A Unified Approach for Second-Order Control of the Manipulator With Joint Physical Constraints

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Pei Jiang ◽  
Shuihua Huang ◽  
Ji Xiang ◽  
Michael Z. Q. Chen
Keyword(s):  
Joint Space ◽  
Second Order ◽  
The Self ◽  
Dynamic Feedback ◽  
Unified Approach ◽  
Physical Constraints ◽  
Dynamic Feedback Control ◽  
Joint Limits ◽  
Joint Velocity ◽  
Self Motion

Kinematic control of manipulators with joint physical constraints, such as joint limits and joint velocity limits, has received extensive studies. Many studies resolved this problem at the second-order kinematic level, which may suffer from the self-motion instability in the presence of persistent self-motion or unboundedness of joint velocity. In this paper, a unified approach is proposed to control a manipulator with both joint limits and joint velocity limits at the second-order kinematic level. By combining the weighted least-norm (WLN) solution in the revised joint space and the clamping weighted least-norm (CWLN) solution in the real joint space, the unified approach ensures the joint limits and joint velocity limits at the same time. A time-variant clamping factor is incorporated into the unified approach to suppress the self-motion when the joint velocity diverges, or the end-effector stops, which improves the stability of self-motion. The simulations in contrast to the traditional dynamic feedback control scheme and the new minimum-acceleration-norm (MAN) scheme have been made to demonstrate the advantages of the unified approach.

scholarly journals Motion Planning of Nonholonomic Mobile Manipulators with Manipulability Maximization Considering Joints Physical Constraints and Self-Collision Avoidance

2021 ◽  
Vol 11 (14) ◽  
pp. 6509
Author(s):  
Josuet Leoro ◽  
Tesheng Hsiao
Keyword(s):  
Motion Planning ◽  
Collision Avoidance ◽  
Trajectory Tracking ◽  
Practical Implementation ◽  
Mobile Manipulators ◽  
Entire System ◽  
Unified Framework ◽  
Physical Constraints ◽  
Joint Limits ◽  
Joint Velocity

The motion of nonholonomic mobile manipulators (NMMs) is inherently constrained by joint limits, joint velocity limits, self-collisions and singularities. Most motion planning algorithms consider some of the aforementioned constraints, however, a unified framework to deal with all of them is lacking. This paper proposes a motion planning solution for the kinematic trajectory tracking of redundant NMMs that include all the constraints needed for practical implementation, which improves the manipulability of both the entire system and the manipulator to prevent singularities. Experiments using a 10-DOF NMM demonstrate the good performance of the proposed method for executing 6-DOF trajectories while satisfying all the constraints and simultaneously maximizing manipulability.

Minimizing joint‐torques of the flexible redundant manipulator on the premise of vibration suppression

2008 ◽  
Vol 1 (4) ◽  
pp. 634-645 ◽  
Author(s):  
Zhihui Gao ◽  
Chao Yun ◽  
Yushu Bian
Keyword(s):  
Design Methodology ◽  
Vibration Suppression ◽  
Dynamic Performance ◽  
Joint Space ◽  
The Self ◽  
Redundant Manipulator ◽  
Content Type ◽  
Joint Torques ◽  
Self Motion ◽  
Practical Implications

PurposeThe purpose of this paper is to examine a new idea of vibration control which minimizes joint‐torques and suppresses vibration of the flexible redundant manipulator.Design/methodology/approachUsing the kinematics redundancy feature of the flexible redundant manipulator, the self‐motion in the joint space can be properly chosen to both suppress vibration and minimize joint‐torques.FindingsThe study shows that the flexible redundant manipulator still has the second optimization feature on the premise of vibration suppression. The second optimization feature can be used to minimize joint‐torques on the premise of vibration suppression.Research limitations/implicationsTo a flexible redundant manipulator, its joint‐torques and vibration can be reduced simultaneously via its kinematics redundancy feature.Practical implicationsThe method and algorithm discussed in the paper can be used to minimize joint‐torques and suppress vibration for the flexible redundant manipulator.Originality/valueThe paper contributes to the study on improving dynamic performance of the flexible redundant manipulator via its kinematics redundancy feature. The second optimization capability of the flexible redundant manipulator is discovered and used to both minimize joint‐torques and suppress vibration.

A New Method of 6-DOF Serial Robot’s Trajectory Planning under Multi-Constraints

2014 ◽  
Vol 602-605 ◽  
pp. 1352-1357 ◽  
Author(s):  
Yong Ting Zhao ◽  
Bin Zheng ◽  
Hong Lin Ma
Keyword(s):  
Coordinate System ◽  
Trajectory Planning ◽  
Angular Displacement ◽  
Joint Space ◽  
New Method ◽  
Position Information ◽  
Physical Constraints ◽  
Dynamic Constraints ◽  
Quaternion Interpolation ◽  
And Performance

This paper proposes a new method of 6-DOF serial robot’s trajectory planning. Ensuring to satisfy the physical constraints of space conditions, the robot’s trajectory is interpolated in the Cartesian coordinate system, and using quaternion interpolation to solve the multiple solution problem in RPY interpolation. Meanwhile, the interpolated position information is transformed into the angular displacement information of the joint coordinate system, and the joint space trajectory planning is achieved using the genetic algorithms integrated velocity, acceleration, jerk and torque and other important kinematic and dynamic constraints. In robot safety and stability, the method is better than the general approach, and it has both the ideal trajectory parameters of the global search ability and performance planning.

On-line multi-criteria based collision-free posture generation of redundant manipulator in constrained workspace

Robotica ◽  
2002 ◽  
Vol 20 (6) ◽  
pp. 625-636 ◽  
Author(s):  
Jin-Liang Chen ◽  
Jing-Sin Liu ◽  
Wan-Chi Lee ◽  
Tzu-Chen Liang
Keyword(s):  
Null Space ◽  
Large Degree ◽  
Redundancy Resolution ◽  
Secondary Tasks ◽  
End Effector ◽  
Robotic Arms ◽  
Tracking Motion ◽  
On Line ◽  
Joint Limits ◽  
Joint Velocity

The manipulator with a large degree of redundancy is useful for realizing multiple tasks such as maneuvering the robotic arms in the constrained workspace, e.g. the task of maneuvering the end-effector of the manipulator along a pre-specified path into a window. This paper presents an on-line technique based on a posture generation rule to compute a null-space joint velocity vector in a singularity-robust redundancy resolution method. This rule suggests that the end of each link has to track an implicit trajectory that is indirectly resulted from the constraint imposed on tracking motion of the end-effector. A proper posture can be determined by sequentially optimizing an objective function integrating multiple criteria of the orientation of each link from the end-effector toward the base link as the secondary task for redundancy resolution, by assuming one end of the link is clamped. The criteria flexibly incorporate obstacle avoidance, joint limits, preference of posture in tracking, and connection of posture to realize a compromise between the primary and secondary tasks. Furthermore, computational demanding of the posture is reduced due to the sequential link-by-link computation feature. Simulations show the effectiveness and flexibility of the proposed method in generating proper postures for the collision avoidance and the joint limits as a singularity-robust null-space projection vector in maneuvering redundant robots within constrained workspaces.

Bi-criteria velocity minimization of robot manipulators using LVI-based primal-dual neural network and illustrated via PUMA560 robot arm

Robotica ◽  
2009 ◽  
Vol 28 (4) ◽  
pp. 525-537 ◽  
Author(s):  
Yunong Zhang ◽  
Kene Li
Keyword(s):  
Neural Network ◽  
Piecewise Linear ◽  
Linear Structure ◽  
Robot Arm ◽  
Planning Scheme ◽  
Primal Dual ◽  
Joint Limits ◽  
Joint Velocity ◽  
High Computational Efficiency ◽  
Minimization Scheme

SUMMARYIn this paper, to diminish discontinuity points arising in the infinity-norm velocity minimization scheme, a bi-criteria velocity minimization scheme is presented based on a new neural network solver, i.e., an LVI-based primal-dual neural network. Such a kinematic planning scheme of redundant manipulators can incorporate joint physical limits, such as, joint limits and joint velocity limits simultaneously. Moreover, the presented kinematic planning scheme can be reformulated as a quadratic programming (QP) problem. As a real-time QP solver, the LVI-based primal-dual neural network is developed with a simple piecewise linear structure and high computational efficiency. Computer simulations performed based on a PUMA560 manipulator model are presented to illustrate the validity and advantages of such a bi-criteria velocity minimization neural planning scheme for redundant robot arms.

The directions of nystagmus and apparent self-motion evoked by caloric tests and angular accelerations

2002 ◽  
Vol 11 (6) ◽  
pp. 349-355
Author(s):  
Ognyan I. Kolev
Keyword(s):  
Motion Perception ◽  
Frontal Plane ◽  
Vertical Axis ◽  
The Body ◽  
The Self ◽  
Whole Body ◽  
Caloric Stimulation ◽  
Infrared Video ◽  
Axis Rotation ◽  
Self Motion

Purpose: To further investigate the direction of (I) nystagmus and (II) self-motion perception induced by two stimuli: (a) caloric vestibular stimulations and (b) a sudden halt during vertical axis rotation. Subjects and methods: Twelve normal humans received caloric stimulation at 44°C, 30°C, and 20°C while in a supine position with the head inclined 30° upwards. In a second test they were rotated around the vertical axis with the head randomly placed in two positions: tilted 30° forward or tilted 60° backward, at a constant velocity of 90°/sec for 2 minutes and then suddenly stopped. After both tests they were asked to describe their sensations of self-motion. Eye movements were recorded with an infrared video-technique. Results: Caloric stimulation evoked only horizontal nystagmus in all subjects and induced a non-uniform complex perception of angular in frontal and transverse planes (the former dominated) and linear movements along the antero-posterior axis (sinking dominated) of the subject's coordinates. The self-motion was felt with the whole body or with a part of the body. Generally the perception evoked by cold (30°C) and warm (44°C) calorics was similar, although there were some differences. The stronger stimulus (20°C) evoked not only quantitative but also qualitative differences in perception. The abrupt halt of rotation induced self-motion perception and nystagmus only in the plane of rotation. The self-motion was felt with the whole body. Conclusion: There was no difference in the nystagmus evoked by caloric stimulation and a sudden halt of vertical axis rotation (in head positions to stimulate the horizontal canals); however, the two stimuli evoked different perceptions of self-motion. Calorics provoked the sensation of self-rotation in the frontal plane and linear motion, which did not correspond to the direction of nystagmus, as well as arcing and a reset phenomenon during angular and linear self-motion, caloric-induced self-motion can be felt predominantly or only with a part of the body, depending on the self-motion intensity. The findings indicate that, unlike the self-motion induced by sudden halt of vertical axis rotation, several mechanisms take part in generating caloric-induced self-motion.

scholarly journals Dynamic feedback control through wall suction in shear flows

PAMM ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Moritz Linkmann ◽  
Bruno Eckhardt
Keyword(s):  
Feedback Control ◽  
Shear Flows ◽  
Dynamic Feedback ◽  
Wall Suction ◽  
Dynamic Feedback Control
Sign in / Sign up

Export Citation Format

Share Document