Gear‐shifting control of non‐synchronizer electric‐driven mechanical transmission with active angle alignment

Abstract

Non‐synchronizer electric‐driven mechanical transmission (EMT) has advantages of low cost and simple mechanical structure, which is a key assembly in electric vehicles. In such an system, as the synchronizer is removed from the mechanical transmission, big impacts between the sleeve and clutch gear arise during a gear shift, which cause a long power‐off interruption. In this article, our contribution is to propose a novel control strategy to avoid impacts by achieving both zero relative rotational speed and angle differences between the sleeve and clutch gear. To obtain this strategy, we first derive the dynamic model of the gear‐shifting process as a hybrid automaton (HA) model. Based on the HA model, we can see that impacts can be eliminated when the rotational speed and angle differences become zeros. Then, to obtain zero rotational speed and angle differences and reduce the gear‐shifting time, a time‐optimal control law to synchronize the rotational speed and angle is first solved based on Pontryagin's minimum principle. Meanwhile, to resolve the solution difficulty brought by the period‐varied rotational angle difference, we introduce an optimal initial angle difference, and then use an incremental angle difference to replace the period‐varied one. Based on that, a model tracking strategy is proposed to enhance the system's antidisturbance capacity. For the gear‐shifting actuator, a dual bang‐bang control law is solved to save the gear‐shifting time. Finally, we carry out simulations and bench tests to validate the control strategy. Results show that the control strategy can indeed reduce impacts and power‐off time.

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

“…Recent research has extensively explored active angle alignment control as a means of synchronizing the speed of the sleeve with that of the target gear through coordinated regulation of the shift actuator and drive motor [19][20][21]. This approach aims to minimize shift time and mitigate impact during shifting [6,14,22]. As a result of the precise control of the engagement of the sleeve with the target gear, the teeth of the sleeve can smoothly enter the tooth groove of the gear ring without any collision, thereby achieving a shifting process characterized by minimal impact and zero tooth collision.…”

“…Simulation and bench test results demonstrate that this control method can effectively reduce shift duration and minimize maximum impact. The dynamic model of the shifting process was initially derived as a hybrid automaton (HA) model by Ziwang Lu et al [6,22]. Subsequently, utilizing the minimum principle of Pontryagin, they solved for the time-optimal control law of synchronous speed and angle to achieve zero speed and angle difference, thereby reducing shifting time.…”

“…The NSAMT exhibits the advantages of cost-effectiveness, high transmission efficiency, and low development expenditure, rendering it a pivotal avenue for advancing electric vehicle transmission systems [1][2][3][4][5]. Nevertheless, the AMT suffers from power interruption during gear changes and significant shift impact, which constitute its primary drawback [6,7]. The synchro-less automatic mechanical transmission structure, depicted in Figure 1, showcases a simplified design and cost-effectiveness by seamlessly integrating the motor with the AMT while eliminating components such as the clutch, synchronization ring, and friction cone.…”

“…The drive motor exhibits rapid response and precise torque and speed adjustment capabilities [10], enabling active synchronization between the sleeve speed and target gear speed without relying on the synchronization ring and friction cone. The sleeve effectively engages the target gear for power transmission, minimizing shifting impact and reducing overall shifting time [6]. Despite its simple structure and cost-effectiveness, coordinating the control of the shift actuator and drive motor remains a significant challenge.…”

Dynamic Modeling of the Dog Clutch Engagement Process Using Hybrid Automata

“…They used the CHA model to solve an optimal control problem, and the synthesized controller could reduce the meshing duration by 71.05% and reduce impact impulse by 85.72% compared to an existing controller. Lu [37] designed a control strategy for non-synchronizer electric-driven mechanical transmission (EMT). He developed a HA model for the gear shifting process and showed that the impacts could be avoided by achieving both zero relative rotational speed and zero angle differences between the sleeve and clutch gear.…”