Stability Control Study Based On The Stability Boundary Of Phase Plane For Light Vehicle

Vehicle handling stability performance has an important influence on the quality andsafety of the car’s performance. Driving conditions factors often make the vehicle in anon-linear state in the vehicle driving process. Compared to the vehicle stability controlsystem based on the ideal vehicle model, using the vehicle stability boundary based on phaseplane nonlinear methods to design vehicle stability control system, can improve adaptability,robustness of the vehicle in extreme driving conditions, as well as poor traveling roadenvironment, and enhance the performance quality and safety of the automotive.Combined with the cooperation project “the study of passenger cars through evaluationwhen ice and snow weekly attached to ground” of the Faw Car Co.,Ltd., and “the car ESPtest evaluation technology research” of Geely Automobile Research Institute, as well as“application phase plane theory analysis braking instability mechanism of technologydevelopment” of FAW Technology Center, the study of nonlinear vehicle stability controlsystem was carried out using the phase plane method for light vehicle. Firstly the stateparameters about the vehicle operation were estimated, and then the analysis of the effect ofvarious factors for vehicle stability region was completed.The control boundary of thestability region was determined by nonlinear phase plane method, and the main loopcontroller of vehicle stability control system was completed based on the phase plane. Theactive brake controller was designed for the study of wheel movement.The control algorithmwas preliminary tested and verified in offline simulation test. During experimentalverification, select the appropriate condition according to driver’s burden degree, the stabilityof the vehicle, vehicle trajectory tracking ability, and side tumbling stability. During HILstage, in order to evaluate and test the stability control algorithm, hardware platform wasconstructed based on rapid prototype. The main content of this paper includes the followingsections：1. Present and summarize the vehicle stability control algorithm and systemdevelopment flow means.Then determine the overall research program about vehiclestability control system based on the the stability boundary of phase plane.Firstly,the stateparameters about the vehicle operation were estimated for light cars, and then design the yawmoment control algorithm in the external part and the internal of the phase plane stabilityboundaries.Finally,the control algorithm of the active brake controller was designed for the study of wheel movement.2. On the basis of a two DOF vehicle model which contains a non-linear tire model,analyze vehicle dynamics stability characteristics by means of the phase plane. Based on thephase plane analysis with yaw angular velocity, sideslip angle and sideslip angle speed statevariables, identify vehicle dynamics stability domain, stability domain boundary functionmethod and qualify the non-steady state of vehicle instability. Finally, analyze the changingof stability boundary for different traveling states, such as longitudinal velocity, roadadhesion coefficient and steering wheel angle. Besides, determine the stability boundarythrough trial data, and the stability boundary was verified in the stable condition andinstability conditions by simulation, which preliminary certified that the control algorithmwas correct.3. Based on the existing vehicle dynamics model software, build offline simulation testplatform, and complete the recognition algorithm for state parameters about the vehicleoperation, the main loop controller algorithm of the phase plane stability and the active brakecontroller algorithm. Select the appropriate simulation working conditions on the behalf ofthe driver’s burden degree, the vehicle trajectory tracking ability, and rollover stabilityevaluation of several vehicle stability test conditions. Finally, run the offline simulationexperiments with selected operating mode, and verify the validity of the stability controlstrategy algorithm preliminary. At the same time, the establishment of offline simulationplatform and offline simulation test, laid the foundation for the software interface design anddevelopment and hardware in the loop test platform.4. Determine the total program for hardware in the loop test with aspects of hardwareand software, which is also the basis for selecting the appropriate sensors, actuators, andreal-time operating system to complete hardware system structures. And complete theacquisition and process of the sensor signal, RTI software of the actuator. Match theprototype of vehicle stability control algorithm with hardware in loop test platform, and runthe offline simulation typical test conditions. In terms of the hardware, the effectiveness ofthe control strategy and algorithms have been verified, which consistent with offlinesimulation results.