JP2711746B2 - Angular velocity measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an angular velocity measuring device that corrects an offset voltage of angular velocity data based on data from an angular velocity sensor itself.

[Prior Art] A current position of a vehicle is displayed on a display device in a vehicle compartment,
In-vehicle navigation systems that provide guidance to destinations include radio navigation that uses radio waves transmitted from satellites and beacon markings as external location information to identify the current location, and inertia that estimates the current location from the vehicle's trajectory. Use one of the navigation. In general, inertial navigation derives the trajectory of a vehicle by sequentially joining unit vectors obtained from a vehicle speed sensor and a direction sensor, so that the accuracy of navigation is poor in detection accuracy compared to a vehicle speed sensor. Depends on accuracy.

By the way, as the direction sensor used in the on-vehicle navigation device, a geomagnetic sensor that uses the horizontal component of the geomagnetism that runs north and south on the earth, a steering sensor that detects the traveling direction of the vehicle based on the steering angle of the steering wheel, An angular velocity sensor or the like that detects an angular velocity whose time integral value corresponds to the azimuth angle of the vehicle is often used.

The relationship between the angular velocity data J of the angular velocity sensor and the angular velocity kω is generally represented by a proportional relational expression J = kω as shown by a solid line in FIG. 11, but the operation reference point of the angular velocity sensor drifts due to the ambient temperature. When the offset voltage Jo occurs due to the drift, the relationship between the angular velocity data J and the angular velocity kω is expressed as J = kω + Jo as shown by the two-dot chain line in FIG. Is done. The offset voltage Jo does not always take a constant value, but changes irregularly according to the external environment. For this reason, if the offset voltage Jo is left uncorrected,
A detection error occurs such that the angular velocity data J changes even though the vehicle is stopped, or the angular velocity data J does not change even if the vehicle is turning. There is a problem in that an error occurs in the calculation of the device, and it becomes impossible to accurately estimate the current position.

In addition, Japanese Patent Application Laid-Open No. 64-29707, "Vehicle Position Detecting Device" previously proposed by the present applicant, determines that the vehicle is traveling straight or stopped when two types of large and small angular velocity data are within a certain range.
An angular velocity measuring device using data at that time as an offset voltage is disclosed. However, in this method, a certain number of average values of angular velocity data obtained by sampling several times are collected, the maximum value and the minimum value are obtained, and if the difference between the two is less than a certain value, the vehicle is in a straight state. Is determined. That is, the two types of angular velocity data are the maximum value and the minimum value of the average value of the angular velocity data, and the difference between the maximum value and the minimum value of the average value data having the same moving average section (or the number of smoothing points) is determined by the threshold value. Just do it. Therefore, the influence of the vehicle vibration and the influence of the offset voltage fluctuating due to the temperature drift can be evaluated only in a fixed observation period, and the offset voltage cannot be corrected by integrating the long- or short-cycle fluctuation factors. It was something to have.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an angular velocity measuring device capable of accurately estimating the current position even if the offset voltage fluctuates by correcting the offset voltage from the data of the angular velocity sensor itself.

Means for Solving the Problems In order to achieve the above object, the present invention provides an angular velocity sensor in which an offset voltage superimposed on a true value changes with time, and a traveling direction of a vehicle based on angular velocity data obtained by the angular velocity sensor. The arithmetic unit calculates two long and short moving averages having different average section lengths from the angular velocity data, and calculates the long and short section moving average values within a certain range. It is characterized in that it is determined that the vehicle is traveling straight or stopped at a certain time, and an arithmetic mean value of a predetermined number of the short-range moving average values at that time is updated as an offset voltage.

Further, the present invention has a distance sensor for inputting distance data to the arithmetic device, and the arithmetic device determines from the distance data whether the offset voltage at the time of the correction is a stop voltage or a running voltage, When it is determined that the offset voltage is equal to the offset voltage, the stop time is retained, and the offset voltage detected especially after the subsequent traveling is calculated by subtracting the stop time from the current time to the maximum allowable change per unit time of the offset voltage of the angular velocity sensor. This is characterized in that it is compared with a value (maximum variation value) obtained by multiplying the time by a given time, and if the value is larger, the offset voltage is not updated.

EXAMPLES Hereinafter, the present invention will be described based on one example shown in the drawings. FIG. 1 is a block diagram showing the overall configuration, FIGS. 2 to 4 are output data diagrams of angular velocity sensors shown with different numbers of smoothing points, and FIG. FIG. 6 is an explanatory diagram of the phase adjustment of two data, and FIG. 6 is a flowchart showing the operation procedure of the arithmetic unit.

In FIG. 1, an angular velocity measuring device 1 includes an angular velocity sensor 2, a sensor amplifier 3, an A / D converter 3, and an arithmetic unit 5 that takes in the A / D converted angular velocity data and calculates the angular velocity of the vehicle.

FIGS. 2 to 4 show output data of the angular velocity sensor 2. First, FIG. 2 shows the number of smoothing points of 1, and the data includes vibrations of the vehicle, and there are variations in the data. Meanwhile, the third
FIGS. 4A and 4B are obtained by using the simple moving average method, and have smoothing points of 11 and 101, respectively.
Although there is a difference of about 0 times, strictly 101/11 times, data D1 (long section moving average value) and D2 (short section moving average value) that show the true behavior of the vehicle with little data variation can be obtained. You can see that. The portion indicated by A in FIGS. 2 to 4 is a portion where it is determined that the vehicle is traveling straight or stopped, and the data D1 and D2 have little fluctuation and fall within a certain range a. Contrary to this, the portion indicated by B is a portion determined to be a vehicle turning, and the data D1 and D2 fluctuate greatly and fall outside the fixed range a. Then, the offset voltage is updated by the angular velocity data of the portion A of the data D1 and D2, which is determined to be traveling straight or stopping, here the data D2.

FIG. 5 is an explanatory diagram of the phase adjustment of data D1 and D2 obtained by the moving average method and stored in the ring buffer. Data D2 is a temporal center of the ring buffer 1 in which data D1 is stored. A total of 11 ring buffers 2 are stored in the ring buffer 2 at five positions before and after the position.

Next, the operation of the present invention having the above configuration will be described. Analog data output from the angular velocity sensor 2 is input to the A / D converter 4 at predetermined time intervals via the sensor amplifier 3 and is converted into a digital value. Then, the data converted into the digital value is input to the arithmetic unit 5, where the angular velocity is calculated and output.

When the vehicle is turning, the data D1 and D2 of the angular velocity sensor 2 fluctuate greatly, and one or both of them deviate from the predetermined range a. However, when the vehicle travels straight or stops, the data D1 and D2 are both within the predetermined range. a, the output data of the angular velocity sensor 2 which is input to the A / D converter 4 is only the offset voltage itself, and thus the output of the A / D converter 4 is also the offset voltage itself. And the angular velocity data calculated by the calculation device 5 is also the offset voltage itself. When the vehicle travels straight or when it stops, in particular, two large and small data D1 and D2 having smoothing points of 101 and 11 respectively obtained by the simple moving average method are sequentially stored in the ring buffers 1 and 2, and the two data D1 and D2 are stored.
When the two data D1 and D2 are within a certain range a, it is determined that the vehicle is traveling straight or when the vehicle is stopped, and when it is out of the certain range a, it is determined that the vehicle is turning. Since the angular velocity data when it is determined that the vehicle is traveling straight or when it is stopped is the offset voltage itself, the offset voltage of the angular velocity sensor 2 is updated with the angular velocity data when traveling straight or when it is stopped.

Next, the operation procedure of the arithmetic unit 5 will be described based on the flowchart shown in FIG. The angular velocity data output from the angular velocity sensor 2 is stored in the sensor amplifier 3, A /
The data is taken into the arithmetic unit 5 through the D converter 4 (step 101). The fetched data is first stored in the ring buffer 1 as A data, for example, 101 data D1 (step 102). Next, an average value (long-section moving average value) of the data D1 stored in the ring buffer 1 is obtained, and B data, for example, 100 data are stored in the ring buffer 2 (step 103). Then, the data D2 obtained by adjusting the phase of the data in the ring buffer 1 as shown in FIG.
Pieces, for example, 11 pieces, and their average value (short section moving average value)
Is obtained, and D pieces of the data are stored in the ring buffer 3, for example,
100 are stored (step 104). Next, steps 103, 1
The difference between the maximum value and the minimum value of B (100) and D (100) stored in 04 is calculated (step 105). The data sequentially stored in the ring buffers 2 and 3, that is, whether or not the difference between the maximum value and the minimum value of the long section moving average value and the short section moving average value is continuously within the certain range a is determined. to decide. As a result, when it is not within the fixed range a,
The average value of the D (100) data stored in the ring buffer 3 is added, and the number is counted (step 106a).
After that, the routine is terminated. On the other hand, when it is within the fixed range a, the D stored in the ring buffer 3 is
An average value of the (100) pieces of data is obtained, and the average value is updated as an offset voltage (step 106b). Then, the routine is terminated (step 106).

7 to 10 show another embodiment.
In this embodiment, the data of the distance sensor 6 is taken into the arithmetic unit 5 to determine the stop of the vehicle, and the accuracy of the data in the above embodiment is further improved. This is because, in order to update the offset voltage, in addition to the fact that the reliability is highest when stopped, the accuracy is deteriorated if the offset voltage of the angular velocity sensor 2 changes beyond an allowable range over time. This is because the maximum change amount M per unit is standardized. That is, as shown in FIG. 8, the offset voltage Jo of the angular velocity sensor 2 has a characteristic that the update width gradually increases as time elapses. However, if the maximum change amount M per unit time is exceeded, the accuracy deteriorates. It is. In this device, every time the distance data (pulse) is output from the distance sensor 6 during traveling, the distance data (pulse) is taken into the arithmetic unit 5, but when the vehicle is stopped, the distance data from the distance sensor 6 is not output. Is not taken in, the arithmetic unit 5 determines that the vehicle is stopped, and holds the time at that time as the stop time ST. Then, the stop time ST is subtracted from the current time T, and the time obtained by the subtraction is multiplied by the maximum change amount M to obtain an allowable change amount b of the offset voltage. Compare the magnitude with the detected offset voltage. When the offset voltage at the current time T is larger than the allowable variation b, the update with the offset voltage detected at the current time T is stopped.

Next, the operation procedure of the arithmetic unit 3 according to the second embodiment is described in ninth embodiment.
This will be described based on the flowchart shown in FIG. 10 and FIG.

The arithmetic unit 5 executes the routine shown in FIG. 9 every time distance data (pulse) is input from the distance sensor 6, and measures the time interval from the previously input pulse (step).
201). And whether the pulse interval is A seconds or more,
That is, it is determined whether or not the vehicle is stopped, and if the pulse interval is not longer than A seconds, the routine is terminated. Keep ST (Step 20
2).

Further, in the arithmetic unit 4, steps 101 to 106 are executed in parallel with the flowchart of FIG. 10 as in the first embodiment. In step 106, the maximum of the data sequentially stored in the ring buffers 2 and 3 is determined. It is determined whether the difference between the value and the minimum value is continuously larger or smaller than a certain range a. If the result is larger than the predetermined range a, the average value of the D (100) data stored in the ring buffer 3 is added, the number is counted (step 106a), and the routine is terminated. On the other hand, when the number is within the predetermined range a, D (100
The average value of the data is obtained, and the offset voltage is obtained (step 107). In step 108, the maximum change value M per unit time of the offset voltage is multiplied by the time obtained by subtracting the stop time ST from the current time T,
The maximum variation b is obtained. Then, in step 109, the maximum fluctuation amount b and the current time T obtained in step 107 are calculated.
With the offset voltage. And the decision step
If the result of the magnitude comparison between the two at 110 is that the offset voltage at the current time T is within the maximum variation b, step 11
At 0a, the offset voltage is updated with the offset voltage, and the routine ends. On the other hand, if it is out of the range of the maximum fluctuation amount b, the routine is terminated without updating with the offset voltage at that time (step 110).
b).

As described above, in the second embodiment, the stop of the vehicle is determined based on the distance data from the distance sensor 6, and the time obtained by subtracting the stop time ST from the current time T is multiplied by the maximum allowable change M per unit time. The magnitude of the maximum fluctuation amount b obtained by the calculation is compared with the offset voltage at the current time T. When the offset voltage is large, the offset voltage is not updated, so that the offset voltage can be updated with higher accuracy.

[Effects of the Invention] As is clear from the above description, according to the present invention, two types of long and short moving averages having different section lengths of the average section are obtained from the angular velocity data, and the long section moving average and the short section moving average are obtained. When the value is within a certain range, it is determined that the vehicle is traveling straight or stopped, and the arithmetic mean value of a predetermined number of short-range moving average values at that time is updated as the offset voltage, so that the influence of vehicle vibration or Based on the output of the angular velocity sensor, which is likely to cause variations in the output data due to the influence of the temperature drift of the offset voltage, etc., it is possible to determine whether the vehicle is traveling straight or stopped based on the relationship between the two types of moving average values of the angular velocity data. When it is determined that the vehicle is traveling straight or stopped, the offset voltage is updated with an arithmetic average of a predetermined number of short short-range moving averages. Therefore, even when the straight traveling period or the stop period is short,
An excellent effect is obtained in that an offset voltage that is sufficiently reliable can be obtained, and the offset voltage can be updated with high accuracy without using other components such as an angle sensor.

Further, the present invention determines a stop of the vehicle based on the distance data from the distance sensor, and multiplies the difference between the stop time and the current time by an allowable maximum change per unit time of the offset voltage (maximum change amount). ) Is compared with the offset voltage at the current time to determine whether or not the offset voltage is within an allowable fluctuation range. When the offset voltage is not within the allowable range, the offset voltage is not updated. Since the distance sensor is used outside, the configuration is slightly complicated, but there is an effect that the offset voltage can be updated with higher accuracy.

[Brief description of the drawings]

The drawings show an embodiment of the angular velocity measuring device according to the present invention. FIG. 1 is a block diagram showing an overall configuration, and FIGS. 2 to 4 show angular velocity sensors shown with different numbers of smoothing points. FIG. 5 is an explanatory diagram of the phase adjustment of two data stored in the ring buffer, FIG. 6 is a flowchart showing the operation procedure of the arithmetic unit, and FIGS. 7 to 10 are the second embodiment. FIG. 7 is a block diagram showing the overall configuration, FIG. 8 is an explanatory diagram of the offset voltage tolerance with respect to the passage of time, and FIGS. 9 and 10 are flowcharts showing the operation procedure of the arithmetic unit. FIG. 11 is an output characteristic diagram of the angular velocity sensor. (Description of reference numerals in drawings showing main parts) 1 ... Angular velocity measuring device 2 ... Angular velocity sensor 3 ... Sensor amplifier 4 ... A / D converter 5 ... Calculating device

Claims (2)

(57) [Claims] 1. An angular velocity sensor in which an offset voltage superimposed on a true value changes with time, and an arithmetic unit for detecting a traveling direction of a vehicle based on angular velocity data obtained by the angular velocity sensor. The two types of long and short moving averages in which the section lengths of the average sections are different from each other are obtained, and when the long section moving average and the short section moving average are within a certain range, it is determined that the vehicle is traveling straight or stopped. An angular velocity measuring apparatus, wherein an arithmetic mean value of a predetermined number of the short section moving average values is updated as an offset voltage. 2. An arithmetic unit having a distance sensor for inputting distance data to the arithmetic unit, the arithmetic unit determines from the distance data whether the offset voltage at the time of the correction is a stop time or a running time, and When it is determined to be the offset voltage, the stop time is held, and the offset voltage detected particularly after traveling is calculated by subtracting the stop time from the current time to the allowable maximum change per unit time of the offset voltage of the angular velocity sensor. 2. The angular velocity measuring device according to claim 1, wherein a comparison is made as to whether the value is larger or smaller than a value obtained by multiplying time (maximum fluctuation value), and if the value is larger, the offset voltage is not updated.