Model-Based Control of a Mobile Platform With Independently Controlled In-Wheel Hydraulic Motors

Abstract

Wheeled mobile platforms are important subsystems of heavy-duty working machines, but precise motion control of vehicles with multiple actuated wheels can be challenging, as linear controllers relying solely on velocity feedback could lead to excessive slippage of the wheels in face of varying terrain conditions. When aiming for more advanced control tasks as opposed to path-following, torque control of individual wheels could become necessary in order to distribute the traction effort in a desired fashion between each wheel. Studies on dynamic-model-based control of wheeled mobile robots concentrate on eletrically driven platforms that exhibit more linear behaviour than hydraulic drives, and dynamics of hydraulic motors are rarely addressed in the control design. In this paper, a model-based control design is pursued for a four-wheel vehicle actuated by in-wheel hydraulic motors, all independently controllable by high-bandwidth valves. Experiments on a heavy-duty mobile platform, equipped with wheel odometry, pressure transducers and satellite positioning, are conducted to study the feasibility of the proposed controller.