Robust Control Design for a Single-Wheel Module Operating in an Off-Road Terrain with Uncertain and Stochastic Attributes

An in-wheel-motor (IWM) powertrain is a state-of-the-art technology, which allows mobility control, maneuverability, and energy efficiency of vehicles. In this paper, an off-road application of a single-wheel module (SWM) operating in severe terrain conditions is considered. The SWM is defined as a corner model of a 4x4 vehicle equipped with an IWM. Further, an agile control system is developed in order to achieve precise tracking of a reference angular speed of the wheel while maintaining tire slippage at a limited range. Specifically, a model-free method for the wheel circumferential force/torque estimation is given using a cascade differentiator design. This differentiator is integrated with a sliding mode controller to achieve a robust and precise tracking solution. It is further discussed how the controller gains/parameters can be regulated to maintain the slippage at all time. Finally, the design is evaluated through a numerical simulation. Specifically, the terrain attributes and height profile are considered to be stochastic and uncertain while the terrain experiences a drastic change through the simulation. The results prove the efficacy and agility of the control system design. Copyright (C) 2021 The Authors.