A method and device for identifying the gradient of a vehicle ramp

Abstract

The invention provides a vehicle ramp slope identification method and device. The method comprises the steps: obtaining the average wheel speed of front wheels, the average wheel speed of rear wheels,the engine torque change rate, the brake master cylinder pressure and the longitudinal acceleration measured by an inertial acceleration sensor of a vehicle; performing filtering differential processing on the average wheel speed of the rear wheel and the average wheel speed of the front wheels to obtain a rear wheel acceleration filtering value and a front wheel acceleration filtering value; filtering the longitudinal acceleration measured by the inertial acceleration sensor to obtain an inertial longitudinal acceleration filtering value; and determining the slope angle of the vehicle on a ramp according to the difference between the rear wheel acceleration filtering value and the front wheel acceleration filtering value, the engine torque change rate, the brake master cylinder pressureand the difference between the rear wheel acceleration filtering value and the inertia longitudinal acceleration filtering value. According to the identification method, the ramp is identified by adopting the existing sensor of the vehicle, so that the control of the vehicle can be corrected, the cost can be saved, and the accuracy of the obtained ramp slope can be effectively ensured to be higher.

Description

technical field [0001] The invention relates to the field of vehicle transmission control, in particular to a method and device for identifying the gradient of a vehicle ramp. Background technique [0002] At present, most passenger cars have been installed with automatic transmissions. The shift logic is generally based on the vehicle speed and accelerator opening. The shift logic is calibrated on flat roads. When driving uphill, due to the large change in the accelerator opening, frequent shifts will occur. When driving downhill, the throttle opening is low, the vehicle is in high gear, and the engine cannot be used for braking. In addition, in the starting control of electric vehicles, it is necessary to adjust the starting torque according to the slope to prevent the vehicle from sliding downhill. Therefore, for vehicle longitudinal control, it is necessary to identify slopes. [0003] The existing slope identification methods mainly include: one is a sensor-based iden...

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Problems solved by technology

[0003] The existing slope identification methods mainly include: one is a sensor-based identification method, which is relatively simple and direct, but if accurate detection is required, a high-precision sensor must be used, but the use of a high-precision sensor will increase the cost of the vehicle;

[0004] The other is a method based on the dynamics of the whole vehicle, which calculates through a large number of calculations, has a large amount of calibration data, and is affected by vehicle loads, road conditions, and wind speeds, which will cause greater uncertainty;

[0005] There is also a method of using a gyroscope to directly measure the slope of the vehicle to reflect the slope. It uses a gyroscope to measure the slope, but the gyroscope can only directly measure the acceleration of the vehicle in the X, Y, and Z directions and the X, Y, and Z axes. Angular velocity, because of the integral error, inertia compensation and gravity acceleration compensation are used, and new sensors need to be added, resulting in high cost, and this method also needs to obtain the actual longitudinal acceleration of the vehicle, and when measuring the actual longitudinal acceleration of the vehicle Usually has a large noise, which will affect the measurement results and make the measurement results less accurate

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