Repulsive reaction vector generator for whole-arm collision avoidance of 7-DoF redundant robot manipulator

Abstract

In this paper, we propose a repulsive reaction vector generator (RVG) for whole-arm collision avoidance of 7-DoF redundant robot manipulator, and elucidate the case of spherical-revolute-spherical (S-R-S) type manipulator. Furthermore, this article discusses the obstacle-avoiding function of RVG, in which the generated reaction vector can aid the manipulator to achieve collision avoidance in an intuitive way by taking arm angle as the redundant parameter. First of all, we use six representative points to describe the manipulator, and generate the repulsive vectors according to the relationship between obstacle and the tip, wrist, and arm body of the manipulator, respectively. Next, after the pose of the manipulator, including position, orientation, and arm angle, is rectified by the reaction vector, the command would be sent to proposed vOTG to complete the reactive motion. As a result, the manipulator can achieve intuitive repulsive reaction, active whole-arm collision avoidance, and meanwhile avoiding the minor-risk obstacle by rotating the arm plane. Experimental results with NTU-iCeiRA arm developed in our lab and Microsoft Kinect depth sensor are presented.

Collision Avoidance for Redundant 7-DOF Robots Using a Critically Damped Dynamic Approach

“…The SRS-type robot is a redundant robot with seven revolute joints (7-DOF) with the possibility of elbow movement, adapted mainly for collaborative tasks between robots or robots and humans [9,44,45]. The scope of applications has encouraged several authors to develop research and proposals for the kinematic modeling of this robot [8,9,26,35,37,46].…”

Motion Planning for Dual-Arm Robot Based on Soft Actor-Critic

“…Currently, a more mature collision-free method has been developed to plan the trajectory in an offline manner before the arm starts to move [8] [9][10] [11] [12]. The method that is more widely studied today is to generate the repulsion vector by the distance between the links, which is inversely proportional to the distance between the links, thereby changing the trajectory of the arm movement to achieve the effect of self-collision avoidance [13] [14], some studies have added vision, and derived this method to avoid obstacles in the environment at the same time [15] [16].…”

Virtual Velocity Vector-Based Offline Collision-Free Path Planning of Industrial Robotic Manipulator

“…Other researchers have constructed virtual velocity functions and utilized velocity control mode to actuate mobile robots [22][23][24] and articulated robot arms [25] in an environment with moving obstacles. In [26][27][28], the potential field function is used to calculate the correc-tion of velocity in task space. The redundancy of planner multi-link robot arms is utilized to avoid obstacles or other robots.…”

“…For this reason, some researchers have used the potential field function to calculate correction of position in task space, utilizing robotic kinematics for robot control [19–21], Other researchers have constructed virtual velocity functions and utilized velocity control mode to actuate mobile robots [22–24] and articulated robot arms [25] in an environment with moving obstacles. Fn [26–28], the potential field function is used to calculate the correction of velocity in task space. The redundancy of planner multi-link robot arms is utilized to avoid obstacles or other robots.…”

“…The real-time/online collision avoidance technologies of manipulators [12, 17, 28–30] calculate and generate the paths and joint trajectories in real time, but the shape, length, and destination of path and total task time are indeterminate, so it is impossible to guarantee the repetitive positioning accuracy and tact time. Even more, the online-generated trajectory is not smooth and optimal, such that the joint velocity may suddenly change or reach the upper/lower limits, which may result in oscillation or unstable movement.…”