Design and implementation of a mechanically heterogeneous robot group

This paper describes the design and construction of a cooperative, heterogeneous robot group comprised of one semi-autonomous aerial robot and two autonomous ground robots. The robots are designed to perform automated surveillance and reconnaissance of an urban outdoor area using onboard sensing. The ground vehicles have GPS, sonar for obstacle detection and avoidance, and a simple color- based vision system. Navigation is performed using an optimal mixture of odometry and GPS. The helicopter is equipped with a GPS/INS system, a camera, and a framegrabber. Each robot has an embedded 486 PC/104 processor running the QNX real-time operating system. Individual robot controllers are behavior-based and decentralized. We describe a control strategy and architecture that coordinates the robots with minimal top- down planning. The overall system is controlled at high level by a single human operator using a specially designed control unit. The operator is able to task the group with a mission using a minimal amount of training. The group can re-task itself based on sensor inputs and can also be re- tasked by the operator. We describe a particular reconnaissance mission that the robots have been tested with, and lessons learned during the design and implementation. Our initial results with these experiments are encouraging given the challenging mechanics of the aerial robot. We conclude the paper with a discussion of ongoing and future work.