Fault-tolerant control of clutch actuator motor in six-speed dry dual clutch transmission downshift process

Abstract

In the shifting process of the six-speed dry dual clutch transmission (DCT), the clutch actuator motors will frequently start, stop and stall, which can increase the probability that the clutch actuator motor will fail during the shifting process as the working hours increase. If no corresponding fault-tolerant control is adopted, it will lead to shifting failure, awful riding comfort, and even affect driving safety. In order to solve this problem, the corresponding fault-tolerant control strategies are developed when one of the clutch actuator motors malfunctions in the power-on downshift process. In these strategies, the disengagement rule of the fault clutch and the engagement rule of the no-fault clutch are designed according to corresponding control theories, and a coordinated control strategy between engine and clutches is developed to reduce the jerk of the vehicle, which can ensure that the jerk is within 10 m/s3 in the entire downshift process. After that, the vehicle can still run safely by using the no-fault clutch and half of the gears of DCT. Finally, the hardware-in-loop test is carried out to evaluate the feasibility of the proposed strategies, and the results show that the performance of the fault-tolerant control is satisfactory.