Motion Strategies for a Cobot in a Context of Intermittent Haptic Interface

Abstract

From the list of interfaces used in virtual reality systems, haptic interfaces allow users to touch a virtual world with their hands. Traditionally, the user’s hand moves the end-effector of a robotic arm. When there is no contact in the virtual world, the robotic arm is passive; when there is contact, the arm suppresses mobility to the user’s hand in certain directions. Unfortunately, the passive mode is never completely seamless to the user. Haptic interfaces with intermittent contacts are interfaces using industrial robots that move towards the user when contact needs to be made. As the user is immersed in the virtual world via a virtual reality head mounted display (HMD), he cannot perceive the danger of a collision when he changes his area of interest in the virtual environment. The objective of this article is to describe four movement strategies for the robot to be as fast as possible on the contact zone while guaranteeing safety. This work uses the concept of predicting the user’s intention through his gaze direction and the position of his dominant hand (the one touching the object) and safe-points outside the human workspace. Experiments are done and analyzed with a Pareto front with a UR5 robot, an HTC vive tracker system for an industrial application involving the analysis of materials in the interior of a car.