Conference Paper

Singularity-Robust Inverse Kinematics Solver for Tele-manipulation

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Abstract

This paper investigates the effect of inverse kinemat-ics (IK) on operator performance during the telemanipulation of an industrial robot. Robotic teleoperation is often preferred when manipulating objects in extreme conditions. In many applications, e.g., hazardous and high-consequence environments, operators cannot directly perceive the robot motions and have to rely only on CCTV views of the scene for situational awareness while teleoperating the heavy-duty industrial robots. Making best guesses for the IK plays a significant role on the task success rate and increases the operator cognitive load significantly. In this context, we develop a new optimisation-based IK solver that is robust with respect to the robot's singularities and assists the operator in generating smooth trajectories. Inspired by a successful algorithm used in computer graphics to solve the IK problem and devise smooth movements (FABRIK), our algorithm takes advantage also of the kinematic structure of the robot in order to decouple the notoriously difficult IK problem of orientation and position. To evaluate the effectiveness of the proposed method, we have compared its performance to that of the commonly used Jacobian pseudo inverse-based method in terms of positional accuracy and task-space reachability. We also report the results of telemanipulation experiments with human test-subjects. Our proposed IK algorithm outperforms classical IK methods on both objective metrics of task success, and subjective metrics of operator preference.

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... Multiple methods have been proposed to solve the inverse kinematics problem of 7-DOF manipulators, and the most widely used approach is velocity solution based on Jacobian matrix, either in closed or iterative form [8][9][10][11][12] . Although these solutions are versatile and have a wide range of applications, they still exhibit several disadvantages: i) require complicated calculations and expansive time costs; ii) have low solution accuracy due to cumulative errors; iii) have Jacobian singularities; iv) need to pre-assign task trajectory. ...
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... Interestingly, humans prefer robot configurations that are more natural or human-like as they are more readable [143]. Inverse kinematics algorithms mapping Cartesian motions to the robot's joint space can also aim at devising overall movements for the robot that are legible to the human partner [144], [145]. ...
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