AMT Drivability Optimization Control During Launch And Gear Shift Process

Drivability of automotive drivetrain is one of the main properties of the vehicles,and is closely related to the comfort of passenger feelings and overall dynamic performance of the vehicle.The change of engine torque,as well as the release and engagement of clutch,influence the drivability of automotive drivetrain greatly.Thus,it is a critical topic worthy of further research on how to improve the drivability of the vehicles on the basis of ensuring the dynamic,economy and meeting the emission limitation.For the traditional internal combustion engine vehicles equipped with Automated Manual Transmission?AMT?,there exists clutch slip during the launch process and clutch disengage duration during gear shift process,which may result in poor drivability,large clutch slip loss,vehicle jerk and power interruption.Aiming at this problem,the AMT hybrid electric drivetrain structure,namely,AMT+motor,is a good solution because of the advantages of fast power output response and wide speed range of the motor.The motor can compensate the driving torque when the engine cannot output power during gear shift,and consequently the power interruption can be eliminated.This can improve the drivability of the vehicle greatly and help to improve the market share of AMT.Good AMT drivability requires a combination of good hardware and software architectures.Traditional rule-based control scheme is commonly applied on AMT,that is,feedforward MAP+feedback PID.It is simple and easy to implement,but requires a huge calibration workload,usually,the code length is more than 1 million lines.In practice,in addition,the vehicles possess the characteristics of complex environmental conditions,multiple control inputs and strong coupling,as well as the diversity of control objectives?fuel economy,emissions,power and comfort?and operating conditions?launch,gear shift,extreme conditions,etc.?.For rule-based control scheme,the control parameters calibrated under specific operating conditions cannot guarantee optimized drivability under various conditions,especially under transient conditions.To solve this problem,the model-based vehicle control system design is a better alternative.As the dynamic model of the vehicle can reflect the main components of system dynamics,the model-based method can ensure the control performance even under transient working conditions.Besides,huge parameters calibration work can be avoided under different working conditions.Thus,from the points above,the model-based control methods are designed to control the drivability of AMT hybrid electric vehicles.During the launch process,a time-varying disturbance rejection controller is designed to control the clutch slip,ensuring the launch performance.During the gear shift process,with the aid of motor power,the gear shift process can be completed by regulating engine speed and without releasing the clutch,which on the one hand,guarantee the drivability,and on the other hand,avoid power interruption.The main research contents of this thesis are as follows:1.For the linear control systems with time-varying disturbance,a quadratic objective function is applied which explicitly consider the various contradictory objectives.A high-order disturbance observer is designed to estimate the disturbances,including unmodelled dynamics,parameter variations and external time-varying disturbances,and their derivatives.To derive the control law,a novel form of multiplier functionlis introduced,and the control law is represented as a feedback form of the system states,the disturbances and their derivatives;2.It is assumed that the disturbance should satisfy t??,d?5??0in the above controller,although d can change transiently in finite time,otherwise,the integrability of the objective function cannot be guaranteed.To solve this problem,the objective function is adapted by multiplying an attenuation factore^-bt.Finally,after the solution of the asymmetric Riccati equation is obtained,the parameters of the controller can be obtained and the finally control law can be determined;3.The time-varying disturbance rejection controller proposed above are validated on clutch slip control during the AMT launch process,through simulation and experimental tests.The results demonstrate that the control law is robust enough and has strong ability in rejecting time-varying disturbances.Besides,by comparison with the rule-based control method,it can be proved that the proposed controller can reduce the parameters calibration workload and improve the efficiency of controller development efficiently;4.A triple-step method is designed to deal with the tracking problem of nonlinear over-actuated systems.During the controller deduction,the tracking performance of the states not related to the system output directly are sacrificed to obtain the desired system output tracking performance,and the convergence of the system output tracking error is proved,besides,the controller is easy to implement;5.A novel AMT hybrid electric vehicle powertrain is proposed;the gear shift process is analyzed to obtain the engine speed regulation objective.Firstly,the influence of engine speed regulation on the AMT drivability is validated by using the software ADAMS.Then the proposed triple-step method is applied to control engine speed,simulation results demonstrate that the proposed controller can allocate the two control inputs properly under transient and stable working conditions,and the engine system can realize a good speed tracking performance.