CN-117207953-B - Tractor front wheel steering control method with strong immunity

Abstract

The invention discloses a tractor front wheel steering control method with strong immunity, which comprises the following steps of (1) setting a time lag processing module D(s) by utilizing a steering system identification model P m , a signal synthesizer II and a signal synthesizer III, wherein the steering system identification model consists of a non-time lag part P m0 and a time lag part The steering system identification model is formed by series connection, the output end of the steering system identification model and the actual front wheel angle feedback y(s) are reversely synthesized in a signal synthesizer III, and then are synthesized in a signal synthesizer II with the output end of a non-time-lag part P m0 of the steering system identification model, the generated signal y is used as one input of a state observer O(s), and the signal is obtained by a signal synthesis method Where u is the output of the front wheel steering angle tracking controller K(s), P 0 is the non-time-lapse portion in the steering system P(s), and e ‑θs is the time-lapse portion in the steering system P(s). The method has the advantages of less calculation amount in the control process, quick and accurate tracking of the angle of the expected front wheel, strong anti-interference capability and capability of improving the steering control performance of the automatic driving tractor.

Inventors

• YIN CHENGQIANG
• GAO JIE

Assignees

• 潍坊学院

Dates

Publication Date

20260505

Application Date

20231012

Claims (1)

1. 1. The front wheel steering control method of the tractor with strong noise immunity is characterized by comprising the following steps of: (1) The time lag processing module D(s) is arranged by using a steering system identification model P m , a signal synthesizer II and a signal synthesizer III, wherein the steering system identification model consists of a non-time lag part P m0 and a time lag part The steering system identification model is formed by series connection, the output end of the steering system identification model and the actual front wheel angle feedback y(s) are reversely synthesized in a signal synthesizer III, and then are synthesized in a signal synthesizer II with the output end of a non-time-lag part P m0 of the steering system identification model, so that the generated signal is synthesized As one input to the state observer O(s); (2) Obtained by a signal synthesis method Where u is the output of the front wheel steering angle tracking controller K(s), and P 0 is the non-time-lapse portion of the steering system P(s); Is a time lag component in the steering system P(s); The state observer O(s) outputs with no delay And the front wheel steering angle tracking controller output u as input for a delay-free actual front wheel angle Estimating uncertainty interference and reference change in the system, and obtaining an estimated value by adopting a linear state observer design method And ; (3) Tractor steering system model obtained according to identification K is model gain, T is time constant, and the model gain and the time constant are obtained through identification: the state space expression of the steering system model is written as follows: ; x 1 denotes a front wheel turning angle, x 2 denotes a steering speed of the front wheel, A further extension represents the overall disturbance present in the system, Is the front wheel rotation angle which can be measured in the system; (4) Design state observer : ; Z 1, z 2 is an estimate of x 1 ,x 2 , and z 3 is a generalized uncertainty function Is used for the estimation of (a), In order for the bandwidth of the observer to be sufficient, In order for the gain of the observer to be achieved, Is output by the time delay processing module Is determined by the estimation of (a); (5) The front wheel steering angle tracking controller K(s) is obtained through a simple sliding mode theory method, and comprises the following steps: 1) In the first signal synthesizer, the desired front wheel angle r(s) and the estimated value are used As the control error of the rotation angle of the tractor, ; 2) Establishing a linear slip plane ; 3) Obtaining the output of a front wheel steering angle tracking controller K(s): ; (6) Solving the expression to obtain the control law of the steering system as follows: ; Wherein, the The gradient of the sliding mode surface is an adjustable parameter, r is a desired front wheel angle, k is an adjustable sliding mode controller parameter; for the sliding mode switching coefficient, Is a normal number of times, and the number of times is equal to the normal number, 。

Description

Tractor front wheel steering control method with strong immunity Technical Field The invention relates to the field of automatic driving of tractors, in particular to a front wheel steering control method of a tractor with strong immunity. Background With the rapid growth of agricultural labor costs, the demand for agricultural machinery automation is becoming more and more evident. The automatic driving technology of the agricultural machinery is one of the most important supporting technologies of modern agricultural equipment, can reduce the dependence on physical labor, improve the product quality and reduce the production cost. Accurate path tracking is the primary function of an autopilot agricultural machine, and automatic steering control is one of the most effective means of achieving accurate path tracking. In general, the automatic steering system executes a steering command sent by the host computer to implement path tracking. In most cases, the upper computer transmits the steering angle obtained through the navigation algorithm to the automatic steering system, so that accurate and stable steering angle control has important significance for popularization and application of the automatic driving technology. At present, a steering mechanism for tractor automatic driving mainly adopts two forms of proportional electromagnetic hydraulic valve and motor control steering. The invention patent of application number CN202210586527 discloses a steering control method of a wheel-side electric tractor, which designs an electric control hydraulic drive steering module and four wheel-side motor control modules to realize five steering modes of the tractor. The patent application number CN201810117103 discloses a hydraulic steering control system and a method for an agricultural wheeled tractor, and mainly relates to the constitution and the working principle of a steering system. The patent application number CN202210877235 discloses a tractor hydraulic system with a bidirectional driving function and a steering control method, and the bidirectional driving function is realized by additionally arranging an electromagnetic directional valve, a differential lock control valve, a hydraulic pump, a flow dividing valve and other hydraulic steering devices on the basis of the existing tractor steering system. The common defects of the prior art are that the change of the working environment and the steering load can cause disturbance to the steering control during the operation of the tractor, the steering system is easy to generate oscillation and divergence after being disturbed, and the control method of the prior art is difficult to overcome the influence of the disturbance on the steering precision. In order to solve the disturbance problem, the patent application number 201611103825.1 discloses a hydraulic steering control system and a control method for tractor navigation, and a voltage servo controller and an anti-disturbance controller are designed for the hydraulic steering system. The method of this patent has a suppressing effect only on small-amplitude disturbances present in the system, and the steering control system fluctuates to a large extent in the tracking of the set front wheel steering angle when a disturbance occurs. That is, the prior art can not better solve the disturbance problem, greatly weaken the influence of disturbance on the steering performance of the front wheels on the premise of ensuring the accuracy and the rapidity of steering control, and improve the stability and the reliability of steering control during the field operation of the automatic driving tractor. Disclosure of Invention The invention aims at solving the technical problems of delay and disturbance phenomena in a front wheel steering system of a tractor, and provides a front wheel steering control method of the tractor with strong disturbance resistance, which greatly weakens the influence of disturbance on the steering performance of the front wheel and improves the stability and reliability of steering control during the field operation of an automatic driving tractor on the premise of ensuring the accuracy and the rapidity of steering control. The invention adopts the following technical scheme to realize the aim of the invention: a tractor front wheel steering control method with strong noise immunity comprises the following steps: (1) The time lag processing module D(s) is arranged by using a steering system identification model P m, a signal synthesizer II and a signal synthesizer III, wherein the steering system identification model consists of a non-time lag part P m0 and a time lag part The steering system identification model is formed by series connection, the output end of the steering system identification model and the actual front wheel angle feedback y(s) are reversely synthesized in a signal synthesizer III, and then are synthesized in a signal synthesizer II with the output end of a non-time-