Vehicle rear wheel steering assist control system and control method therefor

Abstract

A vehicle rear wheel steering assist control system is provided where a wheel deflection angle measuring instrument is mounted at a front wheel for measuring a steering angle of the front wheel, a rotational velocity measuring instrument is also mounted at the front wheel for testing a velocity of the front wheel, output ends of the wheel deflection angle measuring instrument and the rotational velocity measuring instrument are electrically connected to the data acquisition module, the data acquisition module is electrically connected to the controller, the controller is electrically connected to a data execution module, the rear wheel active steering device is mounted at a rear wheel of the automobile, the rear wheel active steering device is electrically connected to the data execution module, the controller is electrically connected to an ECU of the automobile, each automobile seat is provided with a weight sensor, which are electrically connected to the controller.

Claims

1. A vehicle rear wheel steering assist control system applied to an automobile provided with a rear wheel active steering device and powered by a power supply of the automobile, comprising a controller, a data execution module, a data acquisition module, a rear wheel active steering device, a wheel deflection angle measuring instrument and a rotational velocity measuring instrument, wherein the wheel deflection angle measuring instrument is mounted at a front wheel for measuring a steering angle of the front wheel, the rotational velocity measuring instrument is also mounted at the front wheel for testing a velocity of the front wheel, output ends of the wheel deflection angle measuring instrument and the rotational velocity measuring instrument are electrically connected to the data acquisition module, the data acquisition module is electrically connected to the controller, the controller is electrically connected to a control end of the data execution module, the rear wheel active steering device is mounted at a rear wheel of the automobile, a control end of the rear wheel active steering device is electrically connected to an output end of the data execution module, the controller is electrically connected to an ECU of the automobile, each automobile seat is internally provided with a weight sensor, and the weight sensors are electrically connected to the controller.

2. The vehicle rear wheel steering assist control system according to claim 1, wherein the data execution module is connected to a control endpoint of an initiation airbag, and four initiation airbags are provided, wherein two of the initiation airbags are arranged between an automobile frame and a front axle, and the other two are arranged between the automobile frame and a rear axle.

3. The vehicle rear wheel steering assist control system according to claim 2, wherein the controller is a single chip.

4. The vehicle rear wheel steering assist control system according to claim 2, further comprising a multiple adjusting button, wherein the multiple adjusting button is electrically connected to the controller, and the multiple adjusting button is arranged on a control panel of the automobile.

5. A vehicle rear wheel steering assist control method applied to a vehicle rear wheel steering assist control system comprising a controller, a data execution module, a data acquisition module, a rear wheel active steering device, a wheel deflection angle measuring instrument and a rotational velocity measuring instrument, wherein the wheel deflection angle measuring instrument is mounted at a front wheel for measuring a steering angle of the front wheel, the rotational velocity measuring instrument is also mounted at the front wheel for testing a velocity of the front wheel, output ends of the wheel deflection angle measuring instrument and the rotational velocity measuring instrument are electrically connected to the data acquisition module, the data acquisition module is electrically connected to the controller, the controller is electrically connected to a control end of the data execution module, the rear wheel active steering device is mounted at a rear wheel of the automobile, a control end of the rear wheel active steering device is electrically connected to an output end of the data execution module, the controller is electrically connected to an ECU of the automobile, each automobile seat is internally provided with a weight sensor, and the weight sensors are electrically connected to the controller, wherein the data execution module is connected to a control endpoint of an initiation airbag, and four initiation airbags are provided, wherein two of the initiation airbags are arranged between an automobile frame and a front axle, and the other two are arranged between the automobile frame and a rear axle, and further comprising a multiple adjusting button, wherein the multiple adjusting button is electrically connected to the controller, and the multiple adjusting button is arranged on a control panel of the automobile, the method comprising comprising: step I, manually setting existing parameters that comprise a wheel base B and an axle base L, a net weight M of an automobile body, and a standard center of gravity G of the automobile body, the standard center of gravity G of the automobile body being composed of half wheel base data a and preset height data of the center of gravity h; step II, obtaining a deflection angle .sub.1 of a left wheel of the automobile and a velocity v.sub.1 of a left front wheel by the vehicle rear wheel steering assist control system during cornering, obtaining a weight m of the automobile according to the net weight M of the automobile body and a sum of numerical values of all weight sensors by the vehicle rear wheel steering assist control system, a distance r.sub.1 between an instantaneous center and an axis of the left front wheel being a target calculated value, and reading a preset minimum cornering radius r.sub.0 and a preset safe wheel rotational velocity v.sub.0 in the meanwhile; if v.sub.1>v.sub.0, then stopping the operation of the rear wheel active steering device in the vehicle rear wheel steering assist control system, and the rear wheel of the automobile being in pure rolling, and if v.sub.1v.sub.0, then performing step III; step III, calculating, by the controller, a centripetal force moment T.sub.G according to the existing parameters and a following formula: $T_G=\mathrm{mh}\left[r_1\cos \left({}_1\right)+\left(B-a\right)\right]{\left(\frac{v_1}{r_1}\right)}^2,$ wherein, since T.sup.G=T.sup.Gravity is obtained through moment equilibrium, a following algorithm is obtained: $\mathrm{mga}=\mathrm{mh}\left[r_1\cos \left({}_1\right)+\left(B-a\right)\right]{\left(\frac{v_1}{r_1}\right)}^2,$ therefore, a following algorithm is obtained: $r_1=\frac{\cos \left({}_1\right)+\sqrt{{\cos \left({}_1\right)}^2-4\mathrm{ga}\left(a-B\right)/v_1^2}}{2\mathrm{ga}/v_1^2},$ obtaining the distance r.sup.1 between the instantaneous center and the axis of the left front wheel; if r.sub.1<r.sub.0, then stopping the operation of the rear wheel active steering device in the vehicle rear wheel steering assist control system, and if r.sub.1r.sub.0, then performing step IV; step IV, calculating a target deflection angle .sub.2 of the rear wheel according to all the parameters above, ${}_2={\tan }^{-1}\left(\frac{L-r_1\sin \left({}_1\right)}{r_1\cos \left({}_1\right)}\right);$ and step V, obtaining a final deflection angle of the rear wheel after multiplying target deflection angle .sub.2 of the rear wheel by an adjustment multiple, outputting the final deflection angle to the rear wheel active steering device, and operating the rear wheel active steering device, the rear wheel of the automobile being reverse to the front wheel of the automobile after rotating by the angle .

6. The vehicle rear wheel steering assist control method according to claim 5, wherein in step II, if v.sub.1 is greater than 1.5 times of v.sub.0 and 1.5 times of r.sub.1 is smaller than r.sub.0, then the controller outputs a control signal to the initiation airbag at a steering side, and the initiation airbag at the steering side is initiated.

7. The vehicle rear wheel steering assist control method according to claim 5, wherein the adjustment multiple in the step V is an adjustment multiple obtained by the control through inputting according to the multiple adjusting button.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an indicating diagram illustrating low velocity turning of an automobile provided with the present invention;

(2) FIG. 2 is an indicating diagram illustrating high velocity turning of an automobile provided with the present invention;

(3) FIG. 3 is an indicating diagram illustrating low velocity turning of an automobile not provided with the present invention;

(4) FIG. 4 is a block diagram illustrating a centre of an automobile; and

(5) FIG. 5 is a mechanical analysis diagram of the present invention.

DETAILED DESCRIPTION

(6) The technical solutions of the present invention are further described in details hereunder with reference to the specific embodiments and drawings.

(7) Embodiment 1:

(8) A vehicle rear wheel steering assist control system (refer to FIGS. 1 to 5) applied to an automobile provided with a rear wheel active steering device and powered up by a power supply of the automobile includes a controller, a data execution module, a data acquisition module, a rear wheel active steering device, a wheel deflection angle measuring instrument and a rotational velocity measuring instrument, wherein the wheel deflection angle measuring instrument is mounted at a front wheel for measuring a steering angle of the front wheel, the rotational velocity measuring instrument is also mounted at the front wheel for testing a velocity of the front wheel, output ends of the wheel deflection angle measuring instrument and the rotational velocity measuring instrument are electrically connected to the data acquisition module, the data acquisition module is electrically connected to the controller, the controller is electrically connected to a control end of the data execution module, the rear wheel active steering device is mounted at a rear wheel of the automobile, a control end of the rear wheel active steering device is electrically connected to an output end of the data execution module, the controller is electrically connected to an ECU of the automobile, each automobile seat is internally provided with a weight sensor, and the weight sensors are electrically connected to the controller. Two initiation airbags are arranged between an automobile frame and a front axle, two initiation airbags are also arranged between the automobile frame and a rear axle, and control ends of the four initiation airbags are all electrically connected to the data execution module. The controller is a single chip. A multiple adjusting button is further included, wherein the multiple adjusting button is electrically connected to the controller, and the multiple adjusting button is arranged on a control panel of the automobile.

(9) A vehicle rear wheel steering assist control method applied to the vehicle rear wheel steering assist control system according to claim 4 includes the following steps of:

(10) step I, manually setting existing parameters that include a wheel base B and an axle base L, a net weight M of an automobile body, and a standard centre of gravity G of the automobile body, the standard centre of gravity G of the automobile body being composed of half wheel base data a and preset height data of the centre of gravity h;
step II, obtaining a deflection angle .sub.1 of a left wheel of the automobile and a velocity v.sub.1 of a left front wheel by the vehicle rear wheel steering assist control system during cornering, obtaining a weight m of the automobile according to the net weight M of the automobile body and a sum of numerical values of all weight sensors by the vehicle rear wheel steering assist control system, a distance r.sub.1 between an instantaneous centre and an axis of the left front wheel being a target calculated value, and reading a preset minimum cornering radius r.sub.0 and a preset safe wheel rotational velocity v.sub.0 in the meanwhile; if v.sub.1>v.sub.0, then stopping the operation of the rear wheel active steering device in the vehicle rear wheel steering assist control system, and the rear wheel of the automobile being in pure rolling, and if v.sub.1v.sub.0, then performing step III;
through a centripetal force F.sub.G at the centre of gravity of the automobile:

(11) $F_G=m\frac{v_G^2}{r_G}={\mathrm{mr}}_G{}^2,$
the centripetal force moment of the automobile in a direction of the automobile axle being:

(12) $T_G={\mathrm{mhr}}_G{}^2\cos \left({}_G\right)=\mathrm{mh}\left[r_1\cos \left({}_1\right)+\left(B-a\right)\right]{\left(\frac{v_1}{r_1}\right)}^2,$
deducting out step III, wherein v.sub.g, r.sub.g, .sub.g and are respectively a velocity of a central point of the automobile, a deflection angle of the central point of the automobile, an included angle and an angular velocity between the central point of the automobile and a central rotation angle O;
step III, calculating, by the controller, the centripetal force moment T.sub.G according to the existing parameters and a following formula:

(13) $T_G=\mathrm{mh}\left[r_1\cos \left({}_1\right)+\left(B-a\right)\right]{\left(\frac{v_1}{r_1}\right)}^2,$
wherein, since T.sub.G=T.sub.Gravity is obtained through moment equilibrium, a following algorithm is obtained:

(14) $\mathrm{mga}=\mathrm{mh}\left[r_1\cos \left({}_1\right)+\left(B-a\right)\right]{\left(\frac{v_1}{r_1}\right)}^2,$
therefore, a following algorithm is obtained:

(15) $r_1=\frac{\cos \left({}_1\right)+\sqrt{{\cos \left({}_1\right)}^2-4\mathrm{ga}\left(a-B\right)/v_1^2}}{2\mathrm{ga}/v_1^2},$
obtaining the distance r.sub.1 between the instantaneous centre and the axis of the left front wheel; if r.sub.1<r.sub.0, then stopping the operation of the rear wheel active steering device in the vehicle rear wheel steering assist control system, and if r.sub.1r.sub.0, then performing step IV;
step IV, calculating a deflection angle .sub.2 of a target rear wheel according to all the parameters above

(16) 0${}_2={\tan }^{-1}\left(\frac{L-r_1\sin \left({}_1\right)}{r_1\cos \left({}_1\right)}\right);$
and
step V, obtaining a final deflection angle of the rear wheel after multiplying target deflection angle .sub.2 of the rear wheel by an adjustment multiple, outputting the final deflection angle to the rear wheel active steering device, and operating the rear wheel active steering device, the rear wheel of the automobile being reverse to the front wheel of the automobile after rotating by the angle .

(17) In step II, if v.sub.1 is greater than 1.5 times of v.sub.0 and 1.5 times of r.sub.1 is smaller than r.sub.0, then the controller outputs a control signal to the initiation airbag at a steering side, and the initiation airbag at the steering side is initiated.

(18) The adjustment multiple in the step V is an adjustment multiple obtained by the control through inputting according to the multiple adjusting button.

(19) According to the setting of the embodiment, FIG. 3 illustrates the condition that the ordinary automobile turns a curve of 90, and FIG. 1 is the automobile provided with the rear wheel steering assist system that can round a corner by a smaller radius, and in FIG. 2, the rear wheel steering assist system gives an assistance to the automobile steering under the condition of driving at high velocity, so that the rear wheel can also simply roll, which can make the automobile be stable and reliable during cornering.

(20) The above only describes a preferred embodiment of the invention, and is not intended to limit the invention in any way. Other amendments and modifications without departing from the technical solution recorded in the claims may also be made.