A study on autonomous pipeline maintenance robot. 4th Report. Joint control and its trajectory generation for Mark III.

Abstract

The pipeline maintenace robot Mark III with the inch worm mechanism, presented in the 3rd report, can pass over obstacles on pipelines, such as flanges and T-joints and others. For this motion control, the joint control methods for Mark III, especially the optimal trajectory generation are shown in this report. First, this robot system has the modified dual control mode, A and B with the transfer matrices different from the previous method. The control mode is changed mutually when the basic arm grasping the pipe is changed. Second, the static joint torques are calculated to determine the desired transfer matrix, and a configuration which has the minimum joint torques is selected. Third, an optimal trajectory is generated by dynamic programming in order to control joints from the present angles to the desired angles. It has two criteria : joint torques and position errors.