Safe autonomous stair climbing for a tracked mobile robot using a kinematics based controller

Planning and implementation of a safe autonomous stair climbing algorithm for a tracked mobile robot is presented in this paper. Two major factors are defined to make the climb as safe as possible. Based on these factors a desired trajectory is planned. Data of two laser range finders are used to locate the robot over the stairs. The error signal is generated by comparing the located and desired postures. To compensate this error, a kinematics based controller is utilized. A combination of a nominal feedforward command with a feedback action on error at each time step is used in this tracking control scheme. The proposed algorithm is implemented on ResQuake. This is a tele-operative rescue mobile robot with great capabilities in climbing obstacles in destructed areas, and its performance was demonstrated in Rescue robot league of RoboCup 2005 in Osaka (Japan), achieving the 2^nd Best Design Award, and RoboCup 2008 in China (Suzhou) achieving the 2^nd Best in Class Mobility Award. Implementation of algorithm on different staircases resulted in successful climb in all experiments. Results obtained on a sample staircase are demonstrated at the end of this paper.