JP3975416B2 - Navigation device, sensor output calibration method, and navigation processing program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a navigation device and a recording medium, and more particularly to a navigation device that detects a current position and posture of a vehicle with reference to a signal output from a sensor unit having an acceleration sensor or an angular velocity sensor, and such processing to a computer. The present invention relates to a computer-readable recording medium on which a program to be executed is recorded.
[0002]
[Prior art]
For example, in a navigation apparatus represented by a car navigation system or the like, a current position or posture of a vehicle is detected with reference to output signals from an acceleration sensor or an angular velocity sensor, and a CD-ROM (Compact Disk) is detected according to the detection result. -Read Only Memory) and the like, the map information recorded in the display device is appropriately processed and displayed on the display device.
[0003]
FIG. 12 is a block diagram showing a configuration example of such a conventional navigation apparatus.
In this figure, the sensor unit 1 includes an angular velocity sensor 1a that detects angular velocity and an acceleration sensor 1b that detects acceleration.
[0004]
The arithmetic processing unit 2 refers to the output signal of the sensor unit 1 and detects the current position of the vehicle (hereinafter abbreviated as the current position) and the current state (hereinafter abbreviated as the current state). And after acquiring the map of the area | region corresponding to a present position among the map information memorize | stored in the memory | storage device 3, and processing it suitably, it outputs to the display apparatus 4 and displays it.
[0005]
The storage device 3 is constituted by a CD-ROM drive, for example, and stores map information, a program executed by the arithmetic processing unit 2, and the like.
The display device 4 is configured by, for example, an LCD (Liquid Crystal Display), and displays a map supplied from the arithmetic processing unit 2 and also displays, for example, road information.
[0006]
[Problems to be solved by the invention]
However, in such a conventional navigation device, the current position and the current posture calculated by the arithmetic processing unit 2 include an error depending on the fluctuation error component included in the output of the sensor and the posture of the navigation device attached to the vehicle. There was a situation that would occur.
[0007]
As a method for canceling an error included in a signal output from such a sensor, for example, a method shown in FIG. 13 has been proposed.
When this flowchart is started, the following processing is executed.
[S1] The arithmetic processing unit 2 inputs an output signal from the sensor unit 1.
[S2] The calculation processing unit 2 determines whether or not the vehicle is stopped. If the vehicle is stopped, the process proceeds to step S3. Otherwise, the process proceeds to step S4.
[S3] The arithmetic processing unit 2 corrects the output signal of the sensor.
[S4] The arithmetic processing unit 2 performs normal processing (processing for displaying a map in accordance with a signal from the sensor unit 1).
[0008]
According to such processing, when the vehicle is stopped (when the output of the sensor unit 1 is stable), an error component (for example, an offset component caused by a variation error or the mounting posture of the sensor unit 1). Can be detected and the output signal of the sensor can be corrected.
[0009]
By the way, in order to execute such processing, it is necessary to accurately determine whether or not the vehicle is stopped. However, it is very difficult to make such a determination accurately, and the accuracy is extremely low.
[0010]
Therefore, a method of making such a determination using a vehicle speed pulse detected by a vehicle speed sensor has also been proposed. However, in order to use the vehicle speed pulse from the vehicle speed sensor, it is necessary to connect the navigation device and the vehicle speed sensor, so that there is a problem that the installation work of the navigation device becomes complicated.
[0011]
The present invention has been made in view of the above points, and reliably detects a stop state of a vehicle and eliminates an error included in an output signal of a sensor unit without complicating installation work. It is an object of the present invention to provide a navigation device that enables the above.
[0012]
[Means for Solving the Problems]
In order to solve such problems, in the present invention, in a navigation device that detects the current position and posture of a vehicle based on an output signal from a sensor unit having an acceleration sensor, an output value of the output signal from the sensor unit and a predetermined time And the difference between the output value between the sampling points and the reference value set as the smallest output value is calculated to determine that the vehicle is stopped, and the absolute value of the obtained difference value is If it is determined to be smaller than the set threshold, by the vehicle so as to calibrate the error contained in the output signal from the sensor unit determines that the stopped state, the vehicle is stopped is once determined that the error component included in the output signal of the sensor unit can be reliably corrected can accurately determine the stop of the vehicle, thus resulting the purpose It becomes possible to accurately determine the stop of the vehicle, the error component included in the output signal from the sensor portion can be reliably corrected.
[0013]
According to the present invention, in the sensor output calibration method for calibrating the output signal from the sensor unit having an acceleration sensor or an angular velocity sensor for detecting the current position and posture of the vehicle, the input step of inputting the output signal from the sensor unit And a calculation processing step for obtaining the current position and posture of the vehicle by performing predetermined calculation processing based on the output signal from the sensor unit input in the input step, and the signal value of the output signal from the sensor unit. A reference value setting step for setting a corresponding reference value, a threshold value setting step for setting a predetermined threshold value based on an output signal from the sensor unit, and an output value in an output signal from the sensor unit sequentially input in the input step, A difference calculating step for calculating a difference from the reference value, and a difference value obtained in the difference calculating step is a threshold setting step. If it is determined in the determination step whether or not the difference value is smaller than the threshold value in the determination step, it is recognized that the vehicle is in a stopped state, and the calculation processing step And a calibration step for calibrating the output signal from the sensor unit when performing the arithmetic processing.
[0014]
Further, in the present invention, in the navigation processing program for detecting the current position and posture of the vehicle based on the output signal from the sensor unit having the acceleration sensor or the angular velocity sensor, the computer is input means for inputting the output signal from the sensor unit. , Calculation processing means for obtaining the current position and posture of the vehicle by performing predetermined calculation processing based on the output signal from the sensor unit input to the input unit, and reference according to the output value of the output signal from the sensor unit A reference value setting means for setting a value, a threshold setting means for setting a predetermined threshold based on an output signal from the sensor section, an output value of an output signal from the sensor section sequentially input to the input means, and a reference value Difference calculation means for calculating each difference, whether or not the difference value obtained by the difference calculation means is smaller than the threshold set by the threshold setting means When the determination means determines that the difference value is smaller than the threshold value, the vehicle recognizes that the vehicle is in a stopped state, and calibrates the output signal from the sensor unit input to the arithmetic processing means. Function as calibration means.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of an embodiment of the present invention.
[0016]
In this figure, the sensor part 1 is comprised by the angular velocity sensor 1a and the acceleration sensor 1b. In this figure, for the sake of simplification, one angular velocity sensor 1a and one acceleration sensor 1b are shown, but in actuality, the vehicle traveling direction (X direction), yaw direction (Y direction), and pitch direction are shown. One set of sensors is provided for each (Z direction).
[0017]
FIG. 2 is a diagram illustrating the relationship between the traveling direction of the vehicle and the X, Y, and Z axes. As shown in this figure, the direction parallel to the traveling direction of the vehicle is the X-axis direction. Further, the direction perpendicular to the traveling direction of the vehicle and parallel to the ground is defined as the Y-axis direction. Furthermore, the direction perpendicular to the traveling direction of the vehicle and perpendicular to the ground is taken as the Z-axis direction.
[0018]
FIG. 3 is a diagram illustrating the relationship between the X, Y, and Z axes and the detection amount detected by the angular velocity sensor 1a or the acceleration sensor 1b. For example, an acceleration sensor in the X-axis direction detects acceleration αx. Further, the angular velocity sensor in the X-axis direction detects the angular velocity ωx.
[0019]
That is, the detection amount of each sensor is defined as follows.
αx ・ ・ ・ Acceleration parallel to X axis αy ・ ・ ・ Acceleration parallel to Y axis αz ・ ・ ・ Acceleration parallel to Z axis ωx ・ ・ ・ Angular velocity ωy of rotational movement along X axis ・ ・ ・ Y axis Angular velocity ωz of rotational movement along the angular velocity of rotational movement along the Z axis The angular velocity and acceleration in the axial direction thus detected are supplied to the navigation device 20 as output signals of the sensor unit 1. Is done.
[0020]
The navigation device 20 includes an input unit 20a, an arithmetic processing unit 20b, a reference value setting unit 20c, a threshold setting unit 20d, a difference calculation unit 20e, a determination unit 20f, and a calibration unit 20g, and outputs from the sensor unit 1. The current position and current state of the vehicle are calculated with reference to the signal, the corresponding map information is acquired from the storage device 3 and displayed on the display device 4. Further, when the vehicle is stopped, a correction process for an error included in the output of the sensor unit 1 is performed.
[0021]
The storage device 3 is configured by a CD-ROM drive, for example, and stores map information, a program executed by the navigation device 20, and the like. The display device 4 is configured by, for example, an LCD, and displays a map read from the storage device 3 and also displays, for example, road information.
[0022]
Next, details of the navigation device 20 will be described.
The input means 20a inputs the output signal of the sensor unit 1. The arithmetic processing means 20b refers to the output signal of the sensor unit 1 supplied from the input means 20a, calculates the current position and current state of the vehicle, reads out a map of the area corresponding to the current position from the storage device 3, After performing processing such as appropriately rotating in the direction corresponding to the current state, the image is supplied to the display device 4 and displayed.
[0023]
The reference value setting unit 20 c sets the reference value of the output signal of the sensor unit 1. That is, the output signal of the sensor unit 1 is a signal that fluctuates according to time as shown in FIG. 4 (in this figure, the horizontal axis indicates time, and times t0 to t12 indicate sample points. ) The vertical axis corresponds to the output signal Vout. As can be seen from this figure, the amplitude of the output signal is small when the vehicle is stopped, and is large while the vehicle is running. Thus, the output signal Vou constantly fluctuates, but repeats oscillation around a predetermined voltage, and the voltage value at the center is the reference value Vref.
[0024]
The threshold setting means 20d sets the threshold ΔVthresh shown in FIG. Details of this threshold will be described later.
The difference calculation means 20e calculates the difference between the reference value Vref supplied from the reference value setting means 20c and the output signal Vout of the sensor unit 1 supplied from the input means 20a, and supplies it to the determination means 20f.
[0025]
The determination unit 20f compares the difference value calculated by the difference calculation unit 20e with the threshold value ΔVthresh set by the threshold setting unit 20d, and determines whether the difference value is smaller than the threshold value.
[0026]
The calibration unit 20g calibrates the arithmetic processing unit 20b when the determination unit 20f determines that the difference value is smaller than the threshold value. That is, when the difference value is smaller than the threshold value, it is determined that the vehicle is stopped, and an error included in the output signal from the sensor unit 1 input to the arithmetic processing unit 20b is removed. Perform calibration process.
[0027]
Next, an example of processing executed in the embodiment shown in FIG. 1 will be described with reference to FIG. In this process, the difference value between the output signal Vout of the sensor unit 1 and the reference value Vref is calculated, and when the difference value is smaller than the threshold value ΔVthresh, it is determined that the vehicle is stopped and the arithmetic processing unit 20b is operated. It is a process to calibrate.
[0028]
When this flowchart is executed, the following processing is executed.
[S21] The reference value setting means 20c sets the reference value Vref.
[0029]
Since reference values need to be set for each sensor, the reference value setting means 20c sets a total of six reference values.
[S22] The threshold setting means 20d sets the threshold ΔVthresh.
[0030]
Since the threshold value needs to be set for each sensor, the threshold value setting unit 20d sets a total of six threshold values.
[S23] The input means 20a inputs the output signal Vout of the sensor unit 1.
[S24] The difference calculating means 20e subtracts the reference value Vref from the output signal Vout of the sensor unit 1 to calculate a difference value ΔV.
[S25] The determining unit 20f determines whether or not the absolute value of the difference value ΔV is smaller than the threshold value ΔVthresh. As a result, if it is determined that the absolute value of the difference value ΔV is smaller than the threshold value ΔVthresh, Proceed to S26, otherwise proceed to Step S27.
[S26] The calibration means 20g executes the calibration process of the arithmetic processing means 20b in order to remove an error component included in the output signal of the sensor unit 1, assuming that the vehicle is currently stopped.
[S27] The arithmetic processing means 20b performs normal processing. That is, the arithmetic processing unit 20b refers to the output signal of the sensor unit 1, calculates the current position and current state of the vehicle, reads out a map corresponding to the situation from the storage means 3, and causes the display device 4 to display the map.
[0031]
According to the above processing, it is possible to accurately determine that the vehicle is stopped, so that the error component of the output signal from the sensor unit 1 can be reliably corrected.
[0032]
By the way, in the determination method as described above, for example, as shown in FIG. 6, although the vehicle is stopped, noise generated from the sensor unit 1 and other circuits and minute vibrations of the vehicle are reflected. Thus, when the signal value of the output signal exceeds the threshold value ΔVthresh (in the example of FIG. 6, at times t5 and t9), it is difficult to make an accurate determination.
[0033]
Therefore, in order to cope with such a case, when the absolute value of the difference value ΔV is smaller than the threshold value ΔVthresh, an “equivalent sample number” by which the value is incremented is defined. As shown in the lower part of FIG. 6, the “number of equivalent samples” (Nsame) is increased in portions excluding times t5 and t9. Therefore, the value of the equivalence sample number Nsame increases from the initial value 0 to the value 10 between times t0 and t12. Therefore, after the elapse of a predetermined period (in this example, times t0 to t12), if the number of equivalence samples is larger than the value 10, for example, it is suddenly determined that the vehicle is stopped. It is possible to eliminate the influence of noise and the like.
[0034]
FIG. 7 shows the output signal of the sensor unit 1 of the traveling vehicle and the number of equivalent samples obtained by the same method. In this example, since the output signal of the sensor unit 1 exceeds the threshold value at most sample points, the number of equivalent samples is 3. Therefore, according to the same criterion as described above, in this example, it is determined that the vehicle is traveling.
[0035]
Next, a flowchart for executing the above processing is shown in FIG. When this flowchart is started, the following processing is executed.
[S41] The threshold setting means 20d sets the threshold ΔVthresh.
[S42] The determination unit 20f sets the stop determination sample number Nstop.
[0036]
For example, the stop determination sample number Nstop is set to a value of 10.
[S43] The reference value setting means 20c sets the reference value Vref.
[S44] The determination unit 20f initializes the timer T to the value 0.
[S45] The determination unit 20f initializes the equivalence sample number Nsame to the value 0.
[S46] The input means 20a inputs the output signal Vout of the sensor unit 1.
[S47] The difference calculating unit 20e calculates a difference value ΔV by subtracting the reference value Vre from the output signal Vout of the sensor unit 1.
[S48] The determination unit 20f proceeds to step S49 if the absolute value of the difference value ΔV is smaller than the threshold value ΔVthresh, and otherwise proceeds to step S50, skipping step S49.
[S49] The determination unit 20f increments the value of the equivalence sample number Nsame by one.
[S50] The determination unit 20f increments the value of the timer T by one.
[S51] The determination unit 20f determines whether or not the value of the timer T is larger than the value of Tsamp (number of samples). If larger, the process proceeds to step S52, and otherwise returns to step S46.
[0037]
In the example shown in FIG. 7, the value of the number of samples Tsamp is 12.
[S52] The determination means 20f determines whether or not the equivalence sample number Nsame is larger than the stop determination sample number Nstop. If larger, the process proceeds to step S53. Otherwise, the process proceeds to step S54.
[S53] The calibration means 20g performs the calibration process of the arithmetic processing means 20b.
[S54] The arithmetic processing means 20b performs normal processing.
[0038]
According to the above processing, when the equivalence sample number Nsame is larger than the stop determination sample number Nstop, it is determined that the vehicle is stopped. For example, sudden noise is generated in the output signal of the sensor unit 1. Even in the case where the vehicle is included, it is possible to accurately determine the stop state of the vehicle.
[0039]
By the way, the threshold value ΔVthresh can be determined in advance (at the time of designing the device) with reference to characteristics (noise characteristics, etc.) of the sensor unit 1 and other circuits. However, since the reference value Vref changes depending on the state of the navigation device 20 attached to the vehicle, it is difficult to set an appropriate value in advance at the time of design. Therefore, this reference value Vref needs to be set appropriately after attachment. Therefore, a method for setting the reference value Vref will be described below.
[0040]
FIG. 9 is a diagram for explaining a method of setting the reference value Vref. As shown in this figure, for example, it is assumed that the output signal Vout of the sensor unit 1 at time t1 is temporarily set to the reference value Vref. In that case, the range of the threshold value ΔVthresh based on the reference voltage Vref is far away from the range in which the output signal of the sensor unit 1 fluctuates.
[0041]
Therefore, as shown in FIG. 10, the output signal is sampled within a predetermined time, and the output signal having the smallest change in signal value compared to the previous sample point among the sampled output signals is obtained. Set to reference voltage Vref.
[0042]
In this example, since the change between time t2 and time t3 is the smallest, for example, the signal value of the output signal at time t2 is set to Vref. Note that the signal value of the output signal at time t3 may be set to the reference value Vref.
[0043]
FIG. 11 is an example of a flowchart for executing the above processing. When this flowchart is started, the following processing is executed.
[S61] The determination unit 20f initializes a variable i for counting the number of processings to a value of 0.
[S62] The input means 20a inputs the output signal Vout of the sensor unit 1.
[S63] The determination unit 20f receives the output signal Vout of the sensor unit 1 via the difference calculation unit 20e, and stores the signal value in the array V as the i-th element.
[S64] The determination unit 20f increments the value of the variable i by one.
[S65] If the value of the variable i is greater than 12, the determination unit 20f proceeds to step S66, otherwise returns to step S62 and repeats the same processing as described above.
[S66] The determination unit 20f sets the variable i for counting the number of processings to a value of 1.
[S67] The determination unit 20f sets an appropriate value (= 1000) to the variable ΔVmin that stores the minimum change value of the output signal Vout of the sensor unit 1. Note that this value is a value that cannot normally be generated.
[S68] The determination unit 20f subtracts the (i-1) th element from the i-th element of the array V in which the output signal is stored, and stores the absolute value of the obtained value as the change value. Substitute into the variable ΔV.
[S69] The determination unit 20f proceeds to step S70 if the value of ΔV obtained in step S68 is smaller than the minimum change value ΔVmin, and otherwise proceeds to step S72.
[S70] The determination unit 20f updates the value of ΔVmin with the value of ΔV.
[0044]
As a result, the minimum change value in the processing so far is stored in ΔVmin.
[S71] The determination unit 20f substitutes the value (i−1) for the variable n that stores the sample point having the smallest change value.
[S72] The determination unit 20f increments the value of the variable i by one.
[S73] If the value of the variable i is greater than 12, the determination unit 20f proceeds to step S74, otherwise returns to step S68 and repeats the same processing as described above.
[S74] The determination unit 20f sets the value V [n] of the nth element (the output signal having the smallest change value) of the array V as the reference value Vref.
[0045]
That is, the determination unit 20f supplies and stores the value of V [n] to the reference value setting unit 20c via the difference calculation unit 20e.
According to the above processing, it is possible to set an appropriate reference value Vref according to the output signal of the sensor unit 1, so that, for example, an optimum reference value can be obtained regardless of the installation state in the vehicle. it can. As a result, it is possible to accurately detect the stop state of the vehicle.
[0046]
In the above embodiment, the signal value output earlier is adopted as the reference value Vref among the two sample points with the smallest change, but the signal value outputted later is adopted. You may make it do. In that case, what is necessary is just to substitute the value of the variable i with respect to the variable n in step S71.
[0047]
Alternatively, the average value of the two output signals described above may be calculated and used as the reference value Vref. In that case, the value of (V [n] + V [n + 1]) / 2 may be set as the reference value Vref in step S74.
[0048]
Further, the above processing functions can be realized by a computer. In this case, the processing contents of the functions that the navigation apparatus should have are described in a program recorded on a computer-readable recording medium. By executing this program on the computer, the above processing is realized by the computer. The Examples of the computer-readable recording medium include a magnetic recording device and a semiconductor memory.
[0049]
When distributing to the market, store the program in a portable recording medium such as a CD-ROM (Compact Disk Read Only Memory) or floppy disk, or store it in a computer storage device connected via a network. In addition, it can be transferred to another computer through the network. When executed by a computer, the program may be stored in a hard disk device or the like in the computer, loaded into the main memory, and executed.
[0050]
【The invention's effect】
According to the above process, the vehicle is stopped by determining whether the vehicle is stopped based on the difference between the output signal of the sensor unit and the reference value, and determining whether the difference value is smaller than the threshold value. It is possible to accurately determine the error component included in the output signal from the sensor unit , thus eliminating the error included in the output signal of the sensor unit , and stopping the vehicle It is possible to realize a navigation device that can accurately determine
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of an embodiment of the present invention.
2 is a diagram showing a relationship between a traveling direction of a vehicle on which the navigation device shown in FIG. 1 is mounted and each axial direction. FIG.
FIG. 3 is a diagram showing a relationship between X, Y, and Z axes and detection amounts detected by an angular velocity sensor or an acceleration sensor.
4 is a diagram showing temporal changes in the output signal of the sensor section shown in FIG. 1 during traveling and during stopping.
FIG. 5 is a flowchart for explaining an example of processing for detecting stop of the vehicle, which is executed in the embodiment shown in FIG. 1;
FIG. 6 is a diagram illustrating a temporal change in an output signal of a sensor unit when the vehicle is stopped.
FIG. 7 is a diagram illustrating a temporal change in an output signal of a sensor unit during vehicle travel.
FIG. 8 is a flowchart for explaining another example of the process for detecting the stop of the vehicle, which is executed in the embodiment shown in FIG. 1;
FIG. 9 is a diagram illustrating a case where an output signal at time t1 is used as a reference value.
FIG. 10 is a diagram illustrating a case where an output signal at time t2 is used as a reference value.
FIG. 11 is a flowchart illustrating an example of processing for setting a reference value.
FIG. 12 is a block diagram illustrating a configuration example of a conventional navigation device.
13 is a flowchart illustrating an example of a process for canceling an error included in a signal output from a sensor in the conventional navigation apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sensor part, 1a ... Angular velocity sensor, 1b ... Acceleration sensor, 3 ... Memory | storage device, 4 ... Display apparatus, 20 ... Navigation device, 20a ... Input means, 20b ... Arithmetic processing means, 20c …… Reference value setting means 20d …… Threshold setting means 20e …… Difference calculation means 20f …… Determination means 20g …… Calibration means

Claims (7)

In a navigation device that detects the current position and posture of a vehicle based on an output signal from a sensor unit having an acceleration sensor,
Input means for inputting an output signal from the sensor unit;
Arithmetic processing means for obtaining a current position and posture of the vehicle by performing predetermined arithmetic processing based on an output signal from the sensor unit input to the input means;
A reference value for sampling the output value of the output signal from the sensor unit within a predetermined time in order to determine that the vehicle is stopped, and setting an output value with the smallest change in output value between the sampling points as a reference value Setting means;
Threshold setting means for setting a predetermined threshold in advance ;
Difference calculating means for determining that the vehicle is stopped by calculating the difference between the output value of the output signal from the sensor unit sequentially input to the input means and the reference value;
Determining means for determining whether or not the absolute value of the difference value obtained by the difference calculating means is smaller than the threshold set by the threshold setting means;
If the absolute value of the difference value is determined to be smaller than the threshold value by the determination means determines that the vehicle is in a stopped state, the output signal from the sensor unit to be input to said processing means A navigation device comprising: calibration means for calibrating an error contained in . The calibration unit recognizes that the vehicle is in a stopped state when the determination unit determines that the difference value is smaller than the threshold value within a predetermined time by a predetermined number of times, and notifies the arithmetic processing unit. The navigation apparatus according to claim 1, wherein an input output signal from the sensor unit is calibrated. The reference value setting means samples the output signal from the sensor unit over a predetermined period, extracts two sampling values having the smallest fluctuation among the two consecutive sampling values, and extracts the two sampling values. The navigation apparatus according to claim 1, wherein any one of the values is the reference value. The reference value setting means samples the output signal from the sensor unit over a predetermined period, extracts two sampling values having the smallest fluctuation from two consecutive sampling values, and extracts the two sampling values. The navigation device according to claim 1, wherein an average value is the reference value. The navigation device according to claim 1, wherein the sensor unit further includes an angular acceleration sensor. In a sensor output calibration method for calibrating an output signal from a sensor unit having an acceleration sensor and an angular acceleration sensor for detecting the current position and posture of a vehicle,
An input step for inputting an output signal from the sensor unit;
An arithmetic processing step for obtaining a current position and posture of the vehicle by performing a predetermined arithmetic processing based on an output signal from the sensor unit input in the input step;
A reference value for sampling the output value of the output signal from the sensor unit within a predetermined time in order to determine that the vehicle is stopped, and setting an output value with the smallest change in output value between the sampling points as a reference value Configuration steps;
A threshold setting step for setting a predetermined threshold in advance ;
A difference calculating step of determining that the vehicle is stopped by calculating a difference between an output value of an output signal of the output signal from the sensor unit sequentially input to the input step and the reference value;
A determination step for determining whether or not the absolute value of the difference value obtained in the difference calculation step is smaller than the threshold value set in the threshold value setting step;
When it is determined in the determination step that the absolute value of the difference value is smaller than the threshold value, the sensor unit determines that the vehicle is in a stopped state and performs the calculation process in the calculation processing step. And a calibration step for calibrating an error contained in an output signal from the sensor output calibration method. In a navigation processing program for detecting the current position and posture of a vehicle based on an output signal from a sensor unit having an acceleration sensor and an angular acceleration sensor,
Against the computer,
An input step for inputting an output signal of the sensor unit;
An arithmetic processing step for obtaining a current position and orientation of the vehicle by performing predetermined arithmetic processing based on an output signal from the sensor unit;
Reference value that samples the output value of the output signal from the sensor unit within a predetermined time to determine that the vehicle is stopped, and sets the output value with the smallest change in output value between the sampling points as the reference value Configuration steps ;
A threshold setting step for setting a predetermined threshold in advance ;
A difference calculating step of determining that the vehicle is stopped by calculating a difference between an output value of the output signal from the sensor unit and the reference value;
A determination step of determining whether an absolute value of the difference value obtained by the difference calculation step is smaller than the threshold value set by the threshold value setting step ;
If it is determined in the determination step that the absolute value of the difference value is smaller than the threshold value , the vehicle is in a stopped state, and is included in the output signal from the sensor unit input to the calculation processing step. A navigation processing program that functions as a calibration step for calibrating errors .

Images