Design of an adaptive control for a magnetorheological fluid brake with model parameters depending on temperature and speed

This paper describes experimental/theoretical activities carried out on a magnetorheological fluid brake (MRFB) prototype. A device model is derived and a detailed evaluation of the influence of temperature and speed on its parameters is performed. It can be seen that temperature and speed act as modifying inputs for the system model and change the value of some of its parameters. More specifically, time constant and torque/current gain are affected by velocity whereas fluid viscosity is only affected by temperature. The presence of the above modifying input suggests the employment of an adaptive approach for MRFB feedback control based on the torque measurement only. Starting from the proposed model, a model reference adaptive control is designed, ensuring that the tracking error converges to zero as time t →∞. Simulation activity, carried out on the device validated model, confirms the effectiveness of the proposed adaptive controller.