909 Self-learning approach to automatic transmission shift control in a commercial construction vehicle during the inertia phase J-OHahn 1*,J-W Hur 2,G-W Choi 3,YMCho 2andKILee 2 1Department of Mechanical Engineering, Korea Airforce Academy, South Korea 2School of Mechanical and Aerospace Engineering, Seoul National University, South Korea 3Department of Mechanical Engineering, Korea Naval Academy, South Korea Abstract: Electrohydraulic shift control of a vehicle automatic transmission has been predominantly carried out via open-loop control based on numerous time-consuming calibrations. Despite remark- able success in practice, the variations of system characteristics inevitably cause the performance of the tuned open-loop controller to deteriorate. As a result, the controller parameters need to be continuously updated in order to maintain satisfactory shift quality. This paper presents a self- learning algorithm for automatic transmission shift control in a commercial construction vehicle during the inertia phase. First, an observer reconstructs the turbine acceleration signal (impossible to measure in a commercial construction vehicle) from the readily accessible turbine speed measure- ment. Then, a control algorithm based on a quadratic cost function of the turbine acceleration is shown to guarantee the asymptotic convergence (within a speci/bullet5 ed target bound ) of the error between the actual and the desired turbine accelerations. A Lyapunov argument plays a crucial role in deriving adaptive laws for control parameters. The simulation and hardware-in-the-loop simulation studies show that the proposed algorithm actually delivers the promise of satisfactory performance despite the variations and uncertainties of system characteristics. Keywords: self-learning control, shift control, automatic transmission, commercial construction vehicle, observer NOTATION duty duty ratio applied to the proportional solenoid valve e turbine acceleration error de/bullet5 ned in equations (9) and (10) Pcpressure applied to the clutch Tcfriction torque of the on-coming clutch Ttturbine torque V(e) Lyapunov function candidate of e a1,a2coe /bullet3cients in equation (1) a¯l,a¯ulower and upper bounds for the desired turbine acceleration atacceleration of the turbine shaft aˆtestimated turbine acceleration The MS was recei vedon12November 2001 and was accepted after revision for publication on 19 August 2002. * Corresponding author: Department of Mechanical Engineering, Faculty Board, Korea Airforce Academy, Ssangsu-Li, Namil-Myeon, Cheongwon-Gun, Chungbook, South Korea. stardust@afa.ac.kr D13301 © IMechE 2002 Proc Instn Mech Engrs Vol 216 Part D: J Automobile Engineering b1,b2coe /bullet3cients in equation (2) c,c¯ positive constants c1,c2adaptive gains for the learning law in equation (13) h1,h2controller parameters l1gain due to the clutch area, e /bullet2ective radius and friction coe /bullet3cient l2o /bullet2set term caused by the return spring force vtangular speed of the turbine shaft vˆtestimated turbine speed 1 INTRODUCTION Electronic control of the automatic transmission for a passenger vehicle has attracted much attention in recent years to reduce fuel consumption and to improve ride quality. The previous research activities have focused on shift control algorithm [ 1–3], shift control supervision [4], development and analysis of new shift hydraulic actuation circuits for active electronic pressure control 910 J-O HAHN, J-W HUR, G-W CHOI, Y M CHO AND K I LEE [5,6], advanced shift scheduling algorithms for im- proved fuel economy [ 7], and feedback control of the torque converter bypass clutch [ 8,9]. In contrast, the auto- matic transmission for a commercial construction vehicle has not been as actively studied as its passenger vehicle counterpart. Since its primary duty is to transport earth and sand, a commercial construction vehicle must be equipped with both large