Research On Two-parameter Shift Schedule And Dynamic Modification Method For A Mining Truck

Shift schedule, directly affecting the vehicle’s dynamic performance, economic performance and other performances, is related to the overall performance of the powertrain system, so it is the core of the automatic transmission control system. By studying one kind of Allison Transmission for a mining truck, research on shift schedule, lock-up rule and dynamic modification method under complex driving conditions were carried out.After analyzing driveline features and characteristics of driving conditions, the vehicle’s simulation model including engine, torque converter, planetary gear, ground resistance and other sub-modules was established based on MATLAB/SimDriveline. Two-parameter power and economy shift schedules as well as the lock-up rule were designed. In addition, a corresponding control strategy was developed and controller model was established. Simulation analysis was conducted to verify the reasonability of the shift schedule and the validity of the control strategy.When the vehicle starts, shifts, brakes and stops, the engine is mostly in a dynamic condition, so the shift points obtained from dynamic and steady characteristics of the engine are different. Although three-parameter shift schedule can theoretically improve shifting performance under the dynamic conditions, it is difficult to apply to reality due to the complex dynamic model of the engine. In this paper, with the vehicle speed, throttle opening and acceleration as the control parameters, fuzzy control is used to modify the shift schedule to be more in line with the driving condition as well as the driver’s intention.Under ramp conditions, if the throttle opening changes greatly, it is easy to produce frequent shifting. Most traditional control strategies determine the best economic or power shift schedule according to good and straight road conditions, while haven’t consider the impact of the environment. In this paper, the decay of the speed is used to amend the traditional shift schedule under ramp conditions. The simulation results showed that the modified shift schedule can improve shift performance under ramp conditions effectively.