Accelerating the Validation of Motion Control for a 4WD4WS Ground Vehicle Using a Hierarchical Controller Hardware-in-the-loop System∗

Due to the actuator redundancy and complexity of the unmanned ground vehicle actuated by four-wheel drive and four-wheel steering powertrains (4WD4WS UGV), it is a significant challenge to conduct fast verification of the complex control system. This work presents a dedicated hierarchical controller hardware-in-the-loop system to accelerate the verification of the motion control system for a 4WD4WS UGV. The hierarchical controller, that is implemented in a combined onboard-computer and embedded micro-controller, adopts a three-layered architecture. The upper layer uses a model predictive control algorithm (MPC) to calculate the desired heading angle and vehicle speed. The middle layer converts the control effect into the desired speeds and steering angles of four wheels. The bottom layer controls the drive motor and steering motor to track the desired speed and steering angle of each wheel. The proposed HC-HIL system establishes a multibody dynamics model of the 4WD4WS UGV with high fidelity, and accelerates the validation process of the motion control performance, via which the complex control strategy can run in the actual control hardwares and be verified in a virtual model with high fidelity. The HC-HIL system provides a fast and low cost method for initial testing prior to the real implementation, thereby reducing the potential failures in future real testing.