Elastic strips: Implementation on a physical humanoid robot

For robots to operate in human environments, they are required to react safely to unexpected changes in the work area. However, existing manipulation task planning methods take more than several seconds or minutes to update their solutions when environmental changes are recognized. Furthermore, the computation time exponentially increases in case of highly complex structures such as humanoid robots. Therefore, we propose a reactive system for high d.o.f. robots to perform interactive manipulation tasks under real-time conditions. The paper describes the implementation of the Elastic Strip Framework, a plan modification approach to update initial motion plans. To improve its real-time performance and reliability, the previous geometric approximation is replaced by an implicit method that constructs an elastic tunnel for collision checking. Additionally, in order to maintain a robust system even in exceptional situations, such as undetected obstacles, the force transformer module executes compliant motions, and the current elastic strip adapts the path tracking motion by monitoring tracking errors of the actual motion. The proposed system is applied to a Honda humanoid robot. Real-time performance is successfully demonstrated in real-world experiments.