Basic steering control methods for the articulated body mobile robot

This article investigates steering control methods for the articulated body mobile robot KORYU-II (KR-lI), a mechanical model composed of seven segments, with total length 3.3 m and total weight 330 kg. The objective is to generate joint commands for all the segments of KR-II, taking the velocity and direction of the foremost segment as input commands, which are provided from a remote human operator. Energy consumption and trajectory tracking performance are considered as criteria for evaluating the performance of the derived control algorithms. The computer simulations of the basic control methods of KRII´s Θ axis (bending motion between the segments) and s axis (rotation motion of the wheels) lead to the conclusion that the best methods are: the “Θ2 method” combined with the “Θ4 method” for the Θ axis, and the “s3 method” for the s axis. The “Θ2 method” takes the moving average value of the control angle Θ₀, which is given from the operator to the foremost segment, over a traveled distance L (intersegment length) as the next segment command Θ₁ and then shifts Θ₁ to the following segments according to the moved distance. The “Θ4 method” entails setting a small position control gain for the Θ axis. The “s3 method” controls the forward velocity of the robot by equally distributed torque commands for all wheels