Abstract
This paper proposes an approach to the quantitative evaluation of robotic compliant motion tasks based on the power consumed by interaction between parts handled by a robot and parts in a task environment. Power is defined as instantaneous work, and in a task such as assembly where a moving parts grasped by a robot makes contact with a parts in a task environment and acts against friction during the contact, it results from the work lost to friction. As an application of the technique for evaluating tasks according to power consumption, a method for tuning the compliant motion parameters in a robotic task is discussed. This method is an experimental approach to motion control planning, whose aim is to obtain optimized motion parameters for a task. It employs the response surface method as a schema for experimental design, because of the method's similarity to the process whereby humans tune parameters. The response surface method is known as an effective means of incremental local optimization. Finally, to confirm the effectiveness of evaluating tasks according to power consumption and to test the mechanism for tuning motion parameters, the proposed tuning method is applied to a plug insertion task. This is a very interesting task in the sense that it is not easy to determine whether a robot has completed such a task from force and position information, even though the task requires only simple operations. If the work done during the task process is used as a task evaluation index, the task can be easily validated, and the motion parameters can be tuned in the same way as by a trained human operator.
