JP3165045B2 - Angular velocity data 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 an attitude angle sensor technique for use in, for example, an attitude control of an automobile, and more particularly to an angular velocity data correction device for correctly correcting output information of an attitude angle sensor using an gyro.

[0002]

2. Description of the Related Art Attitude control technology of vehicles has attracted attention as a technology for making driving more secure and comfortable. VSC (Vehicle stability Control) is one of them. The VSC automatically detects a state in which the vehicle attempts to turn inside or outside the driver's intended angle, such as when turning a curve on a road, using a posture angle sensor. This is a technique that performs appropriate braking control and engine output control for each to ensure vehicle stability. When performing such control, what is indispensable is posture angle change information of the vehicle obtained from the posture angle sensor, in particular, information representing a change in rotational motion.

Conventionally, there have been rotation sensors and angle sensors as attitude angle sensors for detecting changes in the rotation motion of a moving body such as an automobile. Such rotation sensors and angle sensors measure changes in the rotation angle. The rotation axis that serves as a reference is fixed, and the motion generated around the fixed rotation axis is detected.Therefore, it is not always necessary to detect a change in the rotation motion of a vehicle whose rotation axis is not fixed, such as an automobile. There was an unsuitable problem. Therefore, recently, an attempt has been made to configure an attitude angle sensor using an gyro suitable for detecting a rotational motion when the rotation axis is not fixed, for example, a vibration type gyro. A vibration type gyro is a device that outputs a signal proportional to an angular velocity by using a Coriolis force generated in a direction perpendicular to a vibration direction when a rotational angular velocity is applied to a moving body that is vibrating, that is, an automobile. . That is, this output signal is a signal representing the rotational momentum of the vehicle.

[0004]

As described above, the vibratory gyro has a great advantage in that it can detect a rotational motion even if the rotating shaft is not fixed, and is compact and excellent in mass productivity. Even in the state, there is a problem that drift occurs due to vibration and the drift is accumulated. FIG. 12 shows how the drift component amounts are accumulated with time. As a result, when the accumulated value is increased to some extent, a signal indicating that the vehicle is rotating is output as a detection result although the vehicle is not actually rotating. That is, the posture angle is erroneously recognized. Also,
The vibrating gyro also has a problem of lack of stability due to temperature change. In particular, when a car air conditioner used during a hot summer in the middle of summer or a severe cold in the middle of winter causes a sudden temperature change in the vehicle, the temperature change greatly changes the detection result of the rotational momentum.

[0005] Such an error in the detection result of the rotational momentum caused by drift, noise, or temperature change is fatal in realizing a system such as a VSC that emphasizes safety and comfort during driving. Therefore, improvement was desired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an angular velocity data correction device capable of correcting output data of an angular velocity meter such as a vibrating gyroscope so that the detection error of the rotational momentum can be made as close to zero as possible. is there.

[0007]

An angular velocity data correction device according to the present invention comprises: a data conversion means for converting output data of an angular velocity meter into angular velocity data of a predetermined format; extracting a fluctuation component of the angular velocity data; State detecting means for detecting whether the gyro is in motion or in a stationary state based on the accumulated value per unit time, and a drift component included in the angular velocity data at the time of quiescent every time the state detecting means detects a stationary state A first calculating means for calculating the amount, and a second calculating means for storing the calculated drift component amount in an updatable manner and sequentially removing the stored drift component amount from the angular velocity data to calculate correction data. , Is characterized by having.

The state detecting means may include, for example, a high-pass filter that passes a signal having a time constant higher than a time constant of a drift component generated in the gyro, and the angular velocity data that has passed through the high-pass filter to the unit. An integrator that performs time integration, and is configured to determine a stationary state when the output of the integrator is lower than a threshold value.

According to another aspect of the present invention, there is provided an angular velocity data correcting apparatus comprising: a data conversion means for converting output data of an angular velocity meter into angular velocity data of a predetermined format; and a drift component generated in at least the angular velocity meter among fluctuation components of the angular velocity data. A high-pass filter that outputs correction data by passing only a fluctuation component having a time constant higher than the time constant of, a fluctuation tendency detection unit that detects whether the fluctuation tendency of the angular velocity data is high frequency or low frequency, Filter control means for dynamically changing the time constant of the high-pass filter in accordance with the detected fluctuation tendency.

[0010] More preferably, a temperature sensor for detecting an ambient temperature of the gyro and a temperature coefficient value for correcting the angular velocity data or the correction data in accordance with the temperature detected by the temperature sensor are calculated. And an arithmetic means are provided to constitute an angular velocity data correction device. When the fluctuation of the correction data is within a region previously set as a dead zone of the gyro, a fluctuation removing means for removing the fluctuation may be provided.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the present invention is applied to an attitude angle sensor mounted on an automobile will be described in detail. In the following description, for convenience, data per unit time obtained by digitally converting an analog output from the gyro will be referred to as angular velocity data.

(First Embodiment) FIG. 1 is a diagram showing a basic configuration of a posture angle sensor according to a first embodiment. This attitude angle sensor includes a yaw rate gyro 1 which is an example of an angular velocity meter, and an angular velocity data correction device 2. The yaw rate gyro 1 is the above-mentioned vibration type gyro, and outputs a signal proportional to the angular velocity around the rotation axis in the yaw direction, specifically, an analog voltage.

The angular velocity data correction device 2 is, for example, a one-chip board, and is configured to be detachably attached to the same type of yaw rate gyro or another type of gyro sensor. On the board, there is provided an A for converting an analog voltage input from the yaw rate gyro 1 into digital data.
A / D converter 21, a counter 22, which measures the unit time from the A / D converter 21, for example, the number of data per second (number of pulses: angular velocity data), CPU23, CPU23
ROM2 that stores a program for realizing the angular velocity data correction function and necessary data (hereinafter, referred to as a program, etc.)
4. EEPR storing a plurality of adjustment parameter tables for performing scale conversion and the like for each yaw rate gyro
OM25, analog output of corrected angular velocity data A
A / D converter 26 and a temperature sensor 27 for sensing the ambient temperature of the attitude angle sensor are attached.

FIG. 2 shows an example of various adjustment parameter tables stored in the EEPROM 25. FIG. 2A is a gain table showing the correspondence between the value measured by the counter 22 (the number of pulses [number]) and the rotational momentum [degree / sec], and is prepared according to the accuracy of the required measurement result. . FIG. 2B is a specification error table for correcting a specification error specific to the yaw rate sensor. For example, an actual measurement value of a correspondence relationship between the measurement value and the rotational momentum [degree / sec];
Alternatively, it is a collection of correction coefficients. FIG. 2 (c) shows the measured value and the rotational momentum [degree /
5] is a temperature correction table obtained by actually measuring a shift amount of a correspondence relationship with [sec] or a correction coefficient.

FIG. 3 is a block diagram of the functional blocks realized by the CPU 23 using the programs and the like stored in the EPROM 24. In FIG. 3, for example, when the attitude angle sensor is in a stationary state, the initial correction unit 31 monitors the presence or absence of an error in the measurement value output from the counter 22, and if there is an error, corrects the measurement value by the amount of the error. Is what you do. Specifically, the presence or absence of an error and the error value are calculated by accumulating the measured value for a certain period of time during the reset process, calculating an average value, determining whether the average value is other than 0 degrees, and how many pulses are shifted. Is determined by referring to the gain table in the EEPROM 25. FIG. 4 is an explanatory diagram of the processing contents in the initial correction processing unit 31. First, an error value and an error direction are determined, and the measured value is corrected in the opposite direction to the error direction so as to approach the set value. I do. By this processing, the subsequent measurement starts from 0 [degree / sec], and the detection or correction accuracy can be improved.

The scale conversion processing section 32 includes an initial correction section 3
The measurement value of the counter 22 after 1 is converted into an engineering value, for example, fixed-point data in a format that can be processed by the CPU 23 with reference to the gain table and the specification error correction table in the EEPROM 25. Specifically, the fixed-point data is data having a 32-bit intermediate bit as a decimal point position, and represents one-second rotational momentum. The correction of the measurement error of the yaw rate sensor 1 caused by the temperature change is performed by the scale conversion processing unit 3.
2 can be performed. That is, the deviation amount or the correction coefficient corresponding to the temperature sensed by the temperature sensor 27 is stored in the EEPROM.
The data is retrieved from the temperature correction table in 25 and is reflected at the time of scale conversion. In this way, correct angular velocity data can always be obtained even if there is a temperature change.

The stop judging section 33 extracts a fluctuation component of the angular velocity data as shown in FIG. 5A, and based on the accumulated value of the fluctuation component per unit time (for example, 2 seconds), the yaw rate sensor 1 Is to determine whether the vehicle is moving or stationary, that is, whether the vehicle is running or stopped. Specifically, it includes a high-pass filter that passes a signal having a time constant higher than the time constant of the drift component generated in the yaw rate sensor 1, and an integrator that integrates the angular velocity data passed through the high-pass filter for a unit time. It consists of.

The reason why it is possible to determine whether the vehicle has stopped by using one type of angular velocity data is as follows. First, since the drift component is merely accumulated, there is no periodic fluctuation component as apparent from FIG. 7, and if it is about 2 seconds, the influence on the stop determination is small. The angular velocity data that has passed through the high-pass filter is either a noise component due to vibration or a motion component.
The noise component when is stationary is ideally positive and negative as shown in FIG. 5B and becomes zero when integrated, whereas the noise component is not positive and negative when moving. As shown in FIG. 5C, a finite value is always generated by integration. The present invention makes use of this point to determine whether to stop the vehicle. However, in practice, there is a slight error, so that the configuration is such that the stop is determined when the output of the integrator is lower than the threshold value. This threshold can be variable.

The offset value calculating section 34 includes a stop determining section 3
3 detects the stop of the vehicle, calculates the drift component amount included in the angular velocity data at the time of the stop, and sets this as an offset value to be corrected. Then, the offset value is stored (updated) in the offset value storage unit 35. This is repeated every time the stoppage of the vehicle is detected. The offset value removing unit 36 calculates correction data by sequentially removing the latest offset value stored in the offset value storage unit 35 from the angular velocity data obtained by the scale conversion, and sends the correction data to the dead zone processing unit 37.

The dead zone processing section 37 prevents a situation in which data indicating that the vehicle is rotating is output due to some cause, for example, suddenly generated pulse noise even though the vehicle is actually stopped. Specifically, the dead zone processing unit 37 determines in advance the fluctuation range of the correction data to be regarded as the stopped state, and the output from the offset value removing unit 36 falls within this fluctuation range. In such a case, it is configured to output correction data indicating the stop state.

The correction data passed through the dead zone processing section 37 is D
The voltage is converted into an analog voltage by the / A converter 26 and is passed to the subsequent processing.

As described above, according to the present embodiment, the amount of the drift component generated by the yaw rate sensor 1 can be quantified correctly and can be removed from the angular velocity data in real time. Error approaches zero value without limit. Note that, in this embodiment, an example in which the correction accompanying the temperature change is performed at the time of scale conversion has been described, but this correction may be performed in the offset value removing unit 36.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In this embodiment, the angular velocity data is corrected in real time during exercise without detecting the amount of drift component during stoppage. The basic configuration in this case is shown in FIG.
However, some of the functional blocks realized by the CPU 23 by a program or the like stored in the EPROM 24 are partially different.

FIG. 6 is a functional block diagram of the angular velocity data correction device of this embodiment. In this embodiment,
A high-pass filter 41, a fluctuation detecting unit 42 that detects a fluctuation tendency of angular velocity data, for example, a fluctuation frequency between about 2 to 5 seconds, and a high-pass filter 41 according to a detection result of the fluctuation detecting unit 42. The filter control unit 43 that dynamically changes the time constant, the scale conversion processing unit 44, and the dead zone processing unit 45 are realized by the CPU 23. The scale conversion processing unit 44 and the dead zone processing unit 45 have the same functions as the scale conversion processing unit 32 and the dead zone processing unit 37 of the first embodiment.

The high-pass filter 41 outputs correction data by passing at least a fluctuation component having a time constant higher than the time constant of the drift component generated in the yaw rate sensor 1 among the measured values (angular velocity data) of the counter 22. It is. In general, the transfer function F of a high-pass filter is represented by T as a time constant and S as a variable of a conversion function (Laplace transform).
It can be expressed by F = TS · (1 + TS). A function (delta function) obtained by performing an inverse Laplace transform on this transfer function is also a function of the time constant T. Therefore, the filter pass band can be changed by dynamically changing the time constant T. In this embodiment, angular velocity data is corrected by utilizing such a property of a high-pass filter.

The input angular velocity data contains different frequency components depending on the rotational speed of the vehicle. Therefore, when changing the time constant of the high-pass filter 41, first, it is necessary to detect the operation of the system, that is, whether the vehicle is performing a high-frequency operation or a low-frequency operation. The fluctuation detecting section 42 is provided for this purpose. For example, as shown in FIG.
1, an integrator 52, an operation unit 53, an analysis data holding unit 54,
And the fluctuation tendency judging unit 55 is placed in this order. The operation of each unit is as follows. The appropriate critical frequency of the high-pass filter 51 is about 2 Hz in the case of an automobile.

The angular velocity data that has passed through the high-pass filter 51 is as shown in FIGS. That is, at the time of low frequency operation, as shown in FIG.
Are superimposed, but when they pass through the high-pass filter 51, FIG.
As shown in (b), the drift component is removed, and only a relatively low-frequency change component remains. On the other hand, during high frequency operation, the waveform hardly changes before and after passing through the high-pass filter 51 as shown in FIGS. 9 (a) and 9 (b).

Next, when the output of the high-pass filter 51 is passed through an integrator, finite values are accumulated as shown in FIG. In this case, the value approaches zero as shown in FIG. Therefore, the absolute value of the output of the integrator 52 is calculated in the arithmetic unit 53, and the magnitude M (Magnitude) of the integrated value is used as data indicating the tendency of fluctuation of the system (automobile). Normally, in a system having many low frequency components, the integral value M becomes relatively large. Therefore,
The integrated value M is stored in the analysis data holding unit 54. Since the integral value M tends to always increase, the integral value M is reset, for example, to a zero value after being accumulated for about 10 seconds. Then, in a system (vehicle) with many low-frequency operations, the integral value M is more frequently stored than the zero value, and a finite numerical value is maintained for a certain period of time. Therefore, the fluctuation tendency determination unit 55 can determine the fluctuation tendency of the system (automobile) by referring to the integrated value M of the analysis data holding unit 54.

FIG. 11 shows changes in angular velocity data (rotational momentum [degrees / sec]) when the angular velocity data correction device of this embodiment is mounted on an automobile and travels, and an angle [degree] calculated based on the result. It is a figure showing a situation of change of. During normal straight running, angular velocity data due to vehicle vibration and slight movement is output, and the resulting angle has almost no large number (below a threshold level serving as a criterion for determining whether the component is a high frequency component or a low frequency component). However, when a car turns around an intersection, the angular velocity data has a large fluctuation amplitude and a slow motion, and as a result, the angle has a large value. In such a case, the fluctuation tendency determination unit 55 determines that the system (automobile) has a high tendency of low frequency components, and transmits the result to the filter control unit 43.

It should be noted that various methods other than those described above can be considered as a method of detecting the fluctuation. For example, a first fluctuation frequency (high-frequency component) higher than a reference frequency determined for each moving object to which the yaw rate sensor 1 is attached and a second fluctuation frequency (low-frequency component) lower than the reference frequency are detected, and which component is relatively high. It may be possible to compare whether the number is large. The reference frequency in this case is 2 [H
z] is appropriate.

The filter control section 43 dynamically changes the time constant of the high-pass filter 41 according to the detection result of the fluctuation detector 42. Specifically, when the tendency of the high frequency component is large, it is determined that the rotational speed of the automobile is high (the frequency component is high), and the time constant of the high-pass filter 41 is shortened. On the other hand, when the tendency of the low frequency component is large, it is determined that the rotational speed of the vehicle is slow (the frequency component is low), and the time constant of the high-pass filter 41 is increased.

Conventionally, the time constant of the high-pass filter is fixed, and it is extremely difficult to match the time constant with the time constant of the drift component. Therefore, drift removal by the high-pass filter has not been performed. According to the above-described embodiment, the time constant of the high-pass filter 41 dynamically changes according to the frequency of the rotational motion associated with the accumulated amount of the drift component.
The drift component can be removed simply by inputting it to 1.

[0033]

As is clear from the above description, according to the angular velocity data correction apparatus of the present invention, even if an angular velocity meter with a drift component is always used, such as a vibration type gyro, the rotational momentum can be increased. This has the effect that the detection error of approaches the zero value without limit.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an attitude angle sensor according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing examples of the contents of various adjustment parameter tables used in the first embodiment. FIG. 2A is a gain table showing correspondence between measured values and rotational momentum [degrees / sec].
(B) is a specification error table for correcting a specification error peculiar to the yaw rate sensor, and (c) is a deviation amount or a correction amount of a correspondence relationship between a measured value caused by a temperature change and a rotational momentum [deg / sec]. It is the temperature correction table which measured the numerical value.

FIG. 3 is a functional block configuration diagram realized by a CPU according to the first embodiment.

FIG. 4 is an explanatory diagram of an operation of an initial correction processing unit according to the first embodiment.

FIG. 5 (a) is a diagram illustrating a fluctuation state of input angular velocity data, FIG. 5 (b) is a diagram illustrating a fluctuation state of angular velocity data having a high-frequency fluctuation component passed through a high-pass filter, and FIG. FIG. 9 is an explanatory diagram showing an integration result of angle data having a component that fluctuates in frequency.

FIG. 6 is a functional block configuration diagram realized by a CPU according to a second embodiment of the present invention.

FIG. 7 is a detailed block configuration diagram of a fluctuation detection unit according to a second embodiment.

FIG. 8A shows angular velocity data before passing through an (auxiliary) high-pass filter during low-frequency operation, and FIG. 8B shows (auxiliary)
FIG. 4 is an explanatory diagram of angular velocity data after passing through a high-pass filter.

9A and 9B are explanatory diagrams of angular velocity data before and after passing through an (auxiliary) high-pass filter during high-frequency operation.

10A and 10B are explanatory diagrams of the result of integration of the output of the (auxiliary) high-pass filter. FIG. 10A shows an example of a low-frequency operation, and FIG. 10B shows an example of a high-frequency operation.

FIG. 11 shows a change in angular velocity data (rotational momentum [degree / sec]) and a change in angle [degree] calculated based on the result when the angular velocity data correction device according to the second embodiment is mounted on an automobile and travels. FIG.

FIG. 12 is an explanatory diagram of a drift component generated and accumulated by a gyro sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Yaw rate sensor (angular velocimeter) 2 Angular velocity data correction device 21 A / D converter 22 Counter 23 CPU 24 EPROM 25 EEPROM 26 D / A converter 27 Temperature sensor 31 Initial correction part 32, 44 Scale conversion processing part 33 Stop judgment part 34 Offset Value calculation unit 35 Offset value storage unit 36 Offset value removal unit 37, 45 Dead band processing unit 41, 55 High-pass filter 42 Fluctuation detection unit 43 Filter control unit

Continued on the front page (56) References JP-A-7-286852 (JP, A) JP-A-4-329370 (JP, A) JP-A-3-4215 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G01P 21/00 G01C 19/00-19/72 G01P 9/00-9/04

Claims (6)

(57) [Claims] 1. A data conversion means for converting output data of an angular velocity meter into angular velocity data of a predetermined format, and extracting a fluctuation component of the angular velocity data, and based on an accumulated value of the fluctuation component per unit time. State detecting means for detecting whether the robot is in motion or in a stationary state; and calculating a drift component amount included in angular velocity data at the time of stationary state each time the state detecting means detects a stationary state.
And second calculating means for storing the calculated drift component amount in an updatable manner and sequentially removing the stored drift component amount from the angular velocity data to calculate correction data. Angular velocity data correction device. 2. The high-pass filter for passing a signal having a time constant higher than the time constant of a drift component generated in the gyro, and the angular velocity data having passed through the high-pass filter are used as the unit. 2. The angular velocity data correction device according to claim 1, further comprising an integrator for performing time integration, wherein the apparatus is configured to determine a stationary state when an output of the integrator is lower than a threshold value. 3. A data conversion means for converting output data of the gyro into angular velocity data of a predetermined format, and a variation of a time constant higher than a time constant of at least a drift component generated in the gyro among the variation components of the angular velocity data. A high-pass filter that outputs correction data by passing only the component, a fluctuation tendency detecting unit that detects whether the fluctuation tendency of the angular velocity data is high-frequency or low-frequency, and according to the detected fluctuation tendency. An angular velocity data correction device, comprising: filter control means for dynamically changing a time constant of a high-pass filter. 4. An auxiliary high-pass filter for passing the fluctuation tendency detecting means only through a fluctuation component having a time constant higher than a time constant of a drift component generated in the gyro meter among fluctuation components of the angular velocity data, An integrator that periodically integrates the output of the auxiliary high-pass filter; and accumulates the absolute value of the output of the integrator for a certain period of time. The filter control means is configured to dynamically change the time constant of the high-pass filter according to the fluctuation component determined to be large by the determination means. The angular velocity data correction device according to claim 3, wherein: 5. The fluctuation tendency detecting means detects a first fluctuation frequency higher than a reference frequency and a second fluctuation frequency lower than the reference frequency determined from each of the moving bodies to which the gyro is attached, from the angular velocity data. The filter control means is configured to control the first variable frequency and the second
4. The angular velocity data correction device according to claim 3, wherein a time constant of the high-pass filter is dynamically changed in accordance with a ratio of the fluctuation frequency. 6. A temperature sensor for detecting an ambient temperature of the gyro, and a third calculating means for calculating a temperature coefficient value for correcting the angular velocity data or the correction data according to a temperature detected by the temperature sensor. The angular velocity data correction device according to any one of claims 1 to 5, further comprising: