Autonomous Motion Adaptation against Structure Changes for Service Robots

Abstract

Robot motions are designed according to mechanical structures such as frame structure, number of joints and so on. Therefore, structure changes such as joint failures or frame distortion make the designed motions unaccomplished. In service robots working for general users, it is desired to recover the motions autonomously. In trajectory controls, it is desired to realize motions with some trajectories even on the changed robot structures. Conventionally, motion adaptation methods with inverse kinematics and identification of changed structures have been used to solve the problems. But, for multi-degree-of-freedom robots such as service robots, the methods are difficult to apply. New motion adaptation methods are proposed in this paper. In the methods, all motions are expressed as time series of joint angles, and corresponding joint angles are generated efficiently on changed structure based on exploration methods. Representing postures are sorted by the Vector Quantization from the series of designed joint angles. Corresponding joint angles are found by the Simulated Annealing only on the representing postures because of reduction of exploration costs. Adapted motions to realize the intended trajectories on the changed structures are estimated by the Kriging methods. In simulation, the adapted motions which achieve the intended trajectories are generated autonomously without identification. Its exploration costs are reduced about 1/7 comparing with full search method.