Redundancy utilization for obstacle avoidance of planar robot manipulators

1997 ◽  
Vol 211 (6) ◽  
pp. 463-475 ◽  
Author(s):  
U Sezgin ◽  
L D Seneviratne ◽  
S W E Earles
Keyword(s):  
Obstacle Avoidance ◽  
Computer Simulations ◽  
Redundant Manipulators ◽  
Control Points ◽  
Kinematic Redundancy ◽  
End Effector ◽  
Revolute Joints ◽  
Planar Robot ◽  
And Control ◽  
Configuration Control

Two obstacle avoidance criteria are developed, utilizing the kinematic redundancy of serial redundant manipulators having revolute joints and tracking pre-determined end effector paths. The first criterion is based on the instantaneous distances between certain selected points along the manipulator, called configuration control points (CCP), and the vertices of the obstacles. The optimized joint configurations are obtained by maximizing these distances. Thus, the links of the manipulator are configured away from the obstacles. The second criterion uses a different approach, and is based on Voronoi boundaries representing the equidistant paths between two obstacles. The optimized joint configurations are obtained by minimizing the distances between the CCP and control points selected on the Voronoi boundaries. The validities of the criteria are demonstrated through computer simulations.

scholarly journals An Obstacle Avoidance Method for Action Support 7-DOF Manipulators Using Impedance Control

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Masafumi Hamaguchi ◽  
Takao Taniguchi
Keyword(s):  
Angular Velocity ◽  
Obstacle Avoidance ◽  
Impedance Control ◽  
Kinematic Redundancy ◽  
End Effector ◽  
Rate Vector

An obstacle avoidance method of action support 7-DOF manipulators is proposed in this paper. The manipulators are controlled with impedance control to follow user's motions. 7-DOF manipulators are able to avoid obstacles without changing the orbit of the end-effector because they have kinematic redundancy. A joint rate vector is used to change angular velocity of an arbitrary joint with kinematic redundancy. The priority of avoidance is introduced into the proposed method, so that avoidance motions precede follow motions when obstacles are close to the manipulators. The usefulness of the proposed method is demonstrated through obstacle avoidance simulations and experiments.

Analysis and Experimentation of the Robotic System for Archwire Bending

2011 ◽  
Vol 121-126 ◽  
pp. 3805-3809 ◽  
Author(s):  
Yong De Zhang ◽  
Ji Xiong Jiang
Keyword(s):  
Human Factors ◽  
Orthodontic Treatment ◽  
Control Point ◽  
Robotic System ◽  
Control Points ◽  
Coordinate Systems ◽  
End Effector ◽  
Manual Operation ◽  
Orthodontic Wire ◽  
And Control

Archwire bending is one of the key components in orthodontic treatment. However, it is a very difficult work due to the high stiffness and superelasticity of orthodontic wire. The traditional way of acquiring the formed archwire curve is based on manual operation, which will randomly bring numerous errors caused by human factors. This paper proposes a novel robotic system to bend archwire into desired configuration. Structure and elements of robotic system for archwire bending was studied. Coordinate systems of robotic system were built up. Control points of end effector and control angle of each control point were planned. Preliminary orthodontic wire bending experimentation has been done using the robotic system. The experimental results verified the feasibility of the manufacture strategy of formed orthodontic wire fulfilled by robotic system for orthodontic wire bending.

Obstacle avoidance control for redundant manipulators using collidability measure

Robotica ◽  
2000 ◽  
Vol 18 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Su Il Choi ◽  
Byung Kook Kim
Keyword(s):  
Obstacle Avoidance ◽  
Control Algorithm ◽  
Null Space ◽  
Control Law ◽  
Redundant Manipulators ◽  
Redundancy Resolution ◽  
End Effector ◽  
Joint Torques ◽  
Avoidance Control ◽  
Joint Acceleration

We present an efficient obstacle avoidance control algorithm for redundant manipulators using a new measure called collidability measure. Considering moving directions of manipulator links, the collidability measure is defined as the sum of inverse of predicted collision distances between links and obstacles: This measure is suitable for obstacle avoidance since directions of moving links are as important as distances to obstacles. For kinematic or dynamic redundancy resolution, null space control is utilized to avoid obstacles by minimizing the collidability measure: We present a velocity-bounded kinematic control law which allows reasonably large gains to improve the system performance. Also, by clarifying decomposition in the joint acceleration level, we present a simple dynamic control law with bounded joint torques which guarantees tracking of a given end-effector trajectory and improves a kinematic cost function such as collidability measure. Simulation results are presented to illustrate the effectiveness of the proposed algorithm.

scholarly journals Position and Singularity Analysis of a Class of Planar Parallel Manipulators with a Reconfigurable End-Effector

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Tommaso Marchi ◽  
Giovanni Mottola ◽  
Josep M. Porta ◽  
Federico Thomas ◽  
Marco Carricato
Keyword(s):  
Inverse Kinematics ◽  
Kinematic Chain ◽  
Experimental Tests ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
End Effector ◽  
Revolute Joints ◽  
A Chain ◽  
And Control

Parallel robots with configurable platforms are a class of robots in which the end-effector has an inner mobility, so that its overall shape can be reconfigured: in most cases, the end-effector is thus a closed-loop kinematic chain composed of rigid links. These robots have a greater flexibility in their motion and control with respect to rigid-platform parallel architectures, but their kinematics is more challenging to analyze. In our work, we consider n-RRR planar configurable robots, in which the end-effector is a chain composed of n links and revolute joints, and is controlled by n rotary actuators located on the base of the mechanism. In particular, we study the geometrical design of such robots and their direct and inverse kinematics for n=4, n=5 and n=6; we employ the bilateration method, which can simplify the kinematic analysis and allows us to generalize the approach and the results obtained for the 3-RRR mechanism to n-RRR robots (with n>3). Then, we study the singularity configurations of these robot architectures. Finally, we present the results from experimental tests that have been performed on a 5–RRR robot prototype.

Inverse kinematics of redundant manipulators with guaranteed performance

Robotica ◽  
2021 ◽  
pp. 1-21
Author(s):  
Dongsheng Guo ◽  
Aifen Li ◽  
Jianhuang Cai ◽  
Qingshan Feng ◽  
Yang Shi
Keyword(s):  
Path Planning ◽  
Obstacle Avoidance ◽  
Discrete Time ◽  
Inverse Kinematics ◽  
Robot Manipulator ◽  
Superior Performance ◽  
Redundant Manipulators ◽  
End Effector ◽  
Great Performance ◽  
Time Form

Abstract In this paper, the inverse kinematics (IK) of redundant manipulators is presented and studied, where the performance of end-effector path planning is guaranteed. A new Jacobian pseudoinverse (JP)-based IK method is proposed and studied using a typical numerical difference rule to discretize the existing IK method based on JP. The proposed method is depicted in a discrete-time form and is theoretically proven to exhibit great performance in the IK of redundant manipulators. A discrete-time repetitive path planning (DTRPP) scheme and a discrete-time obstacle avoidance (DTOA) scheme are developed for redundant manipulators using the proposed method. Comparative simulations are conducted on a universal robot manipulator and a PA10 robot manipulator to validate the effectiveness and superior performance of the DTRPP scheme, the DTOA scheme, and the proposed JP-based IK method.

scholarly journals Cartesian Aerial Manipulator with Compliant Arm

2021 ◽  
Vol 11 (3) ◽  
pp. 1001
Author(s):  
Alejandro Suarez ◽  
Manuel Perez ◽  
Guillermo Heredia ◽  
Anibal Ollero
Keyword(s):  
Dynamic Models ◽  
Position Control ◽  
Force Sensor ◽  
Monitoring And Control ◽  
End Effector ◽  
Robotic Arms ◽  
Revolute Joints ◽  
Angular Deflection ◽  
Compliant Joint ◽  
And Control

This paper presents an aerial manipulation robot consisting of a hexa-rotor equipped with a 2-DOF (degree of freedom) Cartesian base (XY–axes) that supports a 1-DOF compliant joint arm that integrates a gripper and an elastic linear force sensor. The proposed kinematic configuration improves the positioning accuracy of the end effector with respect to robotic arms with revolute joints, where each coordinate of the Cartesian position depends on all the joint angles. The Cartesian base reduces the inertia of the manipulator and the energy consumption since it does not need to lift its own weight. Consequently, the required torque is lower and, thus, the weight of the actuators. The linear and angular deflection sensors of the arm allow the estimation, monitoring and control of the interaction wrenches exerted in two axes (XZ) at the end effector. The kinematic and dynamic models are derived and compared with respect to a revolute-joint arm, proposing a force-position control scheme for the aerial robot. A battery counterweight mechanism is also incorporated in the X–axis linear guide to partially compensate for the motion of the manipulator. Experimental results indoors and outdoors show the performance of the robot, including object grasping and retrieval, contact force control, and force monitoring in grabbing situations.

A Kind of Kinematically Redundant Planar Parallel Manipulator for Optimal Output Accuracy

2009 ◽  
Author(s):  
Genliang Chen ◽  
Hao Wang ◽  
Yong Zhao ◽  
Zhongqin Lin
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Redundant Manipulators ◽  
Kinematic Redundancy ◽  
End Effector ◽  
Optimal Output ◽  
Parallel Structures ◽  
Planar Parallel Manipulator ◽  
Redundant Structure ◽  
Active Joints

Theoretically, parallel manipulators perform higher precision than their serial counterparts. However, the output accuracy is sensitive to their configurations and dimensions. This paper presents a kind of parallel manipulator with kinematically redundant structure, which can improve the output accuracy by optimizing the error transmission from the active joints to the end-effector. With the kinematic redundancy, free redundant variables can be defined as second task variables, which provide the possibility to select a proper configuration for least error transmission at any pose (the position and orientation) of the end-effector for a given task. Contrast to non-redundant manipulators, the output errors of the proposed manipulator, caused by the active joints input errors, can be optimized rather than determined. By this goal, new limbs with redundant parallel structures are introduced to non-redundant planar parallel manipulators. Numerical example shows that the new architecture has the potential to enhance the output accuracy for a given pose or prescribed trajectory of the end-effector.

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