechanism. From the mechanical point of view, it is different from existing 2DOF spherical mechanisms, since there is no physical constraint on the RCM. Other DOFs of the wrist are realized by a revolute joint and a prismatic joint, which are serially mounted on the movable platform of the parallel mechanism. The function of these DOFs is to realize the roll motion and the in-out translation of the surgical tool. Special attention is paid to the parallel RCM mechanism. The detailed design is provided and the kinematic equations are obtained in the paper. Further, the Jacobian matrix is derived based on the kinematic equations. Finally, the paper examines the singularity configurations and implements the condition number analysis to identify the kinematic performance of the mechanism.
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Das, Jadav, D. Caleb Rucker und Robert J. Webster. „A Testbed for Multilumen Steerable Needle Experiments“. Journal of Medical Devices 4, Nr. 2 (01.06.2010). http://dx.doi.org/10.1115/1.3443751.
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Steerable needles offer the potential to turn corners during insertion, thereby avoiding obstacles, reducing tip placement error and enabling a less invasive access to challenging anatomical locations. In this paper, we describe an experimental testbed designed to facilitate experiments with several popular steering mechanisms. One such mechanism makes use of asymmetric forces generated by a bevel tip for actuating steerable needles, and another uses multiple concentric precurved tubes that can change the needle shaft shape by rotating within one another and extending telescopically. The experimental testbed consists of a new robotic actuation unit for controlling axial rotation and linear translation of multiple tubes. It also includes stereo-optical cameras and a magnetic tracking system for the feedback of needle shape and tip location. The setup can be used in future work for model validation and closed-loop feedback control of steerable needles and cannulae.
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Cao, Wen-ao, Huafeng Ding und Donghao Yang. „A Method for Compliance Modeling of Five Degree-of-Freedom Overconstrained Parallel Robotic Mechanisms With 3T2R Output Motion“. Journal of Mechanisms and Robotics 9, Nr. 1 (22.12.2016). http://dx.doi.org/10.1115/1.4035270.
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This paper presents an approach to compliance modeling of three-translation and two-rotation (3T2R) overconstrained parallel manipulators, especially for those with multilink and multijoint limbs. The expressions of applied wrenches (forces/torques) exerted on joints are solved with few static equilibrium equations based on screw theory. A systematic method is proposed for deriving the stiffness model of a limb with considering the couplings between the stiffness along the constrained wrench and the one along the actuated wrench based on strain energy analysis. The compliance model of a 3T2R overconstrained parallel mechanism is established based on stiffness models of limbs and the static equilibrium equation of the moving platform. Comparisons show that the compliance matrix obtained from the method is close to the one obtained from a finite-element analysis (FEA) model. The proposed method has the characteristics of involving low computational efforts and considering stiffness couplings of each limb.
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Saab, Wael, und Pinhas Ben-Tzvi. „A Genderless Coupling Mechanism With Six-Degrees-of-Freedom Misalignment Capability for Modular Self-Reconfigurable Robots“. Journal of Mechanisms and Robotics 8, Nr. 6 (09.09.2016). http://dx.doi.org/10.1115/1.4034014.
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Abstract This paper presents the design and integration of a genderless coupling mechanism for modular self-reconfigurable mobile robots. Modular self-reconfigurable mobile robotic systems consist of a number of self-sufficient modules that interconnect via coupling mechanisms and adopt different configurations to modify locomotion and/or manipulation capabilities. Coupling mechanisms are a critical element of these robotic systems. This paper focuses on a docking mechanism called GHEFT: a Genderless, High-strength, Efficient, Fail-safe, and high misalignment Tolerant coupling mechanism that aids self-reconfiguration. GHEFT provides a high strength and energy efficient connection using nonback drivable actuation with optimized clamping profiles that tolerate translational and angular misalignments. It also enables engagement/disengagement without gender restrictions in the presence of one-sided malfunction. The detailed design of the proposed mechanism is presented, including optimization of the clamping profile geometries. Experimental validation of misalignment tolerances and achievable clamping forces and torques is performed to demonstrate the strength, efficiency, and fail-safe capabilities of the proposed mechanism, and these results are compared to reported results of some of the existing coupling mechanisms.
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Chen, Samuel, und Marc Arsenault. „Analytical Computation of the Actuator and Cartesian Workspace Boundaries for a Planar 2-Degree-of-Freedom Translational Tensegrity Mechanism“. Journal of Mechanisms and Robotics 4, Nr. 1 (01.02.2012). http://dx.doi.org/10.1115/1.4005335.
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Tensegrity mechanisms are interesting candidates for high-acceleration robotic applications since their use of cables allows for a reduction in the weight and inertia of their mobile parts. In this work, a planar two-degree-of-freedom translational tensegrity mechanism that could be used for pick and place applications is introduced. The mechanism uses a strategic actuation scheme to generate the translational motion as well as to ensure that the cables remain taut at all times. Analytical solutions to the direct and inverse kinematic problems are developed, and the mechanism’s workspace boundaries are computed in both the actuator and Cartesian spaces. The influence of the mechanism’s geometry on the size and shape of the Cartesian workspace are then studied. Based on workspace size only, it is found that the optimal mechanism geometry corresponds to a relatively large ratio between the length of the struts and the width of the base and end-effector.
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Wang, Xu, und Weizhong Guo. „Chasles' Motion Sphere—A Useful Tool to Visually Express the Motion Characteristics Over the Workspace of Robotic Mechanisms“. Journal of Mechanisms and Robotics 12, Nr. 4 (06.03.2020). http://dx.doi.org/10.1115/1.4045849.
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Abstract This paper presents a useful concept/tool, i.e., Chasles' motion sphere (CMSphere), that is able to visually express the motion characteristics over the workspace and capable of investigating the local motion performance of the end-effector of robotic mechanisms. The process of CMSphere generation is in line with people's habit of observing a mechanism. Under a researched pose, give a small pose change to the end-effector by translating with a small length or rotating with a small angle along a direction, then the corresponding Chasles' motion of the small pose change can be calculated. Two key parameters of Chasles' motion, the pitch and the position of the Chasles' axis, are chosen to represent the motion characteristics. This kind of mathematical operation can be carried along many directions to obtain a distribution of the motion characteristics at the researched pose, which can be drawn as a sphere. To illustrate this tool, Robotic Mechanisms with Three Independent Pose Variables (RMTIPVs) are discussed as the research objects. Three categories of RMTIPVs based on the types of independent pose variables are given. For each category, the detailed process of CMSphere generation is discussed. The 3R series mechanism, Tricept, and 3-RPS (the limb consisting of one revolute, one prismatic and one spherical joints) parallel mechanism are used as examples to demonstrate the methodology.
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Acer Kalafat, Merve, Hasan Sevinc, Shahrad Samankan, Atakan Altinkaynak und Zeynep Temel. „A Novel Origami Inspired Delta Mechanism with Flat Parallelogram Joints“. Journal of Mechanisms and Robotics, 29.10.2020, 1–22. http://dx.doi.org/10.1115/1.4048917.
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Abstract In robotics, origami-based design methodology can be used to create small scale parallel mechanisms with easier assembly processes. Delta mechanisms are one of the famous parallel mechanism used mostly in pick and place operations due to their capability to reach high speeds and accelerations. In this work, we present a novel Delta mechanism fabricated with fully 2D layer by layer methods. In our design we have eliminated manual 3D processes in order to provide parallel movement of the links. We have designed a new flat parallelogram providing pure translations in X-Y-Z directions respecting to the conventional kinematic models for Delta mechanism. The assembly process is reduced to an only cut – laminate – repeat steps which are very basic operations in 2D. The kinematic performance of the mechanism has been analyzed using a 6 DoF position sensor placed on the end-effector. The mechanism has a 20x20x20 mm3 cubic stable workspace with a 17.5 mm radius circular footprint when it is completely flat. The tests were done for circular trajectories having 10 mm radius circles with different heights and circles with different radiuses in a specific height. Despite having no feedback control from the end effector, the mechanism was able to follow the trajectory with 1.5 mm RMS precision. We have also changed the materials of the flexible layers in passive links and presented the trajectory results of the end-effector showing how it effects the kinematic performance of the mechanism.
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Yul Shin, Sung, Ashish D. Deshpande und James Sulzer. „Design of a Single Degree-of-Freedom, Adaptable Electromechanical Gait Trainer for People With Neurological Injury“. Journal of Mechanisms and Robotics 10, Nr. 4 (31.05.2018). http://dx.doi.org/10.1115/1.4039973.
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The cost of therapy is one of the most significant barriers to recovery after neurological injury. Robotic gait trainers move the legs through repetitive, natural motions imitating gait. Recent meta-analyses conclude that such training improves walking function in neurologically impaired individuals. While robotic gait trainers promise to reduce the physical burden on therapists and allow greater patient throughput, they are prohibitively costly. Our novel approach is to design a new single degree-of-freedom (DoF) robotic trainer that maintains the key advantages of the expensive trainers but with a simplified design to reduce cost. Our primary design challenge is translating the motion of a single actuator to an array of natural gait trajectories. We address this with an eight-link Jansen mechanism that matches a generalized gait trajectory. We then optimize the mechanism to match different trajectories through link length adjustment based on nine different gait patterns obtained from gait database of 113 healthy individuals. To physically validate the range in gait patterns produced by the simulation, we tested kinematic accuracy on a motorized wooden proof-of-concept of the gait trainer. The simulation and experimental results suggested that an adjustment of two links can reasonably fit a wide range of gait patterns under typical within-subject variance. We conclude that this design could provide the basis for a low-cost, patient-based electromechanical gait trainer for neurorecovery.
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Alikhani, Alireza, Saeed Behzadipour, S. Ali Sadough Vanini und Aria Alasty. „Workspace Analysis of a Three DOF Cable-Driven Mechanism“. Journal of Mechanisms and Robotics 1, Nr. 4 (17.09.2009). http://dx.doi.org/10.1115/1.3204255.
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A cable-driven mechanism based on the idea of BetaBot (2005, “A New Cable-Based Parallel Robot With Three Degrees of Freedom,” Multibody Syst. Dyn., 13, pp. 371–383) is analyzed and geometrical description of its workspace boundary is found. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motions. The mechanism has potentials for large scale manipulation and robotics in harsh environments. A detailed analysis of the tensionable workspace of the mechanism is presented. The mechanism, in a tensionable position, can develop tensile forces in all cables to maintain its rigidity under arbitrary external loading. A set of conditions on the geometry of the mechanism is proposed for which the tensionable workspace becomes a well defined convex polyhedron. The geometrical shape of the workspace is then described and the tensionability of the mechanism inside the workspace is proved. The proof is quite general and based on a geometrical approach.
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Milenkovic, Paul. „Mobility of Multichain Platform Mechanisms Under Differential Displacement“. Journal of Mechanisms and Robotics 2, Nr. 3 (14.07.2010). http://dx.doi.org/10.1115/1.4001725.
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For a platform connected to its base through two chains forming a single loop, the instantaneous mobility may be expressed by a set of motion screws that is in the intersection of the sets of motion screws for each of the two chains. A recent work shows that the platform remains mobile after differential displacement along all mobile paths if the Lie closures of the screw sets of the two chains are each within the span of the union of screw sets of those chains. If this union span is one dimension short of containing the Lie closures of the two chains, a quadratic form determines whether the reference pose is at a constraint singularity and resolves the mobile paths at that singularity. Those results are now extended to a platform manipulator with more than two chains, using a recursive procedure for updating velocity, acceleration, and higher-order descriptions of platform mobility after adding successive chains. The new analytical technique characterizes the bifurcation of the mobility at constraint singularity of 3RSR, 3RER, and 3UPU platform mechanisms proposed for use in constant-velocity couplings, robotic wrists, and translational manipulators.
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R, Kumar. „Architecting and Tailoring of Cell Repair Molecular Machinery: Molecule-by-Molecule and Atom-by-Atom“. Austin Journal of Pharmacology and Therapeutics 9, Nr. 1 (12.02.2021). http://dx.doi.org/10.26420/austinjpharmacolther.2021.1128.
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In cell, any breakdown in cellular (metabolic and anabolic) process because of diseases or disorders, immediately effect functioning of cell and interrupt life, art of healing (medicine) repairs cell to regain its normal functioning as earlier it was. Adverse environmental conditions responsible for damage and exceed the maintenance time of repair in cell, or insufficient repair in functioning of metabolic pathways, leads apoptosis. The endoplasmic reticulum, ER, membrane allows molecules to be selectively processed and transferred inside and outside of the cell though double-layered nuclear envelope, with the help of a pipeline between the nucleus and the cytoplasm, as well as its close association with nucleus to have a check on ribosomal translation through, a several-step process, for maintaining cellular health. Consequently, to penetrate ER equipped with such highly specific qualities, there is need to architecture and tailor of such a refined and accurate healing procedure will work selectively, effectively and precisely: molecule-by-molecule and atomby-atom [1]. For the discovery of molecular machinery capable to do repair at cellular level, an engineered architecturing and well-designed tailoring methodology must applied strategically for such task by implementing research experiences of interdisciplinary areas i.e. Drug Design and Synthesis, Cell Transport Mechanism, Nanomedicine, Molecular Modeling, Computational (Chemistry, Nanotechnology, and Spectroscopy), Atmospheric Stress, Apoptotic Pathways and Mitochondrial Involvement, DNA Damage Pathway, Toxicology, and Clinical Pharmacology). Theoretically designed machines, nanorobots, are quite feasible and will perform with the ability of repair molecule-by-molecule or atom-by-atom in cells wherein metabolic proceedings are not proper by any means. Molecules have a size, a shape, a fairly well-defined surface, and mechanical properties with the quality of natural progression which are helpful in designing, architecting and tailoring of molecular machines as smart materials [2]. The use of highly specific characterization technologies i.e. computational spectroscopy, Single-molecule localization microscopy, atomic spectroscopy: molecular spectroscopy, absorption spectroscopy and emission spectroscopy will play a key role in architecturing and tailoring of molecular machinery [3]. In nature, such molecular machinery within the natural cells persist with capacity to repair damaged cell organelles, rebuilt it, formed new cell and reassembled them. With the deeper understanding of such natural systems, feasibility of new machinery may tested with urgent efforts for designing, architecting and tailoring such frameworks particularly with the capability to repairing cells as molecule-bymolecule or atom-by-atom as demanded by cell repair and matched with necessities. Our efforts will fruitful to design new avenues after the exploitation of all resources where architecting, tailoring and manufacturing of such nano-robots will possible practically [4]. By using interdisciplinary findings, it will be much easier task to sketch the outlines of such machinery with all the capabilities operate able as per the need at molecular level with prospect of understanding of mitochondrial dynamics as living things do [5]. Then, a perfect healing methodology, working decently through molecule-by-molecule or atom-by-atom, as cell repairing mechanism will be feasible, this newly discovered approach will lead to get a breakthrough as assumed and capable to do a half-decent job by taking reactive molecules or atoms, and bringing them up to a surface in a controlled way to perform, with the addition option of making a change in it whenever and wherever required. Molecular machines will be able to sense molecular level and decide, which cell needs repair or not featuring with surgical control by remotic or magnetic regulator, molecule-by-molecule and atom-by-atom, finally, it will be a histrionic and notable breakthrough in area of medicine discovery [6-10]. Designing, architecting and tailoring of molecular machinery, with the ability to distinguish between healthy and damaged cell, is need of hour having no repercussion and with capacity of targeting effected cells or sites only selectively, effectively and precisely, developed as nano-robots, will attain great degree of understanding for cell repair or to regulate metabolic processes perfectly with controlling and diagnostics ability in-built within nano-robotic machinery which will be able to cure any disease; do repair cell; regulate normal metabolic process; control biologically originated disturbances and defects originated by any environmental factors or as a result of transcriptional mechanisms. Curing, not just alleviating, disease has always been a difficult task by any ways; the tools required for diagnosis, and knowledge of medicine which may effectively implemented to repair the affected parts or a cell. Nano-robots if designed accurately can repair at cellular level and will revolutionize the field of medicine, this may become a reality in near future.
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Wang, Nianfeng, Chaoyu Cui, Bicheng Chen, Hao Guo und Xianmin Zhang. „Design of Translational and Rotational Bistable Actuators Based on Dielectric Elastomer“. Journal of Mechanisms and Robotics 11, Nr. 4 (17.05.2019). http://dx.doi.org/10.1115/1.4043602.
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Dielectric elastomer (DE), as a group of electro-active polymers, has been widely used in soft robotics due to its inherent flexibility and large induced deformation. As sustained high voltage is needed to maintain the deformation of DE, it may result in electric breakdown for a long-period actuation. Inspired by the bistable mechanism which has two stable equilibrium positions and can stay at one of them without energy consumption, two bistable dielectric elastomer actuators (DEAs) including a translational actuator and a rotational actuator are proposed. Both the bistable actuators consist of a double conical DEA and a buckling beam and can switch between two stable positions with voltage. In this paper, the analytical models of the bulking beam and the conical DEA are presented first, and then the design method is demonstrated in terms of force equilibrium and moment equilibrium principle. The experiments of the translational bistable DEA and the rotational bistable DEA are conducted, which show that the design method of the bistable DEA is effective.