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Modeling and performance analysis of a magnetorheological fluid actuation system

Magnetorheological (MR) fluid systems have been widely utilized in various industrial applications due to its advantages of fast response, simple mechanic-electric-transform circuit, less motion friction with no-moving part and less energy consumption compared to active force control devices. In this paper, a MR actuation system which uses MR fluids as the transmission medium is introduced. The network of MR valves which forms a Wheatstone bridge in the system is connected to a single rod hydraulic cylinder. The motion of the cylinder shaft can be conveniently controlled through adjusting the damping characteristic of MR control valves. A new working mode is put forward to implement more effective velocity adjustment. The theoretical model of the magnetorheological actuation system is presented, which considers the quasi-static characteristics of MR control valve, motion dynamics of hydraulic cylinder and working flow rate and pressures from pump components. Consequently, the uni-directional motion, bi-directional motion and velocity regulation of the MR actuation system under controllable excitation currents is analyzed along with simulation results. It is shown that the transient performance of the motion of the cylinder shaft can be significantly affected by the excitation current. The modeling and simulations can provide useful evaluation for optimal design and control synthesis of the MR valve actuation system.