Constant speed control method and apparatus for hydraulic retarder based on fuzzy controls

Abstract

The invention discloses a constant speed control method and a constant speed control apparatus for a hydraulic retarder based on fuzzy controls. The method comprises following steps of calculating speed deviation and speed changing rate. If the speed deviation is less than a set value, then fuzzy process is conducted to the fluid filling rate, the speed deviation and speed changing rate so as to obtain a fuzzy control quantity. According to physics theory and fuzzy theory, quantification factors of the speed deviation and the speed changing rate and a scale factor of the fluid filling rate in the fuzzy control quantity are obtained]. Select membership function and obtain membership grade value table. A membership function is selected and a membership value table is obtained. Control rules are created to obtain a control rule table. According to the control rules, a fuzzy relation matrix is formed and a fuzzy process is conducted to the current speed and the targeted speed of a vehicle so as to obtain a fuzzy output quantity. The fuzzy output quantity is then converted to clear quantity. According to the embodiments of the method, under complicated road traffic condition, a hydraulic retarder is capable of automatically outputting required fluid filling rate and brake torque so as to make a vehicle travel at a constant speed. In this manner, a constant speed control can be realized to the hydraulic retarder to ensure the safe travel of the vehicle.

Description

technical field [0001] The invention relates to the technical field of vehicles, in particular to a method and device for controlling a constant speed of a hydraulic retarder based on fuzzy control. Background technique [0002] In related technologies, for example, there is a step-by-step control strategy: the retarder is divided into 4 gears according to the different filling rates: 100%, 75%, 50% and 25%, and different gears correspond to different braking torques , the driver can select the required gear for braking according to the driving road conditions; for example, the continuous iterative constant speed control strategy: by increasing or decreasing the fixed amount of fluid filling rate (10%) per unit time to maintain the vehicle at a constant speed, When the constant speed switch is turned on, the controller judges the vehicle speed: when the actual vehicle speed is greater than the target vehicle speed, the retarder will automatically increase the filling rate by...

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Problems solved by technology

[0003] However, the step-by-step control strategy has disadvantages: there is no constant speed control strategy, and the braking torque can only be adjusted manually by the driver. Although the hydraulic retarder shares part of the performance of the service brake during the downhill process, the effect is not good. not ideal

Disadvantages of the continuously iterative constant speed control strategy: due to the continuous iteration of the controller during the constant speed process, once the driver turns on the constant speed switch, the actual speed of the vehicle will always fluctuate around the target speed and be in a state of continuous adjustment. The retarder cannot give an ideal filling rate, which will make the vehicle go downhill at a constant speed for a long time, and the continuous adjustment of the filling rate has high requirements on the life of the retarder filling rate control valve, which increases the use of cost

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