Journal articles: 'Degree of Freedom (DoF)'

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Akinin, K. P., V. G. Kireyev, І. S. Petukhov, and A. A. Filomenko. "THREE-DEGREE-OF-FREEDOM ELECTRIC MACHINE AND ITS OPERATION MODES." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini 2023, no. 66 (December 4, 2023): 132–43. http://dx.doi.org/10.15407/publishing2023.66.132.

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This paper deals with the operating modes of a 3-degree-of-freedom (3-DOF) electric machine. The design of such a machine allows the rotor axis to rotate along two angular coordinates in a limited range of angles. This is necessary for the machine to operate as part of a small-sized, high-speed precision target detection and tracking system. Based on the 3-DOF machine dynamics model, a block diagram of a servo system has been developed for controlling the rotor motion trajectory at two coordinates. Examples are given of the implementation of rotor motion trajectories with linearly increasing Examples are given of the implementation of rotor motion trajectories with linearly increasing, as well as described by an Archimedes spiral reference signals described by an Archimedes spiral reference signals. Dependencies of the modules of the relative accuracy of rotor movement along given trajectories on the system tunings were obtained. Ref. 12, fig. 9, table. Keywords: control system, motion trajectories, three-degree-of-freedom electric machine.

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Akinin, K. P., and V. G. Kireyev. "TWO- DEGREE-OF-FREEDOM ELECTRIC MACHINE AND ITS OPERATION MODES." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini 2023, no. 65 (August 28, 2023): 145–54. http://dx.doi.org/10.15407/publishing2023.65.145.

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This paper is devoted to the problems of developing an electric machine with two-degrees-of-freedom (2-DOF) of rotor movement and its control system. The structure of the machine with the possibility of rotation of the rotor along two angular coordinates in a limited range of rotation angles is considered. The machine is designed to control the position of the axis of the optical beam along the line and frame trajectories. Based on the electrodynamic state model of the 2-DOF electric machine, a block diagram of the servo system was developed to control the trajectory of the rotor in two coordinates. Relationships between the time constant of the angle controller and the time constants of the high-frequency part of the amplitude-frequency characteristic of an open-loop system are determined. The dependences of the effective values of the currents in the control windings on the frequency of the frames and the duration of the linear part of the triangular signal are obtained. The dependences of the modules of relative accuracy of the rotor movement along a given trajectories on the system tunings are obtained. Ref. 12, fig. 8. Key words: two-degree-of-freedom electric machine, control system, scanning device, line trajectory, frame trajectory.

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Reddy, B. Nithin. "Mechanical Design and Analysis of Six-Degree-of-Freedom (6-DOF) SCARA Robot for Industrial Applications." International Journal for Research in Applied Science and Engineering Technology 12, no. 4 (April 30, 2024): 6080–87. http://dx.doi.org/10.22214/ijraset.2024.59008.

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Abstract: A six-degree-of-freedom (6-DOF) SCARA robot is an advanced robotic system capable of moving and manipulating objects in a three-dimensional space with a high degree of precision and flexibility. The term "SCARA" stands for "Selective Compliance Articulated Robot Arm," indicating its design that allows a combination of rigidity and compliance along specific axes. This unique combination of features makes 6-DOF SCARA robots highly versatile and suitable for a wide range of industrial applications. Unlike traditional SCARA robots that typically have four degrees of freedom, the addition of two extra degrees of freedom enhances the 6-DOF SCARA robot's spatial reach and manipulation capabilities. This enables the robot to perform tasks that require complex orientations, intricate movements, and precise positioning within a 3D workspace. The mechanical design, kinematics, and control strategies of these robots are carefully developed to ensure accurate and efficient performance, making them valuable tools in various industries. 6-DOF SCARA robots find applications in numerous industries where precise manipulation, efficient automation, and versatile positioning are crucial.

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Liu, Yong Qiu, Ying Xin Zhai, and Xiao Feng Liu. "Dynamic Characteristics Analysis of Simulator Six-DOF Platform." Applied Mechanics and Materials 651-653 (September 2014): 716–19. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.716.

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Six degrees of freedom motion platform is an important part of the flight simulator. To study the dynamic characteristics of the simulator, the paper carried a six degree of freedom motion platform dynamics analysis, and proposed fuzzy PID control strategy, and through the ADAMS software to establish a simulation model of six degrees of freedom motion platform, simulation results show that the use of strategy has good control effect for the simulator is designed to provide some reference.

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Liu, Xiao Bo, Xiao Dong Yuan, Xiao Feng Wei, and Wei Ni. "A Novel 3-DOF Parallel Robot and its Kinematic Analysis." Applied Mechanics and Materials 607 (July 2014): 759–63. http://dx.doi.org/10.4028/www.scientific.net/amm.607.759.

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This paper deals with the design and analysis of a novel and simple two-translation and one-rotation (3 degrees of freedom, 3-dof) mechanism for alignment. Firstly, degree of freedom of the parallel robot is solved based on the theory of screw. Secondly considering the demand of motion control, we have conducted the analysis on the 3-dof parallel robot, which includes inverse displacement, forward displacement, and simulation based on SolidWorks Motion. The simulation results indicate that the novel 3-dof robot is suitable for performing the required operations.

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Tsai, Lung-Wen, and Chen-Chou Lin. "The Creation of Nonfractionated, Two-Degree-of-Freedom Epicyclic Gear Trains." Journal of Mechanisms, Transmissions, and Automation in Design 111, no. 4 (December 1, 1989): 524–29. http://dx.doi.org/10.1115/1.3259033.

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To date, most of the multi-DOF (degree-of-freedom) epicyclic gear trains have been used as a series of one-DOF devices. Comparatively little is known with regard to the existence and synthesis of nonfractionated, epicyclic gear trains. This paper presents a systematic methodology for the identification and enumeration of the kinematic structure of nonfractionated, two-DOF epicyclic gear trains. It has been shown that there exists no such gear trains with five or less links. It has also been shown that there exist two nonisomorphic rotation graphs of six vertices and twenty nonisomorphic rotation graphs of seven vertices. An atlas of nonisomorphic displacement graphs which can be used to construct nonfractionated, two-DOF epicyclic gear trains with six and seven links has been developed. It is hoped that this atlas will lead to more optimum and efficient designs of machines with multiple actuating requirements such as robotic wrists, grippers, and walking machines.

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Wang, Shengtong, Linbin Luo, Junhao Zhu, Ningning Shi, and Xinghui Li. "An Ultra-Precision Absolute-Type Multi-Degree-of-Freedom Grating Encoder." Sensors 22, no. 23 (November 22, 2022): 9047. http://dx.doi.org/10.3390/s22239047.

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An absolute-type four-degree-of-freedom (four-DOF) grating encoder that can simultaneously measure the three-axis pose (θx, θy, θz) and one-axis out-of-plane position (Z) of an object with high accuracy is demonstrated for the first time in this research. This grating encoder is composed of a stationary reading head and a movable grating reflector. A light beam from the reading head is projected onto the grating, and three diffracted beams (0th-, +1st-, and −1st-order) are generated, collimated, and received by three separate quadrant photodetectors (QPDs). The information of θx, θy, θz, and Z is coded into spot positions of these three diffracted beams on the QPDs. Thus, the modeling and decoupling algorithms were investigated, and an independent calculation of these four-DOF absolute positions was theoretically guaranteed. A prototype was then designed, constructed, and evaluated. Experimental results verified that the proposed grating encoder could achieve the absolute measurement of four-DOF θx, θy, θz, and Z with an accuracy of sub-arcseconds and sub-micrometers. To the best of our knowledge, the proposed encoder in this research is the first one to achieve absolute simultaneous measurements of four-DOF position and pose with a large measurement range. The success of this new grating encoder can benefit various multi-DOF positioning applications, especially for large-scale synthetic aperture optics (SAO), including stitching off-axis parabolic mirrors and pulse compression grating.

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Jiang, Yuchen, Jun Fu, Bao Li, and Pengfei Jiang. "Distributed Sensitivity and Critical Interference Power Analysis of Multi-Degree-of-Freedom Navigation Interference for Global Navigation Satellite System Array Antennas." Sensors 24, no. 2 (January 19, 2024): 650. http://dx.doi.org/10.3390/s24020650.

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Current research on the interference of GNSS (Global Navigation Satellite System) array antennas focuses on the single interference effect and the improvement of interference hardware capability, while the multi-degree-of-freedom (DOF) interference model and mechanism remain to be fully studied. Aiming at this problem, this paper analyzes the preconditions for the definition of anti-jamming degrees of freedom and the characteristics of super-DOF interference through formula derivation and simulation. First, by analyzing the influence of the number of interfering signals on the angular resolution, the prerequisite of the definition of anti-interference degrees of freedom in the airspace is proposed. Second, the definition of anti-interference degrees of freedom is used to calculate the change rule of the critical power of the interference under different numbers of interfering signals. Finally, the influence of super-DOF interference on the array antenna is analyzed. The results show that the prerequisite for the anti-interference freedom of the array antenna is that the distribution interval of the interfering signal is greater than 15°, taking a four-array element uniform circular array antenna as an example. The critical interference power of the array antenna decreases by about 15 dB when the number of interfering signals exceeds the degrees of freedom of the array antenna’s interference immunity, provided that the interference resolution is satisfied. The conclusions of this paper give the critical power change rule of multi-DOF interference and the effect of super-DOF interference, as well as the prerequisites for the setting of interference signals, which can be used, for example, in the deployment of distributed interference sources and the development of anti-jamming algorithms.

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Liu, Ping, Tao Deng, Zhenhua Su, Lu Jiang, and Zhentao Ding. "Design, control and optimization of multi-degree-of-freedom spherical induction motor." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 236, no. 2 (December 11, 2021): 778–94. http://dx.doi.org/10.1177/09544062211000792.

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In order to meet the requirements of multi-degree-of-freedom (multi-DOF) driving units for omnidirectional vehicle wheels, a multi-DOF spherical induction motor (SIM) is proposed with composite rotor through the conversion of design concept of linear induction motor (LIM), which compensates for the insufficiency of traditional multi-DOF driving scheme with structural complexity, control difficulties and poor dynamic performance. The SIM realizes two DOF driving and has the characteristics of direct output on rotor surface. Firstly, the overall design of SIM is drafted, as well as finite element model and control system are established. Subsequently, in order to optimize SIM performance, the multi-objective optimization design of composite rotor structure is proposed by adopting non-dominated sorting genetic algorithm-II (NSGA-II). The results show that the reasonable design of rotor structure can effectively improve output torque and reduce fluctuation. And the proposed design idea based on theory of LIM can provide a reference for SIM design.

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Huang, Qingqing, Guanwei He, Guodong Feng, and Beichen Ding. "A Novel Cooperative Control Strategy for Three-Degree-of-Freedom Pneumatic Parallel Mechanism." Actuators 13, no. 3 (February 26, 2024): 89. http://dx.doi.org/10.3390/act13030089.

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The three-degree-of-freedom (3-DoF) parallel mechanism (PM) is widely used due to its simple structure and ability to avoid coupling problems commonly found in high-DoF PMs. The conventional control approach is usually independent control for each branch of the mechanism using a PID controller, without considering the consistency among branches. This paper proposes a novel cooperative control strategy for the 3-DoF PM to achieve both synchronized and differential motion. A pneumatic actuated test rig was constructed to validate the effectiveness of the cooperative controller. The results demonstrate our control approach outperforms the PID controller. Our self-designed platform is functional and intuitive, which can be regarded as a control scheme test bench for a 3-DoF PM.

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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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Sun, Yu, Jinsong Zhou, Dao Gong, and Yuanjin Ji. "Study on multi-degree of freedom dynamic vibration absorber of the car body of high-speed trains." Mechanical Sciences 13, no. 1 (March 17, 2022): 239–56. http://dx.doi.org/10.5194/ms-13-239-2022.

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Abstract. To absorb the vibration of the car body of the high-speed train in multiple degrees of freedom, a multi-degree of freedom dynamic vibration absorber (MDOF DVA) is proposed. Installed under the car body, the natural frequency of the MDOF DVA from each DOF can be designed as a DVA for every single degree of freedom of the car body. Hence, a 12-DOF model including the main vibration system and an MDOF DVA is established, and the principle of Multi-DOF dynamic vibration absorption is analyzed by combining the design method of a single DVA and genetic algorithm. Based on a high-speed train dynamics model including an under-car-body MDOF DVA, the vibration control effect on each DOF of the MDOF DVA is analyzed by the virtual excitation method. Moreover, a high static and low dynamic stiffness (HSLDS) mount is proposed based on a cam–roller–spring mechanism for the installation of the MDOF DVA due to the requirement of the low vertical dynamic stiffness. From the dynamic simulation of a non-linear model in the time domain, the vibration control performance of the MDOF DVA installed with a nonlinear HSLDS mount on the car body is analyzed. The results show that the MDOF DVA can absorb the vibration of the car body in multiple degrees of freedom effectively and improve the running ride quality of the vehicle.

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Yoneda, Kan, Yusuke Ota, Fumitoshi Ito, and Shigeo Hirose. "Quadruped Walking Robot with Reduced Degrees of Freedom." Journal of Robotics and Mechatronics 13, no. 2 (April 20, 2001): 190–97. http://dx.doi.org/10.20965/jrm.2001.p0190.

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We advocate the effectiveness of a walking robot to have a structure with a reduced DOF, not based on a model of real animals, to make the robot lightweight and practical, and discuss a technique for reducing the active degrees of freedom (DOF) of a quadruped walking robot as an example for realizing such objectives. If functions required of a quadruped walking robot are properly organized and the required active DOF is examined, 4 active DOF make it possible to select an arbitrary position on uneven terrain and to move in all directions. We describe a mechanism with 4 active DOF and 2 passive DOF as an example of concrete configurations for quadruped walking robots with 4 active DOF. A robot with a reduced active DOF, namely with 3 active DOF and 2 passive DOF, has a capability to reach an arbitrary position at an arbitrary angle on uneven terrain. An actual mechanical model was manufactured as an experimental model, and a walking experiment was conducted. The mechanical model turned out to be about one-4th in weight compared to a conventional biomimetic model of the same size. Based on the walking experiment, it was confirmed that this mechanical model can carry a load up to 4 times its own weight.

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Liu, Chien-Sheng, Yi-Hsuan Lin, and Chiu-Nung Yeh. "Analytical Investigation on Torque of Three-Degree-of-Freedom Electromagnetic Actuator for Image Stabilization." Applied Sciences 11, no. 15 (July 26, 2021): 6872. http://dx.doi.org/10.3390/app11156872.

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In keeping with consumers’ preferences for electromagnetic motors of ever smaller power consumption, it is necessary to improve the power efficiency of the electromagnetic motors used in unmanned aerial vehicles and robots without sacrificing their performance. Three-degree-of-freedom (3-DOF) spherical motors have been developed for these applications. Accordingly, this study modifies the 3-DOF spherical motor proposed by Hirata’s group in a previous study (Heya, A.; Hirata, K.; Niguchi, N., Dynamic modeling and control of three-degree-of-freedom electromagnetic actuator for image stabilization, IEEE Transactions on Magnetics 2018, 54, 8207905.) to accomplish a 3-DOF spherical motor for camera module with higher torque output in the large rotation angle. The main contribution of this study is to improve the static torque in the X- and Y-axes with an improved electromagnetic structure and a particular controlling strategy. In the structural design, eight symmetrical coils with specific coil combination are used instead of conventional four symmetrical coils. In this study, the development of the proposed 3-DOF spherical motor was constructed and verified by using a 3D finite-element method (3D FEM). The simulation results show that the proposed 3-DOF spherical motor has higher torque output in the large rotation angle when compared to the original 3-DOF spherical motor.

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Hale, Michael. "A 6-DOF Vibration Specification Development Methodology." Journal of the IEST 54, no. 2 (October 1, 2011): 103–15. http://dx.doi.org/10.17764/jiet.54.2.j6tr2r787846931n.

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Multiple degree of freedom (MDOF) excitation systems and MDOF vibration control systems continue to improve, and are now standard equipment in many dynamic test laboratories. This paper concentrates on the often overlooked process of determination of an input specification for such MDOF systems. A pair of generalized six-degree-of-freedom (6-DOF) vibration specification development (VSD) techniques are proposed, discussed, and illustrated through an example.

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Iwaki, S. "The Optimal Location of Electromagnets in Multiple Degree-of-Freedom Magnetically Suspended Actuators." Journal of Dynamic Systems, Measurement, and Control 112, no. 4 (December 1, 1990): 690–95. http://dx.doi.org/10.1115/1.2896196.

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This paper discusses a systematic design approach to the optimal location of electromagnets in a multiple degree-of-freedom (DOF) magnetically suspended actuator (MSA). An electromagnet location matrix is defined from the geometrical arrangement. Three design conditions for the optimal location are proposed and their criteria are formulated. These conditions are (1) arbitrarily manipulating the controlled body by electromagnets which actuate only in the attractive direction, (2) mechanically decoupling the linearized MSA dynamics, and (3) being robust against the nonlinearity of electromagnets. Simulation results for a simple 3-DOF model are given to confirm the validity of these conditions. An optimal design for a practical 6-DOF model is also included.

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Guo, Yan, Haobo Cheng, and Gang Liu. "Three-degree-of-freedom autocollimation angle measurement method based on crosshair displacement and rotation." Review of Scientific Instruments 94, no. 1 (January 1, 2023): 015108. http://dx.doi.org/10.1063/5.0126806.

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The classic autocollimation method manages to measure the two-degree-of-freedom (2-DOF) angles, namely pitch and yaw, but fails to measure the roll angle. This paper proposes an autocollimation method that enables the simultaneous measurement of 3-DOF angles in which a carefully designed cooperated reflector (CR) splits the collimated beam into two returning beams parallel to the optical axis. The 3-DOF angles of the CR can be obtained by detecting the displacement and rotation of the crosshair images received by two photodetectors. The measurement principle is dissected, and the experimental results reveal that the constructed system achieves an accuracy of better than ±1.54 arcsec in the range of ±1000 arcsec. In addition, it is demonstrated that the system can be applied to the 3-DOF angle measurement of long-distance targets.

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Chou, Po Huan, Faa Jeng Lin, Chin Sheng Chen, and Feng Chi Lee. "Three-Degree-of-Freedom Dynamic Model Based IT2RFNN Control for Gantry Position Stage." Applied Mechanics and Materials 416-417 (September 2013): 554–58. http://dx.doi.org/10.4028/www.scientific.net/amm.416-417.554.

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A three-degree-of-freedom (3-DOF) dynamic model based interval type-2 recurrent fuzzy neural network (IT2RFNN) control system is proposed in this study for a gantry position stage. To consider the effect of inter-axis mechanical coupling, a Lagrangian equation based 3-DOF dynamic model for gantry position stage is derived first. Then, to minimize the synchronous error and tracking error of the gantry position stage, the 3-DOF dynamic model based IT2RFNN control system is proposed. In this approach, the adaptive learning algorithms of the IT2RFNN on-line are derived from the Lyapunov stability theorem. Finally, some experimental results of optical inspection application are illustrated to show the validity of the proposed control approach.

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Ikeda, Keigo, Kota Kamimori, Ikkei Kobayashi, Jumpei Kuroda, Daigo Uchino, Kazuki Ogawa, Ayato Endo, et al. "Basic Study on Mechanical Vibration Suppression System Using 2-Degree-of-Freedom Vibration Analysis." Vibration 6, no. 2 (May 1, 2023): 407–20. http://dx.doi.org/10.3390/vibration6020025.

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Mechanical vibrations adversely affect mechanical components, and in the worst case, lead to serious accidents by breaking themselves. To suppress vibrations, various studies have been conducted on vibration isolation, suppression, and resistance. In addition, technologies to actively suppress vibration have been rapidly developed in recent years, and it has been reported that vibrations can be suppressed with higher performance. However, these studies have been conducted mostly for low-order systems, and few studies have employed control models that consider the complex vibration characteristics of multi-degree-of-freedom (DOF) systems. This study is a basic study that establishes a control model for complex control systems, and the vibration characteristics of a 2-DOF system are calculated using the vibration analysis of a multi-DOF system. Furthermore, the vibration suppression performance of the 2-DOF system is investigated by performing vibration experiments.

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Kim, Gyunam, and Katsuhiro Hirata. "Motion Control of a Two-Degree-of-Freedom Linear Resonant Actuator without a Mechanical Spring." Sensors 20, no. 7 (March 31, 2020): 1954. http://dx.doi.org/10.3390/s20071954.

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This study aims to present a new two-degree-of-freedom (DOF) linear resonant actuator (LRA) and its motion control method without a position sensor. The design method of 2-DOF LRA which resonates with only detent force without a mechanical spring is proposed. Since the information of displacement and direction is required to control 2-DOF LRA, a sensor or an estimator is needed. Therefore, we proposed a position estimator and a motion controller for 2-DOF LRA. This paper proved that reciprocating motion, elliptical motion, and scrolling motion can be controlled without a position sensor. Finite element analysis (FEA) and dynamic simulation results validated the proposed method as well.

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Nurahmi, Latifah, and Stéphane Caro. "Type Synthesis of Two DOF Hybrid Translational Parallel Manipulators." Applied Mechanics and Materials 836 (June 2016): 48–53. http://dx.doi.org/10.4028/www.scientific.net/amm.836.48.

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This paper introduces a methodology for the type synthesis of two degree-of-freedom hybrid translational manipulators with identical legs. The type synthesis method is based upon the screw theory. Three types of two degree-of-freedom hybrid translational manipulators with identical legs are identified based upon their wrench decomposition. Each leg of the manipulators is composed of a proximal module and a distal module mounted in series. The assembly conditions and the validity of the actuation scheme are also defined. Eventually, some novel two degree-of-freedom hybrid translational manipulators are synthesized with the proposed procedure.

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Teppa, Pedro, Miguel FAGGIONI, and Germain GARCIA. "Optimal tracking in two-degree-of-freedom control systems: Coupled tank system." Journal of Applied Research and Technology 21, no. 4 (August 31, 2023): 560–70. http://dx.doi.org/10.22201/icat.24486736e.2023.21.4.2000.

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This article presents an optimal design of a two-degree-of-freedom (2-DoF) controller that will lead to zero asymptotic steady-state tracking error. The reference inputs are chosen from the set of steps, ramps, and other persistent signals used currently. The main idea is to transform the tracking 2-DoF problem into an equivalent state-space feedback-control synthesis one. Where, an internal model of the reference input is introduced. Then, through the linear quadratic regulator (LQR) technique, the desired performance objectives are addressed by minimizing a quadratic cost function. Finally, the computed state-feedback optimal gains are linked to the polynomials used within the 2-DoF formalism. The fundamental aspect of the design is that it only utilizes the measurable information of the plant provided by its inputs and outputs and take advantage of efficient state-space numerical algorithms. The proposed method is applied to a coupled-tank system, the results achieved confirm the effectiveness of the approach.

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Wei, B., F. Gao, J. Chen, J. He, S. Wu, and Q. Song. "Mechanics performance of three-degree-of-freedom excavating mechanism of an electric shovel." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 6 (May 25, 2011): 1443–57. http://dx.doi.org/10.1177/2041298310395451.

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Electric shovel is one of the most important equipment in surface-mining operations. The medium–tool interaction model is an essential basis in the process of machine design. Therefore, it is important to make the model accurate compared to the actual situation. This article proposes a new medium–tool interaction model based on the analysis of medium–tool interaction mechanism taking into account the actual excavating process. The result of the new model is quite in agreement with the full-scale tests. In order to make the excavating process more efficient, the traditional two-degree-of-freedom (DOF) excavating mechanism is redesigned and a new three-DOF excavating mechanism is obtained. A new electric shovel with three-DOF excavating mechanism is more flexible in that it will perform the excavation process with a favourable excavating angle that can reduce the resistance force involved in medium–tool interaction. Based on the new medium–tool interaction model, the dynamic model of the three-DOF excavating mechanism is established for the mechanics performance analysis. The numeric validation shows that the new excavating mechanism is more efficient in the excavating process.

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Wu, Han, Zhengping Wang, Zhou Zhou, and Rui Wang. "Establishment and Simulation of Twelve-Degree-of-Freedom Model for UAV Parachute Recovery System." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 1 (February 2020): 68–74. http://dx.doi.org/10.1051/jnwpu/20203810068.

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In the UAV parachute recovery process, the UAV and the parachute have always been in the state of dynamic balance, so it is difficult to deal with the constraint between them. In order to solve this problem, the UAV parachute recovery system was divided into three parts:the parachute, riser and UAV. The extension length of riser was obtained by the velocity relationships of the riser connection points. The riser tension was obtained by the product of the elastic coefficient and the extension length of the riser. And it was applied to the parachute and UAV systems respectively. Finally, based on the Newton-Euler equation, the 12-DOF model of UAV parachute recovery system was established, in which the unsteady aerodynamic model of the UAV from the forward flight to the steady descents was established based on the ONERA equation. The simulation and test results shows:the 12-DOF model is consistent with the results of the experimental data, which verifies the accuracy of the 12-DOF model. The 12-DOF model is more accurate than the past 6-DOF model. This model established in this paper can provide reference for the selection of parachute in the UAV parachute recovery system and the determination of the landing point of the UAV.

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Li, Chao, and Jian Qin Mao. "Adaptive Vibration Control on Six Degree-of-Freedom Magnetostrictive Smart Structure." Materials Science Forum 546-549 (May 2007): 2199–204. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.2199.

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Multiple degree-of-freedom (DOF) vibration isolation is essential for precision control of space-borne structures and weapon systems. A new design and analysis of actuators employing magnetostrictive material TbDyFe is presented. Then, this paper studies the design and control problems of a six DOF Stewart platform using the concept of cubic configuration. Optimal geometry for the sensor configuration to get best signal is designed. To control the smart structure, a real time computer control system is built. Improved robust adaptive filtering algorithm based on nonlinear constitutive relation proposed in this paper and used in the computer control system. More than 20 dB of vibration attenuation is achieved in real-time experiments.

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Prusak, Daniel, Konrad Kobus, and Grzegorz Karpiel. "Kinematics Analysis of a Novel Five-Degree-of-Freedom Spatial Parallel Micromanipulator." Journal of Robotics 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/806294.

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A study of the inverse kinematics for a five-degree-of-freedom (DOF) spatial parallel micromanipulator is presented here below. The objective of this paper is the introduction of a structural and geometrical model of a novel five-degree-of-freedom spatial parallel micromanipulator, analysis of the effective and useful workspace of the micromechanism, presentation of the obtained analytical solutions of the microrobot’s inverse kinematics tasks, and verification of its correctness using selected computer programs and computation environments. The mathematical model presented in this paper describes the behaviour of individual elements for the applied 2-DOF novel piezoelectric actuator, resulting from the position and orientation of the microrobot’s moving platform.

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Hao, Guangbo, and Haiyang Li. "Conceptual designs of multi-degree of freedom compliant parallel manipulators composed of wire-beam based compliant mechanisms." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 3 (May 15, 2014): 538–55. http://dx.doi.org/10.1177/0954406214535925.

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This paper proposes conceptual designs of multi-degree(s) of freedom (DOF) compliant parallel manipulators (CPMs) including 3-DOF translational CPMs and 6-DOF CPMs using a building block based pseudo-rigid-body-model (PRBM) approach. The proposed multi-DOF CPMs are composed of wire-beam based compliant mechanisms (WBBCMs) as distributed-compliance compliant building blocks (CBBs). Firstly, a comprehensive literature review for the design approaches of compliant mechanisms is conducted, and a building block based PRBM is then presented, which replaces the traditional kinematic sub-chain with an appropriate multi-DOF CBB. In order to obtain the decoupled 3-DOF translational CPMs (XYZ CPMs), two classes of kinematically decoupled 3-PPPR (P: prismatic joint, R: revolute joint) translational parallel mechanisms (TPMs) and 3-PPPRR TPMs are identified based on the type synthesis of rigid-body parallel mechanisms, and WBBCMs as the associated CBBs are further designed. Via replacing the traditional actuated P joint and the traditional passive PPR/PPRR sub-chain in each leg of the 3-DOF TPM with the counterpart CBBs (i.e. WBBCMs), a number of decoupled XYZ CPMs are obtained by appropriate arrangements. In order to obtain the decoupled 6-DOF CPMs, an orthogonally-arranged decoupled 6-PSS (S: spherical joint) parallel mechanism is first identified, and then two example 6-DOF CPMs are proposed by the building block based PRBM method. It is shown that, among these designs, two types of monolithic XYZ CPM designs with extended life have been presented.

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Cai, Shan Le, Wen Tao Huang, and Li Bin Peng. "The Kinematic Modeling of a 2-DOF Rotational Parallel Fixture." Advanced Materials Research 605-607 (December 2012): 1465–68. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1465.

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Put forward a kind of 2 dof parallel fixture. The moving platform of the fixture has two rotational degrees of freedom relative to the fixed platform. Do the institutional analysis and its degree of freedom calculation. Study the kinematics modeling method, and carry out an analysis on forward and inverse solutions of its positions. The new parallel fixture will have wide appli¬ca¬tion in the field of machining.

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Ren, Hai Ying, Yuan An Liu, Fang Liu, Jin Chun Gao, Kai Ming Liu, and Gang Xie. "The Degrees of Freedom for MIMO Interference Broadcast Channels with no CSIT." Advanced Materials Research 1049-1050 (October 2014): 1776–80. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1776.

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Multiple-input multiple-output (MIMO) interference broadcast channel (IBC) plays an important role in the modern wireless communications. The upper bound of degree of freedom (DoF) and corresponding achievable schemes have been investigated. However, all the achievable schemes require perfect channel state information at transmitters (CSIT). In the absence of CSIT, the DoF value is still unknown. This paper mainly focuses on theG-cellK-user MIMO IBC, where there areMantennas at each transmitter andNantennas at each receiver. The transmitters only know channel coherent time internals rather than the values of channel coefficients. The users in the same cell are assumed to be able to share the channel information. Based on a heterogeneous block fading model, a blind interference alignment (IA) scheme is proposed for this scenario. We show that when and , then a total of degrees of freedom (DoF) can be achieved. The inner bound is same with the decomposition DoF upper bound.

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30

Bi, Meng. "Control of Robot Arm Motion Using Trapezoid Fuzzy Two-Degree-of-Freedom PID Algorithm." Symmetry 12, no. 4 (April 23, 2020): 665. http://dx.doi.org/10.3390/sym12040665.

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Symmetries play very important in the dynamics of robot systems. The relevant control of robot arm motion with fault diagnosis including the optimized fuzzy algorithm based on the error rate adjustment P, I, D value (Fuzzy PID algorithm) model relies on symmetry principles. A robot is a kind of mechanical device that can program and perform certain operations and mobile tasks under automatic control. The manipulator is a very complex multi-input multi-output non-linear system and the main actuator of the robot. This paper focuses on the design of a control algorithm for a two-degree-of-freedom (2-DOF) manipulator. First, the mathematical model of a 2-DOF articulated manipulator is established, that is, the functional relationship between the input driving force vector and the output rotation angle vector of a 2-DOF manipulator. Then, a set of trajectory planning algorithms are designed by using gradient model control, which can calculate the trajectory of the end-effector of a 2-DOF manipulator according to the user’s task requirements. The experimental results verify the effectiveness of the proposed algorithm.

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Meng, Xiangxu, Siwei Sun, Xuetao Yan, Fengman Liu, Liqiang Cao, Qidong Wang, and Yu Sun. "Six-Degree-of-Freedom Posture Measurement Technologies Using Position Sensitive Detectors (PSDs): State of the Art." Micromachines 13, no. 11 (November 3, 2022): 1903. http://dx.doi.org/10.3390/mi13111903.

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Six degree-of-freedom (6-DOF) posture measurement is an important academic research topic which has been broadly applied in many fields. As a high-speed photoelectronic sensor with ultra-high resolution and precision, position sensitive detector (PSD) has shown to be one of the most competitive candidates in 6-DOF measurement. This review presents the research progress of PSD-based 6-DOF posture measurement systems in the field of large-scale equipment assembly, ultra-precision manufacturing and other emerging areas. A total of six methods for implementing 6-DOF measurement are summarized and their advantages and limitations are discussed. Meanwhile, the paper illustrates challenges, potential solutions and future development trends.

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Zhang, Dan, and Fan Zhang. "Design and analysis of a 3-DOF spherical parallel manipulator – CORRECTED VERSION." Robotica 29, no. 7 (September 1, 2011): 1109–16. http://dx.doi.org/10.1017/s0263574711000592.

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SUMMARYIn this paper, we propose a unique, 3 degree-of-freedom (DOF) parallel wrist. Specifically, an over-constrained spherical 3-DOF parallel mechanism is presented and the modified structure, which avoids the redundant constraints, is also introduced.

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Sgobbo, Jerrold N., and Michael G. Parsons. "Rudder/Fin Roll Stabilization of the USCG WMEC 901 Class Vessel." Marine Technology and SNAME News 36, no. 03 (July 1, 1999): 157–70. http://dx.doi.org/10.5957/mt1.1999.36.3.157.

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The U.S. Coast Guard's 270-ft Medium Endurance Cutter (WMEC) operates with an active fin stabilization system. This system was designed using a one-degree-of-freedom (1-DOF) model in the roll direction. The controller was designed separate from the heading autopilot. The effects of the rudders and their ability to produce a significant rolling moment were also neglected as well as the cross coupling of roll motions into other degrees of freedom. This paper studies the effects of the rudders on the rolling motion of the ship using a three-degree-of-freedom (3-DOF) model. A simple optimal heading autopilot is designed and combined with the existing fin roll controller to investigate the effects of the rudders on the roll motions of this class of vessel. A rudder roll controller and a multiple input-multiple output (MIMO) rudder/fin controller are designed as well. Significant roll reduction can be achieved using the MIMO rudder/fin controller.

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34

Priadythama, Ilham, Wen Liang Yeoh, Ping Yeap Loh, and Satoshi Muraki. "The Effect of the Degree of Freedom and Weight of the Hand Exoskeleton on Joint Mobility Function." Robotics 11, no. 2 (April 18, 2022): 53. http://dx.doi.org/10.3390/robotics11020053.

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This study aims to investigate the effects of the degree of freedom (DOF) and weight of the hand exoskeleton (HE) on hand joint mobility function (ease of movement, movement range) in fine hand use activities. A three-digit passive HE prototype was built to fit each of the 12 participants. Two DOF setups (three DOF, two DOF), two digits’ weight levels (70 g, 140 g), and barehand conditions were tested. A productivity task (performed with Standardized-Nine Hole Peg Test) and motion tasks, both performing the tip pinch and tripod pinch, were conducted to measure the task completion time and the range of motion (ROM) of the digit joints, respectively, using a motion capture system. The perceived ease rating was also measured. The results showed that DOF reduction and weight addition caused a significant task completion time increase and rating drop (p < 0.05). Meanwhile, the DOF reduction increased the ROM reduction of the proximal interphalangeal joints; however, the weight addition caused a correction of the ROM reduction of several joints (p < 0.05) at the tripod pinch. In conclusion, wearing an HE reduces hand joint mobility, especially in lower DOF. However, a certain weight addition may improve joint mobility in terms of the fingers’ movement range.

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Hale, Michael, and Jesse Porter. "Validation Techniques for 6-DOF Vibration Data Acquisition." Journal of the IEST 55, no. 1 (October 1, 2012): 10–24. http://dx.doi.org/10.17764/jiet.55.1.27662m34h12v32p6.

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Multiple Degree of Freedom (MDOF) excitation systems and MDOF vibration control systems continue to improve, and are now standard equipment in many dynamic test laboratories. Determination of an input specification for such MDOF systems is critically dependent on properly acquired field data. Validation of field data will be discussed and demonstrated employing the same transformation tools used in both transformation-based 6-degree-of-freedom (6-DOF) vibration control and generalized MDOF vibration specification development (VSD).

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36

Kim, Whee-kuk, Byung-Ju Yi, and Whang Cho. "RCC Characteristics of Planar/Spherical Three Degree-of-Freedom Parallel Mechanisms With Joint Compliances." Journal of Mechanical Design 122, no. 1 (January 1, 2000): 10–16. http://dx.doi.org/10.1115/1.533541.

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A three degree-of-freedom (DOF) planar parallel manipulator has been extensively studied as the fundamental example of parallel manipulators. In this work, we explicitly show that this mechanism possesses a completely decoupled compliance characteristic at the object space, which is the important operational requirement for a RCC device. As the first condition to have a RCC point, this mechanism should maintain symmetric configurations. As the second condition, the same magnitude of revolute joint compliance should be symmetrically placed at the same joint location of each chain. We also investigate the compliance characteristics of a spherical 3 DOF mechanism which has a similar kinematic structure to the planar mechanism through simulation. It turns out that the spherical mechanism also has a RCC point at the intersection point of all nine joint axes in its symmetric configuration. Further, more general output compliance model is derived for those mechanisms with redundant joint compliances. It is expected that these two parallel mechanisms not only can be used as excellent 3 DOF RCC devices, but also can be integrated into the design of a new six DOF RCC device. [S1050-0472(00)01101-6]

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37

Heya, Akira, and Katsuhiro Hirata. "Sensorless attitude estimation of three-degree-of-freedom actuator for image stabilization." International Journal of Applied Electromagnetics and Mechanics 66, no. 2 (June 11, 2021): 249–63. http://dx.doi.org/10.3233/jae-201537.

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Space recognition is a crucial issue for autonomous systems such as unmanned aerial vehicles, walking robots, and autonomous cars. These systems are necessary to obtain information using a camera while moving. However, reduction in recognition accuracy and system size increase has created problems. To solve these problems, we proposed the three-degree-of-freedom (DOF) actuator for image stabilization. This paper proposes a novel initial position estimation method and sensorless attitude estimation method for the three-DOF actuator to further downsize and reduce weight. The effectiveness of the proposed methods is verified by a magnetic field analysis, using a three-dimensional finite element method and numerical simulations.

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38

Qin, Wu, Wen-Bin Shangguan, and Zhihong Yin. "Sliding mode control of double-wishbone active suspension systems based on equivalent 2-degree-of-freedom model." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 13 (May 26, 2020): 3164–79. http://dx.doi.org/10.1177/0954407020919588.

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As a critical component of transportation vehicles, active suspension systems (ASSs) have widely attracted attention for their outstanding capability of improving the riding comfort and the maneuverability. However, due to the effects of the suspension kinematic structure and the rubber elements containing bushings and top mount, the practical double-wishbone ASS cannot achieve the desired performance resulting from the control design based on a simple 2-degree-of-freedom (DOF) model. In this paper, a sliding mode control (SMC) based on an equivalent 2-DOF model is proposed to suppress the sprung mass vibration of a double-wishbone ASS, which is to improve the riding comfort of vehicle. The SMC for a double-wishbone ASS is designed in four steps. First, an equivalent 2-DOF model of a double-wishbone ASS, which considers suspension kinematic structure and rubber properties, is established. The parameter values of an equivalent 2-DOF model are identified by using least square method. Second, an SMC is designed for an equivalent 2-DOF model, and the effect of the parameter value of the 2-DOF model on the riding comfort is investigated by experimental results. Third, a control compensator for a double-wishbone ASS is developed by considering the suspension kinematic structure. Four, the control for double-wishbone ASS is obtained by integrating the compensator into the SMC based on the equivalent 2-DOF model. The numerical simulation results show that the control can effectively suppress the sprung mass vibration of the double-wishbone ASS when the SMC design is based on an equivalent 2-DOF model.

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39

Srinivas, Arjun, Bryson Robertson, Jonah Benjamin Gadasi, Barbara Gwynne Simpson, Pedro Lomónaco, and Jesús María Blanco Ilzarbe. "Impact of Limited Degree of Freedom Drag Coefficients on a Floating Offshore Wind Turbine Simulation." Journal of Marine Science and Engineering 11, no. 1 (January 7, 2023): 139. http://dx.doi.org/10.3390/jmse11010139.

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The worldwide effort to design and commission floating offshore wind turbines (FOWT) is motivating the need for reliable numerical models that adequately represent their physical behavior under realistic sea states. However, properly representing the hydrodynamic quadratic damping for FOWT remains uncertain, because of its dependency on the choice of drag coefficients (dimensionless or not). It is hypothesized that the limited degree of freedom (DoF) drag coefficient formulation that uses only translational drag coefficients causes mischaracterization of the rotational DoF drag, leading to underestimation of FOWT global loads, such as tower base fore-aft shear. To address these hydrodynamic modeling uncertainties, different quadratic drag models implemented in the open-source mid-fidelity simulation tool, OpenFAST, were investigated and compared with the experimental data from the Offshore Code Comparison Collaboration, Continued, with Correlation (OC5) project. The tower base fore-aft shear and up-wave mooring line tension were compared under an irregular wave loading condition to demonstrate the effects of the different damping models. Two types of hydrodynamic quadratic drag formulations were considered: (1) member-based dimensionless drag coefficients applied only at the translational DoF (namely limited-DoF drag model) and (2) quadratic drag matrix model (in dimensional form). Based on the results, the former consistently underestimated the 95th percentile peak loads and spectral responses when compared to the OC5 experimental data. In contrast, the drag matrix models reduced errors in estimates of the tower base shear peak load by 7–10% compared to the limited-DoF drag model. The underestimation in the tower base fore-aft shear was thus inferred be related to mischaracterization of the rotational pitch drag and the heave motion/drag by the limited-DoF model.

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Chen, S.-L., Y.-C. Huang, and M. Tomizuka. "Fabrication Error Sensitivity Analysis of Three-Degree-Of-Freedom Parallel Submicron Positioning Stage." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 5 (May 1, 2006): 741–55. http://dx.doi.org/10.1243/09544062c05105.

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A new type of six-degree-of-freedom (DOF) precision positioning stage is designed and investigated in this study. This stage may be applied to couple and align an array waveguide grating (AWG) with a fibre array. It has an X-Y horizontal motion stage which consists of an X-Y horizontal motion mechanism and wedge-shaped mechanism for reducing positioning error. In addition, a rotational servo stage which provides the vertical γ-axis rotational DOF is arranged on the horizontal X-Y motion stage. The precision positioning stage is complete with three degrees of freedom parallel kinematic mechanism (α, β, and Z axes) on the rotational servo stage. To control this positioning stage precisely, an error model is obviously necessary and it is established in this paper. Because the assembly technology of three-DOF serial positioning stage is well developed, only the fabricating error parameters of the three-DOF parallel kinematic positioning stage are considered and investigated. The inverse and forward kinematics of the stage including error correction will be developed. The error sensitivity is analysed and the results will be used to improve the performance of the developed system. According to the analysis results, the positioning accuracy of Y0-axis is affected insignificantly by fabricating errors. Therefore, the optical axis of AWG or fibre array on the loading flat-top should be parallel to the X0-axis if this positioning stage is applied to couple an AWG with a fibre array.

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41

Gosselin, C. M., and D. Gagnon-Lachance. "Expandable Polyhedral Mechanisms Based on Polygonal One-Degree-of-Freedom Faces." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 7 (July 1, 2006): 1011–18. http://dx.doi.org/10.1243/09544062jmes174.

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In this article, a new family of expandable mechanisms is presented. The proposed mechanisms are expandable polyhedra built using one-degree-of-freedom (one-DOF) planar linkages. The latter planar linkages have the shape of polygons and can be expanded while preserving their shape in any of their configurations. The planar mechanisms are used to form the faces of a polyhedron. They are assembled using spherical joints at the vertices of the polyhedron. The result is a one-DOF movable polyhedron which can be expanded while preserving its shape. The application of the principle on regular polyhedra is first presented. For the five Platonic solids, theoretical maximum expansion ratios are computed, simulation results are given, and two prototypes are shown. Then, two additional examples are provided to illustrate the application of the principle to irregular polyhedra.

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42

Bhuiyan, Moinul, and Muhammad Muaz bin Hanafi. "Two Degree of Freedom Plotter Using Robotic Arm." Advanced Materials Research 1115 (July 2015): 499–502. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.499.

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This paper represents a two degree of freedom (DoF) robot arm as a plotter system. A pencil tool is used as the end effector of the robotic arm and experimented in drawing alphabets, for example ‘IIUM’. The control mechanism of the prototype is designed using Arduino controller. A user interface is also designed to send necessary commands to the hardware application board using serial communication cable. Through the experimentation, the movement of each joint of the robotic arm is presented in this paper. The result proves the feasibility of the system which could be improved in future research in drawing complex images.

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43

Makarios, Triantafyllos K. "Identification of Mode-shapes and Eigen-frequencies of Bi-hinge Beam with Distributed Mass and Stiffness." Journal of Civil Engineering and Construction 9, no. 3 (August 15, 2020): 119–26. http://dx.doi.org/10.32732/jcec.2020.9.3.119.

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In the present paper, an equivalent Three Degree of Freedom (DoF) system of a bi-hinge beam, which has infinity number of degree of freedoms because possesses distributed mass and stiffness along its length, is presented. Based on the vibration partial differential equation of the abovementioned bi-hinge beam, an equivalent, mathematically, three-degree of freedom system, where the equivalent mass matrix is analytically formulated with reference on specific mass locations. Using the Three DoF model, the first three fundamental mode-shapes of the real beam can be identified. Furthermore, taking account the 3x3 mass matrix, it is possible to estimate the possible beam damages using a known technique of identification mode-shapes via records of response accelerations. Moreover, the way of instrumentation with a local network by three accelerometers is shown. It is worth noting this technique can be applied on bridges consist of bays with two hinges at its end sections, supported on elastometallic bearings, where the sense of concentrated mass is fully absent from the beam.

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Kolesnikov, Maxim, and Miloš Žefran. "Generalized penetration depth for penalty-based six-degree-of-freedom haptic rendering." Robotica 26, no. 4 (July 2008): 513–24. http://dx.doi.org/10.1017/s0263574708004207.

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SUMMARYExisting penalty-based haptic rendering approaches are based on the penetration depth estimation in strictly translational sense and cannot properly take object rotation into account. We propose a new six-degree-of-freedom (6-DOF) haptic rendering algorithm which is based on determining the closest-point projection of the inadmissible configuration onto the set of admissible configurations. Energy is used to define a metric on the configuration space. Once the projection is found the 6-DOF wrench can be computed from the generalized penetration depth. The space is locally represented with exponential coordinates to make the algorithm more efficient. Examples compare the proposed algorithm with the existing approaches and show its advantages.

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Li, Yuanhua, Minglei Han, and Xinhai Chen. "Achieve hybrid energy harvesting based on the internal resonance of a two-degree-of-freedom cantilever beam." Journal of Physics: Conference Series 2553, no. 1 (August 1, 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2553/1/012007.

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Abstract Taking a cantilever beam with two-degree-of-freedom (DOF) as an example, this paper studies the energy transfer mechanism between the vibration DOF and the rotation DOF, proposes a hybrid energy harvesting scheme, establishes the dynamic equation and solves it. Through the simulation of the analytical equation, it is found that under the condition of internal resonance of two DOFs, the two nonlinear peaks on the rotation DOF are very conducive to energy harvesting in the wide frequency domain. Furthermore, the influence of excitation amplitude, electromechanical coupling coefficient, time domain constant and other parameters on the resonance frequency and amplitude response of the energy harvesting system is studied.

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46

Ahn, Seongnoh, Gun Park, Hyungchul Yoon, Jae-Hyeok Han, and Jongwon Jung. "Evaluation of Soil–Structure Interaction in Structure Models via Shaking Table Test." Sustainability 13, no. 9 (April 29, 2021): 4995. http://dx.doi.org/10.3390/su13094995.

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Modeling the soil–structure interaction (SSI) in seismic design involves the use of soil response curves for single-degree-of-freedom (SDOF) structures; however, real structures have multiple degrees of freedom (MDOF). In this study, shaking-table-derived p-y curves for SDOF and MDOF superstructures were compared using numerical analysis. It was found that an MDOF structure experienced less displacement than an SDOF structure of the same weight, but the effect of increasing the DOF decreased at greater pile depths. Numerical analysis results estimated using the natural periods and mass participation rates of the structures were similar to those of shaking table tests. Abbreviations: finite element: FE; frequency response function: FRF; multiple degrees of freedom: MDOF; single degree of freedom: SDOF; soil–structure interaction: SSI.

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Zhang, Yan-kui, Hai-yun Xu, Da-ming Wang, Bin Ba, and Si-yao Li. "A Novel Designed Sparse Array for Noncircular Sources with High Degree of Freedom." Mathematical Problems in Engineering 2019 (January 29, 2019): 1–10. http://dx.doi.org/10.1155/2019/1264715.

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The existing coprime array is mainly applicable to circular sources, while the virtual array degree of freedom (DOF) for noncircular sources is enhanced limitedly. In order to perfect the array DOF and the direction of arrival (DOA) estimation accuracy, a high degree of freedom sparse array design method for noncircular sources is put forward. Firstly, the method takes the advantages of the characteristic of the noncircular sources to expand the array manifold and then explores and solves the location distribution of the physical array sensors on the basis of the virtual array model with the help of the searching approach. The array configuration can obtain the longest continuous virtual array. The comparisons between the proposed array configuration and the common array configurations are advanced. The simulation experiments show that the sparse array presented in this paper can effectively increase the continuous virtual array aperture of noncircular sources, improve the array DOF and DOA estimation accuracy, and achieve the purpose of better estimation of multiple DOAs in underdetermined conditions.

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Chen, Wen Jia, Yan Zhong He, and Jiang Zhang. "A Four Degrees of Freedom Parallel Manipulator for Machining." Advanced Materials Research 139-141 (October 2010): 2168–71. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.2168.

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In the past decades, a number of parallel manipulators have been extensively studied. However, most efforts are dedicated to six degrees of freedom (DOF) or three-DOF manipulators. There is a need for equipment providing more than three DOF's arranged in parallel and based on simpler arrangements than six-DOF arrangements in application. This paper presents a novel four-DOF parallel platform manipulator with base mounted prismatic actuators. The manipulator is driven by four linear actuators. The movable platform of the manipulator can translate along two directions and rotate around two axes respectively. The kinematics model is formulated, which describes the inverse and forward kinematics transformation. It is very easy to develop a five-axis NC machine-tool which is of large-workspace based on the four-DOF parallel mechanism presented in this paper.

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Lu, Y., B. Hu, and J. Yu. "Solving active wrench of limited-degree of freedom parallel manipulators based on translational/rotational Jacobian matrices." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 223, no. 3 (April 15, 2009): 221–29. http://dx.doi.org/10.1243/14644193jmbd181.

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A methodology is proposed for unified solving active wrench of the limited-degree of freedom (DOF) parallel manipulators (PMs). First, the geometric constraints and the inverse displacement kinematics are analysed. Second, the formulae for unified solving the inverse/forward velocity and the translational/rotational Jacobian matrices and inverse/forward Jacobian matrices are derived. Third, the analytic formulae for unified solving the active wrench of limited-DOF PMs are derived based on the principle of virtual work. Finally, a 3-DOF PM with linear/rotational active legs is presented to illustrate the use of the methodology.

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Lu, Yi, Xuepeng Li, Canguo Zhang, and Yang Liu. "Analysis of kinematics and statics for a novel 6-DoF parallel mechanism with three planar mechanism limbs." Robotica 34, no. 4 (July 31, 2014): 957–72. http://dx.doi.org/10.1017/s0263574714001994.

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SUMMARYA novel 6-degree-of-freedom (DoF) parallel manipulator with three planar mechanism limbs is proposed and its kinematics and statics are analyzed systematically. First, the characteristics of the proposed manipulator are analyzed and the degree of freedom is calculated. Second, the formulae for solving the displacement, the velocity, and the acceleration are derived. Third, an analytic example is given for solving the kinematics and statics of this manipulator, and the analytic solved results are analyzed and verified by the simulation mechanism. Finally, a workspace is constructed and analyzed based on a comparison between the proposed manipulator and another 6-DoF parallel manipulator.

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Journal articles on the topic 'Degree of Freedom (DoF)'

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