This paper deals with the control logic of an automated manual transmission with a torque gap filler and the experimental validation of the transmission dynamic model and of its control. The equations of motion of the transmission system, derived in Part 1 of this two-part study and there used to demonstrate the effect of the torque gap filler on the vehicle’s longitudinal dynamics, are here rearranged and utilized to develop the control algorithm for the transmission actuators. The controller design is carried out, separating the gearshift phase into seven different subphases characterizing the operations of an automated manual transmission with a torque gap filler. For each phase, the targets are discussed; moreover, the equations used to compute the torque reference values of the engine, the clutch and the brake are derived. Finally, the trigger conditions, which determine the change from one phase to the other, are also reported. The rigid-body hypothesis, which was initially adopted for the transmission components, is here abandoned, with the aim of simulating the first torsional mode of the transmission. Therefore, a more detailed model was implemented, and it is used to test in simulations the performance of the developed controller. Finally, experimental data are presented from two vehicles, one with the torque gap filler module, and the other equipped with a traditional transmission, used to demonstrate the vehicle’s dynamic performance enhancement obtained owing to the powershift module; moreover, data are used for experimental validation of both the transmission model and the control strategy.
This paper deals with a powershift automated manual transmission, i.e. an automated manual transmission with a torque gap filler, which essentially integrates, in a typical manual transmission layout, a torque gap filler assembly with the aim of reducing the torque gap that occurs during gearshifts. The torque gap filler consists of an additional mechanical link between the engine and the transmission output shaft, thus enabling the engine power to flow through this parallel path also when the launch clutch is disengaged, with clear benefits in terms of both sportiness and passenger comfort. This paper is the first part of a two-part study which, after a general description of the transmission architecture and its working principle, examines a practical implementation of the torque gap filler concept; the additional mechanical components and their integration into a traditional automated manual transmission are presented. Then, kinematic analysis and dynamic analysis of the transmission are proposed. The evolution of the transmission speeds are studied in the whole working range of the vehicle; the equations of motion are derived and used to show the effect of the torque gap filler on the torque transmitted to the wheels and consequently on the vehicle acceleration during gearshifts. The companion paper (Part 2) covers control issues and provides experimental validation.
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