JPH0315148B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an orientation detection device for autonomously recognizing the orientation and orientation of a moving object traveling on a trackless track, for example. be.

[Prior art]

In general, as an independent mobile body orientation detection device that does not require ground support equipment, devices using a mechanical gyroscope that utilizes the gyroscope inertia of a high-speed rotating body are often used.

However, mechanical gyroscopes require a high-speed rotating body, making them complex and expensive.
It was difficult to use under harsh industrial conditions, such as requiring periodic maintenance to maintain accuracy.

Therefore, the use of gas rate sensors has been proposed as an alternative to this (for example, "Measurement and Control" vol. 21, No. 7 (July 1980), p. 723 -
730).

A gas rate sensor, like a mechanical rate gyro, is a type of inertial sensor that detects the rotational angular velocity of a moving body. First, the principle of this operation will be explained with reference to FIG. In principle, the gas rate sensor is
It is composed of a gas flow 2 excited by a piezoelectric pump and made into a constant laminar flow by a nozzle 1, and sensor wires 3a and 3b whose resistance value changes as they are cooled by the gas flow 2. When the gas flow 2 is externally rotated at an angular velocity ω, it receives Coriolis and is deflected by Y from the central position 6 as shown in FIG. gas flow 2
v, the speed of the sensor wires 3a, 3 from the nozzle 2
If the distance to b is L, the amount of deviation Y is Y=L ² /vω, which is an amount proportional to the input angular velocity ω. Due to this bias, the way the gas flow 2 hits the sensor wires 3a and 3b changes, causing a loss of resistance balance.
The amount of deflection Y is the sensor wires 3a, 3b and the resistors 4, 5.
The voltage V ₀ is increased by the bridge circuit constructed by
Detected as .

As can be seen from the principle of operation, the gas rate sensor has a simple structure because it does not require a high-speed rotating body, and has advantages such as long-life impact resistance, no maintenance, and low cost.

However, as can be seen from the principle of operation, this sensor has the disadvantage that its characteristics are affected by the outside temperature because it performs detection using changes in resistance values due to temperature of the sensor wires 3a and 3b. in particular,
As shown in Figure 6, the output offset voltage when there is no input is not zero and varies depending on temperature and time, and the scale factor, which is the conversion coefficient between the voltage value and the input angular velocity, changes with temperature as shown in Figure 7. There are problems such as fluctuations due to

Conventionally, there have been measures as shown in FIG. 8 as countermeasures against this temperature fluctuation. This has a structure in which a heater 8 is directly wrapped around the gas rate sensor 7 to keep the outside temperature constant. This structure requires a lot of power to heat the heater, and is not suitable for applications with limited energy sources, such as battery-powered unmanned vehicles. Another disadvantage is that a preheating time for the heater, that is, a certain warm-up time is required until the temperature becomes stable.

[Summary of the invention]

The present invention has been made for the purpose of eliminating such drawbacks, and includes a temperature sensor for detecting the ambient temperature of the rotational angular velocity detection means, an offset correction means for correcting the offset value, and a scale factor correction means for correcting the scale factor. The present invention proposes a high-precision mobile object orientation detection device that is inexpensive, has low power consumption, and is not affected by outside temperature by correcting the characteristics of the rotation angular velocity detection means that are highly temperature-dependent.

[Embodiments of the invention]

The configuration of this invention will be explained with reference to FIG.

The present invention provides an offset correction means 33 which inputs a signal obtained by the rotation angular velocity detection means 32.
The offset value of the angular velocity signal is determined by the angular velocity signal, and the scale factor is determined by the scale factor compensating means 34 which inputs the signal from the temperature sensor 9, and the rotational angular velocity detecting means 32 uses these two values. Azimuth conversion processing means 35 converts input data from
The azimuth angle is converted into a momentary azimuth angle by the azimuth angle output means 36, and the result is outputted by the azimuth angle output means 36.

Next, a specific example thereof will be explained with reference to the drawings.

FIG. 2 is a block diagram showing the electrical connections that realize the configuration shown in FIG. 1. In the figure, 7 is a gas rate sensor that detects the rotational angular velocity of the moving body, and 9 is a gas rate sensor that measures the temperature around the gas rate sensor 7. Temperature sensor, 2
0 is a microcomputer, which includes a CPU 10, memory 11, clock circuit 19, input buffer 12,
14, an output buffer 17, and a communication buffer 16. The signal from the gas rate sensor 7 is converted into a digital value by the A/D conversion circuit 13 and read from the input buffer 12.
The signal from the temperature sensor 9 is sent to the A/D conversion circuit 15.
is converted into a digital value by input buffer 1
It is now loaded from version 4 onwards. Further, the clock circuit 19 generates clock pulses of a constant period to interrupt the CPU 10, so that the processing program is repeatedly executed at regular intervals. Processing programs and intermediate calculation results are stored in memory 1.
1, and the final calculation result is output from an output buffer 17 to a display device 18. Further, the communication buffer 16 is adapted to exchange information such as commands and processing results between the direction detection device and the external controller 37.

FIG. 3 shows the configuration of the gas rate sensor 7 and temperature sensor 9 parts. In order to prevent the ambient temperature of the sensors from changing due to the above-mentioned conditions, both the sensors 7 and 9 are housed in an envelope 30 filled with a heat insulating material 31. Note that the temperature sensor 9
may be incorporated into the gas rate sensor 7 in advance.

Figure 4 shows the microcomputer 2 shown in Figure 2.
4 is a flowchart of the azimuth angle detection program stored in the memory 11 of 0. The operation will be explained below with reference to FIG. 4.

This program is interruptedly activated by a clock pulse from the clock circuit 19 and is repeatedly executed at fixed time intervals Δt. Therefore, the output from the gas rate sensor 7 that is proportional to the rotational angular velocity of the moving body is read in the data reading process of step 21 as angular velocity change data g _i for each time Δt.
The rotation angle can then be obtained by accumulating this data and multiplying it by a conversion coefficient. However, as mentioned above, this data has an offset value, and in order to obtain an accurate angle, this offset value must be used. must be removed.

Therefore, in step 22, the start of azimuth measurement is determined based on a command from the external controller 37, for example. When the azimuth angle is not measured, in the offset correction process of step 23, the powerless offset value z _i is calculated every moment using the following equation (1).

Z _i =1/N _N-1 〓 ^k=0 g _ik ...(1) In other words, the offset value Z _i at the i-th time is
It is obtained as the average value of N unmanned force data before the time.

Further, a scale factor, which is a conversion coefficient between the output of the gas rate sensor 7 and the actual angular velocity, is determined in the scale factor correction process of step 24. Here, the output T from the temperature sensor 9 installed near the gas rate sensor 7 is read and the scale factor SCF is calculated using the following equation (2).
Determine.

SCF=a ₀ +a ₁ T+a ₂ T ² +…+a _o T ⁿ …(2) Here, a ₀ , a ₁ ,…, a _o are scale factors
This is a coefficient that relates SCF and temperature T, and is determined in advance from experimental data using the least squares method or the like.
For this equation (2), a linear equation, a quadratic equation, etc. are selected depending on the characteristics of the rotational angular velocity detection means 32. Alternatively, the range of temperature T may be divided and a polygonal line approximation based on a linear equation may be used.

On the other hand, if it is determined in step 22 that the azimuth angle is to be measured, in step 25 the current input data g _i is compared with the offset value Z _i-1 one sampling before, and g _i and Z _i- It is determined whether the absolute value of the difference from ₁ is greater than the set value L, and if it is smaller, it is determined that there is no input, and in the offset correction process of step 26, the same offset correction process as that of step 23 is performed, and the current offset value is determined. Update the
Conversely, if it is larger, the offset correction process in step 26 is not performed. Note that the set value L used in step 25 is set to a sufficiently small value (for example, 4LSB) so as not to ignore input changes.

The process of converting the current input data g _i obtained in this way into an azimuth angle is performed in steps 27 and 28.

That is, in step 27, the difference ω _i =g _i −Z _i between the current input data g _i and the offset value Z _i is taken as true angular velocity data, and from this value, for example, the following
The cumulative value S _i is calculated using the trapezoidal integral formula shown in equation (3).

S _i = _i 〓 ^k=1 ω _k-1 + ω _k /2 (3) Also, in step 28, the cumulative value S _i obtained in step 27 is multiplied by the scale factor SCF obtained in step 24. Calculate the azimuth angle θ _i .

θ _i =SCF×S _i (4) The instantaneous azimuth angle θ _i calculated in this way is converted to the output buffer 1 in step 29.
7 is displayed on the display device 18 and is also reported to the external controller 37 via the communication buffer 16.

Therefore, it is possible to use an inexpensive gas rate sensor without using an expensive mechanical gyro with a complicated structure, and to detect the orientation with high accuracy without requiring a heater for temperature compensation.

In addition, in the above process, the scale factor during azimuth measurement is treated as constant because the temperature change is gradual, but if the measurement takes a long time, the scale factor correction process is performed. It is also possible to include the processing of

In addition, the coefficient a in equation (2) is calculated by using a separately provided absolute direction detection means, for example, when a moving object recognizes its own attitude using a television camera or the like at a stop position such as a station, and transmits the data. It is received via the buffer 16 and compared with the measured azimuth angle θ _i , and a new scale factor SCF is calculated by inversely calculating equation (4).
By calculating T and applying an algorithm such as the method of least squares from the ambient temperature T at that time, it can be determined automatically without prior experimentation.

〔Effect of the invention〕

As explained above, the present invention includes a temperature sensor,
Since the characteristics of the rotational angular velocity detection means are corrected by the offset correction means, the scale factor correction means, and the azimuth conversion processing means,
Even if a gas rate sensor is used, which is easy to maintain and inexpensive, but has strong temperature dependence and is considered to have poor accuracy, it is possible to independently detect the orientation of a moving body with high precision. In addition, since a heater for constant temperature is not required as in the conventional case, there is an effect that no warm-up time is required and a detection device with low power consumption can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing its electrical connections, and FIG. 3 is a partial sectional view showing the structure of the gas rate sensor section.
Fig. 4 is a flowchart of the direction detection program stored in the memory, Fig. 5 is a conceptual diagram showing the operating principle of the gas rate sensor, and Figs. 6 and 7 are characteristic lines showing the temperature characteristics of the gas rate sensor. 8 are configuration diagrams showing characteristic correction means in a conventional gas rate sensor. 7... Gas rate sensor, 9... Temperature sensor,
20...Microcomputer, 32...Rotation angular velocity detection means, 33...Offset correction means, 3
4... Scale factor correction means, 35... Azimuth conversion processing means, 36... Azimuth output means. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 Calculate the average value of the non-input data of the rotational angular velocity detection means using a gas rate sensor, the temperature sensor that detects the ambient temperature of this rotational angular velocity detection means, and the rotational angular velocity detection means, and use this as the current non-input data. an offset correction means for setting an offset value at the time of input, and a scale for calculating a scale factor based on a relationship coefficient between a temperature signal from the temperature sensor and a scale factor for converting the output of the rotational angular velocity detection means into an angular velocity. Azimuth conversion processing that calculates an azimuth based on the factor correction means, the current input data signal from the rotational angular velocity detection means, the offset value signal from the offset correction means, and the scale factor signal from the scale factor correction means. A mobile object azimuth detecting device comprising: a means for detecting an azimuth; and an azimuth output means for outputting the azimuth.