JPS6035272A - Angular velocity measuring apparatus to be applied to vehicle - Google Patents

Abstract

PURPOSE:To measure angular velocity correctly employing an A/D converter with a relatively small conversion range by a method wherein a difference is obtained between the output of an auxiliary D/A converter and the output of an angular speed sensor and the difference output is converted into a digital signal with an A/D converter to be fed to an arithmetic processing section. CONSTITUTION:The output of an angular velocity sensor 11 is converted into a digital signal with an A/D converter 12 and fed to an arithmetic processing section 13. On the other hand, a vehicle speed sensor 14 detects the vehicle stopping and the detection output thereof is fed to the arithmetic processing section 13. In addition, an analog signal converted with an auxiliary D/A converter 15 is applied to an analog difference circuit 16 to obtain a difference from the output of the angular velocity sensor 11. Thus, the output of the angular velocity sensor is fed to the A/D converter after a value corresponding to the output at the zero point is subtracted with the auxiliary D/A converter thereby enabling the use of an inexpensive angular speed sensor with a large output at the zero point.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that is attached to a vehicle such as an automobile and measures angular velocity.

Examples of angular velocity sensors that measure angular velocity include gas rate sensors and vibration type/single rotation rate sensors, but these produce an output when the angular velocity is zero, and the output is dependent on the ambient temperature. It has the disadvantage of fluctuating with changes. In this respect, it is conceivable to compensate for the state where the output is zero. For this reason, conventionally, as shown in FIG. 1, the output of the angular velocity sensor 11 is converted into a digital signal by an AD converter 12 and supplied to an arithmetic processing section 13.

On the other hand, when the vehicle speed sensor 14 detects a state in which the vehicle is stopped, and this detection output is supplied to the arithmetic processing section j3, the output of the angular velocity sensor 11 at that time? A: The stored value is stored in the processing unit 13, and the stored value is derived from the measured value of the angular velocity sensor 11 while the vehicle is running to compensate for the zero point. In other words, the measured value V of the vehicle speed sensor and the measured value Ω of the angular velocity sensor are as follows, where R is the turning radius of the vehicle at that time, V=
There is a relationship of RΩ, and if R1 is known, Ω can be found by measuring ■. However, even if R is not known, it is sufficient to know whether the vehicle speed V is zero or not based on whether the angular velocity Ω is zero. That is, the angular velocity when ■ is zero, Ω is also zero, therefore, remember the input of the AD converter 12 at this time, and use the input value of the AD converter 12 when the vehicle speed V is finite. By subtracting the memorized value, the correct angular velocity can be determined, and by doing this every time the vehicle stops, for example at each intersection, it is possible to determine the correct angular velocity. Correct angular velocity measurements can be made without being affected.

However, in this case, if the output when the angular velocity is zero is relatively large, an angular velocity signal is added to it, so it is necessary to increase the input range of the AD converter 12. Increasing the input range and performing the conversion more frequently, in other words, increasing the number of conversion bits, makes the AD converter expensive. To avoid this, it is recommended to use an angular velocity sensor with a small output when the angular velocity is zero, or an expensive one.

The purpose of this invention is to use a relatively inexpensive angular velocity sensor,
An object of the present invention is to provide an on-vehicle angular velocity measuring device that can accurately measure angular velocity using an AD converter whose conversion range is still relatively narrow.

According to this invention, the correction DA converter is used to calculate the difference between the output of each DA converter and the output of the angular velocity sensor, and the difference output is converted into a digital signal by the AI) converter. supply The value of the AI) converter, which was manually inputted when both the ox/zeta center are substantially stopped, is converted into the correction DA.
Input to f converter. In this case, the DA converter may be an inexpensive one with a relatively small number of hits, and only the upper bits of the AD converter may be supplied to the DA converter, and the lower bits may be corrected by the arithmetic processor. .

FIG. 2 shows an example of an on-vehicle angular velocity measuring device according to the present invention, and the parts corresponding to those in FIG. The analog signal converted by the correction DA converter 15 is subjected to an analog difference circuit (for example, a differential amplifier) 16, where the difference between the output and the output of the angular velocity sensor 11 is calculated. The signal is converted into a digital signal and supplied to the electric signal processing section 13.

In the arithmetic processing unit 13, for example, the vehicle speed sensor 14 detects the first condition when the vehicle is substantially stopped, that is, when the vehicle speed is below a certain level. The input value (
In other words, the DA converter 15 has a built-in latch circuit, which latches the correction digital signal (the output of the angular velocity sensor 11 with zero angular velocity). Therefore, the output of the DA converter 15 corresponds to the output of the angular velocity sensor 11 when the angular velocity is zero, and the output at zero angular velocity is removed from the difference circuit 16, and only the correct angular velocity signal is supplied to the AD converter 12, which is converted into a digital signal. is converted to Therefore, even if the output curve of the angular velocity sensor 11 at zero angular velocity is large, the conversion range of the AD converter 12 only needs to be a value corresponding to the maximum variation range of the angular velocity, and the variation range of the AD converter 12 is relatively narrow. things can be used.

Naori h = As the output value of the angular velocity sensor 11 when the angular velocity is zero, which is given to the converter 15, only the upper bits of the input value when the angular velocity is zero, manually input from the AD converter 12, are given, and the DA converter 15・Use a small number of inexpensive ones, and store the lower bits that are not given to the DA converter 15 in the arithmetic processing unit 13, so that the lower bits that are not given to the DA converter 15 at that time are stored in the arithmetic processing unit 13. It is also possible to obtain the correct angular velocity by subtracting the stored lower bits from the input signal. Also, the trowel processing section 1
3, the angular velocity is measured, but the measured value is not output to the outside, for example, the vehicle speed sensor 14 is used within the arithmetic processing unit 13.
The traveling position of the vehicle may be calculated from the vehicle speed obtained in the above manner and the angular velocity obtained as described above.

As described above, this invention has the following problems: 1) Since the A converter subtracts the output corresponding to the output at the zero point and supplies the angular velocity sensor output to the AD converter, the output at the zero point is large and inexpensive. It is possible to use a high-precision angular velocity sensor, and it is also possible to measure with high precision.By constantly performing such compensation operations, it is possible to obtain the correct angular velocity for zero point fluctuations over a long period of time without being affected by temperature fluctuations. Moreover, as the AD converter 12, an inexpensive one with a relatively small input range can be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional vehicular angular velocity measuring device, and FIG. 2 is a block diagram showing an example of a vehicular angular velocity measuring device according to the present invention. 11: Speed sensor, 12: AD converter, 13: Arithmetic processing unit, 14: Vehicle speed sensor, 15: DA converter for correction, 16
:Differential amplifier. Patent Applicant Yazaki Sogyo Co., Ltd. Agent Takashi Kusano 1f″11 Figure 2 not shown

Claims (1)

[Claims] (1) Vehicle stop detection means that detects when the vehicle is substantially stopped, an angular velocity sensor, a correction DA converter that converts a digital signal into an analog signal, and a correction D
A difference circuit that outputs the difference between the output of the A converter and the output of the angular velocity sensor, an AD converter that converts the output of the difference circuit into a digital signal, and the output of the AD converter is input,
An on-vehicle angular velocity measuring device comprising: an arithmetic processing section that supplies the output of the AD converter to the correction DAi converter when the stop detection means is in the process of detection.