JPS61244669A - Device for detecting operating condition of car - Google Patents

Abstract

PURPOSE:To accurately detect whether a car is under a steady revolving movement or not by comparing the estimate of a lateral acceleration estimated from the detected value of a yaw rate, with the detected value of the lateral acceleration. CONSTITUTION:An estimate means 104 estimates a lateral acceleration which is considered to be generated when a yaw rate is generated, based on the yaw rate of a car detected by a yaw rate sensor 101. A judging means 105 judges whether a deviation between lateral accelerations detected by two lateral acceleration sensors 102, 103 which are placed with a certain distance apart from each other in the longitudinal direction of a car, is below a certain value or not. A judging means 106 judges whether a deviation between the estimate of the lateral acceleration and at least one of the detected values of the lateral accelerations is below a certain value or not. And, a detecting means 107 detects whether a car is in a condition of steady revolving movement or not, based on the two judging means 105, 106.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for detecting a vehicle motion state, in which a vehicle motion state, particularly a steady turning motion state, can be detected relatively easily and accurately using a small number of sensors. Regarding a detection device.

(Prior art) As prior art related to the present invention, for example, Japanese Patent Application No. 58
- As shown in No. 201287, the vehicle's steering characteristics are set in advance, the vehicle's yaw rate or lateral acceleration is detected, and the wheel steering angle is varied so that this detected value matches a separately determined target value. Techniques for controlling steering characteristics have been proposed.

(Problem to be Solved by the Invention) However, as described above, when the vehicle's yaw rate or C' lateral acceleration is constantly detected and the vehicle performs a finiedback, turning motion is not started. During a transient movement from when the vehicle is rotated until entering a steady turning motion, the deviation between the target value and the detected value becomes large, and the control amount of the wheel steering angle becomes excessive, resulting in unstable vehicle behavior. There is a possibility that the yaw rate change will become oscillatory.In addition, if only the yaw rate or the lateral acceleration is detected and the steering angle is controlled, control accuracy may be affected.

In order to increase the sensor detection accuracy, sensor detection accuracy must be increased, which leads to increased costs, and sensor failure has a large impact, so a highly accurate checking method is required to check for sensor failure. (For example, if the check is performed by a microcomputer, the processing time for the check will be long.) Furthermore, in order to determine whether or not the steady turning motion state has entered, it is necessary to determine the rate of change over time of the detected value. In order to solve the above-mentioned problems, the present invention includes the means shown in FIG. The acceleration estimating means 104 estimates the lateral acceleration that is thought to be occurring when the yaw rate occurs, based on the value of the small yaw rate of the vehicle 100 detected by the two yaw rate sensors. 'Detected value deviation determination means]
05 determines whether the deviation between the two lateral accelerations αF and αR detected by the two lateral acceleration sensors 102 and 102m arranged at a predetermined interval in the longitudinal direction of the vehicle 100 is less than or equal to a predetermined value. .

The estimated value/detected value deviation determining means 106 determines whether the deviation between the estimated value α of the lateral acceleration estimated by the lateral acceleration estimating means 104 and at least one of the detected values αF and αR of the lateral acceleration is one foot or less. Determine whether it exists or not.

The steady turning movement detection means 107 is the two discrimination means]
05.106, two lateral acceleration values α1. α
If the deviation of R is determined to be less than or equal to a predetermined value, then the estimated lateral acceleration α and the detected lateral acceleration αF are at least 70,000 yen.
Or the deviation of αR is determined to be below a certain value! When #'・
It is determined that the vehicle is in a turning motion state.

(Function) The present invention uses the lateral acceleration, the detected value, and the deviation of αR to determine whether or not it is in a steady turning motion state. By comparing the estimated value α of the lateral acceleration estimated from the total value of the yaw rate with the detected lateral acceleration values αF and αR, it is possible to check whether the above judgment is correct. Detection with high accuracy and responsiveness can be performed, and at the same time, sensor failure i6 can be checked from the difference between the estimated value α and the detected values αF and αR.

Further, since the yaw rate and lateral acceleration themselves are detected in conjunction with the detection of the steady turning motion, feedback control of these detected values can also be performed, and a complex detection function can be provided with a small number of sensors.

(Example) The configuration of the first embodiment of the present invention is shown in FIG.

The arithmetic processing unit 7 is configured using a microcomputer 8, and the processing unit 7 is configured using a microcomputer 8.
, the front wheel lateral acceleration αF detected by the two lateral acceleration sensors 4 and 5, the rear wheel lateral speed αR1, and the vehicle speed V detected by the vehicle speed sensor 6 are input. Of the input signals, s 9' e ”p
+α is input to the microcomputer 8 via the next filters 9 to 1 which remove noise components caused by vertical vibrations of the vehicle, etc., and A/D converters 12 to 14.
・The yaw rate sensor 8 is located at the center of gravity 24 of the vehicle.
The two lateral acceleration sensors 4.
5 are arranged at predetermined intervals in the longitudinal direction of the vehicle 1 (the left side in the figure is the front of the vehicle).

Then, the microcomputer 8 performs the process shown in FIG. 8. The process shown in FIG. In the process of step 21, which roughly detects sensor failure by determining whether the vehicle is in a "transient state" (hereinafter simply referred to as a "transient state") or a straight-ahead traveling state, the detection value detected by each sensor, i.e. , yaw rate detection values, front wheel lateral acceleration αF, rear wheel lateral acceleration αR1, and vehicle speed ■ are fully read.

Then, in the process of step 22, it is first determined whether the front wheel lateral acceleration αF is less than a predetermined value, that is, αFzO. Here, if the front wheel lateral acceleration is χO, it means that the vehicle is traveling straight (this can be determined by determining the rear wheel lateral acceleration αR; 0), so it is determined that the vehicle is traveling straight. A straight-travel flag F1t is set to indicate that the vehicle has moved straight (step 27).

If the determination in step 22 is NO, it means that the vehicle is in a turning motion, so next it is determined whether the vehicle is in a steady turning motion or a transient motion.

That is, through the process of step 28, it is determined whether the deviation between the front wheel lateral acceleration α1 and the rear wheel lateral acceleration αR is less than or equal to a predetermined value. This is done by determining whether or not αF to αR.

Here, if αFzα, it can be determined that the lateral acceleration acting on the vehicle 1 is approximately equal at the front and rear of the vehicle, that is, the vehicle is in steady turning motion. On the other hand, αF and α
If the deviation of F is larger than the predetermined value, it means that the vehicle 1 is experiencing yaw angular acceleration. That is, it is determined that the vehicle l is in a transient state, and transient state flags F and t are set to indicate that this determination has been made (step 29
).

If the determination in step 28 is YES, and it is determined that the vehicle l is in steady turning motion, further check the yaw rate detection value φ to confirm whether or not this determination is accurate. The estimated lateral acceleration values α are compared with the detected lateral acceleration values αF and αTuna.

The lateral acceleration sensor α* is obtained through the process of step 24. That is, α*=v−(11) is calculated from the detected yaw rate and the vehicle speed V.

This α ne is the lateral acceleration that acts on the vehicle during a steady turning motion, so the detected lateral acceleration values αF, α
If R is equal to α, it can be determined with certainty that the vehicle is in a steady turning motion state.

This judgment is made by the process of step 25, where the estimated value α
and either the detected value αF or αR (in this example, αF
whether the deviation from the
This is done by determining whether α* is αF-poor or not. Here, if α - αF, it is clear from the determination (αFzαR) from step 28 that it is α - αR.

When the determination in step 2F+ becomes YES and the determination that the vehicle is in steady turning motion is confirmed, a steady turning flag F is set indicating that it has been determined that the vehicle is in steady turning motion (step 26).

In this embodiment, it is assumed that the yaw rate curve detected at this time is a reliable value as a steady yaw rate.
Allow a small output (step 80).

Hereinafter, the steady yaw rate obtained through this step 80 will be expressed as a ship. In addition, at this time, the detected value α of the above-mentioned lateral acceleration
1. αF may be output as steady lateral acceleration.

On the other hand, if the determination in step 25 is NO, that is, even though the deviation of the detected values αF and αR of the lateral acceleration is less than the predetermined value, the estimated value α tree of the lateral acceleration and the detected value If α is different, it means that a failure has occurred in either the yaw rate sensor 8 or the lateral acceleration sensors 4 and 5, so the sensor fail flag F8 is set to indicate the occurrence of this sensor failure. (Stats 7
'28).

In this way, this embodiment can detect the steady turning motion state with high accuracy by using only one yaw rate sensor 8 and two lateral acceleration sensors 4 and 5, and moreover, it is possible to detect the steady turning motion state with high accuracy. Since it is not necessary to obtain the following, it is possible to determine whether or not the vehicle is in a steady turning motion state in an extremely short processing time, and detection with good responsiveness can be performed.

Further, since the failure check of each sensor can be performed simultaneously by the process of confirming the determination of the steady turning movement state (the process of step 25), there is no need to set a separate process for detecting sensor failure.

Furthermore, in addition to the above-mentioned function of detecting the steady turning motion state, it is also provided with the function of detecting the steady yaw rate and steady lateral acceleration9, thus providing multiple functions with a small number of components. In addition, by adding simple calculation processing, the yaw angular acceleration −
It is also possible to detect ° (obtained by ° - (αF - αR) / L). Note that when the vehicle speed is high, the steering characteristics of the vehicle become nonlinear, and the detection accuracy of the steady turning motion state becomes less accurate. Therefore, in the above embodiment, it is possible to perform highly reliable detection by restricting the conditions for detecting the steady turning motion state (this can be done in the “second
For example, when the steering gear ratio of the vehicle is 20 and the stability factor is approximately 0.002, when the conditions in the hatched region A are satisfied in FIG. This can be realized by executing the process shown in FIG. In this area A, the lateral acceleration α of the vehicle is 5 m/
As an eighth embodiment of the present invention, an example in which the device of the first embodiment is applied to a wheel steering angle control device will be described. In order to achieve the same driving performance in one's own vehicle (referring to a vehicle equipped with the device of this embodiment),
A vehicle with the preset driving performance (this is referred to as the "target driving performance") is set as a simulation model, and this simulation model is referred to as the "target vehicle".
), the variable during steering, i.e. steering tool 1
The steering angle of the front wheels 41, 42 and rear wheels 48° 44 of the own army is controlled based on the steering angle of the steering wheel 48 (detected by the steering wheel steering angle sensor 47) θS and the motion characteristics exhibited by the target vehicle corresponding to the vehicle speed V. By doing so, it was realized as a movement characteristic of the own army.

Therefore, the front wheels 4], 42 and the rear wheels 48. j4 is a servo-type steering device 4.9, such as a hydraulic or electric type.
These steering devices 49 and 50 are controlled by the front wheel steering device 45 or the rear wheel steering device 46.

The front wheel steering device 45 and the rear wheel steering device 46 calculate a target value of the steering angle of the front wheels and a target value of the steering angle of the rear wheels, which are necessary to achieve the target motion performance, through calculations in the arithmetic processing device 40. are obtained, and these δF and δR are given as inputs. The front wheel steering device 45 includes front wheels 41 and 42.
The steering device 49 is controlled so that the actual steering angle of the rear wheels 48.degree. The steering device 50 is controlled accordingly.

The configuration of the first embodiment is incorporated into the configuration of this embodiment, and in the arithmetic processing unit 40, the eighth
The process shown in the figure is performed, and a control gain in wheel steering angle control is determined based on the determination and detected value by this process.

The flowchart shown in FIG. 6 shows the control gain determination process and the wheel steering angle control process.

In the process of step 61, it is determined whether or not the vehicle is in a steady turning motion in the process shown in FIG. 8, based on whether the steady state flag F is set to cert.

Here, if the upper flag F,=1, step 62
The steady yaw rate ship detected in the process shown in FIG. 8 is read by the process shown in FIG. Make a decision on the control gain based on.

The control gain is determined by comparing the steady yaw rate with a yaw rate target value 'small' obtained in step 66, which will be described later. Note that the yaw rate target value used here is the value determined in the previous process. The specific calculation for the control gain is performed according to the following equation.

K = ψ/ψ. ...(2) Here,
K is the control gain subjected to the filtering process performed in the next step 64, and i used in the above calculation.
is the value found in the previous process. l'J,
The initial value of K is set to 1 when the ignition switch is turned on.

Therefore, if the actual steady yaw rate of the ship detected by the yaw rate sensor 8 is larger than the yaw rate target value τ ψ, the control gain will be smaller than the yaw rate target value τ ψ.

If ψ is smaller than ψ, the control gain will be large.Next, in the process of step 64, if the width value changes frequently within a short period of time, if the value of the control gain changes each time, the control gain will increase. Since steering angle control cannot be performed stably, filtering processing is performed to average short-term changes in the value of the control gain. This filtering process is performed according to the following formula.

K=(]-0)K+OK...(8) However, 0(0(I).

K obtained in this way (hereinafter, K after this filtering process will be referred to as a "control gain") is used to correct a motion variable target value, which will be described later, during steady turning motion.

Note that when the steady state flag F is not set,
That is, the value of the control gain is not modified while the vehicle is running straight or during transient motion (step 70).

Then, control of the wheel steering angle is performed by the processing in steps 65 to 69.

In the process of step 66, the yaw rate, yaw angular acceleration, yaw rate, yaw angular acceleration, Find the values of lateral acceleration and lateral velocity, and use these as the target values for the movement variables of your army.

Below, these target values are referred to as yaw rate target value, yaw angular acceleration target value V, lateral acceleration target value α, and lateral velocity target value V.
Let it be y.

In the process of step 67, each target value meeting, °φ.

α, ■9 is multiplied by the control gain K and then multiplied by .

In the process of step 68, calculations are performed to obtain the front wheel steering angle target value and the rear wheel steering angle target value necessary for realizing the above-mentioned motion variable target values by the own army, and in the process of step 69, pl δF , δ, are output to the front wheel steering device 4 or the rear wheel steering device 5.

Then, the actual steering angles of the front wheels 41 and 42 are steered so that they are equal to the front wheel steering angle target value 6, and the actual steering angles of the rear wheels 48 and 44 are steered so that they are equal to the rear wheel steering angle target value δ. By being steered, the yaw rate, yaw angular force U velocity, lateral acceleration, and lateral velocity of the own army are determined by the above-mentioned yaw rate target value, yaw angular acceleration target value, lateral acceleration target value α, and lateral velocity target value. vyI becomes equal, and the target movement performance is realized by the own army.

Here, during the steady turning movement, the processing in steps 61 to 64 and the processing in step 67 allows for more appropriate control during the steady turning movement, even though the actual steady yaw rate is fed back.

In other words, for example, if the friction coefficient of the road surface is small, the accuracy of achieving the target motion performance will decrease, resulting in a discrepancy between the actual vehicle motion performance and the target motion performance. requires feedback of the actual motion variables.

In addition, during transient motion, the motion characteristics become nonlinear, so
It becomes difficult to perform appropriate control by performing the feedback control described above.

Therefore, as in this embodiment, by feeding back the steady yaw rate as an actual motion variable, accurately detecting that steady turning motion is in progress, and performing feedback control only during this steady turning motion, it is possible to reduce waste. This makes it possible to perform appropriate control without any problems.

Note that if an upper limit is set for the control gain K to prevent the value of the control gain from becoming too large, when driving on a road surface with a low coefficient of friction, K will become too large and the wheels will It is possible to prevent the behavior of the vehicle from becoming unstable due to excessive steering angle.

(Effects of the Invention) As explained in detail above, the present invention provides a method for determining whether or not the steady turning motion state is based on the deviation between two detected lateral acceleration values, which differs from the lateral acceleration. By comparing the estimated lateral acceleration value estimated from the detected value of yaw rate, which is a motion state quantity, with the detected horizontal blade speed value, it is possible to check whether or not the above judgment is correct. , it is possible to perform detection with high precision and good responsiveness, and at the same time, it is possible to check for sensor failure from the difference between the estimated value and the detected value.

As a result, even if a relatively unreliable sensor is used, it is possible to accurately detect whether or not a steady turning motion is being performed, thereby making it possible to use a low-cost sensor.

Furthermore, since the yaw rate and lateral acceleration can also be detected in conjunction with the detection of the steady turning motion, feedback control of these detected values can be performed, and a complex detection function can be provided with a small number of sensors.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a block diagram of a first embodiment of the present invention, Fig. 8 is a flowchart showing the processing executed in the microcomputer in Fig. 2, and Fig. 4 is a block diagram of the present invention. FIG. 5 is a diagram showing the control area in the second embodiment of the invention, FIG. 5 is a configuration diagram of the eighth embodiment of the invention, and FIG. 6 is a flowchart showing the processing executed in the arithmetic processing device in FIG. 5. . 100... Vehicle 1o1... Yaw rate sensor 101
, 108...Lateral acceleration sensor 104...Lateral acceleration estimation means 105...Detected value deviation determining means 106...Estimated value/detected value deviation determining means 107...
Steady turning motion detection means 8... Yaw rate sensor 4.5... Lateral acceleration sensor 6... Vehicle speed sensor 7, 40... Arithmetic processing unit φ... Yaw rate αF, αR... Lateral acceleration. 6 lines: Estimated lateral acceleration Width: Steady yaw rate Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 4 JILty (Kmlk) Figure 5

Claims (1)

[Claims] 1. a yaw rate sensor that detects the yaw rate of the vehicle; two lateral acceleration sensors that are arranged at a predetermined interval in the longitudinal direction of the vehicle and detect the lateral acceleration of the vehicle; and a value of the yaw rate of a single vehicle detected by the yaw rate sensor. lateral acceleration estimating means for estimating the lateral acceleration that is considered to be occurring when the yaw rate occurs based on the yaw rate; and a deviation between the two lateral accelerations detected by the two lateral acceleration sensors is less than or equal to a predetermined value. detection value deviation determination means for determining whether or not the deviation between the estimated value of the lateral acceleration estimated by the lateral acceleration estimation means and at least one value of the two lateral accelerations detected by the lateral acceleration sensor is constant; estimated value/detected value deviation determining means for determining whether the detected value is equal to or less than a predetermined value, and the two determining means determine that the deviation between the two detected values of lateral acceleration is equal to or less than a predetermined value, and a steady turning motion detection means that determines that the vehicle is in a steady turning motion state when the deviation between the detected value and at least one of the detected values of lateral acceleration is determined to be below a certain value. Condition detection device.