Behavior-based autonomous cooperative control of intelligent mobile robot systems with embedded Petri nets

This paper presents a methodology of distributed control system design for autonomous cooperative control of intelligent mobile robots. Following the natural concept of control architecture evolution, a bottom-up approach for control system design is presented. First, microcomputer based intelligent device modules, such as multiple infrared range finding sensor modules, and odometry and locomotor control modules, are constructed as a device manager layer on a distributed multi-microcontroller network based hardware structure to detect walls and obstacles and to move around the surroundings of a two-wheeled mobile robot. Then functional control modules, such as landmark and obstacle recognition and localization, robot motion control are implemented based on the device layer. Environment features such as lines and corners are estimated using a set of range sensors and a vision sensor. Next, some intelligent behavior modules, such as wall following, obstacle rounding, and target seeking, and environment mapping are implemented as cooperative activities based on the functional control modules. Upon these hierarchical activity modules, a non-centralized control approach is applied to implement the autonomous coordination of concurrent activities among behavior modules for the high-level tasks such as sensory navigation in unknown environments. The system integration and implementation issues are discussed for the proposed approach.