Accurate Clutch Slip Controllers During Vehicle Steady and Acceleration States

Over the past years, the control of the clutch clamping force has been studied to guarantee a smooth/fast and low-wear engagement. Recent studies have highlighted the interest in controlling the clutch clamping force in order to limit vibrations in vehicle drivelines. However, the major risk with any clutch clamping control strategy is an unexpected clutch opening due to the ignorance of the nonlinear and time-varying relationship between clutch clamping and clutch slip. Inspite of improvements, an accurate clutch slip control currently remains a challenge due to high nonlinear dynamics, uncertain parameters, and noisy environments, which render the clutch slip control more complex. In line with this challenging premise, this study presents two accurate clutch slip controllers used during vehicle steady states (constant engine speed) and vehicle acceleration states (increasing engine speed). The first controller, based on punctual least square adaptations of a clutch slip relation, yielded accurate clutch slip tracking results only in the vehicle steady state. In contrast, the second controller, based on a nearly continuous least mean square adaptation of the clutch slip relationship in parallel with a proportional-integral compensator, yielded accurate clutch slip tracking results both in vehicle steady and acceleration states.