Control of A Cooperative Transportation System with Two Car-Like Mobile Robots Based on Chained Form (Experimental Verification of Its Open Loop Control)

Abstract

We have developed a cooperative transportation system with two tricycle mobile robots which are kinematically equivalent to car-like mobile robots, and we have verified the validity of an open loop control method based on chained form for the cooperative transportation system using the developed experimental apparatus. A mechanical feature of the developed tricycle mobile robot is that it is capable of controlling its single-steering wheel angle at high precision since it steers the single-steering wheel by a zero backlash spur geared motor. Another mechanical feature of the tricycle mobile robot is that it has a motor with a differential capable of driving its two rear wheels without slipping them, i.e., without spinning or dragging one of the rear wheels, when cornering. These features mean that the motion of the tricycle mobile robot is described by its kinematical equation precisely, and the controlling accuracy of the motion of the tricycle mobile robot is high enough to examine the validity of the open loop control method experimentally. We have performed a cooperative transportation task in which the two tricycle mobile robots trnsport a carrier cooperatively without changing the carrier orientation. Such task cannot be performed by a traditional single-trailer system. The validity of the open loop control method is verified by the experimental examination.