Application of an adaptive fuzzy sliding mode controller in velocity control of a secondary controlled hydrostatic transmission system

A secondary controlled hydrostatic transmission system (SC-HST), which considered being an energy-saving system, can recuperate most of the lost vehicle kinetic energy in decelerating and braking time and it shows advantage in fuel economy improvement of vehicle. Because of nonlinear characteristics of almost secondary control units (SCU) in a SC-HST, such as dead-zone input, it is difficult to obtain precise position or velocity control by conventional linear controllers. This problem limits the application of SC-HST in industry and mobile vehicle. To solve the problem, this paper gives a description of SC-HST and proposes an adaptive fuzzy sliding mode controller (AFSMC) for velocity control of SCU. Experiments were carried out in the condition of disturbance load by using both the proposed controller and PID controller for comparison and evaluation the effectiveness of the proposed controller. The experimental results indicated that the proposed controller was excellent from the standpoints of performance and stability for velocity control of SC-HST.