Automobile cornering rollover prevention method and system

Abstract

An automobile cornering rollover prevention system comprises a speed controller, a wheel deflection measuring instrument mounted on a front wheel of the automobile, force sensors mounted on axis positions of four wheels, and an angular speed measuring instrument and a speed controller mounted on the front wheel of the automobile, and the wheel deflection measuring instrument, the angular speed measuring instrument and the force sensor are all electrically connected to the speed controller. The speed controller is connected to a brake system of the automobile, so that the speed can be intelligently reduced through the brake system. When a driver changes .sub.1 according to a road condition, the speed controller may calculate a critical radius in real time and then compare the speed and give a command in real time for controlling the speed, so that the speed is maintained in an ideal range.

Claims

1. An automobile cornering rollover prevention method, comprising: A. obtaining inherent parameters of the automobile, and measuring a center-of-gravity position, a deflection angle .sub.1 of a front wheel and an angular speed of the front wheel of the automobile in real time, wherein the inherent parameters of the automobile comprise a distance L between axes of the front wheel and a rear wheel at the same side, a distance B between axes of two front wheels or two rear wheels, and a height h of the center-of-gravity position of the automobile from ground; defining a cornering direction of the automobile as a cornering side and defining a negative cornering direction as an opposite side, i.e., a left side being the cornering side while a right side being the opposite side if the automobile turns left; and then the right side being the cornering side, while the left side being the opposite side if the automobile turns right; wherein, a distance between the center-of-gravity position and a connecting line of the axes of the two front wheels is b, and a distance between the center-of-gravity position and a connecting line of the axes of the front wheel at the opposite side and the rear wheel at the opposite side is a; B. calculating a distance between the front wheel at the cornering side and an instantaneous center, which is r.sub.1=L/sin(.sub.1) C. calculating a center-of-gravity angle .sub.G formed by the center of gravitythe instantaneous centerthe axis of the rear wheel of the automobile, wherein a calculation formula is as follows:
.sub.G=tan.sup.1((Lb)/(Ba+r.sub.1 cos(.sub.1))); D. calculating a distance r.sub.G between the instantaneous center and the center of gravity, wherein a calculation formula is as follows: $r_G=\frac{L-b}{\sin \left({}_G\right)};$ E. calculating a speed at the center of gravity when the rollover is about to occur, which is $v_G=\sqrt{\frac{r_G\mathrm{ga}}{h\cos ({}_G)}}$ wherein, g is a gravity acceleration; F. calculating a critical speed of the front wheel at the cornering side, which is $v_1^{\max }=v_G\frac{r_1}{r_G};\mathrm{and}$ G. measuring a current speed of the front wheel at the cornering side through the angular speed of the front wheel, and comparing the current speed of the front wheel at the cornering side with the critical speed, reducing the speed if the current speed is larger than the critical speed, until the current speed of the front wheel at the cornering side is smaller than or equal to the critical speed; and not controlling the speed if the current speed is smaller than the critical speed.

2. The automobile cornering rollover prevention method according to claim 1, wherein the center-of-gravity position is determined through a following manner: obtaining values F.sub.1, F.sub.2, F.sub.3 and F.sub.4 of four force sensors mounted on the axis positions of the front wheel at the cornering side, the front wheel at the opposite side, the rear wheel at the opposite side and the rear wheel at the cornering side, wherein a distance a between the center-of-gravity position and the connecting line of the axes of the front wheel at the opposite side and the rear wheel at the opposite side is obtained through a following formula: $a=\frac{\left(F_1+F_4\right)B}{F_1+F_2+F_3+F_4};\mathrm{and}$ a distance b between the center-of-gravity position and the connecting line of the axes of the two front wheels is obtained through a following formula: $b=\frac{\left(F_3+F_4\right)L}{F_1+F_2+F_3+F_4}.$

3. The automobile cornering rollover prevention method according to claim 1, wherein when the current speed is detected to be larger than the critical speed, and needs to be reduced, alarming is given through an alarm.

4. An automobile cornering rollover prevention system controlled using the method according to claim 1, comprising a speed controller, a wheel deflection measuring instrument mounted on a front wheel of the automobile, force sensors mounted on axis positions of four wheels, and an angular speed measuring instrument and a speed controller mounted on the front wheel of the automobile, and the wheel deflection measuring instrument, the angular speed measuring instrument and the force sensor are all electrically connected to the speed controller.

5. The automobile cornering rollover prevention system according to claim 4, further comprising an alarm, wherein the alarm is electrically connected to the speed controller.

6. The automobile cornering rollover prevention system according to claim 5, wherein the alarm comprises a sound alarm and/or a light alarm, the sound alarm is mounted in a driving cab, and the light alarm is mounted on an instrument board or a steering wheel.

7. The automobile cornering rollover prevention method according to claim 1, wherein when the current speed is detected to be larger than the critical speed, and needs to be reduced, alarming is given through an alarm, and wherein when a deceleration caused by triggering the alarm continuously occurs within a time frame, a second-class alarming is given through the alarm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structure diagram of an automobile cornering rollover prevention system according to the present invention; and

(2) FIG. 2 is a parameter block diagram during left turning according to the present invention;

(3) in the figures: 1 refers to wheel deflection measuring instrument, 2 refers to force sensor, 3 refers to speed controller, 4 refers to alarm, and 5 refers to angular speed measuring instrument.

DETAILED DESCRIPTION

(4) The technical solutions of the present invention are further described in details hereunder with reference to the embodiment and drawings. Embodiment: An automobile cornering rollover prevention system according to the embodiment, as shown in FIG. 1, includes a wheel deflection measuring instrument 1, force sensors 2, a speed controller 3, an alarm 4, and an angular speed measuring instrument 5. The wheel deflection measuring instrument is mounted on a left front wheel of the automobile to measure a deflection angle .sub.1 of the left front wheel in an instantaneous cornering process of the automobile, an angular speed measuring instrument is mounted on the front wheel of the automobile to measure an instantaneous angular speed of the front wheel of the automobile, four force sensors are respectively mounted on axis positions of four wheels, and the wheel deflection measuring instrument, the force sensor, and the alarm are all electrically connected to the speed controller. The alarm includes a sound alarm and/or a light alarm, the sound alarm is mounted in a driving cab, and the light alarm is mounted on an instrument board or a steering wheel.

(5) The speed controller is connected to a brake system of the automobile, so that the speed can be intelligently reduced through the brake system.

(6) As shown in FIG. 2, the embodiment is explained by taking the automobile while turning left for example.

(7) A value detected by the force sensor mounted on an axis of a left front wheel is F.sub.1, a value detected by the force sensor mounted on an axis of a right front wheel is F.sub.2, a value detected by the force sensor mounted on an axis of a right rear wheel is F.sub.3, and a value detected by the force sensor mounted on an axis of a left rear wheel is F.sub.4,

(8) a distance a between a centre-of-gravity position and the connecting line of the axes of the right front wheel and the right rear wheel is obtained through a following formula:

(9) $a=\frac{\left(F_1+F_4\right)B}{F_1+F_2+F_3+F_4};$
and

(10) a distance b between the centre-of-gravity position and the connecting line of the axes of two front wheels is obtained through a following formula:

(11) $b=\frac{\left(F_3+F_4\right)L}{F_1+F_2+F_3+F_4}.$

(12) A height h of the centre-of-gravity position from ground is a fixed parameter.

(13) When the automobile steers, the system needs to guarantee that each wheel simply rotates around the same centre in a rotation process, i.e., O is a speed centre; B is a distance between interactions of axial lines of key pins at two sides and the ground, i.e., a wheel base; L is an axle base of the automobile; .sub.1 is the deflection angle of the wheel, r.sub.1 is a distance between the instantaneous centre O and the axis of the left front wheel, and G is the centre o gravity of the automobile body.

(14) The wheel at an inner side is just to leave the ground when the automobile is just to roll over. A centripetal force F.sub.G at the centre of gravity of the automobile may be obtained according to a kinematics rule:

(15) $\begin{array}{cc}{F}_G=m\frac{v_G^2}{r_G}& \left(1\right)\end{array}$
wherein, V.sub.G is a maximum speed at the centre of gravity that can be tolerant, and r.sub.G is a distance between the instantaneous centre and the centre of gravity, which may be denoted as:

(16) $\begin{array}{cc}{r}_G=\frac{L-b}{\sin \left({}_G\right)}& \left(2\right)\end{array}$
wherein,
.sub.G=tan.sup.1((Lb)/(Ba+r.sub.1 cos(.sub.1))).
By taking a connecting line between the wheel and a contact point with the ground as a rotation axis, it may be obtained through moment balance that:
mga=F.sub.Gh cos(.sub.G)(3)
It may be obtained from the formula (3), a critical speed at the centre of gravity when rollover occurs is:

(17) 0$\begin{array}{cc}{v}_G=\sqrt{\frac{r_G\mathrm{ga}}{h\cos \left({}_G\right)}}& \left(4\right)\end{array}$
According to a kinematics theory, when the automobile rolls over, a critical speed of the wheel at the left front wheel is:

(18) $\begin{array}{cc}{v}_1^{\max }=v_G\frac{r_1}{r_G}& \left(5\right)\end{array}$
wherein, the distance between the left front wheel and the instantaneous centre is
r.sub.1=L/sin(.sub.1).

(19) Therefore, the effect of the speed controller is: to control the rotation speed v.sub.1 of the left front wheel in real time according to an allowable critical speed v.sub.1.sup.max of the left front wheel calculated in real time during the driving process of the automobile, so that v.sub.1<v.sub.1.sup.max can be implemented by the controller during cornering; therefore, the object of preventing rollover through intelligent deceleration during cornering of the automobile is achieved. When a current speed is detected to be larger than the critical speed, and needs to be reduced, alarming is given through the alarm.

(20) The speed controller in the text above plays roles of calculating, judging, and giving commands. During cornering, a driver may judge a rotation angle .sub.1 of the front wheel by unaided eyes, calculate the allowable maximum rotation speed v.sub.1.sup.max in the case that the automobile does not roll over according to the formula, calculate the speed v.sub.1 of the left front wheel through measuring the angular speed of the left front wheel, and compare the speed v.sub.1 of the left front wheel with the critical value v.sub.1.sup.max, so as to judge that whether the automobile is overspeed. If the automobile is overspeed, then braking interference is conducted through intelligently controlling the system, to uniformly reduce the speed to a safety range.

(21) The system is flexible on a calculation aspect. When the driver changes .sub.1 according to a road condition, the speed controller may calculate a critical radius in real time and then compare the speed and give a command in real time for controlling the speed, thus both avoiding a risk of rollover due to overspeed and avoiding increase of fuel consumption due to excessive deceleration. In this way, the driver does not need to decelerate deliberately, and risks may be effectively reduced when the driver makes error judgment, so as to protect personnel safety.

(22) The embodiment described in the text is illustrative only for the spirit of the present invention. Various amendments or supplements to the specific embodiment described may be made or similar manners may be used as replacements by those skilled in the arts of the present invention, without departing from the spirit of the present invention or exceeding the ranged defined by the claims attached.

(23) Although the instantaneous centre, the cornering side, and other terms are frequently used in the text, the probability of using other terms is not eliminated. These terms are only used for expediently describing and explaining the essence of the present invention; and it is contrary to the spirit of the present invention to explain them into any additional restriction.