Abstract
Robots have been proceeded to be introduced into operations with constraints from the manipulated object such as deburring, human assisting. In these operations, not only the position but also the operating force has to be controlled, and the proper compliance is required to absorb oscillations or impact forces. A pneumatic robot with the inherent compliance due to the air compressibility can meet this requirement. However, for its practical applications, the improvement of the controllability is essential.
The hybrid control is one of methods to control both the position and the force simultaneously. The purpose of this study is to realize the hybrid control of high performance with the pneumatic robot.
To execute the hybrid control, both position and force control systems have to be constructed. Generally, in this kind of robot the force control is relatively easy, but the satisfactory position control performance is not easy to obtain. Firstly, to overcome this deficiency, a sliding mode control with a pressure feedback compensation is proposed and applied to the position control. It can stabilize the response by inhibiting the chattering being a serious problem in the usual sliding mode control, and realize the continuous path control which has been considered to be difficult for a pneumatic robot. Next, the hybrid control is implemented using this position control manner in combination with usual PI type force control. As a result, the satisfactory performance can be obtained.
Further, it is pointed out that to obtain the higher control performance some considerations for the friction are necessary.
