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Chen et al. Complex Eng Syst 2023;3:8 Complex Engineering
DOI: 10.20517/ces.2022.50 Systems

Research Article Open Access

Nonlinear hierarchical control for four-wheel-independent-
drive electric vehicle

1
1
Xiang Chen 1,2 , Yuan Qu , Taowen Cui , Jin Zhao 1
1 Vehicle Lab of Intelligent Vector Control Technology, Chery Automobile Company Limited, Wuhu 241000, Anhui, China.
2 College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, Jiangsu, China.

Correspondence to: Dr./Associate Prof. Xiang Chen, College of Energy and Power Engineering, Nanjing University of Aeronautics
and Astronautics, 29 Yudao Street, Nanjing 210016, Jiangsu, China. E-mail: jluchenxiang@163.com
How to cite this article: Chen X, Qu Y, Cui T, Zhao J. Nonlinear hierarchical control for four-wheel-independent-drive electric
vehicle. Complex Eng Syst 2023;3:8. http://dx.doi.org/10.20517/ces.2022.50

Received: 28 Nov 2022 FirstDecision: 31 Jan 2023 Revised: 26 Mar 2023 Accepted: 25Apr 2023 Published: 20May2023
Academic Editor: Hamid Reza Karimi Copy Editor: Fangling Lan Production Editor: Fangling Lan

Abstract
As under-constrained systems, four-wheel-independent-drive (4WID) electric vehicles have more driving degrees of
freedom. In this context, reasonable control and distribution of driving or braking torque to each wheel is extremely
important from the vehicle safety perspective. However, it is difficult to provide the optimal wheel torque because of
the time-varying characteristics and typical over-actuated nature of the system. In light of these challenges, a novel
hierarchical control scheme comprising a top- and bottom-level controller is proposed herein. First, for the top-level
controller, a time-varying model-predictive-control (TV-MPC) controller is designed based on an extended 3-degree-
of-freedom (3-DOF) reference vehicle model. The total driving force and additional yaw moment can be obtained
using the TV-MPC. Second, for the bottom-level controller, the torque expression of each wheel is determined using
the equal-adhesion-rate-rule -based algorithm. The co-simulation results obtained herein indicate that the proposed
control scheme can effectively improve vehicle safety.

Keywords: Safety, four-wheel-independent-drive electric vehicle, time-varying model-predictive-control, equal ad-
hesion allocation

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0
International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, shar-
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