JPH02236172A - Acceleration detector for vehicle - Google Patents

Abstract

PURPOSE:To realize high accuracy in detecting acceleration with a simple structure by a method wherein acceleration can be obtained with error component in acceleration based on oscillation of a vehicle eliminated only by using two acceleration sensors with respect to a direction of the acceleration to be detected. CONSTITUTION:At two different points above the oscillation axis YC of a vehicle, that is, at a first acceleration point and a second acceleration point, acceleration in a direction for crossing the vertical plane VP including the oscillation axis YC is detected by first and second acceleration detectors M1 and M2 respectively. Then an acceleration compensating device M3 compensates the detected acceleration based on a distance from the oscillation axis YC to the first acceleration detected point and a distance from the oscillation axis YC to the second acceleration detected point respectively, from the detection results of the acceleration detectors M1 or M2 with rotating acceleration component generated in terms of the oscillation axis as the center eliminated. Thus error components based on the oscillation contained in the detected acceleration of the detectors M1 and M2 are offset and true acceleration components can be obtained.

Description

[Detailed Description of the Invention] 1. Industrial Application Field of the Invention 1 Companion of the Invention Vehicle acceleration detection for detecting the acceleration of a vehicle rocking around a rocking axis substantially parallel to the road surface 12 Regarding equipment.

[Prior Art] Acceleration occurring in a vehicle, especially lateral and longitudinal acceleration (
1 It is often used as a parameter to calculate the estimated load movement amount in vehicle attitude control, braking control, etc. As a device for detecting such acceleration, a device is known in which an acceleration sensor is installed near the center of gravity of the vehicle, and this acceleration sensor detects the acceleration in the lateral or longitudinal direction of the vehicle. Since the rotational acceleration component generated due to the shaking of the vehicle is included as an error component in the detected acceleration in the above cases, various techniques have been proposed to remove this error component.

For example, lf? ．． A pair of acceleration sensors are installed on the vehicle floor to detect the rocking state of the vehicle floor when the vehicle is rocking up and down, and based on the detection results, the vehicle's vertical rocking trajectory is determined.Specifically, rolling. An error component in the lateral or longitudinal acceleration caused by pitching is calculated, and the lateral or longitudinal acceleration of the vehicle detected by an acceleration sensor installed separately from this pair of acceleration sensors is corrected using the error component. The technique is known (Japanese Unexamined Patent Publication No. 70766/1983).
This technology makes it possible to remove error components of vehicle acceleration even when the vehicle is rolling or pitching, making it possible to detect acceleration in the lateral or longitudinal directions with high precision. It is. [Problems to be Solved by the Invention] However, one problem with the above-mentioned conventional technology is that three acceleration sensors must be used even though the acceleration is measured in one direction (lateral or longitudinal direction). However, there is a problem that the structure is complicated, and the steering angle of the vehicle is not fixed. Some methods have been proposed that estimate acceleration by detecting steering angular velocity, etc., but there are 1. t. Since error components due to road surface μ, etc. are included separately from the rotational acceleration component mentioned above, sufficient accuracy cannot be obtained and this is not a practical solution. An object of the present invention is to simplify the structure of a vehicle acceleration detection device while maintaining high accuracy in detecting vehicle acceleration. [Means for solving the problem] Table 1: Means adopted by the present invention to achieve the above object As shown in Fig. 1, which is a schematic configuration diagram illustrating its basic configuration, A vehicle acceleration detection device detects the acceleration of a vehicle rocking about a substantially parallel rocking axis YC, wherein the rocking axis YC is detected at a first acceleration detection point above the rocking axis YC. a first acceleration detection means M1 that detects acceleration in a direction intersecting a vertical plane VP including a first acceleration detection point above the swing axis YC and at a distance from the swing axis YC; a second acceleration detection means M2 that detects acceleration in a direction intersecting the vertical plane vP at different second acceleration detection points; and each from the swing axis YC to the first and second acceleration detection points. and the detection results of the first and second acceleration detection means (Ml, M2), the swing axis is determined from the detected acceleration of the first or second acceleration detection means (Ml, M2). The gist thereof is to include an acceleration correction means M3 for correcting the detected acceleration by removing a rotational acceleration component centered on YC.
At two different points above the vehicle's swing axis YC, that is, at the first acceleration detection point and the second acceleration detection point, the swing axis YC
The acceleration in the direction intersecting the vertical plane vP including C is detected by the first acceleration detection means M1 and the second acceleration detection means M2, respectively. Then, the acceleration correction means M3
Detection of the distance from the swing axis YC to the first acceleration detection point, the distance from the swing axis YG to the second acceleration detection point, and the first acceleration detection means M1 and the second acceleration detection means M2 Based on the result, the first acceleration detection means M
The rotational acceleration component generated around the swing axis YC is removed from the acceleration detected by the first or second acceleration detection means M2 to correct the detected acceleration. That is, only the true acceleration component is obtained by canceling out the error component based on the swing included in the acceleration detected by the first acceleration detection means M1 and the second acceleration detection means M2. Therefore, even if the swing axis YG is the rolling center axis of the vehicle, I
L A direction that intersects the vertical plane VP that includes this rolling center axis. For example, the lateral acceleration of the vehicle is detected. on the other hand,
If the swing axis YG is the pitching center axis of the vehicle, it is 1'L.
A direction intersecting the vertical plane VP including the pitching center axis, for example, the longitudinal acceleration of the vehicle is detected.

The first and second acceleration detection points need not be vertically above the swing axis YG, nor are they limited to the same line extending diagonally upward from the swing axis YG.

[Example] Next 1: An example of the vehicle acceleration detection device according to the present invention will be described based on the drawings. Fig. 2 shows a schematic configuration of a vehicle equipped with the vehicular acceleration detection device of the embodiment. Fig. 3 shows a schematic configuration of an acceleration sensor used. Fig. 4 shows signals when detecting acceleration in this vehicular acceleration detection device. It is a block diagram showing the flow. As shown in Figure 2, 1:. Acceleration detection device for vehicle 1 Acceleration sensors 2 and 4 installed above the rolling axis RC of the vehicle and at different positions on the vertical line passing through the center of gravity of the vehicle,
Acceleration sensors 6 and 8 installed above the pitching axis PC of the vehicle and at different positions on the vertical line passing through the center of gravity of the vehicle
, the distance between the left front wheel and the vehicle body (i.e., the left front vehicle height)
A vehicle height sensor 10 that detects the right front vehicle height, a vehicle height sensor 12 that similarly detects the right front vehicle height, a vehicle height sensor 14 that detects the left rear vehicle height, a vehicle height sensor 16 that detects the right rear vehicle height,
Acceleration detection circuit 20, air circuit AC, and suspension pressure control valves 31FL, 31 that calculates acceleration in the lateral and longitudinal directions based on inspection signals from each acceleration sensor, etc.
The well-known electronically controlled air suspensions 32FL, 32FR, 32RL, and 32RR, which suspend each wheel independently, are connected via the FR, 31RL, and 31RR, respectively. Suspension pressure control valve 31FL, 31FR, 31RL,
31RR to drive and control each of the above-mentioned suspensions to control the attitude of the vehicle.

Next 1:. Acceleration sensors 2, 4, 6. The configuration of 8 will be explained. Since each acceleration sensor has the same configuration, one of them, acceleration sensor 2, will be explained. As shown in Figure 3, 1:. Acceleration sensor 21 is a so-called strain-type acceleration sensor in which a weight 2d is supported via a piezoelectric body 2C at both ends of an elastic member 2b installed upright in the upper housing 2a. 2 in the diagram
Detects acceleration in the direction indicated by A and outputs it as an electrical signal. Acceleration sensors 2, 4, 6 having such a configuration
．． Acceleration sensor 2 , 41 top Detects the acceleration in the vehicle lateral direction. On the other hand, the acceleration sensor 6,81i detects the acceleration in the longitudinal direction of the vehicle. Each acceleration sensor is connected to an acceleration detection circuit 20 and outputs the detected acceleration to the circuit 20. In addition, the symbols A, written near each acceleration sensor in Fig. 2,
Acceleration sensors 2, 4, 6 when the Bl friend vehicle rolls or pitches. 8, which corresponds to the acceleration detection direction 2A in FIG. 3 described above. Distances Q2, Q4 from rolling axis RC to acceleration sensors 2 and 4 when the vehicle is at a predetermined reference vehicle height,
and distances 116 and 1181 from the pitching axis PC to each of the acceleration sensors 6 and 8. Tables 116 and 1181 are stored in advance in the acceleration detection circuit 20 as standard arm lengths. In the following, the subscripts used are 1 and 2 and 4 for each acceleration sensor.
, 6. It is attached in correspondence with 8. Each vehicle height sensor 10, 12, 14, 161 is connected to the electronic control circuit 30, and when the vehicle height is higher than a predetermined reference vehicle height, it outputs a signal corresponding to a positive vehicle height difference. When the vehicle height is higher, a signal corresponding to the negative vehicle height difference is output to the electronic control circuit 30. Each air suspension 32FL, 32FR, 3
2 R L, 3 2 R R l friend gas spring 33
FL, 33FR, 33RL, 33RR and shock absorber 34FL, 34FR, 34RL, 34
RR, and receives air supply and discharge through suspension pressure control valves 31FL, 31FR, 31RL, and 31RR that control air supply and discharge to and from the gas springs based on control signals from the electronic control circuit 30, It is configured so that constant damping force etc. can be changed. The electronic control circuit 30 (top) is connected to an acceleration detection circuit 20 that calculates the acceleration of the vehicle as described later, and transmits and receives various control data related to the attitude control of the vehicle.Furthermore, this electronic control circuit 30C Each vehicle height sensor 10, 12, 14.1
The detected vehicle height signal is input from 6, and based on these vehicle height signals and the detected acceleration from the acceleration detection circuit 20, the estimated load movement during vehicle turning, acceleration/deceleration, etc. is performed. The target pressure of each air suspension is determined by calculating the air supply/exhaust control amount, etc., and a drive signal corresponding to the target pressure of each air suspension is sent to each suspension pressure control valve 31FL, 31FR, 31RL,
It is configured to output to 31RR. Low Attitude control executed by the electronic control circuit 30 (Top) This is performed by driving each suspension according to the target pressure of each air suspension, but since it is well known, the explanation will be omitted. Acceleration detection circuit 20 (Friend) Connects to each acceleration sensor and electronic control circuit 3o Inputs acceleration signals and control data, calculates acceleration in the lateral direction and longitudinal direction based on the input control data, etc. Acceleration in this acceleration detection circuit 20 Prior to explaining the signal flow of the calculation process, first, the acceleration detection signal of the acceleration sensor will be explained.

Lateral acceleration detection signal N detected by acceleration sensors 2 and 4
V2, NV4, and the longitudinal acceleration detection signals Nx6 and Nx8 detected by the acceleration sensors 6 and 8 have a roll angle θR,
Pure lateral or longitudinal acceleration Ny (estimated actual lateral acceleration) with respect to pitch angle θP, ? In addition to the cosine component of IX (estimated actual longitudinal acceleration):. Roll angular acceleration component, pitch moment acceleration component, and each tilt acceleration component based on roll angular acceleration δR for roll angle θR or pitch angular acceleration 4P for pitch angle θP, and gravitational acceleration G for roll angle θR and pitch angle θP
, and the relationship between them is expressed by the following equation (1) ~
It is expressed as (4). N y2 = Ry − COSθR+L2・4R+α・
θR+G-SINθR...(1) N y4 = [y-COSθR+ L4・dR +a
・4R+G-SINθR...(2) N x 6 = N X-COSθP +L6-JP+β
-9P+G-SINθP...(3) N x 8 =Q x-COSθP +L8-iP+β
-9P+G-SINθP...(4) However, since the roll angle θR and pitch angle θP {upper when the vehicle is rocking are usually extremely small values, their cosine value (COS
θR, COSθP) can be approximated to 1, and its sine value (
SINθR, SINθP) can be approximated to O, so
The above formulas (1) to (4) can be rewritten as the following formulas (1A) to (4A).

N y2 =Qy+L2- 4R +a ・4R-
(I A) Ny4 ='FJy+L4- dR +a
・dR − (2A)N x6 = [x +L6・e
P10B ・4P - (3 A)N x8 = 艮x+L
8・7P+β-9P. ．． ．． (4A) In the above formula, L2, L4+1 is the actual roll arm length, which is the distance from the rolling axis RC to each acceleration sensor 2, 4, L6
,L8LL From the pitching axis PC to each acceleration sensor 6
, 8 is the actual bitch arm length. In addition, tilt acceleration components based on angular acceleration (α・δR, β・θ
P) 1 friend The strain type acceleration sensor is number 2B in Figure 3.
As long as the acceleration in the direction 2A in the figure is detected while rocking around the rocking axis (in this example, the rolling axis RC and the pitching axis PC), the characteristic inevitably mixed into the acceleration detection signal. is the swing acceleration component of Then, the constants α and β (tilt detection constants) of the above tilt acceleration component (friend
This is the output coefficient of the detection signal for this acceleration component, and is constant regardless of the installation location if the acceleration sensor is the same. In addition, the constants α and β {table are determined in advance by tests.

θR from formula (IA), (2A), and formula (3A)
, estimated actual loss acceleration Ny and estimated actual longitudinal acceleration FJ x It obtained by eliminating θP from (4A), lateral acceleration detected by acceleration sensor 4, and acceleration sensor 8
The detected longitudinal acceleration and its correction amount are summarized by the following equations (5) and (6). ...- (5) ... (6) Next 1:. The acceleration detection circuit 20 connected to each acceleration sensor and the electronic control circuit 30 detects the estimated actual lateral acceleration N as described above.
The signal flow when calculating y and the estimated actual longitudinal acceleration Rx will be explained based on the block diagram of FIG. 4.

As shown in the figure, 12 acceleration detection circuits 201 and various discrete computing units 22, 23, 24.
Equipped with 25 etc., each vehicle height sensor 10, 12, 1
Input the actual vehicle height value Rx, which is the control data calculated by the electronic control circuit 30 by weighted averaging the left and right front vehicle heights HFL, HFR and the left and right rear vehicle heights HRL, HRR from 4.16. Arithmetic unit 22 and 241 friend
Based on the input actual vehicle height value i1x and the standard arm length mentioned above, each acceleration sensor 2, 4, 6. Current roll arm lengths L2, L4, and bitch arm length L of 8.
6, L8 are calculated using the following equations (7) to (10) and output.

L2 = l”lx+112 +++ (
7) L4 =llx+(!4 ---
(8) L6=l"lx+96... (9
) 8”Rx+Q8... (10) In other words,
Correct the roll arm length and bitch arm length according to the vehicle height. Calculator 23.25m From the input roll arm length, pitch arm length, and inclination detection constant α or β, calculate the lateral acceleration detection error cancellation coefficient KR and the longitudinal acceleration detection error cancellation coefficient KP using the following formula (11). Calculate using the formula shown in (12) and output. On the other hand, the formula (1A
) to (4A), which is the difference between the lateral acceleration detection signals Ny2 and NV4 of the acceleration sensors 2 and 4 (NV4 - NV2), and the acceleration sensor 6
．． 8 detected longitudinal acceleration detection signals Nx6 and Nx8
The longitudinal acceleration detection difference (Nx8 - Nx
6) can be obtained for each. Then, this lateral acceleration detection difference (Ny4 −Ny2)
The lateral acceleration detection error cancellation coefficient K obtained by the calculator 23 in
By multiplying by R, the correction amount of the second term on the right side in the above-mentioned equation (5) is obtained.

(Ny4-Ny2)KR Similarly, from the longitudinal acceleration detection difference (Nx8-Nx6) and the longitudinal acceleration detection error cancellation coefficient KP, formula (6) is obtained.
The amount of correction is found. (Nx8-Nx6)K
P Next 1:, Lateral acceleration detection signal NV4 of acceleration sensor 4
The estimated actual loss acceleration Ry expressed by the above-mentioned equation (5) is obtained by subtracting the correction amount expressed by the above equation (13) from the equation (13), and outputted from the acceleration detection circuit 20 to the electronic control circuit 30. Similarly, the estimated actual longitudinal acceleration Rx expressed by equation (6) is calculated from the longitudinal acceleration detection signal Nx8 of the acceleration detection sensor 8 and the correction amount of equation (14) above, and the electronic control circuit 3
1; Output. And the estimated actual lateral acceleration? 1y and estimated actual longitudinal acceleration R
．． The electronic control circuit 301 that inputs the following calculates the air supply/exhaust control amount to avoid roll dive and pitch dive, determines the target pressure of each air suspension, and outputs a drive signal according to the target pressure of each air suspension. Each suspension pressure control valve 31FL, 31FR, 31RL, 31
Output to RR. As explained above, according to this embodiment, the acceleration error component generated based on the roll angular acceleration 4H when the vehicle rolls, that is, the roll moment acceleration component (L2
-9R). (L4-9R) and tilt acceleration component (α・
JR) etc. are removed from the lateral acceleration detection signals Ny2 and Ny4 detected by the lateral acceleration sensor 2.4, so the influence of acceleration error components on these acceleration detection signals can be blocked. In addition, the pitch moment acceleration component (L
6-9P). (Le-9p), tilt acceleration component (β
・The influence of 49P) is also blocked. For this reason,
Accurate lateral or longitudinal acceleration 'Ry. Wx can be detected. The accurately detected lateral and longitudinal acceleration 'FJy. 'FJx can be used to calculate various control amounts for vehicle attitude control by the electronic control circuit 30.
It becomes possible to perform attitude control that is more suited to the driving conditions, improving control accuracy. For example (f), as shown in Figure 5 (A), if the steering angle suddenly increases and then becomes O, the conventional method is to install one acceleration sensor near the center of gravity of the vehicle to detect the lateral acceleration. As shown by the broken lines in Table 5 (B) and (C), an error component based on the roll angular acceleration 5R is constantly superimposed on the detected acceleration, so this detected acceleration is used. Even if posture control is carried out, it is not possible to sufficiently suppress rolling or avoid overturning.On the other hand, according to this embodiment, l@' Figure 5 (B). As shown in 1:, accurate lateral acceleration 'Ry is detected after removing the error component caused by roll angular acceleration δR, and more appropriate attitude control is constantly performed based on this detected acceleration, so that the steering angle does not increase before the steering angle increases. Immediately after returning to the value of LX, the rolling is resolved and roll angle θ occurs.
It is also possible to suppress the increase in Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that the present invention can be implemented in various forms without departing from the spirit thereof. For example, the acceleration sensors 2 and 4 for detecting 1'L lateral acceleration and the acceleration sensors 6 and 8 for detecting longitudinal acceleration are arranged on the same vertical line passing through the center of gravity of the vehicle. Any arrangement is acceptable, even if it is above the oscillation axis and at a different distance from the swing axis. Although the sample embodiment is configured to simultaneously detect lateral acceleration and longitudinal acceleration, it is of course possible to detect either one of the accelerations. 1 five elements 1 As detailed above including the examples 1:. IL According to the vehicle acceleration detection device of the present invention, it is possible to calculate accurate acceleration in the direction of the acceleration to be detected by removing error components of acceleration due to vehicle rocking just by using two acceleration sensors. can. In other words, it is possible to simplify the configuration while maintaining high acceleration detection accuracy. This not only simplifies maintenance and inspection work, but also improves control accuracy when controlling the vehicle's attitude using the detected acceleration.

[Brief explanation of drawings]

FIG. 1 shows a schematic configuration illustrating the basic configuration of the present invention.
Figure 2 shows the general configuration of a vehicle equipped with the vehicle acceleration detection device of the embodiment. Figure 3 shows the schematic configuration of the acceleration sensor used. Figure 4 shows the signals used when detecting acceleration in this vehicle acceleration detection device. The block line showing the flow is
FIG. 5 is an explanatory diagram for explaining the effects of the embodiment.
1... Vehicle acceleration detection device RC... Rolling axis RP, PP... Vertical plane P
C... Pitching axis 2, 4, 6. 8... acceleration sensor 10,
12, 14. 16...Vehicle height sensor 20...
Acceleration detection circuit 30...Electronic control circuit agent Patent attorney Tsutomu Adachi (and 2 others) Figure 1 Figure 5

Claims (1)

[Claims] 1. A vehicle acceleration detection device that detects the acceleration of a vehicle rocking about a rocking axis that is substantially parallel to a road surface, wherein the rocking axis is detected at a first acceleration detection point above the rocking axis. a first acceleration detection means for detecting acceleration in a direction intersecting a vertical plane including a second acceleration detection point, which is above the swing axis and whose distance from the swing axis is different from the first acceleration detection point a second acceleration detection means for detecting acceleration in a direction intersecting the vertical plane at an acceleration detection point; respective distances from the swing axis to the first and second acceleration detection points; and the detection result of the second acceleration detection means, remove a rotational acceleration component about the swing axis from the acceleration detected by the first or second acceleration detection means, and correct the detected acceleration. 1. An acceleration detection device for a vehicle, comprising: acceleration correction means.