The engagement control of an automatic mechanical transmission (AMT) clutch during the hill start of a heavy-duty vehicle has a significant impact on the comfort, safety and service life of the vehicle. However, the control effect of a traditional control strategy can be easily affected by interference (clutch wear, temperature). Therefore, this paper proposes a two-layer structure control strategy based on an AMT clutch automatic actuator with the clutch engagement speed as the control target. First, the clutch automatic actuator is designed and the governing characteristics of the diesel engine and the control characteristics of the solenoid valve are studied. Second, a logic threshold control method and PID control method are adopted in the proposed two-layer structure control method. Moreover, the robustness of the proposed control algorithm is validated by a co-simulation platform (TruckSim, MATLAB/Simulink). Finally, experimental research under different slopes (13% and 22%) is carried out to verify the simulation results. The experimental results prove that compared with a single-layer control strategy, the two-layer control strategy proposed in this paper can shorten the start time by more than 10%, and reduce the vehicle start-up jerking by approximately 20%, which significantly improves the performance of the vehicle in the hill start process.

Vehicle mass estimation is the key technology to improve vehicle stability. However, the existing mass estimation accuracy is easily affected by the change of road gradient, and there are few studies on the mass estimation method of the light truck. Aiming at this problem, this paper uses sensors to measure road gradient and rear suspension deformation and proposes a sensor-based vehicle mass estimation algorithm. First, factors that affect the mass estimation are analyzed, road gradient error correction method and mass estimation error correction method are established. Besides, the suspension deformation is decoupled from the road gradient. Second, the mass estimation algorithm model was established in Matlab/Simulink platform and compared with the mass estimation iterative algorithm. Finally, the road test was carried out under various conditions, the results show that the proposed mass estimation algorithm is robust, and the accuracy of the mass estimation will not be affected by the sudden change of road gradient.