Robot Contact Reflexes: Adaptive Maneuvers in the Contact Reflex Space

Abstract

In order to transform a robot into an intelligent machine it needs to be enabled to react to unforeseen events (most importantly collisions) during task execution and have a plan on how to continue the task afterwards. This requires a flexible operational framework that allows to define adaptive reactions and interactions with the motion generation and task planning stage. Within this work we first reason about the choices the robot has for reactions to unforeseen events such as collisions with respect to safety of humans in the workspace, the robot itself and the environment as well as the successful task execution. We further present a flexible reflex engine together with a concept of integration into the motion generation and control work flow. The reflex engine and it's reflex maneuvers are a combination of state machines and decision trees that take into account the state of the robot and the world. It is capable of choosing safe reactions and can differentiate between different levels of contact severity and according reaction sets. Several reflex maneuvers are evaluated towards safety performance criteria in real robot experiments using an ISO/TS 15066 conform measurement device. Some of the tested reflexes are furthermore integrated into an implementation of the proposed approach for a simple real world example task where the robot needs to pickup a container and dispose it's content into a bin.