Research On Anti Spin And Lateral Stability Control Algorithm For Parallel Hybrid Vehicle Under Acceleration

Safety and environmental protection is the eternal theme of the automobile industry.Hybrid cars, as a model of energy-saving and new energy vehicles, have good marketprospects. In the aspect of the vehicle active safety, the demand of electronic stability controlsystem for hybrid cars is consistent with conventional cars. Electronic stability controlsystem (ESC), as a vehicle active safety control system, can improve the vehicle’s lateralstability under extreme working conditions such as driving condition, coasting condition andbraking condition, which can prominently reduce vehicle accidents occurring rate. It is aninevitable trend that ESC will be combined with the hybrid cars.Many new problems exist in achieving hybrid vehicle stability control. The electronicstability control system needs to be coordinated with regenerative braking system while thehybrid car is coasting or braking, which has been conducted in extensive research bydomestic scholars; at the same time, the traction control and lateral stability controlalgorithm under driving conditions are important parts of the electronic stability controlalgorithm, how to implement the vehicle lateral stability control and anti spin control underdriving conditions while achieving the coordination of the motor and engine torque controlwith the hybrid control system effectively and reasonablely, is also one of the currentresearch focus.Researching of stability control for hybrid cars has important significance not only inenhancing R&D capabilities of China’s automotive industry， but also in developingenergy-saving and new energy automotive industry.This paper bases on the major projects ofthe Technology Support Program of Jilin Province, in close cooperation with China FAWGroup Corporation Technology Center,focusing on the development of anti spin and lateralstability control algorithm under the driving condition for parallel hybrid vehicle. The paperfocuses on four aspects, which are designing of overall algorithm structure, the tractioncontrol algorithm, the lateral stability under the driving condition and the coordinating control algorithm of the hybrid powertrain with stability control,the effectiveness ofalgorithm has been validated through simulation with software-in-loop and bench test withhardware-in-loop. The main works of this paper are as follows:(1) Structural design of anti spin and lateral stability control algorithm of hybrid car:According to the modular and hierarchical design principle, the algorithm is divided into twoparts, the traction and lateral stability control and the coordination control between hybridpowertrain control and stability control. The anti spin and lateral stability control algorithmexists in the stability controller, the coordination control between hybrid powertrain controland stability control algorithm exists in the hybrid vehicle controller, the two algorithm partsexchange data via bus communication; the lateral stability control algorithm, as the upperlayer module, calculates the vehicle target yaw moment, while the anti spin controlalgorithm, as the lower module, calculates the target driving torque and the target brakingtorque.(2) Study on anti spin control algorithm for hybrid car. On the basis of the designedalgorithm structure, optimum drive torque estimation algorithm is designed and the averagewheel speed of two drive wheels and the wheel speed difference of two drive wheels aretaken as control variables, the control algorithm is designed base on Fuzzy PID and finitestate machine.(3) Study on the lateral stability control algorithm under driving condition. The controlalgorithms are designed respectively for the yaw moment control and drive system torquecontrol to improve the vehicle lateral stability under driving condition. Firstly, the impactionof driving condition on the vehicle lateral stability is analyzed with the vehicle sideslip angleand phase plane method; secondly, a control algorithm of correcting the calculation of targetyaw angular rate and sideslip angle under drive condition is proposed; thirdly,for yawmoment control, the lateral stability controller is designed based on quadratic optimal theory;fourthly,for the under steering under driving condition, the fuzzy PD controller is designed tocontrol the output torque of the hybrid drive system. The coordination method based on thetarget slip ratio of the driving wheel is proposed during the study on the coordinationbetween the anti spin control and lateral stability control algorithm; the coordination ofdriving torque between the anti spin control and lateral stability control algorithm has beenstudied. (4) Study on the coordination control algorithm between hybrid powertrain control andstability control. The work modes coordinate strategies and torque allocation algorithm aredesigned respectively for hybrid powertrain torque demand, working mode and torquedistribution during stability control process. Working mode coordinating strategy can preventfrequent switching of operating mode of the hybrid powertrain due to the changes of targetvalue in stability control. Making use of that the motor responses faster than the enginethrottle control, under different mode, with the principle of allocating the dynamic portion oftorque demand to motor and allocating the static portion of torque demand to engine,torquedemand distribution algorithm is designed for different modes of operation based on theprinciple of low-pass filter.(5) Software-in-loop verification of control algorithm. Firstly, a stability control systemoffline simulation platform has been established in Matlab/Simulink environment. With thisplantform,the anti spin control algorithm has been verified on the homogeneous road, theμ-split road and μ-jump road conditions; the open-loop verifications of stability controlalgorithm has been implemented by step steering and sine with dwell steering underaccelerating condition; the closed-loop verification of stability control algorithm has beenimplemented by double lane and the steering in a circle with a radius of200meters underaccelerating condition. The validation results show that, through the coordinate control of thehybrid powertrain control and stability control, the developed anti spin and lateral stabilitycontrol algorithm for hybrid cars can improve the acceleration and lateral stability of thevehicle under acceleration condition.(6) Hardware-in-loop verification of control algorithm. The real-time performance andeffectiveness of the control algorithm are verified on the hardware in the loop test bentch forhybrid cars based on Matlab/xPC. The test platform bases on offline simulation platform,including Matlab/xPC Target real-time system platform, data acquisition and processingsystem, and system hardware bench, of which the hardware bench includes a hydraulic brakesystem bench, a motor bench and a control desk. With the platform, the verifications of antispin control algorithm on the homogeneous road, the μ-split road and μ-jump roadconditions, the open-loop verifications of stability control algorithm on step steering underaccelerating condition, the closed-loop verification of stability control algorithm on thedouble lane under accelerating condition. The validation results show that the developed stability control algorithm for hybrid cars in this paper can improve the acceleration andlateral stability of the vehicle on driving condition.