Operability of a Control Method for Grasping Soft Objects in a Construction Teleoperation Robot Tested in Virtual Reality

Abstract

The purpose of this research was to evaluate an operation system that includes a control method of feedback previously proposed by our lab, in a virtual reality setting. Specifically, we examined a master-slave control system for a teleoperation construction robot. The master comprises two joysticks adopted to manipulate objects from a remote location, and the slave corresponds to an excavator with four degrees of freedom, regarded as a construction robot. The authors previously proposed a control method to provide an operator with a realistic sensation of grasping by introducing a noticeable reaction torque to the joystick's handling and a variable master torque gain according to an object's hardness when the robot moves slowly to grasp a soft object. In this research, an operability test was conducted when the control method was introduced to actual tasks, including grasping, conveying and classifying tasks using concrete blocks and sponge foam blocks. Measurement of mental strain using NASA-TLX and measurement of physiology strain using heart rate variability were recommended as evaluation methods in addition to the use of task efficiency and danger indices. According to statistical analysis of the experimental results, we verified that the control method used in the operation system could contribute to improving efficiency and safety during teleoperation work as well as alleviating the operator's mental fatigue and stress.