腕の筋骨格系モデルに対する運動と粘弾性特性の同時制御

抄録

Arm musclo-skeletal systems, driven by pairs of agonist and antagonist muscles, have redundancy in motor commands. The redundancy is caused by inherent arrangement of the antagonistic muscles and its synergistic coactivation, and is known to serve for flexible manipulation tasks, where positional movement and visco-elastic property of the arm should be controlled simultaneously. Additional pair of double-joint muscles, expands control range of visco-elastic property, increases more redundancy. Thus reduction of such motor command redundancy is a primary subject in the control of muscloskeletal systems.
In this paper, we propose a method for reducing the redundancy by explicitly specifying visco-elastic property and for realizing simultaneous control of positional movement and visco-elastic property. First, a musclo-skeletal system of the arm is modeled by a planar two-link manipulator with four single-joint muscles and two double-joint muscles. Then, motor commands to track the desired trajectories, specified with movement and visco-elastic matrices, are calculated by a relaxation method that uses a forward system model of the arm. Motor command redundancy is dissolved by optimizing a criterion function, composed of quadratic errors between the desired and the computed trajectories by the forward system model. Simulation results show that coactivation of double-joint muscles is important to control elastic property, and that the arm is controlled to execute the same positional movement with different elastic matrices..