Journal articles: 'Degrees-of-freedom actuator'

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YANO, Tomoaki. "Actuator with Multi Degrees of Freedom." Journal of The Institute of Electrical Engineers of Japan 127, no. 5 (2007): 294–96. http://dx.doi.org/10.1541/ieejjournal.127.294.

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Suzuki, Aya, and Minoru Hashimoto. "Development of a PVC Gel Actuator with a Particulate Structure." Journal of Robotics and Mechatronics 34, no. 2 (April 20, 2022): 273–75. http://dx.doi.org/10.20965/jrm.2022.p0273.

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Actuators are usually driven in a uniaxial direction, which limits their ability to be driven with multiple degrees of freedom. In this study, we propose an actuator that is not limited to a uniaxial direction. We developed a polyvinyl chloride gel actuator with a particulate structure. The actuator can change its surface shape by displacing each particle in the structure. As the first step in this experiment, each particle was displaced independently, by applying a voltage to the anode to change the actuator’s surface into an uneven shape.

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Safavi, Sahba, A. Selk Ghafari, and A. Meghdari. "Efficient Design of a Torque Actuator for Lower Extremity Exoskeleton Based on Muscle Function Analysis." Advanced Materials Research 328-330 (September 2011): 1041–44. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1041.

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Several lower extremity exoskeletal systems have been developed for augmentation purpose. Common actuators, have important drawbacks such as complexity, and poor torque capacities. The main scope of this research is to propose a series elastic actuator for lower extremity exoskeletal system which was designed based on muscle functional analysis. For this purpose, a biomechanical framework consisting of a musculoskeletal model with ten degrees-of-freedom actuated by eighteen Hill-type musculotendon actuators per leg is utilized to perform the muscle functional analysis for common daily human activities. The simulation study illustrated functional differences between flexor and extensor muscles and the results were utilized for efficient design of the series elastic torque actuator employed in lower extremity exoskeletons.

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Biswal, Deepak Ranjan, and Pramod Kumar Parida. "Modelling and Finite Element Based Analysis of a Five Fingered Underactuated Robotic Hand." International Journal for Research in Applied Science and Engineering Technology 10, no. 9 (September 30, 2022): 100–108. http://dx.doi.org/10.22214/ijraset.2022.46579.

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Abstract: Imparting the dexterity and autonomous competence to a robotic system is a significant burden in humanoid robotics, especially in the fields of industrial manufacturing, prosthetics, orthopedic rehabilitation, etc. Operating a humanoid hand requires a very innovative actuator and transmission system. The under-actuated concepts are proving to be a possible means of achieving extremely dexterous robotic hands without the need for diverse mechanical design. The main characteristics of an under-actuated robotic hand are that fewer actuators are required to operate it than the degrees of freedom. The under-actuated equivalent hand is significantly less expensive than the fully-actuated equivalent hand and remarkably reduces the complexity of the control system. The existing work dealt with the modeling and finite element-based analysis of an anthropomorphic underactuated robotic hand using five fingers including the thumb and palm with dexterity and with a total of twenty-one degrees of freedom.

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Bansevicius, Ramutis, Dalius Mazeika, Vytautas Jurenas, Genadijus Kulvietis, and Asta Drukteiniene. "Multi-DOF Ultrasonic Actuators for Laser Beam Positioning." Shock and Vibration 2019 (February 10, 2019): 1–13. http://dx.doi.org/10.1155/2019/4919505.

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A novel design concept of multi-degree-of-freedom (multi-DOF) piezoelectric actuator is introduced in the paper. The main idea is to connect two identical piezoelectric transducers by hyperelastic material in order to increase the total number of degrees-of-freedom of the system. Such design principle also allows to separate vibrations of two piezoelectric transducers and to control them independently. The ring- and cylinder-type piezoelectric transducers were used to design two multi-DOF ultrasonic actuators for precise laser beam positioning. Reflecting mirror is mounted on the top of the actuator and is preloaded by magnetic force. Both disc- and cylinder-type actuators can realize up to six degrees-of-freedom, i.e., to rotate the mirror about three axes employing one transducer and to position mirror in the plane by using another transducer. Bidirectional rotation and translation motion of the mirror are obtained by switching excitation signals between different electrodes of the transducers. Both the numerical simulation and physical prototype were used to verify operating principle of the actuators. Numerical investigation of the piezoelectric actuator was performed to investigate modal-frequency and harmonic response analysis while experimental study was performed to measure electrical and mechanical output characteristics of the piezoelectric actuator. A mathematical model of contacting force control was proposed, and numerical verification was performed when the mirror need to be rotated according to the specific motion trajectory.

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Park, F. C., and J. W. Kim. "Singularity Analysis of Closed Kinematic Chains." Journal of Mechanical Design 121, no. 1 (March 1, 1999): 32–38. http://dx.doi.org/10.1115/1.2829426.

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This paper presents a coordinate-invariant differential geometric analysis of kinematic singularities for closed kinematic chains containing both active and passive joints. Using the geometric framework developed in Park and Kim (1996) for closed chain manipulability analysis, we classify closed chain singularities into three basic types: (i) those corresponding to singular points of the joint configuration space (configuration space singularities), (ii) those induced by the choice of actuated joints (actuator singularities), and (iii) those configurations in which the end-effector loses one or more degrees of freedom of available motion (end-effector singularities). The proposed geometric classification provides a high-level taxonomy for mechanism singularities that is independent of the choice of local coordinates used to describe the kinematics, and includes mechanisms that have more actuators than kinematic degrees of freedom.

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Alfaro Barrantes, Juan, Paola Vega Castillo, Marta Vílchez Monge, and Marco Rodríguez Montero. "Simulation of laminar bimorph piezoelectric microactuators with application in miniaturized robots." Revista Tecnología en Marcha 25, no. 5 (November 21, 2012): 116. http://dx.doi.org/10.18845/tm.v25i5.484.

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In order to implement miniaturized robots different possibilities for electromechanical actuation at the microscale must be evaluated according to their function on the robot, as well as, size, mechanical strength and deformation, resolution, power supply, energy and degrees of freedom required. The piezoelectric actuators are among the most suitable possibilities to incorporate microactuators in miniaturized robots.This article presents an overview of piezoelectric actuation and the evaluation of a simple x-y micropositioning actuator for a miniaturized robot using COMSOL Multiphysics.

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Sun, Qiang, Shizhong Zhang, Xuan Li, Weiwei Chen, Wuxiang Sun, and Hu Huang. "A novel two-degrees of freedom (2-DOF) piezo-driven positioning platform with the working stroke being over 20 cm." Review of Scientific Instruments 93, no. 10 (October 1, 2022): 105002. http://dx.doi.org/10.1063/5.0106657.

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Multi-degrees of freedom piezo-driven precision positioning platforms with large working strokes are demanded in many research fields. Although many multi-degrees of freedom piezo-driven positioning platforms have been proposed, few of them can achieve both large working stroke and high speed, which hinders their applications. In this study, a two-degrees of freedom piezo-driven positioning platform was proposed by stacking two identical stick–slip piezoelectric actuators. To simplify the practical implementation of a large working stroke, the actuator employed a special structure, in which the compliant mechanism and the slider were connected together as a mover and the guide rail was fixed as a stator. The working stroke of the actuator can be increased easily by increasing only the length of the guide rail without changing the output performances. By designing a lever-type compliant mechanism (LCM) on the side surface of the slider, a large loading space was obtained. Theoretical calculation and finite element analysis of the LCM were performed in detail. As the structures of these two stick–slip piezoelectric actuators are the same, only the output performances of the upper actuator ( x direction) were tested as an example. Experimental results indicated that the upper actuator had a stable bi-direction motion with a working stroke being over 20 cm. The maximum speeds along the positive x and negative x directions reached 17.864 and 18.73 mm/s, and the resolutions were 100 and 230 nm, respectively. Furthermore, the vertical loading capacity was larger than 60 N.

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Peerdeman, Bart, Stefano Stramigioli, Edsko E. G. Hekman, Dannis M. Brouwer, and Sarthak Misra. "Development of Underactuated Prosthetic Fingers with Joint Locking and Electromyographic Control." Mechanical Engineering Research 3, no. 1 (April 24, 2013): 130. http://dx.doi.org/10.5539/mer.v3n1p130.

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Modern hand prostheses possess a large number of degrees of freedom. These degrees of freedom cannot simply be actuated by a single motor each, since their combined size and weight would exceed the limitations of an anthropomorphic prosthesis. Some hand prostheses try to remedy this by way of underactuation of the fingers or addition of entirely passive fingers, but this reduces the hand's ability to execute different grasp types. We present a joint locking system, allowing certain degrees of freedom to be fixed during actuation of an underactuated finger. These locks are actuated by miniature solenoids, and allow the fingers to support a variety of grasp types. In this paper, these locks are implemented in a two-fingered prosthesis prototype, which is able to perform several grasping motions important for prosthesis users. This prototype is controlled by pre-recorded electromyographic signals, which control different grasp types and their opening/closing. Various grasping experiments show that the prototype is able to execute three essential grasp types for daily living with a single main actuator, and can be intuitively controlled by means of six different electromyographic signals. This prototype demonstrates new joint locking mechanisms and control systems that can provide an anthropomorphic, myoelectric hand prosthesis with minimal actuation and intuitive control.

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Gardner, J. F., K. Srinivasan, and K. J. Waldron. "Closed loop trajectory control of walking machines." Robotica 8, no. 1 (January 1990): 13–22. http://dx.doi.org/10.1017/s026357470000727x.

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SUMMARYThe global trajectory control of walking machines is addressed here with particular attention paid to the consequences of actuator redundancy for control and to the inclusion of actuator dynamics in trajectory controller design. Redundancy of actuation, typical of walking machines, results in the trajectory control problem being formulated perforce in a global coordinate frame, instead of the joint space, as in nonredundant manipulators. This lack of one-to-one correspondence between the degrees of freedom of motion in the global coordinate frame and the actuators results in coupling between the different trajectory control loops. A mechanism for reducing this coupling effect is proposed here, along with a procedure to take into account approximately the effect of actuator dynamics in designing the trajectory controllers. The proposed methods are evaluated by simulation for an example problem in legged locomotion and are shown to be effective.

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MARTIN, JAN, SEBASTIAN BECK, ARNE LEHMANN, RALF MIKUT, CHRISTIAN PYLATIUK, STEFAN SCHULZ, and GEORG BRETTHAUER. "SENSORS, IDENTIFICATION, AND LOW LEVEL CONTROL OF A FLEXIBLE ANTHROPOMORPHIC ROBOT HAND." International Journal of Humanoid Robotics 01, no. 03 (September 2004): 517–32. http://dx.doi.org/10.1142/s0219843604000253.

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The successful control of a robot hand with multiple degrees of freedom not only requires sensors to determine the state of the hand but also a thorough understanding of the actuator system and its properties. This article presents a set of sensors and analyzes the actuator properties of an anthropomorphic robot hand driven by flexible fluidic actuators. These flexible and compact actuators are integrated directly into the finger joints, they can be driven either pneumatically or hydraulically. The sensors for the measurement of joint angles, contact forces, and fluid pressure are described; the designs utilize mostly commodity components. Hall sensors and customized half-ring rare-earth magnets are used to integrate the joint angle sensors directly into the actuated joints. A force sensor setup allowing soft finger surfaces is evaluated. Fluid pressure sensors are needed for the model-based computation of joint torques and to limit the actuator pressure. Static and dynamic actuator characteristics are determined in a theoretical process analysis, and suitable parameters are identified in several experiments. The resulting actuator model incorporates the viscoelastic material behavior and describes the relations of joint angle, actuator pressure, and actuator torque. It is used in simulations and for the design of a joint position controller.

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Si, Guoning, Liangying Sun, Zhuo Zhang, and Xuping Zhang. "Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom." Micromachines 12, no. 4 (April 15, 2021): 444. http://dx.doi.org/10.3390/mi12040444.

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This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

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Chernyshenko, Sergei I., and Aleksei V. Privalov. "Internal Degrees of Freedom of an Actuator Disc Model." Journal of Propulsion and Power 20, no. 1 (January 2004): 155–63. http://dx.doi.org/10.2514/1.9242.

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Wang, Pengchuan, and Andrew Conn. "Elastic Cube Actuator with Six Degrees of Freedom Output." Actuators 4, no. 3 (September 7, 2015): 203–16. http://dx.doi.org/10.3390/act4030203.

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Nishiura, Yusuke, Katsuhiro Hirata, and Yo Sakaidani. "3-DOF Outer Rotor Electromagnetic Spherical Actuator." International Journal of Automation Technology 10, no. 4 (July 5, 2016): 591–98. http://dx.doi.org/10.20965/ijat.2016.p0591.

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Conventionally, many single-degree-of-freedom (single-DOF) actuators have been used to realize devices with multiple-degrees-of-freedom (multi-DOF). However, this makes their structures larger, heavier, and more complicated. In order to remove these drawbacks, the development of spherical actuators with multi-DOF is necessary. In this paper, we propose a new 3-DOF outer rotor electromagnetic spherical actuator with high torque density and wide rotation angles. The dynamic characteristics are computed employing 3-D FEM and its effectiveness is verified by carrying out measurements on a prototype. Then, in order to realize further high torque density, the electromagnetic pole arrangement is optimized using Genetic Algorithm (GA) and the effectiveness of the optimized stator poles arrangement is verified.

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Akagi, Tetsuya, and Shujiro Dohta. "Development of Wearable Pneumatic Actuator and Multiport Pressure Control Valve." Journal of Robotics and Mechatronics 17, no. 5 (October 20, 2005): 529–36. http://dx.doi.org/10.20965/jrm.2005.p0529.

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Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. Some involve an actuator and a driving device, such as a pneumatic cylinder and a control valve, worn by the user. Such devices must be compact, lightweight and flexible to avoid excessive load on and injury to the user. The purpose of our study is to develop a flexible and lightweight actuator which can be safe enough to be attached to the human body. We proposed new flexible pneumatic actuators that operate even if the actuator is deformed by external force. We tested a push-pull and flexible pneumatic actuator that moves straight and rotates. We proposed and developed a multiport pressure control valve that drives multiple wearable actuators while reducing the weight of the control valve for multiple degrees of freedom of motion.

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Furutani, Katsushi, and Taizo Makino. "Influence of Matrix Circuit Switching Device Junction Capacitance on Piezoelectric Actuator Drive Performance." International Journal of Automation Technology 3, no. 3 (May 5, 2009): 313–18. http://dx.doi.org/10.20965/ijat.2009.p0313.

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Piezoelectric actuators are widely used as fine-motion actuators for positioning devices. Current pulse driving reduces displacement hysteresis, and the drive circuit provides current pulses considered constant charge pulses to the piezoelectric actuator. The circuit for devices with multiple degrees of freedom using multiple piezoelectric actuators should be simple. Matrix circuits are used to drive liquid crystal displays to reduce the number of drive-circuit control signals and components. A group of 2 × 2 piezoelectric actuators was driven alternately using a 4-switch matrix circuit, and two field effect transistors were used as a fast matrix circuit switch. Piezoelectric actuator drive performance was studied in the case of using the current pulse circuit and the matrix circuit. When the matrix circuit drove actuators performing as capacitive loads, switching device junction capacitors adversely affected drive performance.

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Vílchez Monge, Marta, Estuardo Herrera Muñoz, Natalia Rodríguez Rodríguez, and Paola Vega Castillo. "Simulation of translational piezoelectric microactuators with application in miniaturized robots." Revista Tecnología en Marcha 25, no. 5 (November 21, 2012): 124. http://dx.doi.org/10.18845/tm.v25i5.485.

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In the design of miniaturized robots, different types of microelectromechanical actuators must be evaluated to determine the most appropriate one for each specific function as well as the best actuation effect for the size, force, supply voltage, energy, precision and degrees of freedom required.The piezoelectric effect is one of the most promising effects to incorporate microactuators in miniaturized robots. This paper presents a brief comparison on actuation methods for translational displacement and discusses its feasibility for application in miniaturized robots. The specific case of evaluation of a translational piezoelectric actuator using COMSOL Multiphysics is described, as well as an application example for a microgripper to be incorporated in a miniaturized robot for grasping submicrometric objects.

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Protas, Bartosz, and Takashi Sakajo. "Harnessing the Kelvin–Helmholtz instability: feedback stabilization of an inviscid vortex sheet." Journal of Fluid Mechanics 852 (August 3, 2018): 146–77. http://dx.doi.org/10.1017/jfm.2018.523.

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In this investigation, we use a simple model of the dynamics of an inviscid vortex sheet given by the Birkhoff–Rott equation to obtain fundamental insights about the potential for stabilization of shear layers using feedback control. As actuation, we consider two arrays of point sinks/sources located a certain distance above and below the vortex sheet and subject to the constraint that their mass fluxes separately add up to zero. First, we demonstrate using analytical computations that the Birkhoff–Rott equation linearized around the flat-sheet configuration is in fact controllable when the number of actuator pairs is sufficiently large relative to the number of discrete degrees of freedom present in the system, a result valid for generic actuator locations. Next, we design a state-based linear-quadratic regulator stabilization strategy, where the key difficulty is the numerical solution of the Riccati equation in the presence of severe ill-conditioning resulting from the properties of the Birkhoff–Rott equation and the chosen form of actuation, an issue that is overcome by performing computations with a suitably increased arithmetic precision. Analysis of the linear closed-loop system reveals exponential decay of the perturbation energy and the corresponding actuation energy in all cases. Computations performed for the nonlinear closed-loop system demonstrate that initial perturbations of non-negligible amplitude can be effectively stabilized when a sufficient number of actuators is used. We also thoroughly analyse the sensitivity of the closed-loop stabilization strategies to the variation of a number of key parameters. Subject to the known limitations of inviscid vortex models, our findings indicate that, in principle, it may be possible to stabilize shear layers for relatively large initial perturbations, provided that the actuation has sufficiently many degrees of freedom.

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Yao, Haiying, Yintang Wen, Zixiang Zhou, Hongmiao Tian, Yuyan Zhang, and Xiaoyuan Luo. "Adaptive regulation strategy of the soft deformable actuator based on angle self-sensing." Journal of Physics: Conference Series 2402, no. 1 (December 1, 2022): 012029. http://dx.doi.org/10.1088/1742-6596/2402/1/012029.

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Abstract Soft robots can adapt to various unstructured environments and have received extensive attention. The integrated structure of sensing and actuation makes soft robots more miniaturized and integrated, enriching their usage scenarios. The multiple degrees of freedom of soft actuators facilitate flexible deformation but also bring challenges to precisely control the deformation. This work presents a novel Liquid Crystal Elastomer-based soft actuator with self-sensing. The kinetic model of a soft finger structure made of the above soft actuator is proposed to facilitate the controller design. Considering the non-predetermined external excitation, a deformation regulation strategy based on a sliding mode controller is designed. Under the action of the controller, the bending angle of the finger joint can be stabilized in a smaller range around the desired value based on the feedback of the self-sensing information. This research realizes the integration of sensing, actuation, and control, enabling the flexible structure can organically adapt to the environmental dynamics and uncertainty in nature, which cannot be achieved by the existing flexible structure deformation control.

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Habibi, Hossein, and William O’Connor. "Wave-based planar motion and vibration control of under-actuated mass-spring arrays." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 2 (June 2018): 269–78. http://dx.doi.org/10.1177/1461348418780026.

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This paper considers the problem of position control and active vibration damping of a planar, array (or grid) of masses and springs, by a single actuator, attached to one corner of the array, which is required to translate and rotate the entire system from rest to rest, through target linear and angular displacements, simultaneously. An obvious challenge is that the system has many degrees of freedom, with many undamped vibration modes, and is clearly highly under-actuated. The control technique is a development of “wave-based control,” whereby rapid and effective control of the entire system is achieved, robustly, using measurements made only at the actuator, of the actuator’s own motion and of the forces between the actuator and the attached flexible system. No detailed system model or system identification is needed. The actuator need not be ideal. The array does not have to be uniform, in its geometry or in the mass and spring values. The control strategy is simple to implement. The 2D array is of interest in itself as a benchmark control challenge, but it can also be considered a model of various lumped structures, or a discretisation of distributed systems.

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Butcher, E. A., and R. Lu. "Constant-Gain Linear Feedback Control of Piecewise Linear Structural Systems via Nonlinear Normal Modes." Journal of Vibration and Control 10, no. 10 (October 2004): 1535–58. http://dx.doi.org/10.1177/1077546304042065.

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We present a technique for using constant-gain linear position feedback control to implement eigen-structure assignment of n-degrees-of-freedom conservative structural systems with piecewise linear nonlinearities. We employ three distinct control strategies which utilize methods for approximating the nonlinear normal mode (NNM) frequencies and mode shapes. First, the piecewise modal method (PMM) for approximating NNM frequencies is used to determine n constant actuator gains for eigenvalue (pole) placement. Secondly, eigenvalue placement is accomplished by finding an approximate single-degree-of-freedom reduced model with one actuator gain for the mode to be controlled. The third strategy allows the frequencies and mode shapes (eigenstructure) to be placed by using a full n × n matrix of actuator gains and employing the local equivalent linear stiffness method (LELSM) for approximating NNM frequencies and mode shapes. The techniques are applied to a two-degrees-of-freedom system with two distinct types of nonlinearities: a bilinear clearance nonlinearity and a symmetric deadzone nonlinearity.

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Truc, Le Ngoc, Le Anh Vu, Tran Van Thoan, Bui Trung Thanh, and Tung Lam Nguyen. "Adaptive Sliding Mode Control Anticipating Proportional Degradation of Actuator Torque in Uncertain Serial Industrial Robots." Symmetry 14, no. 5 (May 7, 2022): 957. http://dx.doi.org/10.3390/sym14050957.

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The paper focuses on faulty actuator problems in an industrial robot using servomotors, and provides an adaptive sliding mode control law to overcome this circumstance. Because of multifarious reasons, robot actuators can undergo a variety of failures, such as locked or stuck joints, free-swinging joints, and partial or total loss of actuation effectiveness. The robot behavior will become worsen if the system controller has not been designed with adequate faulty tolerance. The proportional degradation of actuator torque at unknown degrees of loss, which is one type of partial loss of actuation effectiveness, is considered in this study to design a suitable controller. The robot model is constructed with uncertain parameters and unknown friction, whereas the controller uses only the approximate parameters. Symmetry and skew-symmetry give important contributions in robot modeling and transformation, as well as in the process of proving the system stability. An adjustable coefficient vector of the proposed controller can adaptively reach the upper bounds of an uncertain parametric vector, which guarantees the criterion of Lyapunov stability. In the numerical simulation stage, the selected industrial robot is a Serpent 1 robot with three degrees of freedom. A quasi-physical model based on MATLAB/Simscape Multibody for the robot is built and used in order to increase the reliability of the simulation performance closer to reality. Simulation results illustrate the efficiency of the proposal control methodology in the presence of the mentioned failure. The controller can still deliver satisfactory responses to the robot system under reasonable levels of actuator torque degradation.

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Kim, Hyo Young, Hyunchang Kim, Dae-Gab Gweon, and Jaehwa Jeong. "Development of a Novel Spherical Actuator With Two Degrees of Freedom." IEEE/ASME Transactions on Mechatronics 20, no. 2 (April 2015): 532–40. http://dx.doi.org/10.1109/tmech.2014.2308417.

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Lee, Kok-Meng, Jianfa Pei, and Ronald Roth. "Kinematic analysis of a three-degrees-of-freedom spherical wrist actuator." Mechatronics 4, no. 6 (September 1994): 581–605. http://dx.doi.org/10.1016/0957-4158(94)90026-4.

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Ngoc, Le Kim, and Tran Ich Thinh. "Optimum problem of piezoelectric laminated composite plate using genetic algorithm." Vietnam Journal of Mechanics 31, no. 2 (June 17, 2009): 87–96. http://dx.doi.org/10.15625/0866-7136/31/2/5486.

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The finite element model based on First Shear Displacement Theory to study the mechanical and electrical behaviors of cantilever laminated composite plate bonded piezoelectric patches on surface is presented. A nine-node isoparametric rectangular element with 5 degrees of freedom for the generalized displacements and 2 electrical degrees of freedom at each node is used. Optimization techniques based on genetic algorithm (GAs) are applied in order to maximize the piezoelectric actuator efficiency, improve the structural performance. The illustrative examples and results of the appropriate applied voltages, position of bonded piezoelectric actuator patches and fiber angle to achieve the desired displacement of the cantilever composite plate are presented.

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Tzou, H. S., and C. I. Tseng. "Distributed Modal Identification and Vibration Control of Continua: Piezoelectric Finite Element Formulation and Analysis." Journal of Dynamic Systems, Measurement, and Control 113, no. 3 (September 1, 1991): 500–505. http://dx.doi.org/10.1115/1.2896438.

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“Smart” continua with integrated sensor/actuator for structural identification and control have drawn much attention in recent years due to the rapid development of high-performance “smart” structures. The continua are distributed and flexible in nature. Thus, distributed dynamic measurement and active vibration control are of importance to their high-demanding performance. In this paper, continua (shells or plates) integrated with distributed piezoelectric sensors and actuators are studied using a finite element technique. A new piezoelectric finite element with internal degrees of freedom is derived. Two control algorithms, namely, constant gain feedback control and Lyapunov control, are implemented. Structural identification and control of a plate model with distributed piezoelectric sensor/actuator is studied. Distributed modal voltage and control effectiveness of mono and biaxially polarized piezoelectric actuators are evaluated.

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Jiabin Wang, Weiya Wang, G. W. Jewell, and D. Howe. "A novel spherical permanent magnet actuator with three degrees-of-freedom." IEEE Transactions on Magnetics 34, no. 4 (July 1998): 2078–80. http://dx.doi.org/10.1109/20.706803.

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Tham, Vu Van, Tran Huu Quoc, and Tran Minh Tu. "OPTIMAL PLACEMENT AND ACTIVE VIBRATION CONTROL OF COMPOSITE PLATES INTEGRATED PIEZOELECTRIC SENSOR/ACTUATOR PAIRS." Vietnam Journal of Science and Technology 56, no. 1 (January 30, 2018): 113. http://dx.doi.org/10.15625/2525-2518/56/1/8824.

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In this study, a finite element model based on first-order shear deformation theory is presented for optimal placement and active vibration control of laminated composite plates with bonded distributed piezoelectric sensor/actuator pairs. The model employs the nine-node isoparametric rectangular element with 5 degrees of freedom for the mechanical displacements, and 2 electrical degrees of freedom. Genetic algorithm (GA) is applied to maximize the fundamental natural frequencies of plates; and the constant feedback control method is used for the vibration control analysis of piezoelectric laminated composite plates. The results of this study can be used to aid the placement of piezoelectric sensor/actuator pairs of smart composite plates as well as for robust controller design.

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Poletkin, Kirill. "On the Static Pull-In of Tilting Actuation in Electromagnetically Levitating Hybrid Micro-Actuator: Theory and Experiment." Actuators 10, no. 10 (September 29, 2021): 256. http://dx.doi.org/10.3390/act10100256.

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This work presents the results of the experimental and theoretical study of the static pull-in of tilting actuation executed by a hybrid levitation micro-actuator (HLMA) based on the combination of inductive levitation and electrostatic actuation. A semi-analytical model to study such a pull-in phenomenon is developed, for the first time, as a result of using the qualitative technique based on the Lagrangian approach to analyze inductive contactless suspensions and a recent progress in the calculation of mutual inductance and force between two circular filaments. The obtained non-linear model, accounting for two degrees of freedom of the actuator, allows us to predict accurately the static pull-in displacement and voltage. The results of modeling were verified experimentally and agree well with measurements.

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Rodriguez-Barroso, Alejandro, Roque Saltaren, Gerardo A. Portilla, Juan S. Cely, and Marco Carpio. "Cable-Driven Parallel Robot with Reconfigurable End Effector Controlled with a Compliant Actuator." Sensors 18, no. 9 (August 22, 2018): 2765. http://dx.doi.org/10.3390/s18092765.

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Redundancy in cable-driven parallel robots provides additional degrees of freedom that can be used to achieve different objectives. In this robot, this degree of freedom is used to act on a reconfigurable end effector with one degree of freedom. A compliant actuator actuated by one motor exerts force on both bodies of the platform. Due to the high tension that appears in this cable in comparison with the rest of the cables, an elastic model was developed for solving the kinestostatic and wrench analysis. A linear sensor was used in one branch of this cable mechanism to provide the needed intermediate values. The position of one link of the platform was fixed in order to focus this analysis on the relationship between the cables and the platform’s internal movement. Position values of the reconfigurable end effector were calculated and measured as well as the tension at different regions of the compliant actuator. The theoretical values were compared with dynamic simulations and real prototype results.

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Wei, Baochen, and Feng Gao. "Output force capacity polytope approach for actuator forces selection of three degrees of freedom excavating manipulator." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 11 (December 2, 2013): 2007–17. http://dx.doi.org/10.1177/0954406213512629.

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Output force or velocity polytopes are usually used as an index of the manipulability of robot. This paper discusses the relationship between the actuator force and the variation of the output force capacity polytope and proposes the output force capacity polytope method for the selection of actuator forces of a three degrees of freedom excavating manipulator with the requirement that the output force on the end effector is a set of all possible forces rather than a single force. In this paper, the method to calculate capacity polytope is introduced with the consideration of gravity effect. With the concept that the required output force space should be within the output capacity polytope, the output force capacity polytope approach for selecting actuator forces is proposed.

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Ren, Rui, Chang Chun Ye, and Guo Bin Fan. "Testing and Analysis of Actuator Parameter Identification of Heavy Load Stewart Platform." Applied Mechanics and Materials 226-228 (November 2012): 2036–41. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2036.

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Being relatively new to the field, electromechanical actuators of Stewart platform in vibration control and motion simulation applications lack the knowledge base compared to ones accumulated for the other actuator types, especially when it comes to characterization and system identification. This paper focuses in the modeling of an electromechanical linear actuator to be used in a heavy load six-degrees-of-freedom platform application intended for motion control technology. The paper keeps the main kinematic and dynamic parameters unaffected, ignoring others. After obtaining the structure of model, parameters is derived by system identification. Provides a comparison of output of real system and simplified model by same input signal, the experimental result shows that the method is accurate and have good ability.

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Si, Guoning, Liangying Sun, Zhuo Zhang, and Xuping Zhang. "Theoretical Thermal-Mechanical Modelling and Experimental Validation of a Three-Dimensional (3D) Electrothermal Microgripper with Three Fingers." Micromachines 12, no. 12 (December 4, 2021): 1512. http://dx.doi.org/10.3390/mi12121512.

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This paper presents the theoretical thermal-mechanical modeling and parameter analyses of a novel three-dimensional (3D) electrothermal microgripper with three fingers. Each finger of the microgripper is composed of a bi-directional Z-shaped electrothermal actuator and a 3D U-shaped electrothermal actuator. The bi-directional Z-shaped electrothermal actuator provides the rectilinear motion in two directions. The novel 3D U-shaped electrothermal actuator offers motion with two degrees of freedom (DOFs) in the plane perpendicular to the movement of the Z-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with polyimide films. In this work, the static theoretical thermal-mechanical model of the 3D U-shaped electrothermal actuator is established. Finite-element analyses and experimental tests are conducted to verify and validate the model. With this model, parameter analyses are carried out to provide insight and guidance on further improving the 3D U-shaped actuator. Furthermore, a group of micro-manipulation experiments are conducted to demonstrate the flexibility and versality of the 3D microgripper on manipulate different types of small/micro-objects.

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Ohgi, Takeyuki, and Yasuyoshi Yokokohji. "Control of Hydraulic Actuator Systems Using Feedback Modulator." Journal of Robotics and Mechatronics 20, no. 5 (October 20, 2008): 695–708. http://dx.doi.org/10.20965/jrm.2008.p0695.

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Heavy-duty robots using hydraulic actuators are expected to support rescue operations by removing heavy rubble in hostile -wet, dusty, or muddy- environments. The high friction generated by their hydraulic actuator, however, makes it difficult to use them in operations requiring high precision. The servovalves used to control a hydraulic actuator precisely are more expensive than conventional proportional valves, making it impractical to install them in all joints of heavy-duty robots having many degrees of freedom. In this paper, a new hydraulic actuator control method using a feedback modulator is proposed. The proposed controller improves the performance of hydraulic systems using conventional proportional valves, making it as good as that with servovalves. This paper also proposes exclusive control for controlling multiple joints simultaneously to prevent asynchronous joint movement under unbalanced loads. The effectiveness of the proposed method is confirmed through simulations and experiments.

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Ichihara, Junichi. "Computer Mechanics. Positioning Control of an Actuator with Two Degrees of Freedom." Transactions of the Japan Society of Mechanical Engineers Series C 60, no. 576 (1994): 2641–48. http://dx.doi.org/10.1299/kikaic.60.2641.

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Wang, Yuanyuan, Shota Kokubu, Shaoying Huang, Ya-Hsin Hsueh, and Wenwei Yu. "Towards an Extensive Thumb Assist: A Comparison between Whole-Finger and Modular Types of Soft Pneumatic Actuators." Applied Sciences 12, no. 8 (April 7, 2022): 3735. http://dx.doi.org/10.3390/app12083735.

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Soft pneumatic actuators used in robotic rehabilitation gloves are classified into two types: whole-finger actuators with air chambers that cover the entire finger and modular actuators with chambers only above the finger joints. Most existing prototypes provide enough finger flexion support, but insufficient independent thumb abduction or opposition support. Even the latest modular soft actuator realized thumb abduction with a sacrifice of range of motion (RoM). Moreover, the advantages and disadvantages of using the two types of soft actuators for thumb assistance have not been made clear. Without an efficient thumb assist, patients’ options for hand function rehabilitation are very limited. Therefore, the objective of this study was to design a modular actuator (M-ACT) that could support multiple degrees of freedom, compare it with a whole-finger type of thumb actuator with three inner chambers (3C-ACT) in terms of the RoM, force output of thumb flexion, and abduction, and use an enhanced Kapandji test to measure both the kinematic aspect of the thumb (Kapandji score) and thumb-tip pinch force. Our results indicated superior single-DoF support capability of the M-ACT and superior multi-DoF support capability of the 3C-ACT. The use of the 3C-ACT as the thumb actuator and the M-ACT as the four-finger actuator may be the optimal solution for the soft robotic glove. This study will aid in the progression of soft robotic gloves for hand rehabilitation towards real rehabilitation practice.

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Takeda, Yukio, and Hiroaki Funabashi. "Kinematic Synthesis of In-Parallel Actuated Mechanisms Based on the Global Isotropy Index." Journal of Robotics and Mechatronics 11, no. 5 (October 20, 1999): 404–10. http://dx.doi.org/10.20965/jrm.1999.p0404.

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To develop a mechanism that minimizes directional variation of pose accuracy, maximum operation speed, and maximum output force over a prescribed working space and minimizes required sensor resolution and maximum actuator power for generating required accuracy, speed, and force, we propose a global isotropy index as an evaluation index in mechanism design. The effectiveness of the global isotropy index was numerically confirmed through error analysis of output displacement and kinematic synthesis of spatial in-parallel actuated mechanisms with 6 degrees of freedom.

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Nishimori, Yuuki, Hideta Ooiso, Shunsuke Mochizuki, Nobuyo Fujiwara, Toshiyuki Tsuchiya, and Gen Hashiguchi. "A multiple Degrees of Freedom Equivalent Circuit for a Comb-Drive Actuator." Japanese Journal of Applied Physics 48, no. 12 (December 21, 2009): 124504. http://dx.doi.org/10.1143/jjap.48.124504.

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Bayram, A., and M. Kemal Özgören. "The conceptual design of a spatial binary hyper redundant manipulator and its forward kinematics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 1 (September 19, 2011): 217–27. http://dx.doi.org/10.1177/0954406211412156.

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The hyper redundant manipulators (HRMs) have excessively many degrees of freedom. As a special but practicable subset of them, the binary hyper-redundant manipulators (BHRMs) use binary (on–off) actuators with only two stable states such as pneumatic cylinders and/or solenoids. This article describes the conceptual design of a spatial BHRM together with its forward kinematics. This BHRM consists of many modules with the same constructive characteristics. The modules increase in size from the tip to the base so that the actuator powers also increase in the same order. Each module consists of three submodules. The first and second submodules have the shapes of variable geometry trusses and they work in mutually orthogonal planes. The third submodule is a discrete twister. The manipulator is assumed to be driven by pneumatic on–off actuators. Because of the discrete nature of the on–off actuators, a small but continuously actuated six-joint manipulator is installed as the last module of the BHRM in order to compensate the discretization errors.

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KERUR, S. B., and ANUP GHOSH. "ACTIVE VIBRATION CONTROL OF COMPOSITE PLATE USING AFC ACTUATOR AND PVDF SENSOR." International Journal of Structural Stability and Dynamics 11, no. 02 (April 2011): 237–55. http://dx.doi.org/10.1142/s0219455411004075.

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A finite element formulation for active vibration control of laminated composite plate integrated with active fiber composite (AFC) layer acting as distributed actuator and PVDF layer as sensor is presented in this paper. An eight noded quadratic isoparametric element with five mechanical degrees of freedom and one electrical degree of freedom per node of the element is considered. Newmark time integration method is used to calculate the dynamic response and negative velocity feedback control algorithm is used to control the dynamic response of the laminated composite plate. The effect of piezoelectric fiber orientation in actuator layer on the control of vibration is studied.

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Jiang, Jingang, Qiyun Tan, Tianhua He, Jianpeng Sun, and Jiawei Zhang. "Safety Analysis, Design and Evaluation of 2-DOF Parallel Lifting Actuator on Stereo Parking Robot." Actuators 11, no. 7 (June 29, 2022): 181. http://dx.doi.org/10.3390/act11070181.

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Stereo garage technology can effectively alleviate the problem of parking difficulties, but the safety problems of its actuators, via which the core of stereo parking function can be realized, seriously affect its promotion and further development. In this paper, a two degrees of freedom (2-DOF) parallel lifting actuator for a stereo parking robot is designed by researching the type synthesis of the mechanism based on the screw theory. The limb constrained triangle method, the flexibility of limb constrained triangle, and the failure probability are proposed to determine the final configuration of the parallel lifting actuator. Then, this paper completes the dimensional optimization of the parallel lifting actuator based on the multi-motion performance indexes and kinematic analysis, which improves the safety and stability of the actuator. Finally, this paper verifies the validity of the parallel lifting actuator by establishing a parallel lifting actuator verification model system. By verifying the dynamic characteristics of the model mobile platform under different load conditions, it is proven that the kinematic stability of the mobile platform decreases with the increase of load mass under load conditions. Additionally, through practical application experiment, it is proven that the parallel lifting mechanism can effectively alleviate the parking difficulty problem.

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Nakajima, Shin-ichi, Toyohiko Hayashi, and Hiroshi Kobayashi. "Development of 2-D Jaw Movement Simulator (JSN/S1)." Journal of Robotics and Mechatronics 10, no. 6 (December 20, 1998): 499–504. http://dx.doi.org/10.20965/jrm.1998.p0499.

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Human mastication is performed by coordinated activities of several jaw muscles. To clarify functions of these muscles, we developed a jaw movement simulator (JSN/Sl) consisting of a 2 degrees of freedom (2DOF) mechanism and five muscle actuators able to reproduce jaw movements on a sagittal plane. The actuator is a cable-tendon driven by a DC servomotor controlled by a compliance control scheme to obtain viscoelastic muscle characteristics. To simulate life-like clenching, we controlled occlusal position and force by incorporating position and force sensors, using neural network learning control. Occlusal force successfully converged to a desired value through learning. Tension patterns of muscle actuators during clenching well coincided with human jaw activities.

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Tiré, Jan, Jan Victor, Patrick De Baets, and Matthias Verstraete. "Control of the boundary conditions of a dynamic knee simulator." International Journal Sustainable Construction & Design 6, no. 2 (July 7, 2015): 7. http://dx.doi.org/10.21825/scad.v6i2.1125.

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At Ghent University a dynamic knee simulator to analyse the kinematics of a human knee has been developed. The rig is designed to perform tests on a mechanical hinge or on a human knee (with or without a prosthesis). The rig has one degree of freedom in a hip joint and four degrees of freedom in an ankle joint. There is currently one actuator that simulates the quadriceps forces. Two additional actuators are proposed in this paper to simulate the hamstrings forces. The magnitude and phase of the forces varies significantly during the movement (e.g. cycling or squatting). Literature indicates that the maximum muscle forces do not exceed 2000 N. An inverse dynamic analysis, using the musculoskeletal software AnyBody, is proposed to determine the evolution of these forces during the studied movements.

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Hu, Fuwen, and Tian Li. "An Origami Flexiball-Inspired Metamaterial Actuator and Its In-Pipe Robot Prototype." Actuators 10, no. 4 (March 26, 2021): 67. http://dx.doi.org/10.3390/act10040067.

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Usually, polyhedra are viewed as the underlying constructive cells of packing or tiling in many disciplines, including crystallography, protein folding, viruses structure, building architecture, etc. Here, inspired by the flexible origami polyhedra (commonly called origami flexiballs), we initially probe into their intrinsic metamaterial properties and robotized methods from fabrication to actuation. Firstly, the topology, geometries and elastic energies of shape shifting are analyzed for the three kinds of origami flexiballs with extruded outward rhombic faces. Provably, they meet the definitions of reconfigurable and transformable metamaterials with switchable stiffness and multiple degrees of freedom. Secondly, a new type of soft actuator with rhombic deformations is successfully put forward, different from soft bionic deformations like elongating, contracting, bending, twisting, spiraling, etc. Further, we redesign and fabricate the three-dimensional (3D) printable structures of origami flexiballs considering their 3D printability and foldability, and magnetically actuated them through the attachment of magnetoactive elastomer. Lastly, a fully soft in-pipe robot prototype is presented using the origami flexiball as an applicable attempt. Experimental work clearly suggests that the presented origami flexiball robot has good adaptability to various pipe sizes, and also can be easily expanded to different scales, or reconfigured into more complex metastructures by assembly. In conclusion, this research provides a newly interesting and illuminating member for the emerging families of mechanical metamaterials, soft actuators and soft robots.

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Kitayama, F., and R. Kondo. "Development of a two degrees-of-freedom linear oscillatory actuator for vibration control." Nanotechnology Perceptions 15, no. 3 (October 30, 2019): 212–19. http://dx.doi.org/10.4024/n23ki19a.ntp.15.03.

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Xie, Qing, Tao Wang, Shengda Yao, Zhipeng Zhu, Ning Tan, and Shiqiang Zhu. "Design and modeling of a hydraulic soft actuator with three degrees of freedom." Smart Materials and Structures 29, no. 12 (November 14, 2020): 125017. http://dx.doi.org/10.1088/1361-665x/abc26e.

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SASAE, Keisuke, Kiyoshi TOI, Yasuo OHTSUKI, and Yoshimitsu KUROSAKI. "Development of a Small Actuator with Three Degrees of Rotational Freedom (1st Report)." Journal of the Japan Society for Precision Engineering 61, no. 3 (1995): 386–90. http://dx.doi.org/10.2493/jjspe.61.386.

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SASAE, Keisuke, Kiyoshi IOI, Yasuo OHTSUKI, and Yoshimitsu KUROSAKI. "Development of a Small Actuator with Three Degrees of Rotational Freedom (2nd Report)." Journal of the Japan Society for Precision Engineering 61, no. 4 (1995): 532–36. http://dx.doi.org/10.2493/jjspe.61.532.

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SASAE, Keisuke, Kiyoshi IOI, Yasuo OHTSUKI, and Yoshimitsu KUROSAKI. "Development of a Small Actuator with Three Degrees of Rotational Freedom (3rd Report)." Journal of the Japan Society for Precision Engineering 62, no. 4 (1996): 599–603. http://dx.doi.org/10.2493/jjspe.62.599.

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Journal articles on the topic 'Degrees-of-freedom actuator'

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