Longitudinal Speed Control Method of Unmanned Vehicle Under Undulating Road Conditions

To improve the accuracy of the speed control of unmanned vehicles under undulating road conditions, a method for preview detection of road slopes on the target trajectory was proposed. Firstly, the response delay parameters of the vehicle speed control system were measured by experiments to determine the preview time. The lidar point cloud was stored in a circle with the diameter of the vehicle width, and the number of circles and the center coordinates of the stored point cloud were determined according to the preview time, the vehicle speed, the detection blind area of the lidar, and the length of the target trajectory. According to the Euclidean distance between the center of the circle and the center of the front axle of the vehicle, the preview time, and the vehicle speed, the circles of the stored point cloud are dynamically updated and extracted, and the slope of the road surface in the preview area relative to the vehicle attitude is calculated by the trigonometric function method. Finally, the absolute slope of the road surface in the preview area is obtained by superimposing the pitch angle of the vehicle provided by the inertial navigation system. Experimental results show that the proposed road slope preview detection method can improve the accuracy of the speed control of unmanned vehicles under undulating road conditions. According to the analysis of the minimum speed of unmanned vehicles in the process of going uphill, compared with the control method that ignores the road slope and uses the pitch angle provided by inertial navigation as the road slope, the accuracy of speed control is increased by 5.9% and 2.5% respectively when passing through a 4° ramp, and the accuracy of speed control is increased by 85% and 17.5% when passing a 16° ramp, respectively. © 2024 Science Press. All rights reserved.