Dynamic modeling of a variable force solenoid and a clutch for hydraulic control in vehicle transmission system

A control oriented solenoid and clutch model for a passenger car automatic transmission is presented. The model captures the essential dynamics of the variable force solenoid and clutch circuit, which operates on a given pressure range commanded by transmission shifting signal. Based on the hardware design parameters and experimental measurements, a nonlinear low frequency model is developed using SIMULINK^MT. The model simulates the key phenomena of the component, such as pressure filling and stroking of the clutch during engagement. Comparing to the first principal models described in other publications, the simple structure and closed form of this model provides a computational test bench for control analysis. The model is validated against the data obtained from a FORD modified CD4E transaxle and the comparison shows a good agreement. The nonlinearity and the time delay presented in the model suggests that a controller other than conventional PID should be considered when designing the control strategy