Research Of Automatic Parallel Parking System Based On Clothoid

With the increasing number of cars in cities, parking space is narrowing. It is asevere test for some inexperienced drivers when they are parking in a narrow space,meanwhile, it is easy to make mistakes when the driver estimate the distance betweenthe vehicle and the obstacle through the rearview mirror. For this reason, reversingcollision and scratched phenomenon occurs frequently, which causes great social andeconomic losses.Reversing radar or camera was used in the traditional parking auxiliarytechnology which can help the driver observe the environment behind the car, but thedriver have to operate the car all the way to park in. This thesis presented anautomatic parallel parking system based on clothoid which can realize the fullautomatic parking. The method of using clothoid to connect circular arc andstraight-line was adopted in this system, clothoid curve can match vehicle motioncharacteristics well and it doesn’t need to stop to steer in the process of parking. Thewhole path was divided into seven sections, the equation of each section was deduced,and the coordinate of two adjacent path’s connection point, the direction of thevehicle and the range of the time for each section were calculated. Based on these, thepossibility of collision was analyzed and the minimum effort was obtained. Thesimulation of the path was performed in the MATLAB, and the results show the pathis feasible.On the basis of the path planning above, two level fuzzy control technologieswas adopted to real-time tracking and controlling of the vehicle path. Dead reckoningmethod was used to get the vehicle’s actual location, the change of speed wasconsidered in the control. The position error, angular error and speed error were choseas the basic inputs to determine the angle and speed of the front wheel. This controlmethod ensures vehicle can follow the reference path well under the situation ofnon-constant speed.The working principle, structural design and control system design wereconducted in this thesis. Freescale intelligent vehicle was utilized to build theexperimental platform, the system was divided into the speed control module, steeringcontrol module, ultrasonic distance measuring module and navigation module.Experiments were done on a model car according to the distance of starting positionbetween the vehicle and the parking lot, the experimental results demonstrated that this parking system can control the intelligent vehicle model effectively to achieveautomatic parallel parking with high stability and precision.