A nonlinear spring model of hydraulic actuator for passive controller design in bilateral tele-operation

Abstract

Abstract-In this paper, the expressions that define compressibility of hydraulic medium are used to develop a nonlinear spring-like model for a hydraulic actuator. Using this model, an energy based controller for passive bilateral tele-operation of hydraulic actuator is designed. The control problem is posed to achieve power amplification from the master to the slave. The unknown external forces on the slave system are assumed to be constant and are estimated using techniques from direct adaptive control. Efficacy of the controller is evaluated by implementing it on a single degree-of-freedom setup. Experimental results demonstrate good co-ordination characteristics both in free space and when encountering a hard surface.

Bilateral Control of a Velocity Control System Using Electric and Hydraulic Actuators

“…If the proposed method is not used, further improvements in control performance will be difficult. Figures 7,9,and 11 show that the velocity closely tracks the position in all the control systems, and that judging the differences due to the control systems on the basis of these figures is difficult. However, an examination of Table 5 reveals that the position-symmetric approach has the smallest average position and velocity response errors, followed by the proposed method and the force-feedback approach.…”

“…In bilateral control [1,2,[7][8][9] using a conventional hydraulic actuator, force control is not performed on the slave side. This is because even though the flow control values used in this investigation are inexpensive, easily handled, and widely used, an actuator driven using a flow-rate proportional control valve constitutes a speed control system, and consequently, force control is difficult.…”

“…This is because even though the flow control values used in this investigation are inexpensive, easily handled, and widely used, an actuator driven using a flow-rate proportional control valve constitutes a speed control system, and consequently, force control is difficult. In bilateral control [1,2,[7][8][9] using a conventional hydraulic actuator, force control is not performed on the slave side. Furthermore, the position control described in Ref.…”