Nonlinear model predictive control of vehicle trajectory tracking using tilting technology

Abstract

To enhance the performance of trajectory tracking in high-speed autonomous vehicles, this paper adopts a new technology for controlling the vehicle body to tilt toward the inside of a curve, known as “tilting technology.” It achieves this tilt through an active suspension system that inclines the vehicle body toward the inside of the curve, thereby reducing or offsetting the torque generated by gravity with the torque produced by centrifugal force. This significantly improves the vehicle’s handling stability and anti-rollover capability. Integrating this technology with active steering control, a nonlinear model predictive trajectory tracking controller has been designed. For this integrated controller, the Fiala lateral tire force model is used to establish a nonlinear vehicle model with steering-rolling dynamics, while a double-lane-change and single-lane-change tests are designed as the reference paths. To avoid the tilting angle of the vehicle body being too large to exceed the effective stroke of the suspension, a clipped ideal tilt angle is adopted as the desired tilting angle. Simulation verification is carried out to confirm the validity of the integrated trajectory tracking control. The proposed controller is compared with two other trajectory tracking controllers, the controller that takes zero rolling angle as the control target and the controller without rolling control. The results show that, compared with the latter two, the proposed trajectory tracking controller can ensure well tracking ability, meanwhile effectively improving the handling stability, anti-rollover capability, and occupant lateral ride comfort during trajectory tracking for high-speed unmanned vehicles.