JP2009216484A - Positioning method, program, and positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption in a positioning device for performing positioning by a GPS and that by inertial navigation. <P>SOLUTION: A car navigation apparatus 1 determines whether an index value indicating the reception situation of GPS satellite signals satisfies first predetermined low-level conditions, turns on a sensor for inertial navigation when it is determined that the first predetermined low-level conditions are satisfied, and turns off the sensor when it is determined that the first predetermined low-level conditions are not satisfied. When it is determined that the first low-level conditions are satisfied, it is determined whether the index value satisfies the second low-level conditions that are lower than the first low-level conditions. When it is determined that the second low-level conditions are satisfied, an inertial navigation operation processing is performed and an inertial navigation operation position is determined to be an output position. When it is determined that the second low-level conditions are not satisfied, a GPS positioning position positioned by a GPS reception section 20 is determined to be an output position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a positioning method and the like performed by a positioning device that is mounted on a moving body and measures the current position of the moving body.

As a positioning system using an artificial satellite, a GPS (Global Positioning System) is widely known, and is used in a positioning device built in a mobile phone, a car navigation device, or the like. In GPS, the values of four parameters, the three-dimensional coordinate value indicating the position of the aircraft and the clock error, are calculated based on information such as the positions of a plurality of GPS satellites and the pseudoranges from each GPS satellite to the aircraft. The current position of the aircraft is measured by performing the required positioning calculation.

However, in environments where GPS satellite signals cannot be received, such as in tunnels or indoors, G
Since positioning by PS cannot be performed, a technique for performing inertial navigation calculation processing using an inertial navigation sensor such as a gyro sensor or an acceleration sensor to determine the current position is widely used (for example, Patent Document 1). ).
JP-A-6-341847

However, in the conventional technology, since it is necessary to always operate both the GPS positioning system and the positioning system using the inertial navigation sensor, there is a problem that power consumption in the positioning device increases. It was.

  The present invention has been made in view of the above-described problems.

A first invention for solving the above-described problem is a first positioning mode that is mounted on a mobile body and performs a predetermined positioning calculation based on a positioning signal received from a positioning satellite, thereby positioning the current position;
A positioning method performed by a positioning device having a second positioning mode for performing a predetermined inertial navigation calculation process using a predetermined inertial navigation sensor to determine a current position, and an index indicating a reception status of the positioning signal Determining whether the value satisfies a first low level condition determined in advance, and if it is determined that the first low level condition is satisfied, the inertial navigation sensor is activated, When it is determined that the first low level condition is not satisfied, control is performed to stop the inertial navigation sensor, and when it is determined that the first low level condition is satisfied, the first low level condition is determined. Determining whether the index value satisfies a second low level condition whose level is lower than one low level condition; and, if it is determined that the second low level condition is satisfied, the second positioning Positioning by mode There, the second when it is determined not to satisfy the low-level condition is a positioning method comprising: a carrying out the positioning by the first positioning mode.

As another invention, there is provided a first positioning mode for performing a predetermined positioning calculation based on a positioning signal received from a positioning satellite and positioning a current position, and a predetermined inertial navigation sensor. A positioning device having a second positioning mode for performing a predetermined inertial navigation calculation process and measuring a current position, wherein an index value indicating a reception status of the positioning signal is a predetermined first value.
A first low level condition determining unit that determines whether or not a low level condition is satisfied; and when it is determined that the first low level condition is satisfied, the inertial navigation sensor is activated, and the first
When it is determined that the low level condition is not satisfied, a control unit that performs control for stopping the inertial navigation sensor, and when it is determined that the first low level condition is satisfied, the first
When it is determined that the second low level condition is lower than the low level condition, the second low level condition determining unit that determines whether the index value satisfies the second low level condition, and the second low level condition is satisfied And a positioning unit that performs positioning in the second positioning mode and performs positioning in the first positioning mode when it is determined that the second low-level condition is not satisfied. Also good.

According to the first aspect of the invention, it is determined whether or not the index value indicating the reception status of the positioning signal satisfies the first low level condition determined in advance. When it is determined that the inertial navigation sensor is in an activated state and is not satisfied, control is performed to stop the inertial navigation sensor in a stopped state. In other words, when the positioning signal reception status is good, the inertial navigation sensor is stopped, so there is no need to always activate the inertial navigation sensor, and power consumption can be reduced.

If it is determined that the first low level condition is satisfied, whether or not the index value indicating the positioning signal reception status satisfies the second low level condition whose level is lower than the first low level condition. Is determined and satisfied, positioning is performed in the second positioning mode. If it is determined not to be satisfied, positioning is performed in the first positioning mode. Accordingly, reception of the positioning signal is performed. If the situation satisfies the second low level condition, the inertial navigation calculation process using the inertial navigation sensor is performed to measure the current position, and the positioning accuracy can be improved.

According to a second aspect of the present invention, in the positioning method of the first aspect, the first and second low-level conditions are: (1) a sky positioning satellite used for positioning in the first positioning mode; (2) an index value representing the accuracy of the positioning result in the first positioning mode, (3) an index value representing the number of positioning satellites used for positioning in the first positioning mode, (4) the first You may comprise the positioning method which is the conditions defined based on at least 1 of the index value showing the signal strength of the signal for positioning used for the positioning by 1 positioning mode.

According to the second invention, in combination with the first invention, the index value indicating the reception status of the positioning signal is related to the positioning satellite, the positioning signal, etc. used for positioning in the first positioning mode. It is determined whether or not the first and second low level conditions determined based on the index value are satisfied.

Further, as a third invention, the positioning method according to the first or second invention, wherein the stop of the moving body is detected, and the detection temperature of a temperature sensor that detects the air temperature when the moving body stops. The detection result of the inertial navigation sensor is stored in association with the detected temperature of the temperature sensor and the detection result of the inertial navigation sensor. Calculating a temperature compensation model equation for compensating for the detection error, and calculating a compensation value of the detection error of the inertial navigation sensor corresponding to the current detected temperature of the temperature sensor from the temperature compensation model equation; The positioning method may further comprise compensating for the above.

The output value of the inertial navigation sensor includes a temperature-dependent bias called a zero point bias. According to the third invention, the detection error of the inertial navigation sensor using a so-called field calibration method. By calculating a temperature compensation model equation that compensates for this, it is possible to appropriately compensate for the zero point bias of the inertial navigation sensor.

Further, as a fourth invention, in the positioning method according to the third invention, when the inertial navigation sensor is in a stopped state when the moving body is stopped, after starting a predetermined stable operation time, You may comprise the positioning method which further includes matching and memorize | stores the detection temperature of a temperature sensor, and the detection result of the said sensor for inertial navigation.

According to the fourth aspect of the invention, in consideration of the fact that the output is not stable for a while after the inertial navigation sensor is activated, after the activation of the predetermined stable operation time, Since the detection results of the inertial navigation sensor are stored in association with each other, a highly reliable temperature compensation model equation can be calculated.

Further, as a fifth invention, in the positioning method of the third or fourth invention, the inertial navigation sensor includes an acceleration sensor, and detects the posture of the moving body; Calculating a gravitational acceleration component included in the detection result based on the posture of the body when stopped and the detection result of the acceleration sensor, and calculating the temperature compensation model equation includes: Considering the influence of the gravitational acceleration component included in the detection result of the acceleration sensor,
You may comprise the positioning method which is calculating the said temperature compensation model type | formula.

According to the fifth aspect of the invention, since the temperature compensation model equation for compensating for the detection error of the acceleration sensor in consideration of the influence of the gravitational acceleration is calculated, it is possible to more accurately compensate the zero point bias of the acceleration sensor. Become.

Further, as a sixth invention, a program for causing a computer built in a positioning device mounted on a mobile object to perform the positioning method of any of the first to fifth inventions may be configured.

Hereinafter, an example of an embodiment suitable for the present invention will be described with reference to the drawings. In the following, a car navigation device mounted on an automobile, which is a kind of mobile body, will be described as an example of a positioning device, and a case where a GPS (Global Positioning System) is used as a positioning system will be described. Possible embodiments are not limited to these.

1. Functional Configuration FIG. 1 is a block diagram showing a functional configuration of a car navigation apparatus 1 in the present embodiment. The car navigation apparatus 1 includes a GPS antenna 10, a GPS receiver 20, a host CPU (Central Processing Unit) 30, an operation unit 40, a display unit 50, a gyro sensor 60, an acceleration sensor 70, and a temperature sensor 90. And ROM (Read Only Memory) 1
00 and a RAM (Random Access Memory) 110.

The GPS antenna 10 is a radio frequency (Ra) including a GPS satellite signal transmitted from a GPS satellite.
dio Frequency) is an antenna that receives a signal, and outputs the received signal to the GPS receiver 20. The GPS satellite signal is a PRN (Pseudo R) which is a kind of spreading code that differs for each satellite.
andom noise) code 1.57542 [G modulated directly by spread spectrum system
Hz] communication signal. The PRN code is a pseudo-random noise code having a repetition period of 1 ms with a code length of 1023 chips as one PN frame.

The GPS receiving unit 20 is a positioning circuit that measures the current position of the car navigation device 1 based on a signal output from the GPS antenna 10, and is a functional block corresponding to a so-called GPS receiver. The GPS receiving unit 20 includes an RF (Radio Frequency) receiving circuit unit 21,
And a baseband processing circuit unit 23. The RF receiving circuit unit 21 and the baseband processing circuit unit 23 can be manufactured as separate LSIs (Large Scale Integration) or as a single chip.

The RF receiving circuit unit 21 is an RF signal processing circuit block, and generates an oscillation signal for RF signal multiplication by dividing or multiplying a predetermined local oscillation signal. Then, by multiplying the generated oscillation signal by the RF signal output from the GPS antenna 10, the RF signal is down-converted to an intermediate frequency signal (hereinafter referred to as an "IF (Intermediate Frequency) signal"), After the IF signal is amplified, it is converted into a digital signal by an A / D converter and output to the baseband processing circuit unit 23.

The baseband processing circuit unit 23 performs correlation processing or the like on the IF signal output from the RF reception circuit unit 21 to capture and extract GPS satellite signals, decodes the data, and extracts navigation messages, time information, and the like. This is a circuit unit that performs positioning calculation. The baseband processing circuit unit 23
It comprises a CPU as a processor and ROM and RAM as memories. As the positioning calculation, for example, a known technique such as positioning calculation using the least square method can be applied.

The host CPU 30 is a processor that comprehensively controls each unit of the car navigation apparatus 1 according to various programs such as a system program stored in the ROM 100.
The host CPU 30 determines an output position that is a position to be displayed on the navigation screen according to the positioning program 103. Then, according to the navigation program 101, a navigation screen in which the output position is plotted is generated and displayed on the display unit 50.

The operation unit 40 is an input device configured by a touch panel, a button switch, or the like, for example, and outputs a pressed icon or button signal to the host CPU 30. This operation unit 40
With this operation, various instructions such as a destination input and a navigation screen display request are input.

The display unit 50 is composed of an LCD (Liquid Crystal Display) or the like, and the host CPU 3
It is a display device that performs various displays based on display signals input from zero. The display unit 50 includes
A navigation screen or the like is displayed.

The gyro sensor 60 is a triaxial sensor (angular velocity sensor) that detects the rotation of the automobile by detecting the angular velocity, and outputs the detected triaxial angular velocity to the host CPU 30. The gyro sensor 60 is a kind of inertial navigation sensor.

The acceleration sensor 70 is a triaxial sensor that detects acceleration and detects the moving state of the automobile, and outputs the detected triaxial acceleration to the host CPU 30. The acceleration sensor 70 is also a kind of inertial navigation sensor.

但し、「Ｔ₀」は基準温度、「Ｂ_T0」は基準温度Ｔ₀におけるゼロ点バイアス、「ｋ₁」
は１次の温度係数、「ｋ₂」は２次の温度係数をそれぞれ示している。 The output of the gyro sensor 60 and the output of the acceleration sensor 70 include a so-called zero point bias. The zero point bias is an output value of the sensor in a state where neither the angular velocity nor the acceleration is present (for example, when the automobile is completely stopped (at rest)), and has a temperature dependency that varies depending on a temperature change. The zero point bias “B _T ” at the temperature “T” can be expressed by, for example, a second-order temperature compensation model equation as shown in the following equation (1).

However, “T ₀ ” is the reference temperature, “B _T0 ” is the zero point bias at the reference temperature T ₀ , and “k ₁ ”.
Represents a first-order temperature coefficient, and “k ₂ ” represents a second-order temperature coefficient.

When the host CPU 30 determines that the vehicle is stopped in the positioning process, the host CPU 30 performs field calibration and calculates / updates the above-described secondary temperature compensation model formula for each of the gyro sensor 60 and the acceleration sensor 70. To do. When the vehicle is traveling, the zero point bias (detection error) of the gyro sensor 60 and the acceleration sensor 70 is compensated using the latest temperature compensation model formula.

However, it should be noted that the original output value of the acceleration sensor 70 includes the influence of gravitational acceleration due to the attitude of the automobile. Therefore, when calculating the temperature compensation model formula for the acceleration sensor 70, the output correction value is obtained by performing the process of correcting the influence of the gravitational acceleration due to the attitude of the vehicle on the original output value of the acceleration sensor 70, and calculating the output correction value. It is necessary to calculate the temperature compensation model equation using the correction value.

Specifically, for example, as shown in FIG. 2, the traveling direction of the vehicle is “x axis” (straight forward direction is the positive direction), and the left and right direction is “y axis” (right direction is the positive direction). ) Consider an orthogonal three-axis moving body coordinate system in which the height direction with respect to the x-axis is the “z-axis” (the downward direction is the positive direction). in this case,
The output correction value of the acceleration sensor 70 in consideration of the influence of gravitational acceleration is calculated according to the following equation (2).

However, “a _x ”, “a _y ”, and “a _z ” are the original output values of the acceleration sensor 70 for the x-axis, y-axis, and z-axis, respectively, “B _x ”, “B _y ”, and “B _z ”. Are output correction values of the acceleration sensor 70 for the x-axis, y-axis, and z-axis, “g” is gravitational acceleration, and “θ” and “φ” are calculated based on detection results of the gyro sensor 60, respectively. The pitch angle (rotation angle about the y-axis) and the roll angle (rotation angle about the x-axis), which are the posture angles of the figure, are shown.

The temperature sensor 90 is a contact-type or non-contact-type sensor that detects the ambient temperature and outputs the detection result to the host CPU 30.

The ROM 100 is a read-only storage device, and stores a system program for the host CPU 30 to control the car navigation apparatus 1 and various programs and data for realizing a navigation function.

The RAM 110 is a readable / writable storage device, and forms a work area for temporarily storing a system program executed by the host CPU 30, various processing programs, data being processed in various processing, processing results, and the like.

FIG. 3 is a diagram illustrating an example of data stored in the ROM 100. In ROM100,
The navigation program 101 read out by the host CPU 30 and executed as navigation processing, the positioning program 103 executed as positioning processing (see FIGS. 8 to 10), and map information data for generating a navigation screen. Map data 10
5 is stored.

In the navigation process, the host CPU 30 uses the map information stored in the map data 105 to perform a map matching process for correcting the output position determined by the positioning process on the road, and plots the corrected position. In this process, a navigation screen is generated and displayed on the display unit 50. Since the map matching process is known,
Detailed description is omitted.

In the positioning process, when the host CPU 30 determines that the vehicle is stopped, the field calibration is performed, and each of the gyro sensor 60 and the acceleration sensor 70 that are inertial navigation sensors has a detection error of zero. This is a process for calculating / updating a temperature compensation model formula for compensating the point bias. When the vehicle is running, the zero point bias of the gyro sensor 60 and the acceleration sensor 70 is compensated according to the latest temperature compensation model formula.

Further, the host CPU 30 determines whether or not the index value indicating the reception status of the GPS satellite signal satisfies a predetermined first low-level condition, and the inertial navigation sensor is turned on according to the determination result. Switch / OFF to measure the current position. Then, it is determined whether or not the above-described index value satisfies a second low level condition whose level is lower than that of the first low level situation, and the positioning position measured by the GPS receiving unit 20 according to the determination result (Hereinafter referred to as “GPS positioning position”) and a positioning position obtained by inertial navigation calculation processing (hereinafter referred to as “inertial navigation calculation position”) are determined as output positions. . The positioning process will be described later in detail using a flowchart.

FIG. 4 is a diagram illustrating an example of data stored in the RAM 110. In RAM110,
Measurement history data 111, gyro sensor zero point bias reference data 113, acceleration sensor zero point bias reference data 115, and gyro sensor temperature compensation model equation data 117
And acceleration sensor temperature compensation model equation data 119 are stored.

FIG. 5 is a diagram illustrating an example of a data configuration of the measurement history data 111. Measurement history data 1
11 includes a triaxial angular velocity 11 detected by the gyro sensor 60 at each time 1111.
12, three-axis acceleration 1113 detected by the acceleration sensor 70, temperature 1114 detected by the temperature sensor 90, GPS positioning position 1115, and inertial navigation calculation position 1116
Are stored in association with each other. The measurement history data 111 is stored in the host CPU 3 in the positioning process.
Updated by 0.

FIG. 6 is a diagram illustrating an example of a data configuration of the gyro sensor zero point bias reference data 113. The gyro sensor zero point bias reference data 113 includes a temperature average value 1131 that is an average value of temperatures detected by the temperature sensor 90 when the automobile is stopped, and the gyro sensor 6.
An original output value average value 1133 that is an average value of zero original output values is stored in association with each other. The gyro sensor zero point bias reference data 113 is updated by the host CPU 30 in the positioning process.

FIG. 7 is a diagram illustrating an example of a data configuration of the acceleration sensor zero point bias reference data 115. The acceleration sensor zero point bias reference data 115 includes a temperature average value 1151 that is an average value of temperatures detected by the temperature sensor 90 when the automobile is stopped, and an output correction value 1153 in which the influence of the gravitational acceleration is corrected according to the equation (2). Are stored in association with each other. The acceleration sensor zero point bias reference data 115 is updated by the host CPU 30 in the positioning process.

The gyro sensor temperature compensation model formula data 117 is data in which the temperature compensation model formula of the gyro sensor 60 is stored. In the positioning process, the host CPU 30 uses the least square method, for example, for the first order based on the data of the plurality of temperature average values 1131 and original output value average values 1133 stored in the gyro sensor zero point bias reference data 113. Temperature coefficient “k ₁ ”
And the secondary temperature coefficient “k ₂ ” is calculated to calculate the secondary temperature compensation model expression expressed by the equation (1). Then, the gyro sensor temperature compensation model formula data 117 is updated with the calculated temperature compensation model formula.

Similarly, the acceleration sensor temperature compensation model formula data 119 is data in which the temperature compensation model formula of the acceleration sensor 70 is stored. In the positioning process, the host CPU 30 uses the least square method, for example, to calculate the first-order temperature coefficient “k” based on the data of the plurality of temperature average values 1151 and output correction values 1153 stored in the acceleration sensor zero point bias reference data 115. ₁ ”and 2
By obtaining the next temperature coefficient “k ₂ ”, a second-order temperature compensation model expression represented by the expression (1) is calculated. Then, the acceleration sensor temperature compensation model formula data 119 is updated with the calculated temperature compensation model formula.

2. Flow of Processing FIGS. 8 to 10 are flowcharts showing the flow of positioning processing executed in the car navigation device 1 when the positioning program 103 stored in the ROM 100 is read and executed by the host CPU 30. .

The positioning process is performed together with the reception of the GPS satellite signal by the RF receiving circuit unit 21 and the host CPU.
Reference numeral 30 denotes a process for starting execution when it is detected that a positioning start instruction is operated on the operation unit 40. Note that the positioning process may be started when the power-on operation of the car navigation device 1 is detected by linking the power on / off of the car navigation device 1 and the activation / stop of the GPS.

Further, although not specifically described, the RF by the GPS antenna 10 is performed during the following positioning process.
Signal reception, down-conversion to an IF signal by the RF receiving circuit unit 21, acquisition / tracking of GPS satellite signals by the baseband processing circuit unit 23, calculation of pseudoranges, positioning calculation, etc. are performed at any time. Shall. In addition, the measurement history data 111 in the RAM 110 is updated as needed by the host CPU 30 according to the detection results of the gyro sensor 60, the acceleration sensor 70, and the temperature sensor 90.

First, the host CPU 30 determines whether or not the automobile is stopped (still) (step A1). This determination is made by determining whether the speed of the vehicle is “0” based on the detection result of the vehicle speed sensor provided in the vehicle, for example, or by positioning positions for the past several times (for example, “3 seconds”). Can be performed by determining whether or not they are located at a short distance (for example, “within 5 m”). It is also possible to determine whether to stop the vehicle based on the detection results of the gyro sensor 60 and the acceleration sensor 70.

If it is determined in step A1 that the vehicle is stopped (step A1; Yes)
The host CPU 30 determines whether or not the power of the inertial navigation sensor is “OFF” (step A3). And when it determines with the power supply of the sensor for inertial navigation being "ON" (step A3; No), the present temperature is acquired from the temperature sensor 90 (step A5).

Further, the host CPU 30 acquires an original output value that is an original output value from the gyro sensor 60 (step A7), and acquires an original output value that is an original output value from the acceleration sensor 70 (step A9). Then, the host CPU 30 determines whether or not a predetermined time (for example, “20 seconds”) has elapsed (step A11), and when determining that it has not yet elapsed (step A11; No), returns to step A5. .

When it is determined in step A11 that the predetermined time has elapsed (step A11)
; Yes), the host CPU 30 calculates the average value of the temperatures acquired during a predetermined time (step A13) and calculates the average value of the acquired original output values of the gyro sensor 60 (step A13).
Step A15). Then, the calculated average value 1131 of the temperature and the average value 1133 of the original output value of the gyro sensor 60 are associated with each other and stored in the gyro sensor zero point bias reference data 113 of the RAM 110 (step A17).

Next, the host CPU 30 calculates an average value of the original output values of the acceleration sensor 70 acquired during a predetermined time (step A19). Further, the host CPU 30 calculates the attitude angle (pitch angle “θ” and roll angle “φ”) of the vehicle based on the detection result of the gyro sensor 60 immediately before the stop of the vehicle compensated for zero point bias (step A21). ).

Then, the host CPU 30 considers the influence of the gravity acceleration component according to the equation (2) using the average value of the original output value of the acceleration sensor 70 calculated in step A19 and the attitude angle of the vehicle calculated in step A21. The calculated output correction value is calculated (step A23). Then, the temperature average value 1151 calculated in step A13 and the output correction value 1153 calculated in step A23 are associated with each other, and the acceleration sensor zero point bias reference data 115 in the RAM 110 is associated.
(Step A25).

Next, the host CPU 30 determines a predetermined elapsed time (
For example, it is determined whether or not “1 hour” has elapsed (step A27). If it is determined that it has not yet elapsed (step A27; No), the process proceeds to step A37.

When it is determined in step A27 that the predetermined elapsed time has elapsed (step A27; Yes), the host CPU 30 determines that the gyro sensor zero point bias reference data 11
3, the first-order temperature coefficient “k ₁ ” and the second-order temperature coefficient “k ₂ ” using, for example, the least square method based on the data of the plurality of temperature average values 1131 and original output value average values 1133. ”Is calculated, and a second-order temperature compensation model equation represented by the equation (1) is calculated (step A29). Then, the gyro sensor temperature compensation model formula data 117 in the RAM 110 is updated with the calculated temperature compensation model formula (step A31).

Similarly, the host CPU 30 uses the least square method, for example, based on the data of the plurality of temperature average values 1151 and the output correction value 1153 stored in the acceleration sensor zero point bias reference data 115, for example, the first-order temperature coefficient “k”. ₁ ”and the second-order temperature coefficient“ k ₂ ”are obtained, and a second-order temperature compensation model expression represented by the expression (1) is calculated (step A33). Then, the acceleration sensor temperature compensation model formula data 119 in the RAM 110 is updated with the calculated temperature compensation model formula (step A35).

Next, the host CPU 30 determines whether or not a positioning end instruction has been given by the user via the operation unit 40 (step A37). If it is determined that the positioning has not been performed (step A3)
7; No), it returns to step A1. If it is determined that a positioning end instruction has been issued (step A37; Yes), the positioning process ends.

On the other hand, if it is determined in step A3 that the power of the inertial navigation sensor is “OFF” (step A3; Yes), the host CPU 30 turns the power of the gyro sensor 60 “O”.
N ”(step A39), and a predetermined warm-up time (for example,“ 10 ”).
Seconds ") (step A41), and if it has not yet elapsed (step A41; No), it waits as it is. The gyro sensor 6 immediately after power-on.
Since the output of 0 is not stable, data acquisition is not started until the output is stabilized.

If it is determined that the predetermined warm-up time has elapsed (step A41;
Yes) The host CPU 30 acquires the current temperature from the temperature sensor 90 (step A43), and acquires the original output value, which is the original output value, from the gyro sensor 60 (step A45).

Next, the host CPU 30 determines whether or not a predetermined time (for example, “20 seconds”) has elapsed (step A47), and when determining that it has not yet elapsed (step A47; No).
Return to Step A43. If it is determined that the predetermined time has elapsed (step A47)
Yes), the power supply of the gyro sensor 60 is turned “OFF” (step A49).

Next, the host CPU 30 calculates the average value of the temperatures acquired during a predetermined time (step A51) and calculates the average value of the acquired original output values of the gyro sensor 60 (step A53). Then, the calculated average value 1131 of the temperature and the average value 1133 of the original output value of the gyro sensor are associated with each other and stored in the gyro sensor zero point bias reference data 113 of the RAM 110 (step A55). Then, the host CPU 30 executes step A2.
The processing is shifted to 7.

When it is determined in step A1 that the vehicle is not stopped, that is, is moving (step A1; No), the host CPU 30 stores the latest data stored in the gyro sensor temperature compensation model equation data 117 of the RAM 110. The zero point bias at the current temperature detected by the temperature sensor 90 is calculated according to the temperature compensation model equation, and the zero point bias of the gyro sensor 60 is compensated using the calculated zero point bias (step A57).
).

Similarly, the host CPU 30 uses the acceleration sensor temperature compensation model formula data 1 in the RAM 110.
19, the zero point bias at the current temperature detected by the temperature sensor 90 is calculated according to the latest temperature compensation model equation stored in 19, and the zero point bias of the acceleration sensor 70 is compensated using the calculated zero point bias. (Step A59).

Next, the host CPU 30 determines whether or not the index value indicating the reception status of the GPS satellite signal satisfies the first low level condition (step A61). For example, the first low level condition is (
1) PDOP which is an index value indicating the sky arrangement of GPS satellites used by the GPS receiver 20 for positioning
(Position Dilution of Precision) value exceeds “3”, (2) GPS receiver 20
The standard deviation of the GPS positioning position measured by (hereinafter referred to as “position σ value”) exceeds “10 m”. (3) The number of GPS satellites used for positioning by the GPS receiver 20 (hereinafter “ The number of satellites used for positioning is less than “5”. (4) GP used by GPS receiver 20 for positioning
The average value of the signal intensity of the S satellite signal (hereinafter referred to as “signal intensity average value”) is “−135 dB.
It is a condition determined based on at least one of m ″.

Here, as shown in the following equation (3), the PDOP value is defined as the square root of the trace of the diagonal element of the observation matrix by the gaze direction vector from the observation point to the GPS satellite.

但し、「Ｃｏｖ（δｘ）」は位置σ値、「Ｈ」は観測点から衛星への視線方向ベクトル
による観測行列、「Ｃｏｖ（Ｒ）」は疑似距離の分散共分散行列、添え字の「Ｔ」は転置
行列をそれぞれ示している。 The position σ value is calculated according to the following equation (4).

However, “Cov (δx)” is a position σ value, “H” is an observation matrix based on a gaze direction vector from the observation point to the satellite, “Cov (R)” is a pseudo-distance variance-covariance matrix, and a subscript “T” "Indicates a transposed matrix, respectively.

And when it determines with satisfying 1st low level conditions (step A61; Yes),
The host CPU 30 turns on the power supply of the inertial navigation sensor (step A63). Satisfying the first low level condition means that the reception status of the GPS satellite signal is getting worse. Therefore, in this case, in preparation for positioning by inertial navigation, the power of the inertial navigation sensor is turned “ON” to warm up the inertial navigation sensor.

Thereafter, the host CPU 30 determines whether or not the index value indicating the reception status of the GPS satellite signal satisfies a second low level condition whose level is lower than the first low level condition (step A6).
5). The second low level condition is, for example, (1) PDOP value exceeds “4”, (2) Position σ value exceeds “20 m”, (3) Number of positioning satellites is less than “4” (4) The condition determined based on at least one of the signal intensity average values of less than “−140 dBm”. In addition, the threshold value of each index value in the first and second low level conditions is merely an example, and may be changed as appropriate.

And when it determines with satisfying 2nd low level conditions (step A65; Yes),
The host CPU 30 performs a known inertial navigation calculation process using the detection result of the inertial navigation sensor to calculate the position of the own apparatus (step A67), and determines the calculated inertial navigation calculation position as an output position (step A69). ). Satisfying the second low-level condition means that the reception status of the GPS satellite signal is extremely poor or that positioning by GPS is impossible in the first place. Therefore, in this case, inertial navigation calculation processing is performed to determine the current position, and that positioning position is determined as the output position.

When it is determined in step A61 that the first low level condition is not satisfied (step A61; No), the host CPU 30 turns off the power of the inertial navigation sensor (step A71). And after determining the GPS positioning position acquired from the GPS receiving part 20 as an output position (step A73), it transfers a process to step A37. The fact that the first low level condition is not satisfied means that the GPS satellite signal reception status is good. Therefore, the power consumption of the inertial navigation sensor can be reduced to “OFF” to reduce power consumption. I am trying.

If it is determined in step A65 that the second low level condition is not satisfied (step A65; No), the host CPU 30 shifts the process to step A73 and performs GPS.
The positioning position is determined as the output position. Even if the first low level condition is satisfied, if the second low level condition is not satisfied, it is estimated that the GPS positioning result will be reliable to some extent, and the GPS positioning position will be used as the output position. ing.

3. Effects According to the present embodiment, in the car navigation apparatus 1, it is determined whether or not the index value indicating the reception status of the GPS satellite signal satisfies the first low-level condition set in advance, and it is determined that the index value is satisfied. If it is determined that the inertial navigation sensor is in the activated state (ON), and it is determined that the inertial navigation sensor is not satisfied, the inertial navigation sensor is controlled to be stopped (OFF). That is, when the GPS satellite signal reception status is good, the inertial navigation sensor is stopped.
It is not necessary to always activate the inertial navigation sensor, and power consumption can be reduced.

When it is determined that the first low level condition is satisfied, it is determined whether or not the index value described above satisfies the second low level condition whose level is lower than that of the first low level condition. If it is determined, inertial navigation calculation processing is performed and the inertial navigation calculation position is determined as the output position. If it is determined that the second low-level condition is not satisfied, positioning is performed by the GPS receiver 20. The GPS positioning position is determined as the output position. Therefore, when the GPS satellite signal reception status is such that the second low-level condition is satisfied, positioning accuracy is obtained by performing inertial navigation calculation processing using the inertial navigation sensor and positioning the current position. Can be improved.

4). Modified example 4-1. Electronic Device The present invention can be applied to any electronic device provided that it has a positioning device. For example, the present invention can be similarly applied to a notebook personal computer, a PDA (Personal Digital Assistant), and the like. However, when installed on the moving body, it is necessary to fix the relative posture of the electronic device with respect to the moving body. That is, it is necessary to always make the relative relationship between the coordinate system detected by the inertial navigation sensor of the electronic device and the moving body coordinate system constant, and to detect the three-axis values of the moving body coordinate system. In other words, the relative posture of the electronic device with respect to the moving body is arbitrary as long as the values of the three axes in the moving body coordinate system can be detected.

4-2. Mobile body The mobile body is not necessarily limited to an automobile, and the present invention can also be applied to mobile bodies such as buses and trains and pedestrians.

4-3. Satellite positioning system In the above-described embodiment, the GPS has been described as an example of the satellite positioning system.
AS (Wide Area Augmentation System), QZSS (Quasi Zenith Satellite System)
Other satellite positioning systems such as GLONASS (GLObal NAvigation Satellite System) and GALILEO may be used.

4-4. Differentiation of processing Part or all of the processing performed by the host CPU 30 is performed by the CPU of the baseband processing circuit unit 23.
You may decide to do. Specifically, for example, the CPU of the baseband processing circuit unit performs the positioning process. Then, the host CPU 30 performs a map matching process or the like on the output position obtained by the positioning process to generate a navigation screen, and performs a navigation process for displaying the generated navigation screen on the display unit 50. Further, the CPU may perform all the processes performed by the host CPU 30 including the navigation process.

4-5. Sensor ON / OFF Control In the above-described embodiment, it has been described that only the inertial navigation sensor is switched on / off, but the temperature sensor 90 is also turned on / off as necessary.
It is good also as switching.

Specifically, when the GPS satellite signal reception status satisfies the first low level condition, the power of all the sensors including the temperature sensor 90 is turned “ON” and the first low level condition is not satisfied. Performs control to turn off the power of all sensors. In addition, when field calibration is performed when the vehicle is stopped, if all the sensor power is “OFF”, at least the gyro sensor 60 and the temperature sensor 90 are powered on after field calibration is performed. Then, control is performed to turn off the power of all sensors again.
As a result, the power consumption can be further reduced.

4-6. Temperature compensation model equation In addition to correcting the zero point bias of the inertial navigation sensor using the second-order temperature compensation model equation, the zero-point bias is corrected using the third-order or higher temperature compensation model equation. It is good as well. In this case, for example, the least square method is used in each of the case where the gyro sensor temperature compensation model equation is calculated in step A29 of the positioning process in FIG. 9 and the case where the acceleration sensor temperature compensation model equation is calculated in step A33. In addition to the primary and secondary temperature coefficients “k ₁ ” and “k ₂ ”, a third-order or higher temperature coefficient “k ₃ ,...” May be obtained.

The block diagram which shows the function structure of a car navigation apparatus. The figure which shows an example of a mobile body coordinate system. The figure which shows an example of the data stored in ROM. The figure which shows an example of the data stored in RAM. The figure which shows an example of a data structure of measurement log | history data. The figure which shows an example of a data structure of a gyro sensor zero point bias reference data. The figure which shows an example of a data structure of acceleration sensor zero point bias reference data. The flowchart which shows the flow of a positioning process. The flowchart which shows the flow of a positioning process. The flowchart which shows the flow of a positioning process.

Explanation of symbols

1 car navigation device, 10 GPS antenna, 20 GPS receiver,
21 RF receiving circuit section, 23 baseband processing circuit section, 30 host CPU,
40 operation unit, 50 display unit, 60 gyro sensor, 70 acceleration sensor,
90 temperature sensor, 100 ROM, 110 RAM

Claims (7)

A first positioning mode in which a predetermined positioning calculation is performed based on a positioning signal received from a positioning satellite and mounted on a mobile body, and a predetermined inertial navigation calculation using a predetermined inertial navigation sensor. A positioning method performed by a positioning device having a second positioning mode for performing processing and positioning a current position,
Determining whether or not the index value indicating the reception status of the positioning signal satisfies a predetermined first low level condition;
When it is determined that the first low level condition is satisfied, the inertial navigation sensor is activated, and when it is determined that the first low level condition is not satisfied, the inertial navigation sensor is stopped. Performing control to the state,
When it is determined that the first low level condition is satisfied, it is determined whether or not the index value satisfies a second low level condition whose level is lower than the first low level condition;
If it is determined that the second low level condition is satisfied, positioning is performed in the second positioning mode. If it is determined that the second low level condition is not satisfied, positioning is performed in the first positioning mode. And doing
Positioning method including. The first and second low-level conditions represent (1) an index value indicating a sky arrangement of positioning satellites used for positioning in the first positioning mode, and (2) accuracy of positioning results in the first positioning mode. Index value, (3) an index value indicating the number of positioning satellites used for positioning in the first positioning mode,
(4) The positioning method according to claim 1, which is a condition determined based on at least one of index values representing signal strength of a positioning signal used for positioning in the first positioning mode. Detecting the stop of the moving body;
Storing the detected temperature of the temperature sensor for detecting the temperature and the detection result of the inertial navigation sensor in association with each other when the moving body is stopped;
From the stored detection temperature of the temperature sensor and the detection result of the inertial navigation sensor,
Calculating a temperature compensation model equation that compensates for the detection error of the inertial navigation sensor for an arbitrary temperature;
Calculating a compensation value of a detection error of the inertial navigation sensor corresponding to a current detection temperature of the temperature sensor from the temperature compensation model equation, and compensating the detection error;
The positioning method according to claim 1 or 2, further comprising: If the inertial navigation sensor is stopped when the moving body is stopped, a predetermined stable operation time is started, and then the temperature detected by the temperature sensor is associated with the detection result of the inertial navigation sensor. The positioning method according to claim 3, further comprising storing. The inertial navigation sensor includes an acceleration sensor,
Detecting the posture of the moving body;
Calculating a gravitational acceleration component included in the detection result based on the posture of the moving body when stopped and the detection result of the acceleration sensor;
Further including
Calculating the temperature compensation model formula is to calculate the temperature compensation model formula in consideration of the influence of the gravitational acceleration component included in the detection result of the acceleration sensor.
The positioning method according to claim 3 or 4. The program for making the computer incorporated in the positioning apparatus mounted in a moving body perform the positioning method as described in any one of Claims 1-5. A first positioning mode in which a predetermined positioning calculation is performed based on a positioning signal received from a positioning satellite and mounted on a mobile body, and a predetermined inertial navigation calculation using a predetermined inertial navigation sensor. A positioning device having a second positioning mode for performing processing and positioning a current position,
A first low level condition determining unit that determines whether or not an index value indicating a reception status of the positioning signal satisfies a predetermined first low level condition;
When it is determined that the first low level condition is satisfied, the inertial navigation sensor is activated, and when it is determined that the first low level condition is not satisfied, the inertial navigation sensor is stopped. A control unit for controlling the state, and
When it is determined that the first low level condition is satisfied, a second low level condition determination is performed that determines whether the index value satisfies a second low level condition that is lower than the first low level condition. And
If it is determined that the second low level condition is satisfied, positioning is performed in the second positioning mode. If it is determined that the second low level condition is not satisfied, positioning is performed in the first positioning mode. A positioning unit that performs
Positioning device equipped with.

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