scholarly journals Theory Analysis and Experiment Research of the Leg Mechanism for the Human-Carrying Walking Chair Robot

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Lingfeng Sang ◽  
Hongbo Wang ◽  
Shuaishuai Wang ◽  
Na Chen ◽  
Yuehua Wen
Keyword(s):  
Control Strategy ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Position Control ◽  
Structural Constraints ◽  
Experiment Research ◽  
Theory Analysis ◽  
Optimal Motion ◽  
Reachable Workspace ◽  
Circular Track

For the high carrying capacity of the human-carrying walking chair robot, in this paper, 2-UPS+UP parallel mechanism is selected as the leg mechanism; then kinematics, workspace, control, and experiment of the leg mechanism are researched in detail. Firstly, design of the whole mechanism is described and degrees of freedom of the leg mechanism are analyzed. Second, the forward position, inverse position, and velocity of leg mechanism are studied. Third, based on the kinematics analysis and the structural constraints, the reachable workspace of 2-UPS+UP parallel mechanism is solved, and then the optimal motion workspace is searched in the reachable workspace by choosing the condition number as the evaluation index. Fourth, according to the theory analysis of the parallel leg mechanism, its control system is designed and the compound position control strategy is studied. Finally, in optimal motion workspace, the compound position control strategy is verified by using circular track with the radius 100 mm; the experiment results show that the leg mechanism moves smoothly and does not tremble obviously. Theory analysis and experiment research of the single leg mechanism provide a theoretical foundation for the control of the quadruped human-carrying walking chair robot.

Smart Prosthetic Hand with Object Slippage Detection, Measurement, and Control

2014 ◽  
Vol 5 (3) ◽  
pp. 25-48
Author(s):  
Girish Sriram ◽  
Alex Jensen ◽  
Steve C. Chiu
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Degrees Of Freedom ◽  
Sensory Feedback ◽  
Position Control ◽  
Tactile Feedback ◽  
Human Hand ◽  
Computing Platform ◽  
Emg Signal ◽  
A New Technique

The human hand along with its fingers possess one of the highest numbers of nerve endings in the human body. It thus has the capacity for the richest tactile feedback for positioning capabilities. This article shares a new technique of controlling slippage. The sensing system used for the detection of slippage is a modified force sensing resistor (FSR®). The control system is a fuzzy logic control algorithm with multiple rules that is designed to be processed on a mobile handheld computing platform and integrated/working alongside a traditional Electromyography (EMG) or Electroencephalography (EEG) based control system used for determining position of the fingers. A 5 Degrees of Freedom (DOF) hand, was used to test the slippage control strategy in real time. First a reference EMG signal was used for getting the 5 DOF hand to grasp an object, using position control. Then a slip was introduced to see the slippage control strategy at work. The results based on the plain tactile sensory feedback and the modified sensory feedback are discussed.

scholarly journals Displacement Analysis and Design of a (2–RRU)–URR Parallel Mechanism Performing 2R1T Output Motion for Thumb Rehabilitation

Robotics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 67
Author(s):  
Woo-hyeok Choi ◽  
Yukio Takeda
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Human Hand ◽  
Displacement Analysis ◽  
Analysis And Design ◽  
Reachable Workspace ◽  
Flexion Extension ◽  
Basic Characteristics ◽  
Narrow Space ◽  
Input Torque

The thumb assists other fingers, and any damage in its functionality prevents the human hand from performing dexterous functions. In this paper, the kinematic design of the (2–RRU)–URR parallel mechanism as the application of the thumb rehabilitation device is proposed. This mechanism is an over-constrained mechanism capable of achieving the required mobility with fewer joints. Three degrees of freedom exist—two rotational and one translational mobility—that are related to each thumb movement: adduction–abduction and flexion–extension. Considering the narrow space of the hand, actuators are designed to divide its placement into the surface of the palm. To avoid the collisions between the device and the hand, an offset was adopted. The displacement analysis problem is solved by dividing it into two parts: the planar motion generator (PMG) and orientation generator (OG), according to each functional motion, and the corresponding equations and procedures are presented. To clarify the basic characteristics of this mechanism, the reachable workspace of the PMG and rotational ability and sensitivity of the OG is demonstrated numerically. Because a large input torque difference is dangerous in the rehabilitation mechanism, the effective workspace is determined according to the magnitude of the input torque differences and compared with the measured thumb movements.

scholarly journals Kinematic analysis of a novel 3-CRU translational parallel mechanism

2015 ◽  
Vol 6 (1) ◽  
pp. 57-64 ◽  
Author(s):  
B. Li ◽  
Y. M. Li ◽  
X. H. Zhao ◽  
W. M. Ge
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Structural Characteristics ◽  
Parallel Mechanisms ◽  
Reachable Workspace ◽  
Potential Applications ◽  
Moving Platform ◽  
And Performance

Abstract. In this paper, a modified 3-DOF (degrees of freedom) translational parallel mechanism (TPM) three-CRU (C, R, and U represent the cylindrical, revolute, and universal joints, respectively) structure is proposed. The architecture of the TPM is comprised of a moving platform attached to a base through three CRU jointed serial linkages. The prismatic motions of the cylindrical joints are considered to be actively actuated. Kinematics and performance of the TPM are studied systematically. Firstly, the structural characteristics of the mechanism are described, and then some comparisons are made with the existing 3-CRU parallel mechanisms. Although these two 3-CRU parallel mechanisms are both composed of the same CRU limbs, the types of freedoms are completely different due to the different arrangements of limbs. The DOFs of this TPM are analyzed by means of screw theory. Secondly, both the inverse and forward displacements are derived in closed form, and then these two problems are calculated directly in explicit form. Thereafter, the Jacobian matrix of the mechanism is derived, the performances of the mechanism are evaluated based on the conditioning index, and the performance of a 3-CRU TPM changing with the actuator layout angle is investigated. Thirdly, the workspace of the mechanism is obtained based on the forward position analysis, and the reachable workspace volume is derived when the actuator layout angle is changed. Finally, some conclusions are given and the potential applications of the mechanism are pointed out.

scholarly journals Research on Kinematics and Pouring Law of a Mobile Heavy Load Pouring Robot

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Long Li ◽  
Chengjun Wang ◽  
Hongtao Wu
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Position Control ◽  
Screw Theory ◽  
Great Influence ◽  
Inverse Kinematic ◽  
The Novel ◽  
Heavy Load ◽  
Motion Characteristics ◽  
The Relationship

In order to meet the requirement of continuous pouring in many varieties and small batches in casting production, a mobile heavy load pouring robot is developed based on a new 4-UPU parallel mechanism due to its strong carrying capacity. Firstly, the instantaneous motion characteristics of the novel 4-UPU parallel mechanism with four degrees of freedom (DOF) are analyzed using screw theory. By using the geometric method, both the forward and inverse kinematic solutions of the proposed robot system are given out. Secondly, based on a common pouring ladle, the volume change of pouring liquid in pouring process and the relationship between tilting angular velocity and flow rate are analyzed, and the results show that the shape of the ladle and the design of the pouring mouth have great influence on the tilting model. It is an important basis for the division of the sectional model. Finally, a numerical example is given to verify the effectiveness of the developed tilting model. The mapping relation between the tilting model and the parallel mechanism shows that the pouring flow can be adjusted by controlling the movement of parallel manipulator. The research of this paper provides an important theoretical basis for the position control of mobile heavy load pouring robot and the research of pouring speed control.

scholarly journals A novel human-carrying quadruped walking robot

2017 ◽  
Vol 14 (4) ◽  
pp. 172988141771659 ◽  
Author(s):  
Lingfeng Sang ◽  
Hongbo Wang ◽  
Hongnian Yu ◽  
Luige Vladareanu
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Carrying Capacity ◽  
Parallel Mechanism ◽  
Position Control ◽  
Kinematics Analysis ◽  
Walking Robot ◽  
Universal Joint ◽  
Gait Planning ◽  
Quadruped Walking Robot

This article adopts a 2-UPS+UP (U, P, and S are universal joint, the prismatic joint, and sphere joint, respectively) parallel mechanism as the leg mechanism of the quadruped walking robot based on the bionic concept and the motion capacity of the leg mechanism. The article investigates the kinematics (including the leg mechanism and the whole mechanism), gait planning, control, and experiment in detail. The following tasks are conducted: (1) designing the whole mechanism and developing the kinematics equations for both the leg mechanism and the whole mechanism; (2) planning the trotting gait and designing the foot trajectory based on the robot characteristics and conducting the kinematics analysis; (3) building the control system of the robot using self-developed controllers and drivers and studying the compound position control strategy; and (4) conducting the experiments for validating the controller, the compound position control strategy, the trotting pace, carrying capacity, and human-carrying walking. The results confirm that the proposed human-carrying walking robot has good performance and it is also verified that the controller and the compound position control strategy are suitable.

Performance Mapping and Motion Simulation of a 4UPS+PU Redundantly Actuated Parallel Manipulator

2010 ◽  
Author(s):  
Zhen Gao ◽  
Dan Zhang
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Position Control ◽  
Parallel Manipulators ◽  
Inverse Kinematic ◽  
Reachable Workspace ◽  
Redundantly Actuated ◽  
Inverse Kinematic Analysis ◽  
Motion Characteristics ◽  
Operational Capacity

In this paper, a new 4UPS+PU redundantly actuated parallel manipulator is proposed. This mechanism possesses three degrees of freedom (DOF), one translation and two rotations. Different from general parallel manipulators, a passive leg is connected to both centers of the base and the moving platform to constrain the unwanted motion. The mobility study and inverse kinematic analysis are conducted. The reachable workspace is generated with boundary-searching based discretization method. The local and global performance indices including stiffness and dexterity and their atlas are investigated in details. Comprehensive simulation of kinematics, dynamics and proportional-integral-derivative (PID) position control are implemented based on Adams to evaluate and testify the high operational capacity and well motion characteristics.

A hybrid robot for friction stir welding

2014 ◽  
Vol 229 (14) ◽  
pp. 2639-2650 ◽  
Author(s):  
Qinchuan Li ◽  
Weifeng Wu ◽  
Ji’nan Xiang ◽  
Hongjun Li ◽  
Chuanyu Wu
Keyword(s):  
Friction Stir Welding ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Welding Process ◽  
Fusion Welding ◽  
Friction Stir ◽  
Reachable Workspace ◽  
Rotational Degrees Of Freedom ◽  
Singular Configuration

Friction stir welding (FSW) has been widely applied in a number of fields instead of traditional fusion welding. However, a huge axial downward force is required to maintain a steady welding process. Moreover, the task of welding along a curved surface requires an orientation ability, which traditional FSW machines cannot provide. To overcome this limitation, we propose a 5-axis hybrid robot for FSW. This hybrid robot comprises a 2-SPR-RPS parallel mechanism (with one translational degree of freedom and two rotational degrees of freedom) and two gantries. First, mobility of the parallel mechanism in the initial and general configuration is analyzed using screw theory and continuous rotational axes are identified. Second, forward and inverse position solutions to the hybrid robot are studied, and the Jacobian matrix of the parallel mechanism is obtained. By analyzing the motion/force transmissibility, the architectural parameters of the parallel mechanism are optimized. Finally, the reachable workspace of the end effector is obtained considering the constraints of actuation links, joint angles, and singular configuration.

scholarly journals Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1015
Author(s):  
Mingfei Huang ◽  
Yongting Deng ◽  
Hongwen Li ◽  
Jing Liu ◽  
Meng Shao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Torque Ripple ◽  
Current Loop ◽  
Two Degrees Of Freedom ◽  
Robust Stability Analysis ◽  
Resonant Controller ◽  
Testing Environments

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

scholarly journals A New Approach of Soft Joint Based on a Cable-Driven Parallel Mechanism for Robotic Applications

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1468
Author(s):  
Luis Nagua ◽  
Carlos Relaño ◽  
Concepción A. Monje ◽  
Carlos Balaguer
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Humanoid Robots ◽  
Inverse Kinematic ◽  
Element Analysis ◽  
New Approach ◽  
Flexible Polymer ◽  
The Mathematical Model

A soft joint has been designed and modeled to perform as a robotic joint with 2 Degrees of Freedom (DOF) (inclination and orientation). The joint actuation is based on a Cable-Driven Parallel Mechanism (CDPM). To study its performance in more detail, a test platform has been developed using components that can be manufactured in a 3D printer using a flexible polymer. The mathematical model of the kinematics of the soft joint is developed, which includes a blocking mechanism and the morphology workspace. The model is validated using Finite Element Analysis (FEA) (CAD software). Experimental tests are performed to validate the inverse kinematic model and to show the potential use of the prototype in robotic platforms such as manipulators and humanoid robots.

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