Design and control of ball-ramp dual clutch transmission using self-energizing principle

Abstract

Due to the strengthening of fuel economy regulations and increasing demand for high-performance automobiles, Dual Clutch Transmission (DCT) for fast and smooth shifting is widely used. However, DCT consumes a lot of energy from the clutch actuator for shifting and a tie-up phenomenon that can cause breakage to the clutch shaft occurs. In addition, although precise control of the clutch torque is required, the actuator model for generating control input is inaccurate. To compensate for these shortcomings, in this paper, a design method for a ball-lamp DCT (BR-DCT) using the self-energizing principle, an uncertainty estimation method for the actuator model error, and a disturbance rejection control method are proposed. The design method of BR-DCT presents constraints for implementing various functions. First, to improve fuel efficiency and shift control performance, actuator energy consumption is reduced and the clutch is automatically disengaged when tie-up occurs. Second, a new model that can remove the friction coefficient from the actuator model is used. The BR-DCT designed with these constraints can achieve improved shifting performance than the conventional DCT using the same shift controller. However, the measurement error of the force sensor causes uncertainty in the actuator model. To estimate these uncertainties, the High-order Disturbance Observer (H-DOB) can be used. However, when applied to BR-DCT, convergence of estimation errors cannot be guaranteed. Therefore, Extended H-DOB (EH-DOB) is proposed. When EH-DOB was used for estimating actuator uncertainty of BR-DCT, convergence was guaranteed and estimation accuracy could be improved. Next, a disturbance rejection shift controller is designed. A modified composite control law was proposed to overcome the limitations of the DOB-based controller design method of previous studies. The design method of the BR-DCT, the disturbance estimation performance of the EH-DOB, and the performance of the disturbance rejection controller to which the modified composite control law is applied were verified using a test bench that simulates the powertrain equipped with the BR-DCT.