A Hybrid Approach to Practical Self Collision Detection System of Humanoid Robot

Online self collision detection system for humanoid robots is an essentially important function for developing sensor based behaviors without worrying about breaking hardware. In this paper, we propose a practical and real-time self collision detection system for humanoid robots that satisfy both enough a range of movement and a safety margin. Previous researches usually add a safety margin around each link to cope with errors in both modeling and control. However this margin significantly decreases a range of movement of a joint, especially a compound joint, a joint between adjacent links and composed of 2 or 3 revolute joints whose axis intersect in a same point. In order to gain enough a range of movement and safety margin, we developed hybrid approach that uses both table based collision checking for compound joints and online geometrical model checking with a simplified link shape for other joints. We have experimentally evaluated our self collision detection system using a HRP2-JSK humanoid robot. Our demonstration shows that the robot automatically stops its motion when self collision occurs