A unified modelling and model updating procedure for electrorheological and magnetorheological vibration dampers

Abstract

Magnetorheological (MR) and electrorheological (ER) dampers are known to exhibit nonlinear behaviour which can make it difficult to predict their performance, particularly when they are integrated into engineering structures. As a result it can be impossible to properly assess the feasibility of using such semi-active devices to solve practical engineering problems. In this paper, a new model format is proposed which represents an extension of earlier work by the authors. The proposed model is more general and yet maintains the physical significance of key parameters. A novel model updating (or system identification) technique is developed so that the model can account for the behaviour of various configurations of device without the need for prior knowledge of the fluid properties. The technique relies upon the iterative adjustment of the model’s stiffness parameter so that the quasi-steady behaviour of the device can be estimated. Correlation between a bi-viscous model and the estimated quasi-steady behaviour is used as the criterion for choosing the most suitable value of stiffness. The modelling technique is completed by establishing empirical shape relationships between the pre-yield parameters, post-yield parameters, yield force and the applied excitation conditions. The modelling and identification procedures are applied to an MR damping device and the results are validated by comparing predicted and experimental responses under both non-sinusoidal and broadband excitation conditions.

Observer Based Optimal Control of MR Dampers

“…In order to model the nonlinear behaviour of the MR damper, the lumped-parameter model shown schematically in Figure 2 was used [8]. In the absence of an applied current the force/velocity characteristics is a straight line through the origin, indicating Newtonian behaviour as seen in Figure 2(b).…”

“…As the magnetic field increased up to a maximum current so the yield force produced by the damper is seen to increase. In Figure 2(a) the valve flow which is quasi-steady is described by the nonlinear function and is a function of the quasi steady velocity of and the control signal to the smart damper: (5) Where , and are the modal parameters referred to the Sims et al work [8]. The force produced by the controllable MR damper is: (6) Here the represents the absolute displacement of the fluid inertia and represents the relative displacement of the piston.…”

“…Scientists have been studying the vibration theory since the first quarter of the twentieth century [5][6][7][8][9][10][11][12][13][14][15][16][17]. Some of the earliest research was done by Timoshenko [17] and Den Hartog [5] who described the primary solutions to vibration problem of the engineering structures.…”

Development of novel devices for upper-extremity rehabilitation

“…Speed-dependent resistance, for instance needed for isokinetic control, is more difficult to accurately achieve at high levels of torque and speed. Finally, contrary to the presence of residual resistance torques in other actuators like electro motors and magneto-rheological dampers [195,198,196], the achievable minimal impedance with disk brakes is zero. The only impedance torques exerted on the arm come from the inertia of the exoskeleton, not the brakes.…”

“…A recently developed damper uses electrical currents to control the damping in a magnetorheological fluid [195,198,118,196,235]. These magneto-rheological dampers have been used in prosthetic knees [76] and resistance training devices [63,41].…”