Upshift Process Research Articles

Anti-jerking and traction torque compensation strategy for P3 + hybrid electric vehicle during power upshift

In this study, an anti-jerking and traction torque compensation strategy for P3 + hybrid electric vehicle (HEV) equipped with hybrid automated mechanical transmission (HAMT) during power upshift is proposed. Firstly, to investigate the power upshift characteristics, a powertrain model with three torque ports and flexible drive shaft is established. Secondly, based on the established powertrain model, a hierarchical structure optimization strategy for power upshift is developed. The optimization strategy makes full use of the fast and accurate torque response of the traction motor, aims at simultaneously suppressing the longitudinal jerk and compensating the traction torque, solves the optimal traction motor torque to improve the power upshift performance of P3 + HEV. Finally, a layer-by-layer simulation and a real vehicle test of the power upshift process from first gear to second gear are implemented to verify the effectiveness of the proposed optimization strategy. The verification results show that the proposed strategy can realize smooth and traction torque uninterrupted power upshift process at the same time. Compared with the traditional PI controller the proposed optimization strategy can achieve smaller longitudinal jerk.

Upshift optimization control of dedicated hybrid transmission with P2 configuration

Based on the traditional automatic transmission, Dedicated Hybrid Transmission (DHT) with P2 configuration is developed by replacing hydraulic torque converter with a wet electronically controlled clutch and a driving motor. The paper proposed a coordinated control strategy of the upshift process for the P2 configuration parallel hybrid vehicle equipped with DHT to ensure the shift quality. Firstly, considering the meshing transmission loss, the dynamics modelling of DHT shifting process was built by Lagrange method, and the model parameters were identified by bench test; Secondly, taking no jerk as the constraint and minimum slipping work as the optimisation goal, the forward discrete dynamic programming was used to solve the optimal control law of the transmission torque of the shifting clutch and the input shaft torque of transmission. Besides, for the hybrid operation mode, further considering the influence of the motor, engine and main clutch, two coordinated control strategies of the main clutch engagement and slipping were proposed. The simulation results show that the two coordinated control strategies can achieve small jerk and slipping work, ensure smoothness in the course of gear shift. And by the method of slipping control of the main clutch, the shifting time can be shortened.

Improved Decoupling Control for a Powershift Automatic Mechanical Transmission Employing a Model-Based PID Parameter Autotuning Method

Automatic mechanical transmission (AMT) with a gearshift assistant mechanism is a novel transmission architect concept aiming to improve the torque interruption and driveline jerk of AMT. During the shifting process, the shifting performance deteriorates as the varying road gradient and the friction coefficient worsen the coupling effect between the motor torque and the clutch friction torque. This paper focuses on improving the controller’s robustness of AMT with a gearshift assistant mechanism against the perturbed parameters during the stage of torque gap filling. In this paper, a detailed powertrain simulation model was presented. Based on a decoupling controller and a disturbance compensator, proportional-integral-differential (PID) controllers are applied to enhance the robustness and the decoupling effect. The PID parameters are automatically tuned by employing the Nelder-Mead method. In the tuning process, a cost function was established to demonstrate the outputs’ reference tracking performance, and the PID parameters are tuned by minimizing the cost function. Finally, the tuned parameters are stored in PID maps to make them adjustable online. Simulation results show that with the perturbed parameters well estimated, the upshift process was successful and the torque filling effect was also acceptable. The proposed transmission is a promising structure for industry applications.

Stage-by-phase multivariable combination control for centralized and distributed drive modes switching of electric vehicles

This paper presents a new modes switching control method based on a dual-motor centralized and distributed coupling drive system, which can achieve the centralized and distributed coupling drive and reduce the modes switching shock to improve electric vehicle dynamics performance. Initially, the influence of the switching speed on the shock is analyzed and the models of each modes switching stage are established. Furthermore, a stage-by-phase multivariable combination controller based on the control of position, velocity and force of the actuators is designed, and a load torque state observer is developed to estimate system interference. Finally, the shock suppression effect is testified by the upshift process simulation and the experiments of a centralized and distributed coupling drive electric vehicle. The research shows that the peak value of the switching process with the controller is 9 m/s3, which is lower than the recommended value of 10 m/s3. It laid the theoretical foundation for solving the mode switching problem of the centralized and distributed coupling drive electric vehicles.

Fault-tolerant control of clutch actuator motor in the upshift of 6-speed dry dual clutch transmission

As the working hours of dual clutch transmission (DCT) increase, the probability of a fault occurring in the clutch actuator motor increases. If no fault-tolerant control is adopted after an actuator motor fault occurs, it will lead to shifting failure and even damage the actuator motor. This study devises corresponding fault-tolerant control strategies for 6-speed DCT vehicle when the actuator motor of one of the clutches malfunctions in the upshift process. In those strategies, once the actuator motor fails, the vehicle is designed to disengage the fault clutch and engage the no-fault clutch, after which the vehicle can be driven either in the current gear or in higher/lower gear by jumping upshift with single clutch depending upon the driver demand. This ensures that the vehicle maintains better power performance and fuel economy even after a fault occurs in one clutch actuator motor. Lastly, the strategies were verified in the DCT hardware-in-the-loop test bench.

Cooperation mode optimization between two clutches for dual clutch transmission during the torque phase

The study focuses on the control method optimization for the Dual Clutch Transmission upshift process during the torque phase. The upshift process and two power flow paths are analyzed in detail. According to the analysis results, if two clutches slip together during the DCT upshift process, either torque hole or power circulation generates. To avoid these two conditions, the torque relationship between two clutches is optimized to enable the off-going clutch to disengage without slippage. The Matlab/Simulink platform is used to establish the DCT dynamic model. The obtained simulation results illustrate that, compared with the control methods based on two clutches slippage, the optimized one can not only avoid torque hole and power circulation, but achieve the highest system efficiency during the torque phase, which means the least friction work and the extension of clutch life.

Data-Driven Predictive Control Applied to Gear Shifting for Heavy-Duty Vehicles

In this paper, the data-driven predictive control method is applied to the clutch speed tracking control for the inertial phase of the shift process. While the clutch speed difference changes according to the predetermined trajectory, the purpose of improving the shift quality is achieved. The data-driven predictive control is implemented by combining the subspace identification with the model predictive control. Firstly, the predictive factors are constructed from the input and output data of the shift process via subspace identification, and then the factors are applied to a prediction equation. Secondly, an optimization function is deduced by taking the tracking error and the increments of inputs into accounts. Finally, the optimal solutions are solved through quadratic programming algorithm in Matlab software, and the future inputs of the system are obtained. The control algorithm is applied to the upshift process of an automatic transmission, the simulation results show that the algorithm is in good performance and satisfies the practical requirements.

Optimal control of the gear shifting process for shift smoothness in dual-clutch transmissions

Abstract The control of the transmission system in vehicles is significant for the driving comfort. In order to design a controller for smooth shifting and comfortable driving, a dynamic model of a dual-clutch transmission is presented in this paper. A finite-time linear quadratic regulator is proposed for the optimal control of the two friction clutches in the torque phase for the upshift process. An integral linear quadratic regulator is introduced to regulate the relative speed difference between the engine and the slipping clutch under the optimization of the input torque during the inertia phase. The control objective focuses on smoothing the upshift process so as to improve the driving comfort. Considering the available sensors in vehicles for feedback control, an observer design is presented to track the immeasurable variables. Simulation results show that the jerk can be reduced both in the torque phase and inertia phase, indicating good shift performance. Furthermore, compared with conventional controllers for the upshift process, the proposed control method can reduce shift jerk and improve shift quality.

Upshift control strategy for off-highway vehicles equipped with multi-clutch transmission

The purpose of this article is to propose an upshift control strategy for off-highway vehicles equipped with a new kind of drivetrain architecture, which is called multi-clutch transmission, by means of analysis, modeling, and experiments. First, the structure and working principle of the multi-clutch transmission is investigated in detail. Then, to achieve a smooth 3–4 upshift process with two on-coming clutches and two off-going clutches working together, the method of power flow investigation is introduced. From the analysis results, the optimal relationship between clutches is presented to avoid engine flare and clutch tie-up. Additionally, the engagement sequence of on-coming clutches is also optimized to reduce the shift time and friction work. Then, with the proposed control strategy, a dynamic model for the integrated off-highway vehicle is developed using MATLAB/Simulink. From the variations in torque and speed output obtained from the simulation results, the vehicle equipped with multi-clutch transmission possesses good longitudinal dynamic performance, with acceptable friction work generated from two slipping clutches during the entire upshift process. Finally, to assess the shift quality, the test bench has been conducted. The obtained experimental data show a good agreement with the simulation results and the effectiveness of the control strategy is validated.

Optimal control for jitter suppression of clutch engagement in upshift process of electric vehicles

In the shift process of large-order automatic transmission, jitter phenomenon is common in clutch engagement process, which greatly affects the ride comfort of the vehicle. In this article, the jitter dynamic model of clutch engagement process was established with lumped mass method and virtual displacement principle. Specific to clutch engagement stage, the optimal control of the coordination between driving motor and wet clutch was studied. In accordance with the jitter dynamic model, the state–space equation with controlling variables of motor torque and clutch friction torque was established. In this optimization problem, the torsion angle, torsion angular velocity, and shift jerk are selected as optimization targets. Utilizing the linear quadratic optimal control theory, the optimal trajectory of motor torque and clutch friction torque was obtained. Aiming at the dynamic responses in clutch engagement process, the optimal control in different conditions of weight coefficients, initial torsion angles, and resistance torques was studied. Results showed that the optimal control strategy could obviously reduce the jitter; in addition, the weight coefficient should be determined according to actual situation reasonably.

Research on DCT shifting torque control and a benchmark test

In this study, the working principles of Dual clutch transmission (DCT) are analyzed, the power switching rule for dual clutches during upshift and downshift are formulated, and the model of DCT shift dynamics is established. Subsequently, upshift/downshift control strategies and sliding friction power are simulated and analyzed. A benchmark shift control test is conducted on real DCT vehicles, and test results show that the effect of clutch torque control strategy coincides with actual vehicle control during the upshift process. However, this effect varies during the downshift process. Two different downshift methods are proposed on the basis of the study findings. Moreover, the influence of downshift control method on engine control is analyzed, and the DCT torque control strategy employed during downshift is optimized.

Shift Process Analysis of AMT without Synchronizer Based on Three-phase Induction Motor

In order to achieve synchronous shift on heavy-duty AMT (Automated Mechanical Transmission) without synchronizer, shift process analysis based on three-phase induction motor is proposed in the paper. On the basis of analysis for the speed loss of the transmission output shaft during shift process, the synchronous shift control strategy for AMT without synchronizer driven by three-phase induction motor is put forward for both upshift and downshift program. Estimation algorithms of the load equivalent inertia and the load equivalent resistance torque at the transmission output shaft are proposed to best meet the synchronous shift control. In view of similarity between the start-up process of the vehicle and that of the belt conveyor, AMT without synchronizer based on three-phase induction motor is applied to driving the belt conveyor. Simulation results prove that the strategy of synchronous shift control is effective during upshift process and downshift process.

Constant Acceleration Control for AMT's Application in Belt Conveyor's Soft Starting

In order to start belt conveyor softly, automated mechanical transmission (AMT) is used as a new soft-starting device. Constant belt acceleration control is proposed as a method for AMT’s application in belt conveyor’s soft starting. Belt velocity is adopted as the single parameter for shift schedule. Based on the idea of half engagement point, fast-slow-fast law is taken for clutch engagement. Simulation model is established in AMESim environment. On the basis of horizontal belt conveyor driven by one induction motor with 110 KW power, simulation research on start-up process in first gear and shift process from first gear to eighth gear are carried out respectively. Simulation results show that the constant belt acceleration with 0.2 m/s 2 could achieve the purpose of AMT’s application in belt conveyor’s soft starting. The phenomenon of short-time belt acceleration mutations appears during shift process. The maximum value of belt acceleration is less than 1 m/s 2 while the clutch is just at the beginning of engagement. Under the influence of belt acceleration mutations, main characteristic parameters of the system are within their allowable limits, such as belt maximum tension and driving pulley torque. After the completion of upshift process, the belt maximum tension and other parameters curves tend to be stable.