Development and evaluation of distributed control algorithms for the mobile robot Nomad200

The Nomad200 is an electrical mobile robot who is equipped with different kinds of sensors (infrared, ultrasonic, Laser sensor and contact switches). It can be programmed and controlled in two ways: directly via the on board PC card or remotely via a UNIX workstation. In the late case, commands and data are transmitted by an ethernet radio link. The purpose of this work is to build a robust navigation algorithm that has to be included in a general robotics application. This algorithm uses the laser sensor and the infrared sensors to build a map of the environment. The map is constructed step by step during the motion of the robot and a complete path is computed at each update of the map. The Voronoï retraction method, the A* algorithm and custom techniques are used to obtain the free way. Two different speed controllers, one heuristic and one using the fuzzy logic theory, have also been developed. The program was first written on the remote Host Station. But, in order to give to the robot a better autonomy and to prevent the communication failures, a distributed control of the robot has been implemented. We propose in this work different solutions for the distribution of the control. Each solution has been tested in simulation and with the real robot.