Trajectory tracking control method used for driverless vehicle

Abstract

The invention discloses a trajectory tracking control method used for a driverless vehicle. The method includes the following steps that the current position point of a vehicle body is confirmed according to a reference trajectory; a matching point nearest to the current position point of the vehicle is found, and the road curvature of the nearest matching point is obtained according to a two-point curvature obtaining method; according to the current position point of the vehicle and the nearest matching point, a trajectory tracking error is obtained through calculation and comprises a transverse error and a head pointing error; a dynamic model feeding back cornering force on the basis of front wheels is established, and the optimal feedback control rate is obtained by the adoption of an LQR control algorithm; and the cornering force of the front wheels is determined, a front wheel slip angle is obtained on the basis of a reverse tire model, and then the steering wheel angle controlledquantity is obtained and issued to a steering-by-wire system to achieve trajectory tracking control. By the adoption of the method, the stability of trajectory tracking control of the driverless vehicle is improved, the trajectory tracking accuracy is improved, the tire slip angle is restrained, and the possibility that the tire force of the vehicle is saturated under an extreme working conditionand therefore the vehicle loses stability is avoided.

Description

technical field [0001] The invention belongs to the technical field of vehicle automatic control, and in particular relates to a trajectory tracking control method for unmanned vehicles. Background technique [0002] Unmanned vehicles are an integral part of future intelligent transportation systems, and vehicle automatic steering systems play a very important role in the control of unmanned vehicles. Trajectory tracking control is one of the basic control problems in the automatic steering process, which requires the unmanned vehicle to reach a given or planned trajectory point at a specified time. Since the vehicle is a strongly nonlinear and highly coupled complex system, it is difficult to establish an accurate vehicle dynamics system model, so the trajectory tracking control of unmanned vehicles is always a difficult point. [0003] The current international research on the trajectory tracking of unmanned vehicles often ignores or simplifies the vehicle kinematics cons...

AI Technical Summary

Problems solved by technology

For example, on low-adhesion roads, if the tire slip angle is not restricted, the vehicle is likely to experience lateral tire force saturation. At this time, if there is external interference, the vehicle will become unstable and affect the stability of the vehicle. Safety

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