Safe robot operation alongside humans using spring-assisted modular and reconfigurable robot

Abstract

Recently a novel spring-assisted modular and reconfigurable robot (SA-MRR) has been developed at our laboratory to reinforce its performance and to enable safe and dexterous operation in shared human-robot environments. Upon spring engagement at any joint position, the joint output torque becomes the sum of the actuator torque and spring torque, and the joint displacement range is mechanically limited. Restricting the manipulator's joint displacement limits individually allows the workspace to be confined selectively to a subspace of its entire or natural workspace, and creates an opportunity for a human to enter safely into the robot's natural workspace even while the robot continues to operate. Furthermore, the SA-MRR operating under spring-assistance offers functional benefits; the spring torque may counterbalance the manipulator and payload weight to avail the actuator torque fully for manipulation—an act which may simultaneously increase dexterity and decrease power consumption. The shared human-robot workspace notion as enabled by the SA-MRR is explored first in this work. Then, capabilities of a 3-DOF SA-MRR are investigated through simulations for dexterous operations and for payload handling within limited workspaces.