A Road Surface Adaptive Wheel Dynamic Load Estimation Method

Abstract

The invention discloses a road surface adaptive wheel dynamic load estimation system and method. The system comprises tires used for supporting a vehicle, a suspension system installed between wheelsand a vehicle body, a displacement sensor used for confirming the suspension sprung mass and unsprung mass relative displacement, and an estimation algorithm module used for determining the wheel dynamic load according to the measured sprung mass and unsprung mass relative displacement. The method includes the following steps that firstly, a wheel dynamic load estimation problem is converted intoa nonlinear system unknown input reconstruction problem; secondly, a sliding-mode observer is designed, and the state of a nonlinear system is estimated; thirdly, an observer estimation error equationis calculated; fourthly, an observer gain design method for guaranteeing the stability of the observer estimation error equation is given out; and fifthly, the wheel dynamic load is estimated throughunknown input reconstruction. By the adoption of the method, the influences of the suspension damping force nonlinear characteristic and road surface stochastic disturbance are considered, and the wheel dynamic load can be estimated in real time with low cost under different road surface conditions.

Description

technical field [0001] The invention belongs to the technical field of automobile motion control, and relates to a system and method for estimating wheel dynamic load during vehicle running. Background technique [0002] The force between the tire and the ground at the wheel-ground contact point determines the longitudinal, lateral and vertical movement of the wheel, which in turn affects the movement and safety performance of the car. The wheel dynamic load formed by the elastic and damping characteristics of the vehicle suspension system and the wheel-ground coupling directly affects the longitudinal and lateral forces of the wheel, and is a key factor in the vehicle longitudinal-lateral-vertical dynamic coupling. Therefore, for automobile motion control systems, including brake control systems, traction control systems, vehicle stability control systems, steering control systems, etc., it is necessary to obtain wheel dynamic load information in real time. [0003] The dy...

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Problems solved by technology

Among them, the direct measurement method can realize the direct measurement of the dynamic load of the wheel by installing the tire six-component force sensor, but the sensor is expensive, the installation is complicated, and it is closely related to the tire size, and the versatility is poor; the estimation method based on the tire pressure sensor, with the help of the tire The measurement information of the pressure sensor calculates the dynamic load of the wheel, which puts forward higher requirements on the measurement accuracy and sampling frequency of the tire pressure, and must consider the influence of the tire internal and external temperature, making this method still in the theoretical research stage; based on the model The open-loop estimation method usually uses the longitudinal and lateral acceleration of the vehicle and vehicle parameters to directly calculate the wheel dynamic load, which has the advantages of simple structure and easy implementation, but it ignores the nonlinear characteristics of the suspension system and the influence of random disturbances on the road surface. As a result, it cannot accurately predict the rapidly changing wheel dynamic load under extreme conditions, and the change of vehicle parameters will produce inaccurate wheel dynamic load calculation results; the model-based closed-loop estimation method can use advanced estimation techniques and suspension dynamics to improve the accuracy of The estimation accuracy of the wheel dynamic load, but the existing technology usually ignores the nonlinear dynamic characteristics of the suspension system, and its realization depends on the accurate identification of the suspension dynamic parameters and more sensor measurement information, including vehicle longitudinal and lateral Acceleration sensors, body roll angle velocity sensors, etc., limit their application range in practice

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