The Design of Distance-Warning and Brake Pressure Control Systems Incorporating LiDAR Technology for Use in Autonomous Vehicles

This research presents the design of a brake fluid pressure warning and control system for autonomous vehicles (AVs) used on university campuses to control brake fluid pressure and measure the proximity of objects or obstacles in front of the vehicles using LiDAR. The goal was to reduce the jerking of the vehicle caused by the conventional braking system, which may cause danger to the user. We initially changed the existing brake system, which uses human braking force, to electric motor braking and tested it in a closed area (a test track) before actual use. This research was divided into two parts: Part 1—using LiDAR to create warnings in case there are obstacles in front of the vehicle and Part 2—controlling brake fluid pressure using a linear motor and a PD controller. Under the test conditions employed, at a speed of 20 km/h, the total load of passengers is 600 kg. The design results regarding the PD controller with the most suitable values of the system that prevent the vehicle from jerking are KD = 27.9606 and KP = 32.0490. The test was conducted while an object crossed the vehicle’s path at distances of 5, 10, 15, and 20 m, respectively. It was found that controlling brake fluid pressure by measuring the distance from the object helped reduce the braking time and jerking of the vehicle and could stop the vehicle before experiencing a collision. At a distance of 20 m, the vehicle could be stopped before the crash and was 3.7 m away from the object; at a distance of 15 m, the distance from the object was 3.1 m; and at a distance of 10 m, the distance from the object was 3 m. However, at a distance of 5 m, the brake system could not stop the vehicle, causing collision with the object because the distance from the object for braking was less than the designed distance. This shows that the warning system and the brake fluid pressure control system can operate in accordance with the corresponding conditions correctly, smoothly, and quickly within the specified distance and be applied to other types of vehicles.