Mobile manipulation of humanoid robots-a method of adjusting leg motion for improvement of arm's manipulability

Abstract

A control method of mobile manipulation for a humanoid robot by integrated motion centered arm manipulation is proposed. This method makes the arms carry out the manipulation, and the legs assist manipulation by adjusting its motion in order to keep the arm's manipulability high. Firstly, the arm tips always follow their desired position under the condition with external force by impedance control. Secondly, the shoulder is controlled so that manipulability and stability can be improved. Moreover, we define three functions; they are an average of manipulability measure, and an average and a minimum of stability margin in a locomotion cycle. We utilize their values in a locomotion cycle rather than the values of them at every moment, because manipulability and stability vary with robot motion. Then, we define the total evaluation function expressed by the sum of them. Step length and timing of step motion are determined so that the function can be optimized. The effectiveness of the proposed method is ascertained through the computer simulations.