Dual-mode Adaptive Starting Control Of AMT Vehicles Under No Synchronous Lurch

Automatic mechanical transmission(AMT)has been successfully applied in the field of commercial vehicles because of its outstanding performance in fuel economy,torque capacity,technical feasibility,and low manufacturing cost.However,it performs badly in some performance indicators,including starting ability,and shifting quality.In particular,the synchronous lurch in the clutch engagement in the starting stage should not be ignored.The resultant strong transient stall seriously affects the comfort of drivers and passengers,and thus its promotion and application in the field of passenger cars is restricted.At present,research on the widely used starting control strategies focuses mainly on the promotion of the jerk and slipping friction work of the clutch in the continuous slipping friction stage.However,it ignores the synchronous lurch caused at the synchronous engagement moment of the clutch,thus failing to resolve the resultant transient stall and restricting the promotion of the starting ride comfort of vehicles.This paper examined the dual-mode adaptive starting control strategy of AMT vehicles under no synchronous lurch and the fractional order control method.The main research contents are as follows:The mechanism and the modeling of the clutch dynamic torque transmissibility were examined based on the release-bearing location and dynamic friction coefficient.The deformation characteristics of the clutch diaphragm spring and cushion spring were analyzed.The pressure transmissibility during the process of clutch engagement was studied.The relationship between the pressing force on the clutch friction surface and the release-bearing location was determined on the basis of the experimental data.The effect of clutch friction surface pressure,sliding speed,and surface temperature on the friction coefficient of the clutch was analyzed on the basis of theory of tribology.The clutch dynamic friction coefficient neural network prediction model which contains 45 hidden layer neurons was established using the extreme learning machine(ELM)method.To resolve the difficulty in measuring the clutch surface temperature required for making the real-time prediction of the dynamic friction coefficient,the clutch surface temperature prediction method based on the iterative calculation was put introduced into the relationship among thermal inertia effect,sliding friction work,and temperature rise.This method provided the theoretical basis for quantifying the clutch engagement law through the starting control strategy.The dual-model adaptive starting control strategy of AMT vehicles under no synchronous lurch was proposed.The slipping angular velocity was taken as the synchronous lurch control modal decision variable.When the slipping angular velocity was higher than the modal decision threshold,the quadratic performance indexes were established on the basis of the jerk,sliding friction work,engine torque,and starting time.The comprehensive optimal control method of the starting performance was studied on the basis of the linear quadratic optimal control theory.The influence of the weight coefficients of the quadratic performance indexes on the starting performance was revealed.Thus,the relationship among target engine speed,jerk weight coefficient,and engine torque weight coefficient was determined under the restriction of no synchronous lurch.The quadratic optimal controller under no synchronous lurch was established according to the intention of the driver.The comprehensive optimal mode control of the starting performance under no synchronous lurch was implemented,and the corresponding dynamic target clutch torque was determined.When the slipping angular velocity was equal to or lower than the modal decision threshold,the real-time rolling prediction controller under no synchronous lurch as the optimization goal was established based on the rolling time domain control principle.Thus,the parameter perturbation adaptation is conducted,the impact of system parameter perturbation on the target jerk is eliminated,and the rolling prediction modal control was implemented to ensure no synchronous lurch.Finally,in view of a passenger vehicle equipped with an AMT transmission,a vehicle simulation model was established using the Matlab/Simulink software.Based on dual-model adaptive starting control strategy,the starting performance of AMT vehicles under various start working is simulated.In view of the problem of the decreased vehicle starting performance caused by the poor tracking control accuracy of the release-bearing position due to the nonlinearity of the diaphragm spring load–deformation characteristics,time-varying dynamic friction coefficient,and uncertainty of external disturbance in the clutch system,the clutch actuator system control method was examined on the basis of the fuzzy fractional order sliding mode control(FFOSMC)according to fractional order calculus theory.Then,the fractional order differential sliding mode surface was selected.The equivalent plus switching control law and the real-time self-tuning sliding model with gain of the fuzzy controller were designed to restrict chatter using the inhibitory effect of the fractional order sliding model on the high-frequency switch and the characteristics of the slow transfer energy,to increase the robustness of the release-bearing position control,to realize the rapid and accurate tracking control of the clutch engagement law determined by the dual-model control strategy,and to improve the starting performance of vehicles.The AMT bench experiment system was examined on the basis of the D2 P MotoHawk rapid prototyping platform.The effectiveness of FFOSMC controller in improving the location tracking accuracy of the clutch system based on the fractional order calculus principle was verified.Moreover,the effectiveness of the dual-mode starting control strategy under no synchronous lurch in weakening synchronous lurch and improving ride comfort in the starting process was proved.