An Optimal Steering Control for the Articulated Body Mobile Robot.

Abstract

This paper investigates an optimal steering control method for the articulated body mobile robot KORYU-II (KR-II), considering energy consumption and trajectory tracking performance as the optimization criterions. The computer simulation results of the basic control methods of KR-II's θ-axis (bending motion between the segments) and s-axis (rotation motion of the wheels), yield to the conclusion that the best methods are, the “moving average shift method : θ2” combined with the “position control with small proportional gain method : θ4” for the θ-axis, and the “torque control method : s3” for the s-axis. The θ2 method is to take the average value of KR-II's foremost segment's control angle θ0 over the time to travel distance L (a segment center to center distance) as the next segment command θ1, and shift the command θ1 to the following segments according to the moved distance. The θ4 method is to set the gain much smaller than the conventional gain value. The s3 method is to control the velocity of the robot by equally distributed torque command for all the wheels. The experiment by the mechanical model KR-II revealed that, although the trajectory tracking performance is somewhat deteriorated, the introduced control greatly reduce the energy consumption and produce very smooth locomotion.