Current status and challenges of path tracking control of unmanned driving vehicles
- Available Online:
Abstract: Path tracking control is a key technology in the hierarchical unmanned driving system. Its function is to control the vehicle to drive along the reference path given by the path planning system based on the body pose information given by the perception positioning system. In recent years, the development of path tracking control has been very rapid, and researchers have published a lot of research results. Because there are some common technical problems and solutions in path tracking control under the same or similar scenarios, the research results in recent years are reviewed from the perspective of low-speed path tracking control and high-speed path tracking control. The challenge of low-speed path tracking control mainly comes from the front wheel angle speed constraint. With this constraint, the controller cannot respond quickly when the curvature of the reference path changes largely and suddenly. The current common solutions are to smooth the curvature of the reference path, add preview control, and apply nonlinear model predictive control. In addition, this problem can be solved by increasing the power of the steering mechanism and reducing the vehicle speed. The challenge of high-speed path tracking control mainly comes from the fact that when the vehicle speed is high or the ground adhesion coefficient is low, the centrifugal force may be greater than the limit value of the lateral force resultant force, resulting in greater lateral speed, resulting in reduced path tracking accuracy and even lost vehicle driving stability. The current common solution is to design a path tracking controller using a control method that can take the influence of lateral speed into consideration, such as a linear model predictive control based on a dynamic model. However, when the vehicle speed is high, there is a contradiction between the path tracking accuracy and the vehicle driving stability, and the basic dynamic path tracking control is difficult to solve this problem. For this reason, some researchers have added speed adjustment or game theory to the path tracking control. In addition, in the high-speed path tracking control, the ground adhesion coefficient and tire characteristics also have a greater impact, so it is necessary to further study the online estimation and identification of parameters such as ground adhesion coefficient and tire characteristics.