A MySQL Database for the Systematic Configuration Selection of Redundant Manipulators when Path Planning in Confined Spaces

Abstract

Redundant manipulators offer a continuum of joint configurations which satisfy a specific end-effector pose, an advantage when operating within confined spaces. This, however, challenges a controller to select a single goal configuration from a wide range when path planning. This paper outlines the use of the MySQL database management system to reduce randomisation in goal selection during redundant manipulator path planning in confined spaces. We outline a sampling method to envelope all configurations of a redundant manipulator and utilise it to generate a complete database of configurations. We demonstrate the application of this method to generate a large data-set of manipulator configurations for a KUKA LBR iiwa 14 equipped with a Robotiq 2F-85 gripper. With this database, the controller systematically selects goal configurations during 50 path planning scenarios within the confined space of a glovebox. We compare this to a randomised inverse kinematics search method to select goal configurations as a baseline. The database method achieves a 100% success rate in 42% of the scenarios attempted, in comparison to the baseline method which achieves a maximum success rate of just 25%. Our proposed method also produces repeatable paths, which are similar in length and link swept area for each attempt of the same scenario, whereas the baseline method generates a different path in every attempt.