Design and control of a hydro-mechanical transmission for all-terrain vehicle

A hydro-mechanical continuously variable transmission for the all-terrain vehicle is investigated. The transmission is with single planetary and input differential. A variable hydraulic pump and a hydraulic motor are equipped to get a wider speed range. The parameter effects on the speed and the torque are analysed. The system parameter design method is studied. The active disturbance rejection control algorithm with feedforward compensation is adopted to the speed ratio control. A hydro-mechanical continuously variable transmission prototype has been built up. The vehicle dynamic performance and the speed ratio control are investigated by simulation and experiment. The vehicle driving and braking performance are tested and discussed. The results indicate that the vehicle acceleration and deceleration can be controlled by changing the displacement ratio. The active disturbance rejection control with feedforward compensation is effective in the speed ratio control. It reduces the speed ratio error of the continuously variable transmission and has good adaptability. The results can be used to optimize the structure and the control strategy of the hydro-mechanical continuously variable transmission.