Nonlinear Terminal-Free MPC on Multitype Bend Tracking With Discontinuous Reference Paths for Autonomous Vehicles

In this article, multitype bend tracking with discontinuous reference paths is researched by a nonlinear terminal-free model predictive control (MPC) with an artificial reference path for an autonomous vehicle. The MPC strategy without terminal penalty and terminal state constraints is proposed to deal with the discontinuous reference paths, which improves solvability on an optimization problem effectively. The artificial reference path is designed to realize replanning and smoothing for multitype bend paths. Both recursive feasibility and stability are discussed for the autonomous vehicle by a lower bound of prediction horizon and a controlled forward invariance set. Effectiveness of the nonlinear terminal-free MPC strategy is shown by experimental results on multitype bend path for the autonomous vehicle.

I. Introduction

According to Global Plan for the Decade of Action for Road Safety 2021–2030 by World Health Organization (WHO), road traffic crashes cause nearly 1.3 million preventable deaths and an estimated 50 million injuries each year [1]. It is well known that multitype bends are difficult to drive, such as roundabout [2], U-turns [3], and small-angle turns [4]. Motion control of autonomous vehicles should pay attention to multitype bend tracking with safe, comfortable, and efficient [5]. In multitype bend tracking, motion control is achieved by software algorithms and driving actions for acceleration, braking, and steering [6]. In practical applications, not only motion control but also reference paths are obtained from software algorithms in autonomous vehicles [7]. That is, motion control on multitype bend tracking is investigated under a given reference path for an autonomous vehicle.