Gentle robotic handling - adaptation of gripperorientation to minimize undesired shear forces

Abstract

Today's palletizing and handling robots move their payloads on trajectories that are neither optimized for minimal grasping forces nor for careful object handling. Problems arise with vacuum grippers that can only exert normal forces on payloads. During high-speed transfers undesired shear forces and torques appear that may well lead to the loss of grasped objects and consequently to a production stop and damage to both the object and the environment. A related problem is concerned with handling goods that need special care, such as liquids that should not spill over during transport, or bakery goods on a tray that should not be scrambled and dislocated before being moved into an oven. To be able to handle objects with care but nevertheless with maximum velocity, a new simple and effective methodology based on the adaptation of the gripper orientation is proposed. It leads to robot trajectories (in particular gripper orientations) that minimize shear forces and torques on grasped objects and thus allows gentle robotic handling processes. The methodology is presented as well as simulation and experimental results