Bilateral control using compression type mechanical gravity canceller

Many studies on human support robots have been carried out hitherto. Bilateral control based on 4ch bilateral controller is an efficient method for human support. Bilateral control is a method for realizing transmission of force sensation between master system and slave system. However, in the case of multi-degree of freedom system, containing vertical motion, it is difficult to distinguish reaction force and gravity force. Moreover, it is difficult to actuate multi-degree of freedom robots with direct drive motors because the rating of the motors are limited. Therefore, this paper proposes a bilateral control using mechanical gravity canceller. In the proposed system, compression type mechanical gravity canceller (CGC) is used to compensate the gravity force. CGC is a passive gravity compensation mechanism with slider crank mechanisms and compression springs. As a result of this mechanism, gravity force can be completely suppressed. Thus, the proposed system enables vertical bilateral control without gravity effect. Experimental results are given to show the validity of the proposed system.