JPH067135B2 - Lateral acceleration detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lateral acceleration detecting device capable of accurately detecting lateral acceleration in a vehicle by eliminating the influence of roll motion.

(Prior Art) In recent years, in order to improve the maneuverability and riding comfort of a vehicle, a technology for controlling the suspension and steering system by analyzing the motion characteristics using a control circuit such as a microcomputer has been developed. Various proposals have been made.

One of the motion variables used to analyze the motion characteristics of the vehicle is the lateral acceleration of the vehicle.

Conventionally, as a method of detecting this lateral acceleration, as shown in FIG. 3, an acceleration sensor 1 is mounted on a spring 2 of a vehicle so as to be located right above a center of gravity 4, and an acceleration in a direction parallel to an axle 5 is set. That is, the method of detecting the lateral acceleration α has been generally used.

(Problems to be Solved by the Invention) However, since the conventional lateral acceleration detection device described above does not consider the influence of the roll motion of the vehicle, an error occurs in the detected value.

That is, when the vehicle makes a turning motion, the sprung mass 2 rolls on the unsprung mass 3, so that the sensing direction of the acceleration sensor 1 provided on the sprung mass 2 is inclined by the roll angle φ.

Then, the acceleration (hereinafter referred to as “acceleration detection value”) α _s detected by the acceleration sensor 1 at this time is a true lateral acceleration α (acceleration occurring in the Y-axis direction, α = F / M, where,
F is a cornering force, M is a vehicle mass), and a component force component gsinφ of gravitational acceleration g
Will be a value that includes. That is, α _s = α cos φ + g sin φ ... (1).

Here, the roll angle φ is a small angle of about 5 ° at maximum, so if cosφ1 and sinφφ are given,
Equation (1) can be expressed as α _s α + gφ ……………… (2).

That is, the acceleration detection value α _s obtained by the acceleration sensor 1
Is a value obtained by mixing the true lateral acceleration component with the component component gφ of the gravitational acceleration associated with the rolling motion of the vehicle, and cannot be said to be an accurate value.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an acceleration sensor for detecting an acceleration generated in a direction parallel to an axle at a predetermined position on a vehicle spring. From the acceleration detection value obtained from the low-pass filter that outputs the component force component value equivalent to the component component component of the gravitational acceleration mixed in the acceleration detection value along with the rolling motion of the vehicle, and the component force obtained from the low-pass filter. A mixed component removing means is provided, which includes a subtracter that subtracts a component value from an acceleration detection value obtained from the acceleration sensor and outputs the subtracted value.

(Operation) In the lateral acceleration detection value of the present invention, the acceleration sensor includes an actual lateral acceleration of the vehicle and a component force equivalent to the component component of the gravitational acceleration due to the rolling motion of the vehicle. The mixed component removing means detects a mixed value of component values, and the mixed component removing means mixes the acceleration detected value obtained from the acceleration sensor with the low-pass filter into the acceleration detected value along with the roll motion of the vehicle. The component force component value equivalent to the component is output, and the component force component value obtained from the low-pass filter is subtracted from the acceleration detection value obtained from the acceleration sensor and output by the subtractor. Thus, the component component of the gravitational acceleration mixed in the output of the acceleration sensor can be removed to eliminate the detection error of the lateral acceleration that accompanies this, and the lateral acceleration detection accuracy can be improved.

(Embodiment) FIG. 1 shows a first embodiment of the present invention.

As shown in FIG. 5, the acceleration sensor 1 is attached to a position just above the center of gravity 4 of the sprung mass 2 of the vehicle and detects the acceleration generated in the direction parallel to the axle 5, as shown in FIG.

The mixed component removing circuit 10 includes a low-pass filter 11, a multiplier 12, and a subtracter 13 that subtracts the output of the multiplier 12 from the output of the acceleration sensor 1.

The transfer characteristic L of the low-pass filter 11 is Is designed to be.

Here, I _x : Roll inertia moment of vehicle Kφ: Damping coefficient Cφ: Spring coefficient H _gs : Distance between roll axis and center of gravity M: Vehicle mass.

The above equation (3) is derived as follows.

The rolling motion of a vehicle can be expressed by the following equation as a function of the rolling angle φ.
It becomes like (4).

When this equation (4) is Laplace transformed and the above equation (2) is added and arranged, Then, if the transfer characteristic L of the low-pass filter 11 is a value represented by the right side of the equation (5), it can be rewritten as φ = L (α _s ′) (6) (where α _s ′ is is a function of α _s ).

Therefore, the acceleration sensor 1 is added to the low-pass filter 11.
By inputting the output α _s of the roll angle φ, the roll angle φ can be obtained.

If the output of the low-pass filter 11 is multiplied by g at the input of the multiplier 1 (g is gravitational acceleration), the output of the multiplier 12 becomes gφ.

Therefore, by calculating the difference between the output of the acceleration sensor 1 and the output of the multiplier 12 by the subtracter 13, the calculation α _s −gφ (7) is performed. This calculation is based on (2) above.
Since this is equivalent to the operation of obtaining α from the expression, the output of the subtractor 13 corresponds to the true lateral acceleration α (however, it is output as a negative value from the circuit shown in FIG. 1). ).

FIG. 2 is a diagram showing a configuration example of a specific circuit of the mixed component removing circuit 10.

The low-pass filter 14 is a filter circuit using an operational amplifier 15, and the transfer function L has resistors R ^{1 to} R ³ and a capacitance C.
_When represented by ₁ and C ₂ , And each resistance value and capacitance are selected so that this becomes equal to the above equation (3).

The differential amplifier 16 functions as the multiplier 12 and the subtractor 13, and by setting the values of the resistors R _s and R _g ,-(α _s -gφ) is obtained at the output. Is.

The mixed component removing circuit 10 is provided with the acceleration sensor 1
The acceleration detection value α _s from is input as a voltage signal, and the true lateral acceleration α is output as an inverted voltage signal. The inverted output of the lateral acceleration α may be further inverted and processed as α in a control circuit of a computer (not shown).

In the above embodiment, an example in which an analog circuit is used has been shown. However, in this embodiment, for example, the output of the acceleration sensor 1 is A / D.
It is also possible to realize it by a circuit (including a microcomputer) which processes the digital value after conversion.

(Effects of the Invention) As described in detail above, the present invention provides an acceleration sensor at a predetermined position on a spring of a vehicle to detect an acceleration generated in a direction parallel to an axle, and to obtain the acceleration sensor. By removing the component component of the gravitational acceleration that is included in the acceleration detection value along with the roll motion of the vehicle from the detected acceleration value, the lateral motion of the vehicle is always accurate without being affected by the roll motion of the vehicle. Can be detected. Moreover, since the detected value by the acceleration sensor is corrected to obtain the above-described action and effect, the same purpose can be achieved more easily and cheaply as compared with the case where the acceleration sensor is mounted on the vehicle body as a special measure.

Further, by applying the lateral acceleration detection device of the present invention as a detector of a control device or the like for analyzing the motion characteristics of the vehicle, the control accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a concrete configuration of a mixed component removing circuit in FIG. 1, and FIG. 3 is a mounting position of an acceleration sensor and a vehicle roll. It is a schematic diagram which shows the force which sometimes occurs. DESCRIPTION OF SYMBOLS 1 ... Acceleration sensor, 2 ... Spruce 4 ... Center of gravity, 5 ... Axle 10 ... Mixing component removal circuit 11, 14 ... Low pass filter 12 ... Multiplier, 13 ... Subtractor 16 ... Differential amplifier, α _s ... Acceleration detection value α … (True) lateral acceleration, g… gravity acceleration φ… roll angle

Claims (1)

[Claims] 1. An acceleration sensor for detecting an acceleration generated in a direction parallel to an axle is mounted at a predetermined position on a vehicle spring, and the acceleration is detected in accordance with a rolling motion of the vehicle from an acceleration detection value obtained from the acceleration sensor. A low-pass filter that outputs a component force component value equivalent to the component component of gravity acceleration mixed in the value, and a subtraction that subtracts the component force component value obtained from the low-pass filter from the acceleration detection value obtained from the acceleration sensor and outputs the subtracted value. The lateral acceleration detecting device is provided with a mixed component removing means including a container.