A behaviour-based manipulator for multi-robot transport tasks

In this paper we report on the design, implementation and testing of a manipulator for a multi-robot task involving the transport of an extended payload by two robots. The overall task involves three main manipulation components, namely payload pickup, terrain traversal and putdown at the deployment site. The manipulator was specifically designed to meet the requirements of these manipulation operations. It comprises three main components, a two-degree of freedom arm, a passive but compliant one-degree of freedom wrist, and an active gripper mechanism. Low-level control is accomplished using a small network of PIC microcontrollers. A key design goal of the control architecture was software and hardware modularity: separate modules drive the motors, measure encoder counts and support a range of low-level behaviors suitable for the task. Several sensors were specifically designed to enhance the compliance of the system. High-level control is based on an on-board laptop computer. The paper describes the motivation, the design and implementation, and the experimental results to date.