JP3168758B2 - Detection yaw rate correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detected yaw rate correction device applied to a four-wheel steering device for providing an auxiliary steering angle by yaw rate feedback control during front wheel steering.

[0002]

2. Description of the Related Art Conventionally, as a detected yaw rate correction device applied to a four-wheel steering device for giving an auxiliary steering angle to a rear wheel by yaw rate feedback control during front wheel steering, for example, Japanese Patent Application Laid-Open No. 62-261575 discloses Devices are known.

According to this conventional source, when a vehicle stop state is detected, a value corresponding to a deviation of a sampled detected yaw rate from a reference value is accumulated, and the reference value is updated based on the accumulation result. Accordingly, a technique for correcting a zero point shift of a detected yaw rate has been disclosed.

[0004]

However, in the above-described conventional detected yaw rate correction device, since the detected yaw rate is corrected to a zero point when a vehicle stop state is detected, for example, the vehicle is stopped. If the zero point shift due to the temperature drift of the yaw rate sensor occurs during long running without running, the zero point shift of the detected yaw rate is not corrected until the next stop, and the yaw rate feedback matches the actual yaw rate to the target yaw rate. In the rear wheel steering angle control, since the actual yaw rate in the offset state is used as the control information, the control is directly affected, the control accuracy is reduced, and the turning performance of the vehicle is deteriorated.

That is, although the prior art can cope with the aging of the yaw rate sensor in which the zero point offset gradually occurs over a long period of time, the zero point offset occurs during a short time while the vehicle is running. Temperature drift, sensor voltage change, etc.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. It is an object of the present invention to provide a detection yaw rate correction device which is detected by a yaw rate sensor mounted on a vehicle. When the zero point shift of the yaw rate sensor occurs due to drift or the like, the present invention is to immediately respond to achieve the correction of the zero point shift.

[0007]

In order to solve the above-mentioned problems, in a detection yaw rate correction apparatus according to the present invention, a vehicle is set.
If the vehicle travels substantially straight ahead at the vehicle speed within the vehicle speed range for the set time, the average value of the yaw rate deviation between the target yaw rate and the actual yaw rate during that time is calculated, and when this yaw rate deviation average value is positive, the yaw rate zero correction value is calculated. There is provided a yaw rate zero correction value setting means for making a correction for increasing the value and for reducing the yaw rate zero correction value when the average value of the yaw rate deviation is negative and for setting the yaw rate zero correction value.

That is, as shown in the claim correspondence diagram of FIG. 1, a yaw rate sensor a for detecting a yaw rate applied to a vehicle, a vehicle speed detecting means b for detecting a vehicle speed, and a steering angle detecting means c for detecting a steering angle. Traveling state determining means d for determining that the vehicle is in a substantially straight traveling state at a vehicle speed within a set vehicle speed range, target yaw rate calculating means e for calculating a target yaw rate according to the vehicle speed and the steering angle, An actual yaw rate calculating means f for calculating an actual yaw rate used for control based on the yaw rate sensor value and the latest yaw rate zero correction value, a yaw rate deviation calculating means g for calculating a yaw rate deviation between the target yaw rate and the actual yaw rate, and a vehicle are set. At a vehicle speed within the vehicle speed range
When a substantially straight running state is continued for a set time, a yaw rate deviation average value calculating means h for calculating an average value of the yaw rate deviation during that time, and a correction for increasing the yaw rate zero correction value when the yaw rate deviation average value is positive, When the deviation average value is negative, the yaw rate zero correction value is corrected by decreasing the yaw rate zero correction value to set the yaw rate zero correction value, and the set yaw rate zero correction value is updated as the latest yaw rate zero correction value. And a yaw rate zero correction value updating means j.

[0009]

When the vehicle is traveling and the traveling state determining means d determines that the vehicle is in a substantially straight traveling state at a vehicle speed within the set vehicle speed range , the target yaw rate calculating means e determines the vehicle speed from the vehicle speed detecting means b. The target yaw rate according to the vehicle speed and the steering angle from the steering angle detecting means c is calculated, and the actual yaw rate calculating means f calculates the actual yaw rate to be used for control based on the yaw rate sensor value and the latest yaw rate zero correction value. The yaw rate deviation calculating means g calculates a yaw rate deviation between the target yaw rate and the actual yaw rate.

[0010] Then, the vehicle within the set vehicle speed range.
When the vehicle travels substantially straight ahead at the speed for a set time, the average value of the yaw rate deviation is calculated by the average yaw rate deviation calculating means h, and the average yaw rate deviation value is calculated by the yaw rate zero correction value setting means i. A correction to increase the yaw rate zero correction value, and a correction to decrease the yaw rate zero correction value when the average yaw rate deviation is negative are set to the yaw rate zero correction value,
In the yaw rate zero correction value updating means j, the set yaw rate zero correction value is updated as the latest yaw rate zero correction value.

That is, when the yaw rate deviation between the target yaw rate and the actual yaw rate continues to be positive despite the execution of the yaw rate feedback control,
It is estimated that the yaw rate zero point is offset to the negative side, and when the state where the yaw rate deviation is negative continues, it is estimated that the yaw rate zero point is offset to the positive side.

Focusing on this point, the yaw rate zero correction value setting means i corrects the yaw rate zero correction value in a direction to reduce the offset amount, and updates the corrected value as the latest yaw rate zero correction value. When the zero point shift of the yaw rate sensor a occurs due to a temperature drift or the like while the vehicle is running, the zero point shift can be corrected immediately in response.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The configuration will be described.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which the detected yaw rate correction device according to the embodiment of the present invention is applied.

In FIG. 2, the front wheels 1 and 2 are steered by a steering handle 3 and a mechanical link type steering mechanism 4.
Done by This includes, for example, a steering gear, a pitman arm, a relay rod, side rods 5, 6, knuckle arms 7, 8, and the like.

The steering of the rear wheels 9, 10 is performed by an electric steering device 11. This rear wheel 9,
Between 10, the rack shaft 12, the side rods 13, 1
4. The rack tube 17 in which the rack 12 is inserted and connected by the knuckle arms 15 and 16 has a speed reduction mechanism 1
8, a motor 19, and a fail-safe solenoid 20.
Indicates a vehicle speed sensor 21 (corresponding to vehicle speed detecting means b), a front wheel steering angle sensor 22 (corresponding to steering steering angle detecting means c),
Rear steering angle sub sensor 23, rear steering angle main sensor 24,
Drive control is performed by a controller 26 that inputs signals from a yaw rate sensor 25 (corresponding to a yaw rate sensor a) and the like.

FIG. 3 is a sectional view showing a specific structure of the electric steering apparatus 11.

In FIG. 3, a rack tube 17 in which the rack 12 is inserted is fixed to the vehicle body via a bracket. Side rods 13 and 14 are connected to both ends of the rack 12 via ball joints 30 and 31. The reduction mechanism 18 includes a motor pinion 32 connected to the motor shaft of the motor 19, a ring gear 33 meshing with the motor pinion 32, and a rack pinion 35 fixed to the ring gear 33 and meshing with the rack gear 12a. Have been. Therefore, when the motor shaft of the motor 19 rotates, the rotation is transmitted to the motor pinion 32 → the ring gear 33 → the rack pinion 35, and the rack shaft 12 moves in the axial direction due to the engagement between the rotating rack pinion 35 and the rack gear 12a. The rear wheels 9, 10 are steered. This rear wheel 9,10
Is proportional to the amount of movement of the rack shaft 12, that is, the amount of rotation of the motor shaft.

The rack pinion 35 is provided with a rear steering angle main sensor 24 having a potentiometer structure for detecting a rear wheel steering angle based on the rotation amount.

The fail-safe solenoid 20 includes:
The lock pin 20a is provided so as to be able to advance and retreat, and when a failure occurs in the electronic control system or the like, the lock pin 20a is fitted into a lock groove 12b formed in the rack shaft 12 so that the rack shaft 12 and the rear wheels 9, 10 are moved. It is fixed at a position to maintain the neutral steering angle position.

The operation will be described.

[Rear Wheel Steering Angle Control Operation] FIG. 4 is a flowchart showing the flow of the rear wheel steering angle control operation performed by the controller 26. Each step will be described below.

In step 40, the vehicle speed V, the steering angle θ, the actual yaw rate ψ'O, and the rear steering angle main sensor value δ
rS is read.

Here, the actual yaw rate ψ′O is calculated from the yaw rate sensor value Vψ ′ from the yaw rate sensor 25 and the latest yaw rate zero correction memory value Vψ′0m obtained by the detected yaw rate correction processing of FIG. Is done.

In step 41, a target yaw rate steady value ψ'MO as a yaw rate value per unit steering angle is calculated for each vehicle speed based on the vehicle speed V and the steering angle θ.

In step 42, it is determined whether or not the value obtained by multiplying the steering angle θ by the steering angle differential value θ ′ is 0 or more.

That is, if θ · θ ′ ≧ 0, it is determined that the direction of change in the steering angle is the turning-up direction, and if θ · θ ′ <0, the direction of change in the steering angle is to be returned. The direction is determined.

In step 43, θ · θ ′ ≧ 0, and
When it is determined that the steering angle change direction is the turning direction, the first-order lag time constant TO is set to a low value TOp (<TOm) for obtaining the turning property.

In step 44, θ · θ ′ <0, and
When it is determined that the steering steering angle change direction is the return direction, the first-order lag time constant TO is set to TOm (> TOp) with a high value for obtaining convergence.

In step 45, the target yaw rate ψ'M is calculated by the following equation using the target yaw rate steady-state value ψ'MO and the first-order lag time constant TO set in step 43 or step 44.

Ψ'M = ψ'MO / (1 + TO · S) S;
In the Laplace operator step 46, a deviation ε between the target yaw rate ψ′M and the actual yaw rate ψ′O is calculated.

In step 47, the deviation ε is determined according to the vehicle speed V.
Are set on the basis of the map.

In step 48, the deviation ε and the proportional term K
The feedback rear wheel steering angle δrF / B is calculated by the following equation based on P and the differential term KD.

At step 49, the feedback rear wheel steering angle δrF / B at step 48 is converted into a motor rotation target value THi.

In step 50, the rear steering angle main sensor value δrS is converted to a motor rotation actual value THNO.

In step 51, the motor control current IM is calculated from the motor rotation target value THi and the motor rotation actual value THNO.

In step 52, PW is set according to the output command.
The duty ratio of M is controlled, and a motor control current IM is output.

[Detected Yaw Rate Correction Processing] FIG. 5 is a flowchart showing the flow of the detected yaw rate correction processing operation performed by the controller 26. Each step will be described below.

In step 60, the vehicle speed V, the steering angle θ, the yaw rate sensor value Vψ ', and the latest yaw rate zero correction memory value Vψ'0m are read.

In step 61, the target yaw rate ψ'M is calculated based on the vehicle speed V and the steering angle θ in step 41 of FIG.
To 45 (corresponding to target yaw rate calculating means e).

In step 62, it is determined whether the vehicle is in a running state suitable for performing the detected yaw rate correction (corresponding to the vehicle running state determining means d).

This determination is made when the vehicle speed V is V1 ≦ V ≦ V2
(For example, V1 = 40 km / h, V2 = 160 km / h), and ψ′MV · A (for example, A is equivalent to 0.5 G)
Is determined based on the condition that

In step 63, the yaw rate sensor value V
The actual yaw rate ψ'O is calculated from ψ 'and the latest yaw rate zero correction memory value Vψ'0m (corresponding to the actual yaw rate calculating means f).

In step 64, the yaw rate deviation Δψ 'is calculated from the difference between the target yaw rate ψ'M and the actual yaw rate ψ'O (corresponding to the yaw rate deviation calculating means g).

In step 65, the yaw rate deviation Δψ ′ calculated in step 64 is sequentially stored.

In step 66, the elapsed time from the start of the memory in step 65 is the set time (for example, 10 seconds).
ec) It is determined whether or not the time has elapsed.

In step 67, when the running condition in step 62 is not satisfied, the previously stored yaw rate deviation Δ さ れ 'is cleared.

In step 68, when the time condition of step 66 is satisfied, the average value of the yaw rate deviations Δψ ′ of the plurality of yaw rate deviations Δψ ′ stored during the set time is calculated.
ψ'ave is calculated (corresponding to the yaw rate deviation average value calculating means h).

However, when Δψ'ave> 8 ° / s, Δψ'a
ve = 8 ° / s, Δψ'a when Δψ'ave <−8 ° / s
The average value of the yaw rate deviation Δ is set so that ve = −8 ° / s.
Determine the upper and lower limits of ψ'ave.

In step 69, it is determined whether the average value of the yaw rate deviation Δψ'ave is a positive value, a negative value, or 0.

In step 70, when it is determined that Δψ'ave> 0, the yaw rate zero correction value Vψ'0 is changed to the next 1
0 seconds, every 2 seconds, for example, 0.005
(V) Increase by one. However, the amount of increase in the yaw rate zero correction value Vψ'0 is, for example, the average yaw rate deviation value Δ
5% or less of ψ'ave.

In step 71, when it is determined that Δψ'ave = 0, the yaw rate zero correction value Vψ'0 is changed to the next 1
It is left as it is for 0 sec.

In step 72, when it is determined that Δψ'ave <0, the yaw rate zero correction value Vψ'0 is changed to the next 1
0 seconds, every 2 seconds, for example, 0.005
(V) Decrease by one. However, the amount of decrease in the yaw rate zero correction value Vψ'0 is, for example, the average yaw rate deviation value Δ
5% or more of ψ'ave.

Steps 69 to 72 correspond to the yaw rate zero correction value setting means i.

In step 73, steps 70, 71,
72, the yaw rate zero correction value V
ψ′0 is rewritten and stored as the latest yaw rate zero correction memory value Vψ′0m (corresponding to the yaw rate zero correction value updating means j).

[Detected Yaw Rate Correction Operation] First, as shown in FIG. 6, when the yaw rate sensor value Vψ ′ from the yaw rate sensor 25 is −40 ° / s, 0.5 volt, 0
It is detected by a voltage value such as 2.5 volts at ° / s and 4.5 volts at 40 ° / s.

If the yaw rate sensor value Vψ ′ is offset due to temperature drift during vehicle running, fluctuations in the sensor voltage, etc., for example, the yaw rate sensor value Vψ ′ is not equal to 2. When the output is 5 volts, the yaw rate is detected to be zero, or conversely, when the yaw rate is zero, it is detected that the yaw rate is occurring.

Therefore, when the yaw rate feedback control shown in FIG. 4 is performed without directly correcting the detected yaw rate and using the yaw rate sensor value Vψ 'as it is as an actual yaw rate, the accuracy of the rear wheel steering angle control is directly affected. Therefore, the intended turning performance cannot be obtained by the rear wheel steering angle control.

As described above, when the zero point shift of the yaw rate sensor 25 occurs, it is necessary to correct the zero point shift. Must be done during. However, when the vehicle is running in which the yaw rate sensor value Vψ 'constantly changes due to a turning situation or the like, even if the yaw rate sensor value Vψ' is monitored, it cannot be corrected because there is no reference. However, when the vehicle stops, the occurrence of yaw rate is zero, and this can be used as a correction reference.

Therefore, despite performing the yaw rate feedback control to make the actual yaw rate ψ'O coincide with the target yaw rate ψ'M, the target yaw rate ψ'M
When the state where the yaw rate deviation Δψ 'of the actual yaw rate ψ'O continues to be positive, it is estimated that the yaw rate zero point is offset to the negative side, and when the state where the yaw rate deviation Δψ' continues to be negative, It is estimated that the yaw rate zero point is offset to the positive side.

Focusing on the point based on the yaw rate deviation Δψ ′, as shown in FIG. 5, when the vehicle continues a predetermined running state for a set time, the target yaw rate ψ′M and the actual yaw rate ψ′O The yaw rate deviation average value Δψ'ave is calculated, and when the yaw rate deviation average value Δψ'ave is positive, the correction is made to increase the yaw rate zero correction value Vψ'0. When the yaw rate deviation average value Δψ'ave is negative, the yaw rate deviation value Δψ'ave is negative. A correction is made to reduce the zero correction value Vψ'0, and the corrected value is updated as the latest yaw rate zero correction memory value Vψ'0m.

By this detected yaw rate correction processing, the yaw rate sensor 25
When the zero point deviation occurs, the zero point deviation can be corrected immediately in response, whereby a high rear wheel steering angle control accuracy that can always obtain the target turning performance can be secured.

The effect will be described.

(1) In the yaw rate correction device detected by the yaw rate sensor 25 mounted on the vehicle, when the vehicle continues a predetermined running state for a set time, the target yaw rate ψ'M and the actual yaw rate ψ'O during that time. Is calculated, and when the average yaw rate deviation Δ 算出 'ave is positive, the yaw rate zero correction value V
Correction to increase 増 加 '0, and average yaw rate deviation Δ
When ψ'ave is negative, the yaw rate zero correction value Vψ'0 is corrected to be reduced, and the corrected value is updated as the latest yaw rate zero correction memory value Vψ'0m. When the zero point shift of the yaw rate sensor occurs, the correction of the zero point shift can be achieved immediately in response.

(2) When the average value of the yaw rate deviation Δψ'ave is determined to be a positive value or a negative value, the yaw rate zero correction value Vψ'0 is corrected little by little every 2 seconds within the next 10 seconds. Therefore, a change in vehicle behavior due to the execution of the yaw rate zero correction can be suppressed to a small value.

(3) The amount of increase and decrease of the yaw rate zero correction value Vψ'0 in one yaw rate zero correction is limited to a predetermined ratio or less with respect to the average yaw rate deviation value Δψ'ave. Therefore, in the case of a zero point shift of the yaw rate sensor 25 due to straight running on an inclined road surface, the correction amount of the zero point shift is suppressed to be small, and the rear wheel steering angle control accuracy during the subsequent normal turning is ensured. Can be.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to the embodiment, and even if there are changes and additions without departing from the gist of the invention, the invention is included in the invention. It is.

For example, in the embodiment, an example is shown in which the detected yaw rate correction device is applied to a four-wheel steering vehicle. However, an on-vehicle control system that controls the yaw rate of the vehicle by distributing braking force or driving force between left and right wheels, The present invention can be applied to those using an actual yaw rate as control information.

In the embodiment, the target yaw rate, actual yaw rate,
Although the example of calculating the yaw rate deviation has been described, the calculation result obtained in the rear wheel steering angle control processing shown in FIG. 4 may be taken in to perform the detected yaw rate correction processing.

[0071]

As described above, according to the present invention, the vehicle is set in the detected yaw rate correction device which is detected by the yaw rate sensor mounted on the vehicle .
When the vehicle travels substantially straight ahead at the vehicle speed within the vehicle speed range for the set time, the average value of the yaw rate deviation between the target yaw rate and the actual yaw rate during that time is calculated, and when this yaw rate deviation average value is positive, the yaw rate zero correction value is increased. When the average value of the yaw rate deviation is negative, the yaw rate zero correction value is reduced and the yaw rate zero correction value is set by setting the yaw rate zero correction value. When the zero point shift of the sensor occurs, the effect is obtained that the correction of the zero point shift can be achieved immediately in response.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims showing a detected yaw rate correction device of the present invention.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which the detected yaw rate correction device of the embodiment is applied.

FIG. 3 is a cross-sectional view of the electric steering device of the embodiment device.

FIG. 4 is a flowchart illustrating a flow of a rear wheel steering angle control operation performed by a controller of the embodiment device.

FIG. 5 is a flowchart illustrating a flow of a detected yaw rate correction processing operation performed by a controller of the embodiment device.

FIG. 6 is a graph showing sensor output characteristics from a yaw rate sensor.

[Explanation of symbols]

 a yaw rate sensor b vehicle speed detecting means c steering steering angle detecting means d running state determining means e target yaw rate calculating means f actual yaw rate calculating means g yaw rate deviation calculating means h yaw rate deviation average value calculating means i yaw rate zero correction value setting means j yaw rate zero Correction value update means

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI B62D 113: 00 137: 00 (56) References JP-A-4-231265 (JP, A) JP-A-62-261575 (JP, A) JP-A-5-616 (JP, A) JP-A-6-174741 (JP, A) JP-A-5-278626 (JP, A) JP-A-6-87460 (JP, A) JP-A-4 −2558 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 15/00 G01P 15/14 B62D 6/00 B62D 101: 00 B62D 113: 00 B62D 137: 00 G01B 21 / twenty two

Claims (1)

(57) [Claims] 1. A yaw rate sensor for detecting a yaw rate applied to a vehicle, a vehicle speed detecting means for detecting a vehicle speed, a steering angle detecting means for detecting a steering angle, and a vehicle speed within a set vehicle speed range. Traveling state determining means for determining that the vehicle is traveling straight ahead ; target yaw rate calculating means for calculating a target yaw rate according to the vehicle speed and the steering angle; and an actual yaw rate used for control based on the yaw rate sensor value and the latest yaw rate zero correction value. Actual yaw rate calculating means for calculating the yaw rate deviation between the target yaw rate and the actual yaw rate, and, if the vehicle has been traveling substantially straight ahead at a vehicle speed within the set vehicle speed range for a set time, during that time, Means for calculating an average value of the yaw rate deviation of the yaw rate deviation; When the average deviation is positive, the yaw rate zero correction value is increased.When the average yaw rate deviation value is negative, the yaw rate zero correction value is decreased and the yaw rate zero correction value is set. Means for updating the set yaw rate zero correction value as the latest yaw rate zero correction value, and a yaw rate zero correction value updating means for updating the detected yaw rate zero correction value.