JPH072131A - Method for adjusting yaw rate signal - Google Patents

Abstract

PURPOSE:To simply and appropriately adjust the deviation from the mounting error or the like of a sensor by obtaining the corrective quantity through addition/subtraction when the signal value of the yaw rate sensor is deviated from the neutral zero, and outputting the yaw rate corresponding to the rotational angular velocity of a vehicle by correction to be increased/decreased. CONSTITUTION:In a vehicle provided with a yaw rate sensor, a judgement whether or not the vehicle is stably traveling straight by the sensor signal and the vehicle speed is made, and when the vehicle is traveling straight, the value of the sensor signal is judged, and when the yaw rate value gamma is deviated to the right relative to the neutral zero, subtraction by the specified amount DELTAgamma is repeated until the deviation becomes zero, and the corrective quantity gamma' is calculated by the specified amount DELTAgammaand the number of subtraction. On the other hand, when the yaw rate is deviated to the left, addition by the specified amount DELTAgamma is repeated to calculate the corrective quantity gamma' in a similar manner, and the corrective quantity gamma' corresponding to the deviation of the mounting error of the sensor and the aging change or the like is calculated. Then, the yaw rate gamma is obtained by uniformly adding the corrective quantity gamma' to the signal value of the sensor gamma0. This constitution allows the correction of the yaw rate value gamma to be a correct one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a signal mounting error of a yaw rate sensor used in a four-wheel steering system (4WS) of a vehicle such as an automobile.

[0002]

2. Description of the Related Art In recent years, a yaw rate sensor for directly detecting a yaw rate (rotational angular velocity) of a yawing motion of a vehicle with high accuracy has been developed. With this yaw rate sensor, not only in the case of steering the front wheels, but also changes in the behavior of the vehicle due to disturbances such as road surface conditions and side winds can be promptly detected. Therefore, for example, it has been proposed that the yaw rate of a yaw rate sensor is positively used in a four-wheel steering system, for example, the rear wheel steering control is performed by antiphase steering angle proportional control and yaw rate feedback control.

Here, when the yaw rate sensor is attached to an individual vehicle, the direction and orientation of the sensor actually have slight variations, and the balance of the load of the entire vehicle also differs for each vehicle. By the way, since the yaw rate sensor detects the rotational angular velocity associated with the turning of the vehicle, the above-mentioned various variations have a relatively large influence, and a deviation such as an attachment error is likely to occur in the sensor signal. Therefore, each vehicle is required to be adjusted so as to eliminate the deviation of the signal of the yaw rate sensor.

Conventionally, regarding the adjustment of the signal of the yaw rate sensor, there is a prior art disclosed in, for example, Japanese Patent Laid-Open No. 2-249765. In this prior art, it is shown that when the zero value of the sensor changes due to environmental changes, changes over time, etc., the zero estimated value of the sensor is updated, and the yaw rate is accurately detected based on this updated zero estimated value. ing.

[0005]

By the way, the above-mentioned prior art is an adjusting method when the zero value of the sensor changes due to aging or the like, and therefore the zero value itself is not used when the sensor is attached. It cannot be applied to adjustments that include errors from the initial state.

In view of the above points, the present invention has an object to easily and appropriately adjust the deviation of the yaw rate sensor due to an attachment error or the like.

[0007]

In order to achieve this object, the present invention, in a vehicle equipped with a yaw rate sensor for detecting the rotational angular velocity of the vehicle, determines whether or not the vehicle is traveling straight and stable according to the sensor signal and the vehicle speed. When traveling straight ahead, the value of the sensor signal is judged, and if the sensor signal value deviates from neutral zero, it is added and subtracted by a predetermined amount until the sensor signal value becomes zero at predetermined time intervals. A correction amount is obtained from the number of additions and subtractions, and the signal of the yaw rate sensor is uniformly increased and decreased by the correction amount to output a yaw rate according to the rotational angular velocity of the vehicle.

[0008]

According to the present invention based on the above method, when the vehicle is traveling straight and stable at a medium speed or higher, the deviation of the signal value of the yaw rate sensor is judged, and the deviation occurs due to an installation error, a change with time, or the like. Is a zero adjustment by addition and subtraction of a predetermined amount to obtain a correction amount according to the deviation. Then, the yaw rate sensor signal is uniformly increased / decreased by this correction amount, so that the yaw rate according to the rotational angular velocity when the vehicle behavior changes is always accurately output with respect to the deviation of the sensor signal, and the yaw rate detection accuracy is improved. improves.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, an outline of the vehicle drive system and the four-wheel steering system will be described. First, in the vehicle 1, the engine 2 is connected to the clutch 3 and the transmission 4, and the output side of the transmission 4 is configured to be transmitted to the front wheels 7 via the front differential 5, the axle 6, and the like. The output side of the transmission 4 is also configured to be transmitted to the rear wheel 11 via the propeller shaft 8, the rear differential 9, the axle 10, and the like.
Four-wheel drive runs. Further, it has a front wheel steering device 20 and a rear wheel steering device 30 as a four-wheel steering system.

In the front wheel steering system 20, a steering shaft 22 having a handle 21 has a hydraulic control valve 2.
3 is connected to the front wheels 7 via the power cylinder 24, the rod 25, and the knuckle arm 26, and the front wheels 7 are manually steered by operating the steering wheel. Rear wheel steering device 3
Reference numeral 0 denotes an electric motor 31, which is connected to an eccentric shaft 33 via a worm gear 32 for reduction, and which is connected to the eccentric shaft 33 via a link 34, a lever 35, a knuckle arm 36, and the like. It is connected to the wheels 11 and is configured to automatically steer the rear wheels 11 by driving a motor. In addition, when the motor power is turned off during an abnormality, the worm gear 32
Due to the non-reciprocity, the rear wheel 11 is maintained in a predetermined steering angle state with respect to the road surface external force.

The control system includes a steering wheel angle sensor 40 for detecting the steering wheel angle θ, a steering wheel angular velocity sensor 41 for detecting the steering wheel angular velocity dθ, a rear wheel steering angle sensor 42 for detecting the rear wheel steering angle Er, and a rear wheel steering angular velocity ωr. It has a rear wheel steering angular velocity sensor 43 for detecting. Further, it has a yaw rate sensor 44 for detecting a yaw rate γ of a rotational angular velocity according to the turning state of the vehicle. Further, in order to calculate the control vehicle speed V, a front left wheel speed sensor 45 for detecting the front left wheel speed Nfr and a rear right wheel speed sensor 46 for detecting the rear right wheel speed Nrl are provided, and these sensor signals are used as the control unit 50. Is input to the motor 31 to be electrically processed, and a motor signal corresponding to the steering direction of the rear wheels, the steering angle, and the steering angular velocity is output to the motor 31.

The control unit 50 has a vehicle speed calculator 51 to which the front left wheel speed Nfl and the rear right wheel speed Nrr are input, and calculates the control vehicle speed V by V = (Nfl + Nrr) / 2. The vehicle speed V is input to the steering wheel angle coefficient setting unit 52, the steering wheel angle coefficient Kθ is set as a function of the vehicle speed V, and simultaneously input to the yaw rate coefficient setting unit 53, and the yaw rate coefficient Kγ is similarly set as a function of the vehicle speed V. To do. The steering wheel angle coefficient Kθ has a reverse phase over the entire vehicle speed as shown in the steering angle gain map of FIG. 3A, and has a characteristic that the absolute value of the value decreases and decreases as the vehicle speed V decreases in the low and medium speed range. The yaw rate coefficient Kγ is in-phase throughout the vehicle speed as shown in the yaw rate gain map in the same figure, and has a characteristic that it gradually increases as the vehicle speed V increases. Therefore, both coefficients Kθ and Kγ are set with reference to this map.

The steering wheel angle θ and the steering wheel angle coefficient Kθ are input to the multiplication unit 54 to calculate a multiplication value Kθ · θ of both, and the yaw rate γ and the yaw rate coefficient Kγ are also input to the multiplication unit 55 to be both multiplication values Kγ · θ. Calculate γ. These two multiplication values Kθ · θ and Kγ · γ are input to the target rear wheel steering angle calculation unit 56, and the target rear wheel steering angle ET is calculated by ET = Kγ · γ + Kθ · θ. Therefore, the term of Kγ · γ is a stabilizing element that keeps the vehicle on the stable side, and the term of Kθ · θ is a turning element that promotes turning.

Here, the yaw rate γ is generated in accordance with the turning state of the vehicle due to turning or disturbance in the entire vehicle speed, and the coefficient Kγ is a characteristic of the increasing function of the vehicle speed V. Therefore, the value of Kγ · γ becomes larger as the vehicle speed V increases. growing. The steering wheel angle θ is generally very small in the medium-high speed range, and therefore the value of Kθ · θ becomes close to zero even if the coefficient Kθ is small in the opposite phase direction. Therefore, when the yaw rate γ is detected in the medium-high speed range, the target rear wheel steering angle ET is in the in-phase direction due to the value of Kγ · γ, and stability-oriented control is performed. In the low speed range where the steering wheel angle θ is large, the turning property is controlled with emphasis on the value of Kθ · θ in the opposite phase direction, and at this time, the yaw rate γ is corrected to the stable side by the value of Kγ · γ in the in-phase direction.

The target rear wheel steering angle ET and the rear wheel steering angle Er are input to the deviation calculating section 57 to calculate the deviation ED by ED = ET-Er. This deviation ED is the target rear wheel turning speed setting unit 5
8, and the target rear wheel turning speed ωo corresponding to the deviation ED is set by the map of FIG. 3 (b). Further, the target rear wheel turning speed ωo and the rear wheel steering angular speed ωr are input to the speed difference calculation unit 59, and the speed difference ωd is calculated by ωd = ωo−ωr. Then, the speed difference ωd is input to the control amount setting unit 60,
The control amount Kp of the proportional component is set according to the speed difference ωd, and the driving unit 61 supplies the forward or reverse motor current I according to the control amount Kp to the motor 31.

The adjustment of the yaw rate sensor signal with respect to the mounting error in the control system will be described. First,
It has a correction amount calculation unit 62 to which the sensor signal γo and the vehicle speed V are input, and determines stable straight traveling when the sensor signal γo is substantially neutral and the steering wheel operation is at a medium speed or higher. Then, in the case of straight traveling, a deviation state of the corrected yaw rate value γ with respect to neutral zero is determined, and if it is deviated to the left or right, a correction amount γ'according to the deviation is calculated. Further, a correction unit 63 is provided on the signal input side of the yaw rate sensor 44,
The yaw rate γ according to the rotational angular velocity of the vehicle is output by adding and subtracting the correction amount γ ′ to the sensor signal value γo and performing uniform correction.

Next, the operation of this embodiment will be described. First, the engine 2 is operated, and the transmission power of the transmission 4 is transmitted to the front wheels 7 and the rear wheels 11 by the drive system, so that the vehicle 1 moves
Drive with wheel drive. At this time, when the driver operates the steering wheel 21, the front wheel steering device 20 steers the front wheels 7 to manually steer the vehicle, and the rear wheel steering device 30 drives the vehicle in a traveling state.
The rear wheel 11 is automatically steered according to the steering wheel operation and the behavior of the vehicle.

At this time, the flow chart of FIG. 4 is executed to adjust the signal of the yaw rate sensor 44. That is,
In step S1 of the correction amount calculation routine of (a), the sensor signal value γo and the vehicle speed V are read, and in step S2, the AD conversion value γa as the sensor signal is set to a set value γs (for example, 3 deg / s).
). If it is substantially neutral below the set value γs, the process proceeds to step S3, and the vehicle speed V is set to the set value Vs (40
(km / h) to judge stable straight running at medium speeds or higher. In the case of this traveling condition, the routine proceeds to step S5 every predetermined time (for example, 4 seconds) in step S4,
Check the corrected yaw rate value γ.

Therefore, when the corrected yaw rate value γ deviates to the right as shown in FIG. 5 with respect to neutral zero, a predetermined amount Δγ (0.16 deg / s or less) is added until it becomes zero in step S6. Subtraction is performed, and in step S7, the correction amount γ'is calculated from the predetermined amount Δγ and the number of times C of subtraction. If the corrected yaw rate value γ is shifted to the left, the process proceeds from step S5 to step S8, in which a predetermined amount Δγ is added until it reaches zero, and in step S7 a correction amount γ ′ is calculated in the same manner. Further, when the corrected yaw rate value γ is zero, C = C is set in step S9, and the correction amount γ ′ is held. In this way, the correction amount γ'according to a deviation such as an attachment error of the yaw rate sensor 44 or a change with time is calculated.

In the sensor signal adjustment routine of FIG. 4B, the sensor signal value γo is read in step S10, and the correction amount γ'is uniformly added to the sensor signal value γo in step S11 to obtain the yaw rate γ. Therefore, when the sensor signal value γo of the yaw rate sensor 44 is always deviated to the left or right, the value of the yaw rate γ is corrected to be accurate. Then, in step S12, this yaw rate γ
By outputting, the accurate yaw rate γ corresponding to the rotational angular velocity when the behavior of the vehicle changes can be obtained.

Next, the rear wheel steering control will be described.
Depending on the vehicle speed V, the steering wheel angle coefficient Kθ and the yaw rate coefficient K
γ is set, and the target rear wheel steering angle ET is calculated from the steering wheel angle θ and its coefficient Kθ, and the yaw rate γ and its coefficient Kγ.
Then, a deviation ED between the target rear wheel steering angle ET and the rear wheel steering angle Er is calculated, a target rear wheel steering speed ωo is set according to the deviation ED, and a target rear wheel steering speed ωo and a rear wheel steering angular speed ωr are set. The speed difference ΔNωd is calculated, and the control amount K corresponding to the speed difference ΔNωd is calculated.
The motor current I of p is output to drive the motor 31. Therefore, in the rear wheel steering device 30, the worm gear 32 and the eccentric shaft 33 are rotated by the motor 31, the link 34 and the lever 35 are swung left and right, and the rear wheel 11 is automatically steered.
In this case, the rear wheels 11 are in-phase or anti-phase, and are subjected to anti-phase steering angle proportional control and yaw rate feedback control so as to obtain a desired steering angle or steering angular velocity.

Therefore, when the steering wheel 21 is greatly turned at a low speed such as starting, the target rear wheel steering angle ET becomes negative due to the value of Kθ · θ, and the rear wheel 11 is steered in a small turn by reverse-phase steering.
At this time, if the vehicle makes a sharp turn or the yaw rate γ increases due to the vehicle turning due to the road surface μ, the value of Kγ · γ causes the rear wheel 1
The reverse-phase steering of 1 is reduced and corrected, and the behavior of the vehicle is stabilized. When turning at medium and high speeds, the target rear wheel steering angle ET is mainly K
The value of γ · γ becomes positive, and the rear wheels 11 are in-phase steered. Therefore, the cornering force Fcr of the rear wheel 11 increases, and the cornering forces Fcf, Fcr of the front and rear wheels 7, 11 are balanced with a margin with respect to the centrifugal force Fg. Therefore, the vehicle can travel on a predetermined turning circle in a stable posture, and the turning stability is improved.

When the vehicle suddenly turns to the left or right due to a disturbance such as a crosswind, the yaw rate γ changes greatly, and this behavior change of the vehicle 1 is quickly detected. Then, the rear wheel 11 is steered so as to maintain the in-phase state regardless of the turning of the vehicle 1 by the value of Kγ · γ. For this reason, the vehicle 1 is in a stable opposite posture so as not to be swept by the side wind,
Moreover, it smoothly returns to the original course.

Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be widely applied to various sensors such as a longitudinal acceleration sensor and a lateral acceleration sensor.

[0025]

As described above, according to the present invention,
Since the signal of the yaw rate sensor that is mounted on the vehicle and detects the rotational angular velocity is adjusted to zero for deviations such as mounting errors, an accurate yaw rate can be obtained according to the rotational angular velocity, and the yaw rate detection accuracy is improved. To do. This method is simple and highly accurate because it is a method of determining stable straight running based on the sensor signal and the vehicle speed, obtaining a correction amount according to the deviation of the sensor signal, and uniformly correcting the sensor signal with this correction amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system suitable for a method for adjusting a yaw rate signal according to the present invention.

FIG. 2 is a configuration diagram showing an outline of a vehicle drive system and a four-wheel steering system.

FIG. 3 is a diagram showing a map of a steering wheel angle coefficient, a yaw rate coefficient, and a target rear wheel turning speed.

FIG. 4 is a flowchart showing yaw rate signal adjustment control.

FIG. 5 is a diagram illustrating a yaw rate signal adjustment state.

[Explanation of symbols]

 1 vehicle 44 yaw rate sensor 50 control unit 51 vehicle speed calculation unit 62 correction amount calculation unit 63 correction unit

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Claims (1)

[Claims] 1. In a vehicle equipped with a yaw rate sensor for detecting a rotational angular velocity of the vehicle, it is determined whether or not the vehicle is traveling in a straight line depending on the sensor signal and the vehicle speed. If the signal value deviates from the neutral zero, add / subtract by a predetermined amount until the sensor signal value becomes zero at predetermined time intervals, and obtain the correction amount by the predetermined amount and the number of additions / subtractions. A method for adjusting a yaw rate signal, which comprises uniformly increasing and decreasing a signal from a yaw rate sensor to output a yaw rate according to a rotational angular velocity of a vehicle.