Abstract
The optimal control of automatic transmission plays an important role in the shifting smoothness and fuel economy of heavy-duty mining trucks. In this paper, a dynamic model of the powertrain system is built to study the clutch pressure control during the shifting process. A linear-quadratic optimal regulator is used to achieve the optimum control pressure of clutches, where shifting jerk and clutch friction loss are chosen to a form quadratic performance index function. Besides, a detailed solution of the linear-quadratic problem with the disturbance matrix in the state equations is provided. This paper also carries out a software simulation and verification of the normal condition (no load without slope) and the extreme condition (full load with maximum slope). Compared with the preset reference trajectory control, the simulation results show that the proposed optimal clutch pressure control can effectively reduce jerk and friction loss during the shifting process and has good robustness to different operating conditions.
Highlights
Transmission is the key component of a vehicle that transmits different torque ratios at different speeds [1]
Song and Sun [9] focused on the nonlinear dynamic characteristics of the wet clutch and designed a sliding mode controller to control the on-coming clutch pressure to ensure a smooth clutch-to-clutch shifting in the inertia phase
Under a wide variation of working conditions for heavy-duty mining trucks, the preset reference trajectory cannot be determined as the optimal solution of shifting jerk and clutch friction loss, which are the most important shift performance indicators
Summary
Transmission is the key component of a vehicle that transmits different torque ratios at different speeds [1]. Under a wide variation of working conditions for heavy-duty mining trucks, the preset reference trajectory cannot be determined as the optimal solution of shifting jerk and clutch friction loss, which are the most important shift performance indicators. Erefore, this paper proposes a linear-quadratic optimization-based clutch pressure trajectory for the shifting process of heavy-duty mining trucks equipped with AT to reduce the jerk of shifting and friction loss of clutch simultaneously. KTC, speed ratio iTC, and efficiency ηTC) are used to describe their dynamic equation [19] as follows:
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