A vehicle control-by-wire four-wheel steering system and its control method

Abstract

The invention provides a vehicle four-wheel steer-by-wire system, and a control method thereof. The vehicle four-wheel steer-by-wire system is characterized by comprising a sensor module, an electronic control module and an execution module; the sensor module comprises a steering sensor, a deviation rate sensor, an acceleration sensor and a wire displacement sensor; the electronic control module comprises a state monitoring unit, a driving state optimization unit and a state control unit; the execution module comprises a steering mechanism and a driving mechanism; and in addition, according tothe control method provided by the invention, the modeling process of a complex vehicle system and massive calculation of nonlinear coupling variables are omitted, and the response time is saved. Thevehicle four-wheel steer-by-wire system provided by the invention applies ''decomposition-synthesis'' strategies; four tire systems are ''decomposed'' into a plurality of sub-models, and then the sub-models are weighted and combined together, so the whole system runs stably, and is higher in robustness. The control effect is better.

Description

technical field [0001] The invention relates to the technical field of vehicle steering, in particular to a vehicle-by-wire four-wheel steering system and a control method thereof. Background technique [0002] In the past decade or so, electric vehicles have received more and more attention. The electrification of traditional automobile chassis is getting higher and higher. Handling stability is an important aspect of automobile active safety. It is not only related to the handling stability of automobiles, but also guarantees An important factor in the safety of the car when driving at high speed. Due to the improvement of the electrification of modern automobiles, the application of steer-by-wire has received great attention. The traditional complex mechanical structure is discarded, and the electronic control system is used to achieve precise control of the steering of the car body and filter the driver's misoperation. Maintaining the same steering wheel angle character...

AI Technical Summary

Problems solved by technology

However, there are still some problems in the traditional steer-by-wire system: (1) There are very large differences in the tire characteristics of different tires. In the prior art, most of them only consider the response of a specific wheel on a specific road surface. Its tire stiffness curve and road surface parameters have great specificity and cannot adapt to most situations; (2) For traditional steering mechanisms, there is a certain lag in the steering motor controlling the driving direction of the car through the steering actuator

When driving at high speed, it will undoubtedly magnify the driver's misoperation and bring about serious consequences; (3) The traditional control algorithm is only to optimize the steering performance of the vehicle. After establishing a complex vehicle model and tire model, it follows the output by controlling the input of the corner. poor precision

[0003] For example, the patent application number 201610907946.5 proposes a redundant driving vehicle dynamics control allocation method, which has the disadvantages of large amount of calculation and complex structure. In the tracking algorithm of wheel slip rate and side slip angle, there are system failures Inaccurate system parameters and other deficiencies, after the decision of the upper control algorithm, there is a lag in the response of each wheel

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