Control algorithms development for automatic transmission of vehicles under the law “control current -friction torque”

Abstract

Automatic transmissions (AT) are becoming increasingly common in vehicles, commercial vehicles, agricultural, construction and military equipment. In their designs electro-hydraulic control systems are widely used. The article describes the structure of such a controlling system. Control elements, as a rule, are multi-disk friction clutches. A control loop can be composed by a control system: the torque limit value on the friction control element depends on the pressure value in the booster, which in its turn depends on the value of the solenoid valve current. The pressure value is an intermediate parameter as the control system does not imply the presence of pressure sensors because of their high cost and reliability of the AT. Thus, it is advisable to compose a control loop in which the value of the limiting torque on the friction element is determined directly by the value of the current of the solenoid valve. Such an algorithm will not only simplify the control system, but will also reduce the labor intensity of calibration work. The behavior of the elements in the electro-hydraulic control system is characterized by a significant nonlinearity. Despite this, for the creation and operation of control algorithms, it is sufficient to represent the electro-hydraulic system in the form of a transfer function. It is necessary to identify the parameters value of the used loop transfer function. In the article, such a procedure has been shown on the example of Levenberg-Marquardt identification method by means of a set of experimental data and the use of the MATLAB software package. The comparison of simulation and experiment results is given, according to which it can be concluded that this approach is permissible to use when creating algorithms of the automatic transmission control system.