A sensorless bilateral robot manipulator based on twin drive system

A bilateral robot is one of the remote control robots. By implementing the force feed back, it is possible for the operator to have the sense of the touch. But the force sensor is affected by unknown disturbance such as its temperature variation and so on. For that reason, it is not expected to use the force sensor at the extreme situation. In the sensorless approach, the reaction torque observer is used. But the reaction observer is easy to be influenced of the friction. This makes it difficult to estimate the external force. To address the above issue, this article proposes a twin drive system. This system is composed of two motors and one differential mechanism. It is required to control two motors for two degrees of freedom. To consider the above issue, two virtual motors are proposed. One is deal with the output control and the other is for friction compensation. The twin drive system brings a sophisticated ability to the system, which is a reduction ability of the friction. By using this system, it is possible to realize the remote control robot, where the operator can feel the obstacle which the slave robot touches. This system may help the remote control work more skillfully. The validity of the proposed method is confirmed by the experimental results.