CN104986221A - Hydrostatic-mechanical driven caterpillar chassis discrete following steering control method - Google Patents

Abstract

The invention relates to the field of steering control of a caterpillar chassis, and especially relates to a hydrostatic-mechanical driven caterpillar chassis discrete following steering control method. The method comprises a preprocessing phase, a discretization phase, and a steering following phase. The method is beneficial for realizing a steering wheel type steering electronic control system of a hydrostatic-mechanical driven caterpillar chassis, and steering control performance and safety performance of the hydrostatic-mechanical driven caterpillar chassis can be improved, so steering track is closer to intention of a driver, operation labor intensity of the driver is reduced, cost is relatively low, and wearing influence on a drive axle is not large.

Description

A kind of hydrostatic-mechanically driver type crawler body is discrete follows rotating direction control method

Technical field

The present invention relates to the course changing control field of crawler body, especially a kind of hydrostatic-mechanically driver type crawler body is discrete follows rotating direction control method.

Background technology

Crawler body turn to be by two side drive wheel between differential realize, controlling the accuracy of differential is complete machine can carry out Turning travel guarantee according to the intention of chaufeur.The drive form different according to crawler body, the mode realizing two side drive wheel differentials and control is also varied.Hydrostatic-Mechanical Driven is a kind of crawler belt power chassis type of drive hydrostatic technology combined with mechanical type drive axle, and because structure is simple, cost is low, dependable performance, and it is widely used in crawler type field machine.This kind of mode realizes stepless change in complete machine certain limit by hydrostatic drive, and completes the last transmission of power to drive wheel by mechanical type drive axle.In this drive axle, a pair clutch-brake is housed mostly, with the independent clutch and brake controlling both sides output shaft, power-transfer clutch is castellated, only has break-make two kinds of patterns, and cannot realize the electrodeless differential of drive wheel.In course changing control process, overcome spring force by the shift fork controlled inside turning track and rotated.Therefore, the crawler body of this kind of type of drive is adopted only to have a kind of Turning radius when each joystick effect.When changing Turning radius, operating personnel's experience can only be relied on to adopt the mode of manually " point is stopped ", manipulative capability and safety lower.In addition, along with improving constantly of agricultural operation machinery degree of automation, the remote operation of this type of crawler body is also more and more paid close attention to, and course changing control also becomes primary study content wherein.

Summary of the invention

In order to solve the problem, the object of the present invention is to provide a kind of improve hydrostatic-mechanically driver type crawler body turn to operating performance and safety performance hydrostatic-mechanically driver type crawler body is discrete follows rotating direction control method.

In order to achieve the above object, the invention provides following technical scheme:

A kind of hydrostatic-mechanically driver type crawler body is discrete follows rotating direction control method, it comprises pretreatment stage, discretization stage and turns to the stage of following, and specifically comprises the following steps:

A. initial straight speed of operation and steering wheel angle is inputted;

B. according to the initial straight speed of operation inputted, steering wheel angle, road resistance parameter and crawler body construction parameter, calculate based on the steering angular velocity under slide condition, inner side crawler belt coiling speed and theoretical steering cycle;

C. discrete time section is determined turnaround time according to the response of Mechanical Driven bridge, according to discrete time section by theoretical steering period discrete, obtain discrete segment number, and then determine the operating range of actual travel track and the travel direction corner of the theoretical travel direction corner of crawler body in each discrete time section and operating range and the crawler body under drive axle shift fork effect whether two states;

D., before each discrete time section starts, current crawler body travel direction and position and the error between current theoretical crawler body travel direction and position is calculated;

E. according to judgment rule, drive axle shift fork active state is determined;

In each discrete segment, described judgment rule is as follows:

If position, chassis is greater than the upper limit in actual path position deviation interval, and travel direction is less than actual path orientation angle departs from interval limit, or position, chassis is positioned at the interval upper and lower limit of actual path position deviation, or position, chassis is less than the lower limit in actual path position deviation interval, and travel direction is not more than the upper limit between actual path orientation angle deviation area, all without shift fork effect; If position, chassis is greater than the upper limit in actual path position deviation interval, and travel direction is not less than actual path orientation angle departs from interval limit, or position, chassis is less than the lower limit in actual path position deviation interval, and travel direction is greater than the upper limit between actual path orientation angle deviation area, then inner side shift fork effect;

F. current reality and theoretical crawler body travel direction and position is upgraded;

Whether g. judge the initial straight speed of operation of input and change with steering wheel angle, in this way, then epicycle controls to terminate, and as no, then jumps to steps d.

Compared with prior art, beneficial effect of the present invention is:

The disc type that turns to that the present invention is conducive to realizing hydrostatic-mechanically driver type crawler body turns to electric-control system, handling maneuver performance and the safety performance of hydrostatic-mechanically driver type crawler body can be improved, turning track is intended to closer to navigating mate, reduce navigating mate operation labour intensity, and cost is lower, little to the effect of attrition of drive axle.

Accompanying drawing explanation

Fig. 1 is discrete schematic diagram of following turning track of the present invention;

Fig. 2 be of the present invention hydrostatic-the discrete diagram of circuit of following rotating direction control method of mechanically driver type crawler body.

[primary clustering nomenclature]

In 1 single discrete segment, drive axle turns to the chassis driving trace of inner side shift fork effect, is reduced to the straight-line travelling section that travel direction deflects an angle to the inside;

Without the chassis driving trace of drive axle shift fork effect in 2 single discrete segments, straight-line travelling section

3 theoretical steering tracks

Detailed description of the invention

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described further, but not as limit.

Fig. 1 is discrete schematic diagram of following turning track of the present invention; Fig. 2 be of the present invention hydrostatic-the discrete diagram of circuit of following rotating direction control method of mechanically driver type crawler body.

Of the present invention hydrostatic-mechanically driver type crawler body discrete follow rotating direction control method be according to shift fork response and reset time determine discrete minor time slice Δ t, according to Δ t the theoretical steering cycle T discretization calculated by initial straight speed of operation v and steering wheel angle α, be converted into the effect how determining shift fork in each discrete minor time slice Δ t by course changing control problem, make the whole turning track of complete machine and steering angular speed omega and theoretical value close as much as possible.

Because steering procedure is intended to basis with the control of driver behavior personnel, so whole steering procedure relies on the participation of people.In order to reduce the complexity of control system and improve system reliability, reduce the wearing and tearing of Mechanical Driven bridge and reduce the acting frequency of actr, this control method adopts the open loop control mode not relating to controlled reset.

The real-time follower theory turning track 3 of actual chassis driving trace, theoretical steering track 3 is according to theoretical steering process real-time change, and namely before every Δ t, basis works as front chassis actual path judges the shift fork in this Δ t active state relative to the position, travel direction etc. of current theoretical steering track 3.Shift fork act as switching value, shift fork when side overcomes spring force rotation, then crawler type power chassis crawler belt inside it fixes the rotary motion of radius, and, turning track shape and the crawler body travel direction corner of this process are constant in each discrete time period Δ t independently.Because discrete time section is shorter, can carry out alternative this section of theoretical steering track 3 in model with straight-line displacement, but after being through this process, the travel direction of complete machine has deflected a fixing angle.If without shift fork effect, then complete machine does straight-line motion, sense of motion does not change, and in fixing discrete time section Δ t, operating range is also fixed value.The actual steering track of hydrostatic-mechanically driver type crawler belt power chassis can be reduced to the curve of approximation be made up of several little linear portions, as shown in Figure 1, in figure, theoretical steering track 3 can be approximately several little linear portions, and described little linear portion comprises two kinds: straight-line travelling section 2; Under the shift fork effect of inner side, deflect the straight-line travelling section 1 of an angle to the inside.Based on reducing consideration to the wearing and tearing of mechanical type drive axle, in working control process, controller after steering direction is judged, only to turning to the shift fork of inner side to control.

Of the present invention hydrostatic-the discrete rotating direction control method of following of mechanically driver type crawler body comprises:

Pretreatment stage: input initial straight speed of operation and steering wheel angle; According to initial straight speed of operation and steering wheel angle, crawler body construction parameter and the road resistance parameter of input, calculate based on the turn around parameters under slide condition: steering angular velocity, inner side crawler belt coiling speed and theoretical steering cycle;

The discretization stage: determine discrete time section turnaround time according to the response of Mechanical Driven bridge, according to discrete time section by theoretical steering period discrete, obtain dispersion number, and then determine the operating range of actual travel track and the travel direction corner of the theoretical travel direction corner of crawler body in each discrete time section and operating range and the crawler body under drive axle shift fork effect whether two states;

Turn to the stage of following: before each discrete time section starts, calculate current crawler body travel direction and position and the error between current theoretical crawler body travel direction and position; According to judgment rule, determine shift fork active state;

Upgrade current reality and theoretical crawler body travel direction and position;

Actual Turning Track of Caterpillar Base Plate is by controlling shift fork active state in each discrete time section, and real-time follower theory track, this track is according to theoretical steering process real-time change.

As shown in Figure 2, of the present invention hydrostatic-mechanically driver type crawler body is discrete follows rotating direction control method, specifically comprise the steps:

Pretreatment stage

A. input initial straight speed of operation v, if crawler body is in Turning travel process, then initial straight speed of operation v equals to turn to outside crawler belt coiling linear velocity v ₁; Input direction dish corner α, determines theoretical steering radius R and relative theory Turning radius ρ;

B. according to initial straight speed of operation v and steering wheel angle α, road resistance parameter (the road resistance coefficient f and maximum turn resistance-coefficient μ of input _max) and crawler body construction parameter (track length on ground length L, crawler body gauge B), calculate based on the every turn around parameters under slide condition, as steering angular speed omega, inner side crawler belt coiling speed v ₂with theoretical steering cycle T;

In order to more accurately analyze the kinematics characteristic in its steering procedure in the course changing control of hydrostatic-mechanically driver type crawler belt power chassis, should be taken into account the slide condition of track length on ground.After consideration slide condition, for given initial straight speed of operation v and steering wheel angle α, the ratio K of outer, the inner side crawler belt coiling speed under slide condition _v, steering angular speed omega and theoretical steering cycle T calculating formula as follows:

$\left\{\begin{array}{c}\frac{a_2}{4}\ln \frac{\sqrt{1+{a_2}^2}+1}{\sqrt{1+{a_2}^2}-1}-\frac{a_1}{4}\ln \frac{\sqrt{1+{a_1}^2}+1}{\sqrt{1+{a_1}^2}-1}\\ \frac{f(0.925+0.15\mathrm{\λ})}{{\mathrm{\μ}}_{\max }}=0\\ (\frac{{a_2}^2\mathrm{\λ}}{2}+a_2)\ln \frac{\sqrt{1+{a_2}^2}+1}{\sqrt{1+{a_2}^2}-1}+(\frac{{a_1}^2\mathrm{\λ}}{2}+a_1)\ln \frac{\sqrt{1+{a_1}^2}+1}{\sqrt{1+{a_1}^2}-1}\\ \mathrm{\λ}(\sqrt{1+{a_2}^2}+\sqrt{1+{a_1}^2})=0\end{array}\right.---\left(1\right)$

In formula:

A ₁---outside crawler belt turns to horizontal relative displacement;

A ₂---inner side crawler belt turns to horizontal relative displacement;

λ---crawler body construction parameter, λ=L/B, L are track length on ground length, and B carries out

Band chassis gauge;

F---road resistance coefficient;

μ _max---maximum turn resistance-coefficient;

$\mathrm{\ρ}=\frac{1}{2}\frac{(1+{\mathrm{\λa}}_1)+K_v(1+{\mathrm{\λa}}_2)}{1-K_v}---\left(2\right)$

In formula:

ρ---relative steering, ρ=R/B, R are theoretical steering radius, and B is crawler body gauge;

A ₁---outside crawler belt turns to horizontal relative displacement;

A ₂---inner side crawler belt turns to horizontal relative displacement;

λ---crawler body construction parameter, λ=L/B;

K _v---the ratio of outer, inner side crawler belt coiling speed;

$\mathrm{\ω}=\frac{v_2-v_1}{B+A_1+A_2}---\left(3\right)$

ω---steering angular velocity;

V ₁---outside crawler belt coiling speed;

V ₂---inner side crawler belt coiling speed, v ₂=v ₁/ K _v;

A ₁---outside crawler belt turns to transversal displacement, A ₁=a ₁l/2;

A ₂---inner side crawler belt turns to transversal displacement, A ₂=a ₂l/2;

T＝2π/ω (4)

ω---steering angular velocity;

The ratio K of outer, the inner side crawler belt coiling speed under slide condition is calculated by above-mentioned formula 1-4 _v, steering angular speed omega and theoretical steering cycle T concrete grammar as follows:

First, crawler body construction parameter λ, road resistance coefficient f, maximum turn resistance-coefficient μ _maxfor known quantity, the equation with two unknowns group of through type 1 can be obtained outside crawler belt and turn to horizontal relative displacement a ₁, inner side crawler belt turns to horizontal relative displacement a ₂;

Secondly, ratio K that is outer, inner side crawler belt coiling speed can be obtained according to formula 2 _v, wherein, relative steering ρ, outside crawler belt turn to horizontal relative displacement a ₁, inner side crawler belt turns to horizontal relative displacement a ₂, crawler body construction parameter λ is known quantity;

Then, transversal displacement A is turned to according to outside crawler belt ₁=a ₁l/2; Inner side crawler belt turns to transversal displacement A ₂=a ₂l/2; Inner side crawler belt coiling speed v ₂=v ₁/ K _v, outside crawler belt can be obtained respectively and turn to transversal displacement A ₁, inner side crawler belt turns to transversal displacement A ₂with inner side crawler belt coiling speed v ₂;

Then, can obtain steering angular speed omega according to formula 3, wherein, outside crawler belt turns to transversal displacement A ₁, inner side crawler belt turns to transversal displacement A ₂, outside crawler belt coiling speed v ₁, inner side crawler belt coiling speed v ₂known quantity is with crawler body gauge B;

Finally, theoretical steering cycle T can be obtained according to formula 4.

The discretization stage

C. the discretization stage: determine discrete time section Δ t turnaround time according to the response of Mechanical Driven bridge, according to Δ t theoretical steering cycle T discretization, obtain discrete segment number N=T/ Δ t.After initial straight-line travelling speed of a motor vehicle v and steering wheel angle α inputs, crawler body theoretical steering track theoretical travel direction corner and operating range in each discrete time section Δ t are determined by Current vehicle speed and Δ t; Meanwhile, according to the operating range and the travel direction corner that calculate crawler body actual steering track actual travel track of the crawler body of drive axle shift fork effect whether under two states in each discrete time section Δ t based on the crawler body steer arithmetic under slide condition;

Turn to the stage of following

D. before each discrete time section Δ t starts, calculate current crawler body travel direction and position and the error between current theoretical crawler body travel direction and position, namely get the absolute value of current crawler body travel direction and position and the difference between current theoretical crawler body travel direction and position;

E. according to judgment rule, drive axle shift fork active state is determined;

Judgment rule as shown in table 1 below, wherein R _pfor actual path position deviation is interval, R _θfor between actual path orientation angle deviation area.

Table 1 drive axle shift fork effect judgment rule

Then according to the content in table 1, judgment rule is: wherein R _pfor actual path position deviation limit is interval, R _pthe upper limit be (1+2.5%) ρ, lower limit is (1-2.5%) ρ, and wherein ρ is relative steering (ρ=R/B, R are Turning radius, and B is crawler body gauge); R _θfor actual path orientation angle departs from limit interval, R _θthe upper limit be actual path travel direction corner in discrete time section Δ t lower limit is actual path travel direction corner in discrete time section Δ t wherein x is the absolute value of actual path travel direction corner and theory locus difference of travel direction corner (theory locus travel direction corner in discrete time section Δ t be 360 degree divided by discrete segment number N) in discrete time section Δ t in discrete time section Δ t.

If position, chassis is greater than R _pthe interval upper limit, and travel direction is less than R _θinterval limit, or position, chassis is positioned at R _pin interval upper and lower limit, or position, chassis is less than R _pinterval lower limit, and travel direction is not more than R _θthe interval upper limit, all without shift fork effect; If position, chassis is greater than R _pthe interval upper limit, and travel direction is not less than R _θinterval limit, or position, chassis is less than R _pinterval lower limit, and travel direction is greater than R _θthe interval upper limit, then inner side shift fork effect.

F. current reality and theoretical crawler body travel direction and position is upgraded;

G. judge whether initial straight speed of operation v and the steering wheel angle α of input change,

In this way, then epicycle controls to terminate, and as no, then jumps to steps d.

Claims (1)

1. hydrostatic-mechanically driver type crawler body is discrete follows a rotating direction control method, it is characterized in that: it comprises pretreatment stage, discretization stage and turns to the stage of following, and specifically comprises the following steps:

A. initial straight speed of operation and steering wheel angle is inputted;

B. according to the initial straight speed of operation inputted, steering wheel angle, road resistance parameter and crawler body construction parameter, calculate based on the steering angular velocity under slide condition, inner side crawler belt coiling speed and theoretical steering cycle;

C. discrete time section is determined turnaround time according to the response of Mechanical Driven bridge, according to discrete time section by theoretical steering period discrete, obtain discrete segment number, and then determine the operating range of actual travel track and the travel direction corner of the theoretical travel direction corner of crawler body in each discrete time section and operating range and the crawler body under drive axle shift fork effect whether two states;

D., before each discrete time section starts, current crawler body travel direction and position and the error between current theoretical crawler body travel direction and position is calculated;

E. according to judgment rule, drive axle shift fork active state is determined;

In each discrete segment, described judgment rule is as follows:

If position, chassis is greater than the upper limit in actual path position deviation interval, and travel direction is less than actual path orientation angle departs from interval limit, or position, chassis is positioned at the interval upper and lower limit of actual path position deviation, or position, chassis is less than the lower limit in actual path position deviation interval, and travel direction is not more than the upper limit between actual path orientation angle deviation area, all without shift fork effect; If position, chassis is greater than the upper limit in actual path position deviation interval, and travel direction is not less than actual path orientation angle departs from interval limit, or position, chassis is less than the lower limit in actual path position deviation interval, and travel direction is greater than the upper limit between actual path orientation angle deviation area, then inner side shift fork effect;

F. current reality and theoretical crawler body travel direction and position is upgraded;

Whether g. judge the initial straight speed of operation of input and change with steering wheel angle, in this way, then epicycle controls to terminate, and as no, then jumps to steps d.