Control of Hydraulic Actuator Systems Using Feedback Modulator

Abstract

Heavy-duty robots using hydraulic actuators are expected to support rescue operations by removing heavy rubble in hostile -wet, dusty, or muddy- environments. The high friction generated by their hydraulic actuator, however, makes it difficult to use them in operations requiring high precision. The servovalves used to control a hydraulic actuator precisely are more expensive than conventional proportional valves, making it impractical to install them in all joints of heavy-duty robots having many degrees of freedom. In this paper, a new hydraulic actuator control method using a feedback modulator is proposed. The proposed controller improves the performance of hydraulic systems using conventional proportional valves, making it as good as that with servovalves. This paper also proposes exclusive control for controlling multiple joints simultaneously to prevent asynchronous joint movement under unbalanced loads. The effectiveness of the proposed method is confirmed through simulations and experiments.