On-line identification and compensation for sensor-less force feedback using macro-micro bilateral control

Medical technology and bioengineering have achieved great progress recently. The main reasons are the technique and manipulation system in order to operate a cell directly, but the operational force can not be fedback to the operators. Macro-micro bilateral control is a method for force transmission between an operator and target object. Especially this paper focuses on macro-micro bilateral control in X-Z axis. In macro-micro bilateral control, the gravity force becomes a big problem and an air slider which is mounted on a slave system is used to cancel out the gravity force. However, the difference between air pressure and gravity force, defined as air disturbance, affects the performance of force transmission. Online identification method is necessary to compensate the air disturbance since the value of air disturbance varies according to a shaft´s position and time when experiment is done. In this paper, a reaction force observer (RFOB) with a low cut-off frequency and an acceleration method are utilized to obtain only DC component of estimated disturbance online. From the experiments compared with the proposed method and a normal RFOB, it can be confirmed that the proposed method is effective for compensation of the air disturbance.