A study of the collision detection of robot manipulator without torque sensor

In this study, we proposed the collision observer for real-time detection of collisions between service robot and unknown obstacle. In case of a mobile equipped extra manipulator such as a service robot the safety of the system in service field is very important because a collision between the manipulator and a person may damages against the one. Therefore it is required to detect the collision against the unknown obstacle and to make them safe. This paper proposes current based method to detect unexpected collision without using extra sensor such as the force/torque(F/T), tactile sensor or the visual sensor. Instead of these sensors, the collision is detected by the observer for collision. To detect the collision of the manipulator without force/torque sensor, two parameters are only required for calculation of collision observer. One is current value, the other is control input value. Because the current from the servo amplifier is generated to follow the controller command input, the current can be used for detecting the collision. After detecting the collision of robot manipulator, we can control the robot to make them safe or reduce damage. The proposed collision detection method is implemented in a light weight robot manipulator. It is confirmed that the proposed method is valid by experimental results.