Automatic Mechanical Transmission Research Articles

Optimal Torque Control of the Launching Process with AMT Clutch for Heavy-Duty Vehicles

When launching a heavy-duty vehicle, torque and position control during automatic clutch engagement is critical, and the driver’s intention to launch and changes in the vehicle’s launching resistance make clutch control more complex. This paper analyses the automatic engagement process of automated mechanical transmission (AMT) clutches and proposes an optimal control of the clutch torque for launching heavy-duty vehicles. Firstly, a fuzzy neural network (FNN)-based vehicle launching states recognition (LSR) system is designed for distinguishing the driver’s launching intention and the vehicle’s launching equivalent moment of resistance. Secondly, jerk, friction work, and launching reserve power are taken as the performance indexes for clutch torque optimization, the weight coefficients of each performance index are adjusted according to the LSR results, and the optimal clutch torque is solved by using the minimum value principle based on the shooting method. Finally, simulations and tests are conducted to validate the strategy of optimizing clutch torque, and the impact of torque optimization on the position change during the engagement process is analyzed. The results indicate that under different driver’s intentions, vehicle masses, and road gradient conditions, the jerk, friction work, and slipping time of heavy vehicles during the launching process are improved by applying the optimization strategy.

Research on Precise Tracking Control of Gear-Shifting Actuator for Non-Synchronizer Automatic Mechanical Transmission Based on Sleeve Trajectory Planning

The Non-Synchronizer Automated Mechanical Transmission (NSAMT) demonstrates a straightforward structure and cost-effectiveness; however, the primary obstacle to its widespread application lies in NSAMT shift control. The implementation of active angle alignment effectively addresses the issue of shifting quality, but achieving active angle alignment necessitates precise tracking of the planned shifting curve by the gear-shifting actuator. To tackle the control problem of accurate tracking for NSAMT shift actuators, this paper initially analyzes the structure and shift characteristics of the NSAMT. Based on this analysis, a physical model is established using Amesim, incorporating a drive motor, two-gear NSAMT, shift actuator, sleeve, and DC motor model. An extended state observer (ESO) is designed to mitigate unknown interference within the system. Furthermore, an active angle alignment control algorithm based on “zero speed difference” and “zero angle difference” for double target tracking is constructed while planning the axial motion trajectory of the sleeve. The Backstepping algorithm is employed to successfully track and regulate this planned trajectory. Finally, through Hardware-in-the-Loop testing, we validate our proposed control strategy, which demonstrates consistent results with simulation outcomes, thereby affirming its effectiveness.

Delayed Deep Deterministic Policy Gradient-Based Energy Management Strategy for Overall Energy Consumption Optimization of Dual Motor Electrified Powertrain

The anxiety-provoking driving range has always been an obstacle to the large-scale popularization of electric vehicles (EVs). To improve the driving range without affecting the driving performance, a Dual-Motor Two-Speed All-Wheel-Drive (DMTS-AWD) electrified powertrain is proposed in this work. The system adopts a motor on the front axle and rear axle, respectively, and the rear motor adopts a two-speed automatic mechanical transmission to improve energy efficiency and dynamic performance. An advanced Delayed Deep Deterministic Policy Gradient (TD3)-based Energy Management Strategy (EMS) is used to pursue better motor working efficiency with consideration of practicability. In addition, a direct control method without complicating the structure of the actor network is proposed to realize mode selection and torque distribution simultaneously, which is a discrete(mode)-continuous (motor torque) hybrid action space. The simulation results show that the energy consumption of DMTS-AWD with TD3-based EMS improves by 6.44% compared to the Single-Motor Single-Speed (SMSS) powertrain, which is comparable to the global optimization method. Moreover, the proposed EMS in this paper has a faster convergence speed and better adaptability compared with the classic Deep Deterministic Policy Gradient (DDPG).

Design of a mechanical automatic transmission system for automobiles based on torsional vibration damping

Abstract In order to reduce the vibration damage of the engine and improve the automatic transmission adjustment performance of the automobile, an automatic transmission system based on torsional damping is constructed in this paper to optimize the hardware function of the shift speed. The torsional damper is used as the core control element to reciprocate the automotive mechanical automatic transmission system, and the calculation method of torsional vibration analysis of the crankshaft shaft system is used to determine the indexes of rotational inertia, stiffness, and damping parameters of torsional vibration. The damping coefficient values are set near the equilibrium point, and the loss factor of the automatic transmission system is signal processed to obtain the best damping effect. Using the intrinsic frequency as the central processing unit of the automatic transmission system, the differential equation is used to calculate the excitation torque vector of each cylinder of the engine, and the characteristic module of the automatic transmission system is developed. The tests showed that the cylinder burst pressure of the automatic transmission system with the torsional damper reached a maximum of 67.9 pressure at 4800 amp. The crankshaft front-end torsional angle of the 4th-order main harmonic excitation reached a maximum of 0.57 degrees, which exceeded the engineering allowance of 0.2 degrees and reduced the automatic shift shock by about 28.36%. It indicates that the torsional damper can improve the control performance of the automatic transmission system, which is conducive to enhancing the stability and self-adaptive capability of the transmission adjustment.

Novel shift process control strategy for two-speed clutchless automatic mechanical transmission based on segmented speed regulation

Battery electric vehicles (BEV) equipped with two-speed automatic mechanical transmission (AMT) have gained increasing popularity owing to advantages of a widened high-efficiency operation zone and system costs. In this study, a combined gear shift control strategy including a segmented speed regulation control and torque recovery control was developed for a two-speed AMT in BEV. The switching point of proportional integral control and sliding mode control during speed regulation process is adaptively optimized to ensure minimization of the shift time, while the maximum vehicle jerk is controlled within a defined range. The effectiveness of proposed control strategy is verified by a test bench. Results show that proposed control strategy can not only ensure the impact degree fluctuates within a predetermined range, but also achieve fast and accurate speed regulation which can reduce the speed regulation time by 17%–33%.

Design of automotive mechanical automatic transmission system based on torsional vibration reduction

Automatic transmission system is the core part of vehicle transmission processing, which can improve driving safety. In order to improve the shift effect of automotive automatic mechanical transmission and narrow the gap between the vehicle speed and the expected speed, an automotive automatic mechanical transmission system based on torsional damping was designed in the experiment. On the basis of hardware composed of different modules and fuzzy control algorithm, the system realizes the software design of vehicle automatic mechanical transmission system. The experimental results show that when the system is applied in practice, the gear selection time of the vehicle is between 0.2 s-0.3 s, and the gear shift time is between 0.3 s-0.4 s. The gap between the vehicle speed and the expected speed, and between the vehicle speed and the expected speed is small. The practical application effect is good.

Dynamic coordinated control strategy of power on gear shifting for novel dual motor electric vehicle

In order to solve the gear shifting power interruption problem in electric vehicles with automatic mechanical transmission, this paper proposes a novel dual-motor powertrain system including two motors and one gearbox, which can realize nine combined gears. Based on the working state of the power source, the clutch and the synchronizer in each working mode, as well as the operating characteristics of the vehicle, the dynamics of each gear shifting stage is analyzed, and the dynamic equations are established. The shifting process is simulated based on the co-simulation platform of MATLAB and AMEsim. Finally, a hardware in the loop test system including solenoid valve is designed and developed, and the gear shifting process from 01 to 11 is selected as a representative scheme for the experimental validation. The experimental results show that compared with the control strategy that the motor target speed is greater than the speed of the driven plate of the clutch, the control strategy that the motor target speed is lower than the speed of the driven plate of the clutch proposed in this paper reduces the shift time and sliding friction work by 37.4% and 87.3% respectively.

Double-Loop Control for Torque Tracking of Dry Clutch

Torque tracking is an important control target of a dry clutch. At present, the torque tracking control method of a dry clutch generally uses the relationship between the clutch torque and release bearing position obtained via experiment to convert the torque tracking control of the clutch into the position tracking control of the release bearing. However, due to the nonlinearity and time-varying parameters of the dry clutch, it is difficult to obtain an accurate and fixed relationship between torque and position. At the same time, there are also the nonlinearity and interference problems in the position tracking control process. In order to solve the above problems, this paper takes the torque tracking control process of the dry clutch in a three-speed automatic mechanical transmission of an electric vehicle as an example and proposes a double-loop control controller including torque loop and position loop. Firstly, the drive system dynamic model of electric vehicles and clutch actuator dynamic models is established. Secondly, the torque loop controller is established with the adaptive feedforward-feedback control method. The time-varying parameters are adaptively adjusted with adaptive feedforward control to solve the problem of the time-varying relationship between torque and position. In addition, the feedback control loop is added to improve the robustness of the controller. Thirdly, the position loop controller is established with the backstepping-based active disturbance rejection control method to solve the nonlinear and disturbance problems of the position tracking control. In the end, the torque loop and position loop are cascaded to form a double-loop controller, and the torque tracking control simulations of the dry clutch are carried out. The simulation results show that the double-loop controller has good control performance, and the effectiveness of the controller has been preliminarily verified.

Defect Analysis and Innovation Design of Synchronizer for Clutchless Automatic Mechanical Transmission

The synchronizer is a key component of automatic mechanical transmission (AMT) equipped in electric vehicles, but the inertial lock-ring synchronizer (ILRS) commonly used there is not suitable especially for pure electric vehicles without a clutch because of big shift impact. To make the shifting process rapid and smooth, a new synchronizer named pressure-controllable friction ring synchronizer (PCFRS) was designed. Initially, the inevitable shortcoming of ILRS was verified by simulation and test. Furthermore, the mechanical characteristics and advantages of the new synchronizer over ILRS were analyzed. Then, the formulations describing the dynamic transmission based on the working mechanism of the PCFRS were established. Finally, the shifting simulation results with PCFRS and ILRS based on the same operating conditions were compared and analyzed. The research shows that the PCFRS can meet the main shifting evaluation index of an AMT without complex control methods, as well as it takes only 0.2406 s to finish the comfortable and zero-speed-difference shifting. The shifting quality of PCFRS is better than that of the ILRS. It lays a foundation for using the new synchronizer as a part of clutchless AMTs equipped in pure electric vehicles.

Research on Segmented Belt Acceleration Curve Based on Automated Mechanical Transmission

An automated mechanical transmission (AMT) is proposed as a new soft starter for medium-scale belt conveyors in this paper. The AMT is used to start the belt conveyor and shift gears step by step to make the belt conveyor accelerate softly. Based on analyzing common soft-starting acceleration curves, a segmented belt acceleration curve is proposed as a new soft-starting acceleration curve. By analyzing the AMT soft-starting system, the system modeling is built and the AMT output shaft’s angular acceleration is proposed to be controlled to control the belt acceleration. The AMT soft-starting simulation model is established in the environment of AMESim, and simulation results of the soft-starting process from the first to eighth gear positions are given. The main parameter curves of the AMT soft-starting system including the belt, driving pulley, and AMT output shaft are analyzed. The simulation model can indicate the viscoelastic property of the belt. The simulation results prove that the segmented belt acceleration is appropriate for a medium-scale belt conveyor and provide a theoretical and reasonable basis for using an AMT as a soft starter.

Position Control of Gear Shift based on Sliding Mode Active Disturbance Rejection Control for Small-Sized Tractors.

A modified sliding mode active disturbance rejection control (MSMADRC) position system is designed for small-sized tractors to solve the longer shift time and reduced shifting quality because of the inaccurately motor control used for the automatic mechanical transmission (AMT) gear shift actuator. Firstly, the control model of the motor with total disturbance is established. Then an extended observer is presented to monitor the unmodeled dynamics and various disturbances of the system in real time, at the same time the extended state and the system feedback variables are constructed as the system variables of the sliding mode control (SMC) algorithm. Secondly, a sliding mode surface instead of the nonlinear control law in the active disturbance rejection control (ADRC) algorithm is designed, which realizes the fast and accurate tracking of the position. What's more, the stability of the control system is proved by Lyapunov theory. Lastly, the simulation results demonstrate that the position control precision by MSMADRC is higher 37% than by SMC and higher 75% than by ADRC. Furthermore, the response speed of MSMADRC is the fastest, it only takes about 0.7s.

Multi-parameter predictive shift schedule of automatic mechanical transmission for electric bus

Shift schedule is crucial in improving the dynamic and economic performance of electric vehicles (EVs) equipped with automatic mechanical transmission (AMT). As the driver, vehicle, and road constitute a closed-loop inseparable system, identifying the states of both vehicle and road is fundamental to realizing optimal shift schedule. However, the existing shift strategies neglect the coupling relationship of multiple parameters to the shift strategy. To minimize this gap, this paper presents a novel multi-parameter shift schedule based on model predictive control. Firstly, cubature Kalman filters (CKF) algorithm is employed to accurately estimate vehicle quality and road slope, which could improve the energy economy of EVs. Secondly, an artificial neural network (ANN) is adopted to forecast the compound future short horizon driving conditions, which contains the perdition information of vehicle velocity and road slope. Meanwhile, the AMT predictive shift schedule based on the above estimated and forecast information is constructed, which used dynamic programming to optimize in the rolling horizon. Simulation study results indicate that the ANN-based predictive approach shows better performance on accuracy and robustness than that of Markov chain, and the electricity consumption over China typical urban driving cycle (CTUDC) is further reduced by 6.79% than that of multi-parameter rule-based shift schedule.

AMT Starting Control as a Soft Starter for Belt Conveyors Using a Data-Driven Method

Automated mechanical transmission (AMT) is used as a soft starter in this paper. To improve the soft starting quality, a novel data-driven method is studied. By analyzing and comparing five common soft-starting acceleration curves, a segmented acceleration curve is put forward to be used as the soft-starting acceleration curve for the AMT. Based on the prototype model free adaptive control (MFAC) method, a modified MFAC method with jerk compensation is given to control the AMT output shaft’s angular acceleration and reduce driveline shock. Compared with the methods of prototype MFAC and traditional proportion integration differentiation (PID), the modified MFAC method with jerk compensation can better control the AMT output shaft’s angular acceleration and has excellent characteristics in terms of small tracking error and smaller shock. The research results provide a novel data-driven method for AMT as a soft starter.

In-Wheel Two-Speed AMT with Selectable One-Way Clutch for Electric Vehicles

To improve the efficiency of the electric vehicle (EV) drive systems and EV performance, the use of multi-speed transmissions and distributed drives has been studied extensively. In addition, to develop efficient and compact drive systems, new clutch solutions are needed. In this paper, we propose an in-wheel two-speed automatic mechanical transmission (IW-AMT) with a selectable one-way clutch (SOWC). The IW-AMT consists of a high-speed motor and a mechanical shift actuator, and it can realize shifting without power interruption, thus effectively reducing the unsprung mass and the technical specifications of the motor. We established a virtual prototype model of the IW-AMT to show the shifting process and evaluate the quality of shifting. The simulation results of the upshifting process indicated that the vehicle torque and velocity changed smoothly, and the maximum jerk is less than 10 m/s3. Furthermore, to improve the jerk induced by the downshifting process, we analyzed the momentary state of the SOWC struts that are dropped and attempted to improve the jerk from two aspects: improving the wet multi-plate clutch (WMPC) combination curve and improving the SOWC structure. The results indicated that the downshift-induced jerk can be reduced to 13 m/s3.

Motion Characteristics of a Clutch Actuator for Heavy-Duty Vehicles with Automated Mechanical Transmission

Clutch control has a great effect on the starting quality and shifting quality of heavy-duty vehicles with automated mechanical transmission (AMT). The motion characteristics of a clutch actuator for heavy-duty vehicles with AMT are studied in this paper to investigate the clutch control strategy further. The modeling principle of the automatic clutch system is analyzed, and a simulation analysis is given to prove its validity and rationality. Normalized velocity and velocity modulation percentage are proposed as evaluation parameters for the clutch actuator driven by pulse width modulation (PWM) signals. Based on an AMT test bench, the actuator motion characteristics are analyzed. Experimental results show that the range of normalized velocity and velocity modulation percentage are obtained for the clutch engagement and disengagement processes. By analyzing the experimental data, the engaging velocity and disengaging velocity of the actuator are estimated using the solenoid valves in combination. The research results provide a fundamental basis for precise controlling of the clutch and improving the smoothness of heave-duty vehicles.

Parameter Estimation of a Countershaft Brake for Heavy-Duty Vehicles with Automated Mechanical Transmission

A countershaft brake is used as a transmission brake (TB) to realize synchronous shifting by reducing the automated mechanical transmission (AMT) input shaft’s speed rapidly. This process is performed to reduce shifting time and improve shifting quality for heavy-duty vehicles equipped with AMT without synchronizer. To improve controlled synchronous shifting, the AMT input shaft’s equivalent resistance torque and the TB’s characteristic parameters are studied. An AMT dynamic model under neutral gear position is analyzed during the synchronous control interval. A dynamic model of the countershaft brake is discussed, and its control flow is given. The parameter identification method of the AMT input shaft’s equivalent resistance torque is given on the basis of the least squares algorithm. The parameter identification of the TB’s characteristic parameters is proposed on the basis of the recursive least squares method (RLSM). Experimental results show that the recursive estimations of the TB’s characteristic parameters under different duty cycles of the TB solenoid valve, including brake torque estimation, estimation accuracy, and braking intensity estimation, can be effectively estimated. The research provides some reliable evidence to further study the synchronous shifting control schedule for heavy-duty vehicles with AMT.

THE CONCEPT OF THE CLUTCH CONTROL LAW OF A CAR

Problem. The combination of comfortable automatic control of the car's transmission and at the same time preservation of high indicators of energy efficiency and cost of a design is possible by use of automatic mechanical transmission. The automatic clutch control system plays a significant role in providing comfort in such transmissions. The laws of controlling it are not perfect today. Goal. The aim of the work is to create a clear concept of the law of clutch control, which is easy to implement in a microcontroller and is well adapted to adapt to different driving conditions. Methodology. Graphically, the concept of the perspective law of clutch control is formed by two Bezier curves. One of the curves acts as a guide, and the other forms the surface of the law. Results. On the basis of the Bézier curves of the third degree the concept of the law is formed and the connection of the reference points of the Bézier curves with the physical parameters of the working process of vehicle movement is substantiated. Originality. The formation of the Bézier curve, which is decisive for the concept of the law, is formed on the basis of a typical working process of synchronization of the angular velocity of the clutch discs during the movement of the vehicle. In contrast to the laws of clutch control considered in the scientific literature, the proposed concept provides for clutch control outside the site of the synchronization process and ensures the avoidance of jerks during further acceleration. Practical value. The proposed algorithm provides full engagement of the clutch only after full synchronization of the clutch discs. The formation of a special form of the law in the form of a curve tangent to the abscissa axis reduces the jerks when closing the clutch discs.

Modeling and Analysis of Gear Shifting Process of Non-Synchronizer AMT Based on Collision Model

In the gear shifting process of a clutchless automated mechanical transmission (AMT), the potential collision between sleeve and dog gear may increase both vehicle jerk and gear changing duration. Therefore, the gear shifting process’s mechanism analysis and dynamic modeling are the essential prerequisites to improve gear shifting quality. This paper analyzes the potential collision between the sleeve and the dog gear which both with concave-convex profiles, the tooth-side chamfer considered. To model the collision process, a fast-determining collision face method based on an intersection map is proposed, and the Monte Carlo method and equivalent depth are employed to calculate the collision stiffness. Then, the stiffness-damping model of the collision process and an 8-degree-of-freedom dynamic model of the gear-shifting system are established. Finally, taking a two-speed clutchless and non-synchronizer automated mechanical transmission (NSAMT) as an example, the established dynamic model of the gear-shifting system is applied, and simulation verification is performed in Matlab/Simulink. The simulation results show that the established model can accurately reflect the changes of forces, speeds, and displacements of sleeve and dog gears during the collision and effectively reflect processes of the disengagement of the sleeve, the speed changes in active synchronization, the engagement of sleeve and gear keeping. Besides, the results also show that the tooth-side chamfer will increase the disengagement time, while it is conducive to gear keeping, and that unloading the drive motor can decrease the disengagement time due to the existence of the tooth-side chamfer.

Dry Clutch Control of Two-Speed Electric Vehicles by Using an Optimal Control Scheme With Persistent Time-Varying Disturbance Rejection

A novel two-speed inverse automatic mechanical transmission (I-AMT) is proposed to eliminate the torque interruption in conventional AMT and improve the working performance of electric vehicles (EVs). However, due to the intrinsic structural characteristics of I-AMT, the requirements for clutch slip control are different from current AMT. Besides, clutch slip control is sensitive to internal uncertainties and external persistent time-varying disturbances during gear shifting. This study proposes a unified framework to build a clutch slip model for gear upshift and downshift. A high-order disturbance observer-based optimal controller is developed to reject persistent time-varying disturbances in a dry clutch system. During controller deduction, a novel multiplier function λ is introduced, and the optimal control law is presented as a feedback form of system states, the disturbance, and the derivatives of the disturbance. The controller is then applied to the clutch slip processes during gear shifting of an EV equipped with I-AMT. Simulation and experimental results under gear upshift and downshift demonstrate that the controller guarantees consistent performance under various working scenarios with different kinds of disturbances. The rapidity and smoothness of the clutch slip process are ensured without large speed or torque fluctuation, thus improving the overall gear shift quality.

Analysis on vibration coupling characteristics of high-speed gears in two-shift AMT

In order to study the vibration coupling influence of no-load gear on the loaded gear with the driving motor speed increasing for pure electric vehicles, a two-shift automated mechanical transmission (AMT) is researched. Nonlinear dynamic models of the shift II gear pair and the coupled relationship between the two gear pairs are established. Vibration characteristics of the shift II gear pair under different speeds are analysed. The results show that the multi-gear coupling vibration makes the system easier to enter into complex multi-period motion or chaos at high speed, thus increasing the noise of the drive system.