scholarly journals Design and Validation of a Novel Cable-Driven Hyper-Redundant Robot Based on Decoupled Joints

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Long Huang ◽  
Bei Liu ◽  
Lairong Yin ◽  
Peng Zeng ◽  
Yuanhan Yang
Keyword(s):  
Control System ◽  
Coupling Effect ◽  
Kinematic Model ◽  
Joint Space ◽  
Degree Of Freedom ◽  
Driving Mechanism ◽  
Coupling Effects ◽  
Redundant Robot ◽  
Redundant Robots ◽  
Universal Joints

In most of the prior designs of conventional cable-driven hyper-redundant robots, the multiple degree-of-freedom (DOF) bending motion usually has bending coupling effects. It means that the rotation output of each DOF is controlled by multiple pairs of cable inputs. The bending coupling effect will increase the complexity of the driving mechanism and the risk of slack in the driving cables. To address these problems, a novel 2-DOF decoupled joint is proposed by adjusting the axes distribution of the universal joints. Based on the decoupled joint, a 4-DOF hyper-redundant robot with two segments is developed. The kinematic model of the robot is established, and the workspace is analyzed. To simplify the driving mechanism, a kinematic fitting approach is presented for both proximal and distal segments and the mapping between the actuator space and the joint space is significantly simplified. It also leads to the simplification of the driving mechanism and the control system. Furthermore, the cable-driven hyper-redundant robot prototype with multiple decoupled joints is established. The experiments on the robot prototype verify the advantages of the design.

scholarly journals Compliant behaviour of redundant robot arm - experiments with null-space

2015 ◽  
Vol 12 (1) ◽  
pp. 81-98
Author(s):  
Petar Petrovic ◽  
Nikola Lukic ◽  
Ivan Danilov
Keyword(s):  
Stiffness Matrix ◽  
Jacobian Matrix ◽  
Null Space ◽  
Joint Space ◽  
Robot Arm ◽  
Kinematic Redundancy ◽  
Redundant Robot ◽  
Redundant Robots ◽  
Compliant Behavior ◽  
Congruent Transformation

This paper presents theoretical and experimental aspects of Jacobian nullspace use in kinematically redundant robots for achieving kinetostatically consistent control of their compliant behavior. When the stiffness of the robot endpoint is dominantly influenced by the compliance of the robot joints, generalized stiffness matrix can be mapped into joint space using appropriate congruent transformation. Actuation stiffness matrix achieved by this transformation is generally nondiagonal. Off-diagonal elements of the actuation matrix can be generated by redundant actuation only (polyarticular actuators), but such kind of actuation is very difficult to realize practically in technical systems. The approach of solving this problem which is proposed in this paper is based on the use of kinematic redundancy and nullspace of the Jacobian matrix. Evaluation of the developed analytical model was done numerically by a minimal redundant robot with one redundant d.o.f. and experimentally by a 7 d.o.f. Yaskawa SIA 10F robot arm.

Nine Degree-of-Freedom Kinematic Modeling of the Upper-Limb Complex for Constrained Workspace Evaluation

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Brayden DeBoon ◽  
Ryan C. A. Foley ◽  
Scott Nokleby ◽  
Nicholas J. La Delfa ◽  
Carlos Rossa
Keyword(s):  
Upper Limb ◽  
Evaluation Method ◽  
Kinematic Model ◽  
Joint Space ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Kinematic Modeling ◽  
Joint Angles ◽  
Rehabilitative Treatment ◽  
Rehabilitation Devices

Abstract The design of rehabilitation devices for patients experiencing musculoskeletal disorders (MSDs) requires a great deal of attention. This article aims to develop a comprehensive model of the upper-limb complex to guide the design of robotic rehabilitation devices that prioritize patient safety, while targeting effective rehabilitative treatment. A 9 degree-of-freedom kinematic model of the upper-limb complex is derived to assess the workspace of a constrained arm as an evaluation method of such devices. Through a novel differential inverse kinematic method accounting for constraints on all joints1820, the model determines the workspaces in which a patient is able to perform rehabilitative tasks and those regions where the patient needs assistance due to joint range limitations resulting from an MSD. Constraints are imposed on each joint by mapping the joint angles to saturation functions, whose joint-space derivative near the physical limitation angles approaches zero. The model Jacobian is reevaluated based on the nonlinearly mapped joint angles, providing a means of compensating for redundancy while guaranteeing feasible inverse kinematic solutions. The method is validated in three scenarios with different constraints on the elbow and palm orientations. By measuring the lengths of arm segments and the range of motion for each joint, the total workspace of a patient experiencing an upper-limb MSD can be compared to a preinjured state. This method determines the locations in which a rehabilitation device must provide assistance to facilitate movement within reachable space that is limited by any joint restrictions resulting from MSDs.

scholarly journals Kinematics decoupling analysis of a hyper-redundant manipulator driven by cables

2021 ◽  
Vol 12 (2) ◽  
pp. 1017-1026
Author(s):  
Lei Zhang ◽  
Guangyao Ouyang ◽  
Zhaocai Du
Keyword(s):  
Joint Angle ◽  
Coupling Effect ◽  
Joint Space ◽  
Analysis Method ◽  
Redundant Manipulator ◽  
Redundant Robot ◽  
Precise Control ◽  
Quintic Polynomial ◽  
Decoupling Analysis ◽  
Pseudo Inverse

Abstract. The mapping relationship between the driving space and the workspace is essential for the precise control of a cable-driven hyper-redundant robot. For a hyper-redundant robot driven by cables, the relationships between the driving space and the joint space and between the joint space and the workspace were studied. A joint-decoupling kinematics analysis method was proposed and a kinematic analysis was presented. Based on the analysis of the coupling effect between the cable-driving space and the joint space, a decoupling analysis of the whole cable-driving space and joint space was conducted to eliminate the coupling effect between the joints, and the mapping relationship between the driving cables and the joint angles was obtained. Given the initial and target orientations of the hyper-redundant robot, the variation law for each joint angle was obtained using quintic polynomial trajectory planning and the pseudo-inverse Jacobian matrix, and then the driving cable variation law could be solved. Based on the results, the joint angle changes and the workspace trajectories were solved in turn. By comparing with the initial trajectory, the simulation results verified the appropriateness of the decoupling analysis.

scholarly journals Robot arm trajectory planning study for a table tennis robot

2021 ◽  
Vol 260 ◽  
pp. 03009
Author(s):  
Bo Zhang ◽  
Bingqiang Chen ◽  
Yansong Deng
Keyword(s):  
Success Rate ◽  
Trajectory Planning ◽  
Kinematic Model ◽  
Joint Space ◽  
Degree Of Freedom ◽  
Planning Method ◽  
Robot Arm ◽  
Table Tennis ◽  
Planning Study ◽  
Physical Tests

The 4 degree of freedom robot arm of a table tennis robot has a variety of trajectories. In order to improve the response and the success rate of the shots, we used the joint space trajectory planning method to establish a kinematic model with the robot arm joints as variables, and by combining it with the robot arm kinematics, we obtained the relevant parameters for each joint of the robot arm. Simulation tests and physical tests were carried out to obtain a more accurate trajectory of the robot arm.

Homing Strategy for a Redundantly Actuated Parallel Kinematic Machine

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Jinsong Wang ◽  
Jun Wu ◽  
Liping Wang ◽  
Tiemin Li
Keyword(s):  
Control System ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Control ◽  
The Other ◽  
Numerical Control System ◽  
Parallel Kinematic Machine ◽  
Redundantly Actuated ◽  
Parallel Kinematic ◽  
Singular Configuration

In the homing process of a regular parallel kinematic machine (PKM), all servoaxes are independently driven to return to their homing positions. However, in a redundantly actuated PKM, the redundant limb will interfere with other servoaxes. This paper concerns the homing of a redundant four degree of freedom PKM, and an assistant homing strategy is proposed for the machine to pass the singular configuration in the homing process. After the assistant homing is finished, the other four nonredundant axes are driven to return to their home positions independently. Based on the kinematic model and the length of the redundant limb, the condition that the redundant limb performs assistant homing is determined. The homing strategy is incorporated into the numerical control system of the studied PKM. The test shows that the homing strategy is effective, and it can also be useful for other kinds of redundantly actuated PKMs.

Robust Two-degree-of-freedom Control Based on H∞ Method for PMSM Drive System

2020 ◽  
Vol 13 (4) ◽  
pp. 496-506
Author(s):  
Qixin Zhu ◽  
Lei Xiong ◽  
Hongli Liu ◽  
Yonghong Zhu ◽  
Guoping Zhang
Keyword(s):  
Control System ◽  
Control Theory ◽  
Position Control ◽  
Dynamic Performance ◽  
Servo System ◽  
Degree Of Freedom ◽  
Trade Off ◽  
Standard Design ◽  
Position Controller ◽  
Two Degree Of Freedom

Background: The conventional method using one-degree-of-freedom (1DOF) controller for Permanent Magnet Synchronous Motor (PMSM) servo system has the trade-off problem between the dynamic performance and the robustness. Methods: In this paper, by using H∞ control theory, a novel robust two-degree-of-freedom (2DOF) controller has been proposed to improve the position control performance of PMSM servo system. Using robust control theory and 2DOF control theory, a H∞ robust position controller has been designed and discussed in detail. Results: The trade-off problem between the dynamic performance and robustness which exists in one-degree-of-freedom (1DOF) control can be dealt with by the application of 2DOF control theory. Then, through H∞ control theory, the design of robust position controller can be translated to H∞ robust standard design problem. Moreover, the control system with robust controller has been proved to be stable. Conclusion: Further simulation results demonstrate that compared with the conventional PID control, the designed control system has better robustness and attenuation to the disturbance of load impact.

Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

scholarly journals Comparative study on the redundancy of mobile single- and dual-arm robots

2016 ◽  
Vol 13 (6) ◽  
pp. 172988141666678
Author(s):  
Hongxing Wang ◽  
Ruifeng Li ◽  
Yunfeng Gao ◽  
Chuqing Cao ◽  
Lianzheng Ge
Keyword(s):  
Rate Control ◽  
Control Algorithm ◽  
Redundant Robot ◽  
Motion Models ◽  
Redundant Robots ◽  
Operational Space ◽  
Rate Control Algorithm ◽  
Simulation Results ◽  
Dual Arm Robot ◽  
Dual Arm

A whole resolved motion rate control algorithm designed for mobile dual-arm redundant robots is presented in this article. Based on this algorithm, the end-effector movements of the dual arms of the mobile dual-arm redundant robot can be decomposed into the movements of the two driving wheels of the differential driving platform and the movements of the dual-arm each joint of this robot harmoniously. The influence of the redundancies of the single- and dual-arm robots on the operation based on the fixed- and differential-driving platforms, which are then based on the whole resolved motion rate control algorithm, is studied after building their motion models. Some comparisons are made to show the advantages of this algorithm on the entire modeling of the complicated robotic system and the influences of the redundancy. First, the comparison of the simulation results between the fixed single-arm robot and the mobile single-arm robot is presented. Second, a comparison of the simulation results between the mobile single-arm robot and the mobile dual-arm robots is shown. Compared with the mobile single-arm robot and the fixed dual-arm robot based on this algorithm, the mobile dual-arm robot has more redundancy and can simultaneously track and operate different objects. Moreover, the mobile dual-arm redundant robot has better smoothness, more flexibility, larger operational space, and more harmonious cooperation between the two arms and the differential driving platform during the entire mobile operational process.

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