JPH05187879A - Navigation device - Google Patents

Abstract

PURPOSE:To obtain an accurate advancing azimuth constantly by performing an accurate offset reset properly even when driving without stopping for a long time. CONSTITUTION:The output of an angular velocity sensor (gyro) 2 and that of an azimuth detection sensor (earth magnetism sensor) 1 are constantly monitored by a straight-advance offset reset means during traveling of a traveling body and then, for example, a change rate of an angular velocity data and that of an azimuth detection data allows a straight-advance state or not to be detected. Since no angular velocity is generated in the straight-advance state, the offset is reset by recognizing that the output value of the angular velocity sensor 2 to be the offset value at that time, thus enabling the offset reset to be made in the straight-advance state and a highly accurate angular velocity to be detected even during a high-speed advance without stopping for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device for indicating the current position of a moving body, the direction of travel, etc. to assist the operation of the moving body such as an automobile. More specifically, it relates to an angular velocity sensor such as a gyro. The present invention relates to an offset process for correcting the angular velocity output.

[0002]

2. Description of the Related Art In a navigation device mounted on an automobile or the like, a vehicle position and a heading are accurately measured, and map information corresponding to a vehicle position, that is, a current position, a vehicle position mark, and a mark indicating a heading, Alternatively, it is required to sequentially and accurately display other information in response to the user's request on a display or the like and present it to the driver.

Positioning of the vehicle position and heading is performed by GPS
(Global Positioning System) A device that receives and calculates radio waves from satellites (hereinafter referred to as "GPS positioning"), an angular velocity sensor such as a gyro, an orientation sensor such as a geomagnetic sensor, and a traveling sensor that detects a traveling state etc. Calculated from these detected outputs (hereinafter referred to as "independent positioning")
Said). The GPS positioning is an extremely useful means because it has many advantages that it is not necessary to set the position of the own vehicle on the map in advance, and the positioning error of the position is extremely small and high reliability is obtained.

However, positioning by GPS is not possible in buildings,
It has the disadvantage that it cannot be located in the shadow of tunnels, forests, etc.In addition, self-standing positioning can detect cumulative errors, the effects of temperature changes, the situation inside and outside the car body, especially because the geomagnetic sensor is easily affected on the iron bridge. The data to be stored is not always accurate, and each positioning is not always perfect. Therefore, at present, the GPS positioning and the self-supporting positioning are used together to make up for their respective drawbacks and improve the accuracy.

Conventionally, the output of an angular velocity sensor such as a gyro provided for self-standing positioning fluctuates due to changes in temperature and humidity, so that the angular velocity should originally be "0" when the vehicle is stopped in normal running. By recognizing the output value of as the offset value which is the reference value and subtracting the offset value from the output value after that, the true angular velocity corrected for the output fluctuation (hereinafter referred to as “offset reset”) can be obtained. I was doing.

FIG. 5 shows a flowchart of conventional angular velocity detection processing. This angular velocity detection processing is performed when the angular velocity is periodically obtained from an angular velocity sensor such as a gyro to detect the traveling direction. The conventional angular velocity detection process will be described in detail with the same flowchart. First, it is determined whether or not the vehicle is stopped by obtaining the output of a traveling sensor that outputs a vehicle speed pulse during traveling together with the angular velocity ω output by the angular velocity sensor. (Steps S51 to S53).
When it is stopped, it is determined whether the rate of change of the angular velocity ω, that is, the angular acceleration dω / dt is within a predetermined value k (step S54). Then, when the angular acceleration dω / dt is within the predetermined value k, the angular velocity ω obtained this time is recognized as the offset value ω ₀ (step S55). This offset value ω ₀ becomes “0” as the corrected angular velocity (ω ′ = ω−ω ₀ ) by the offset processing shown in the next step S56, that is, the offset reset. On the contrary,
When the vehicle is traveling and when the angular acceleration dω / dt exceeds the predetermined value k, the offset value ω ₀ is not updated and the process proceeds to step S56 to perform the offset process with the previously set offset value. The corrected angular velocity ω'was obtained.

The offset reset in the above offset process will be described by the following formula. ω _T ; true angular velocity ω; angular velocity output of angular velocity sensor ω _off ; offset value ω _stop ; assuming output of angular velocity sensor when the vehicle is stopped, ω = ω _T + ω _off ω _T = ω-ω _off (1) When the vehicle is stopped, ω _T = 0, so ω _stop = ω _T + ω _off = ω _off , and when this is substituted into equation (1), ω _T = ω-ω _stop . As described above, conventionally, the true angular velocity is obtained by subtracting the output value at the time of stop from the angular velocity output by the angular velocity sensor.

[0008]

However, in the conventional offset reset processing described above, when traveling on a general road, the signal is frequently stopped due to a signal or the like, and the offset reset is performed each time the vehicle is stopped. A very small true angular velocity is required, but when traveling for a long time without stopping when traveling on a highway, of course, the offset value is not required, so the offset value changes due to temperature and humidity changes during that time. Then, there is a problem that an error occurs in the obtained angular velocity and an incorrect traveling direction is calculated.

The present invention has been made in view of the above problems. Even when traveling without stopping for a long time, an accurate offset reset is performed in a timely manner to detect a highly accurate angular velocity. An object of the present invention is to provide a navigation device that can always obtain an accurate traveling direction.

[0010]

The invention according to claim 1 for achieving the above object corresponds to an angular velocity sensor for detecting an angular velocity associated with a direction change of a moving body and outputting angular velocity data, and a direction change of the moving body. And a direction detection sensor for outputting direction detection data, which detects at least the traveling direction of the moving body and gives an instruction display, and detects a straight traveling state of the moving body from at least the angular velocity data and the direction detection data. And when it is in that straight line progress state,
The linear velocity offset reset means for setting the reference value of the output of the angular velocity sensor to the output value at that time is provided.

According to a second aspect of the present invention, in the navigation device according to the first aspect, the current position and the heading are detected and displayed together with the map information. Further, the map information indicates whether the vehicle is in a straight traveling state. It is determined whether or not, and the reference value of the output of the angular velocity sensor is set. That is, an angular velocity sensor that detects the angular velocity associated with a change in the direction of the moving body and outputs angular velocity data, and an azimuth detection sensor that outputs the azimuth detection data corresponding to the change in the direction of the moving body are provided, and at least the current position of the moving body A navigation device that detects a traveling azimuth and indicates and displays it together with map information, detects a linear traveling state of a moving body from at least the angular velocity data, azimuth detection data, and map information, and when in the linear traveling state, The linear velocity offset reset means for setting the reference value of the output of the angular velocity sensor to the output value at that time is provided.

[0012]

According to the navigation device of the present invention, when detecting the traveling direction of the moving body, the output of the angular velocity sensor at the time of stopping is a reference value (offset value) as in the conventional case when the vehicle is stopped.
Reset the offset. Further, even while the moving body is moving, the outputs of the angular velocity sensor and the azimuth detection sensor are constantly monitored by the straight-ahead offset resetting means. For example, is the linear traveling state based on the change rate of the angular velocity data and the change rate of the azimuth detection data? It is detected whether or not the angular velocity is not generated in the straight traveling state. Therefore, in the straight traveling state, the output value of the angular velocity sensor is recognized as the offset value at that time and the offset is reset.
As a result, even if the vehicle is traveling on a highway without stopping for a long time, the offset is reset when the vehicle is traveling straight and the angular velocity with high accuracy is always detected.
The accurate traveling direction of the moving body can be obtained.

According to another aspect of the navigation device of the present invention, the straight-ahead offset reset means detects whether or not the vehicle is in a straight traveling state based on the outputs of the angular velocity sensor and the azimuth detecting sensor, and further the map information, for example, the vector of the road at the current position. It is detected from information or the like whether or not the vehicle is in a straight traveling state. Then, only when each of these three detections indicates that the vehicle is in a straight traveling state, an offset reset is performed to set the offset value of the angular velocity sensor to the output value at that time. As a result, even if there is an error due to some factor in the angular velocity sensor and the azimuth detection sensor, the straight line progress state is further confirmed by the map information, so the offset reset due to the error can be prevented, and a more accurate offset reset can be performed. It

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a vehicle-mounted navigation device according to an embodiment of the present invention. As shown in the figure, the vehicle-mounted navigation device detects a geomagnetic sensor 1 which is an azimuth detecting sensor that outputs absolute azimuth angle data of the vehicle based on the geomagnetism (earth magnetic field) and an angular velocity associated with a change in the direction of the vehicle. A gyro 2 that is an angular velocity sensor that outputs angular velocity data, and a mileage sensor that detects whether the vehicle is moving or stopped and outputs the state and outputs the data of the traveling speed and the traveling distance of the vehicle. GPS that receives radio waves from 3 and a plurality of GPS satellites and performs calculation to generate and output data of latitude, longitude, altitude, and heading
The positioning device 4, a system controller 5 that performs various processes such as calculation and control, an input device 14 for inputting instructions to the system controller 5, and a display 15 such as a liquid crystal or CRT are configured.

The system controller 5 inputs various outputs of the geomagnetic sensor 1, the gyro 2, the traveling distance sensor 3 and the GPS positioning device 4 to perform A / D conversion and the like, and performs various calculations and controls according to programs. CP
U (Central Processing Unit) 7 and R in which various processing programs and other necessary information are written in advance
An OM (Read Only Memory) 8 and a RAM for writing and reading information necessary for executing a program
(Random Access Memory) 9, a recording medium 10 including a CD-ROM, an IC card, etc. for recording digitized map information, and a V-RAM (video RAM)
A buffer memory 1 that is a frame buffer that temporarily stores image information that has been expanded for immediate display.
1, a graphic controller 12 that draws graphic data such as map information sent by a command of the CPU 7 in the buffer memory 11 and outputs the drawn data as image information, and the graphic controller 12
And a display control circuit 13 for controlling the image display on the display 12 by inputting the image information output from the display.

When the navigation device having the above-mentioned configuration is activated, the system controller 5 first reads information for accessing map display information and the like from the recording medium 10 and display information of the vehicle position mark and stores the information in the RAM 9. ..
Next, the latitude / longitude data that is the vehicle position information and the traveling direction data of the vehicle are read from the GPS positioning device 4, the map data corresponding to the vehicle position is read from the recording medium 10 and sent to the graphic controller 12, and the current location is read. Is displayed on the display 15. Further, a process of displaying a vehicle position mark on the map from the vehicle position information and the heading is performed, and then the vehicle position information and the heading data are periodically read from the GPS positioning device 4, and the vehicle is read by the information The display position and direction of the position mark and the map to be displayed are updated if necessary.

Further, the geomagnetic sensor 1, the gyro 2,
Also, the output data of the mileage sensor 3 is periodically read, a predetermined calculation is performed from the output data to calculate the own vehicle position and the heading, and the calculated data is compared with the data from the GPS positioning device 4. Correction processing is performed by adjusting mutual errors. In the calculation of the traveling azimuth based on the output data of the geomagnetic sensor 1, the gyro 2, and the travel distance sensor 3, the angular velocity is obtained by the angular velocity detection processing shown in the flowchart of FIG. 2, and the azimuth is calculated from the angular velocity.
The flowchart shown in FIG. 2 is performed by the system controller 5
In the angular velocity detection process performed in step 1, the straight-line offset reset means of the present invention is included. In the angular velocity detection process of this embodiment, the offset reset is performed not only when the vehicle is stopped but also when the vehicle is traveling straight.

FIG. 3 is an explanatory diagram of the angular velocity ω output by the gyro 2 and the absolute azimuth θ output by the geomagnetic sensor 1 when the vehicle is running straight. (1) in the figure is an example of the output angular velocity ω of the gyro 2 when traveling straight, and an offset occurs due to changes in temperature and humidity, etc.
This shows a state in which the offset value becomes constant after a certain time. When such an offset occurs, the angular velocity ω used for calculating the traveling azimuth includes the offset value generated later, and the calculated traveling azimuth becomes inaccurate.

FIG. 2B shows the change rate of the angular velocity ω output in (1), that is, the change of the angular acceleration dω / dt. Before and after the offset occurs, and after the offset value becomes constant, the change rate is, of course, almost 0, which is within the threshold level (dω / dt) k shown in the figure. The rate of change is the threshold level (dω / d
When t is larger than k, the traveling direction of the vehicle is changing and the angular velocity is changing, or the offset is changing as in (1). Therefore, during traveling, when the rate of change of the angular velocity ω output of the gyro 2 is larger than the threshold level (dω / dt) k, the offset reset must not be performed.

FIG. 3C shows the geomagnetic sensor 1 when traveling straight.
It is the absolute azimuth angle θ which is the output of. As shown in the figure, θ is constant during straight running. FIG. 4 (4) shows the rate of change (angular velocity) dθ / dt of the absolute azimuth angle θ output by the geomagnetic sensor 1 when traveling straight. Θ as shown in (3)
Is constant, the rate of change is almost 0, which is within the threshold level (dθ / dt) k shown in the figure. This rate of change is the threshold level (dθ / dt)
When it becomes larger than k, the traveling direction of the vehicle is changing. If the vehicle is turning at a constant angular velocity,
The rate of change of the angular velocity ω output of the gyro 2 is almost 0,
The rate of change of the output θ of the geomagnetic sensor 1 becomes larger than the threshold level (dθ / dt) k. So gyro 2
Of the output ω of the threshold level (dω / d
t) Within k and when the rate of change of the output θ of the geomagnetic sensor 1 is within the threshold level (dθ / dt) k, it is assumed that the vehicle is in a straight running state and the angular velocity does not change. Can also perform an offset reset.

FIG. 5 (5) shows the relationship between the velocity V and the angular velocity ω when the vehicle turns. As shown in the figure, when the velocity is about 30 Km / h, the angular velocity ω is the largest, and when the velocity V is faster, the angular velocity ω is not so large. Therefore, in order to ensure the resetting of the offset during traveling, as shown in FIG. 6 (6), the threshold level V _k of the vehicle speed V is set so that the vehicle speed V is less than the threshold level V _k. Sometimes it will be more reliable if the offset reset is not performed.

In the present embodiment, the accuracy of the angular velocity to be detected is improved by performing the offset reset in the angular velocity detection processing even during traveling based on the above determination. The angular velocity detection processing of this embodiment will be described with reference to the flowchart shown in FIG.

In the angular velocity detection processing of this embodiment, the output of the angular velocity ω and the output of the traveling distance sensor 3 are obtained from the gyro 2 to first determine whether or not the vehicle is stopped (step). S1 to S3). When it is stopped, the rate of change of the angular velocity ω output by the gyro 2, that is, the angular acceleration dω, is calculated based on the data obtained so far.
/ Dt is determined, and it is determined whether the angular acceleration dω / dt is within the threshold level (dω / dt) k (step S4). In this result, the angular acceleration dω /
When dt is within the threshold level (dω / dt) k, the absolute azimuth angle θ is further obtained from the geomagnetic sensor 1, and the rate of change (angular velocity) dθ / dt of the absolute azimuth angle θ is obtained based on the data obtained so far. And the rate of change dθ / dt
Is within the threshold level (dθ / dt) k (step S5). As a result, the rate of change dθ / dt is the threshold level (dθ / dt
If it is within dt) k, the reference value (offset value) ω _off of the output of the gyro 2 is recognized as the angular velocity ω obtained this time (ω _off = ω; step S6). This offset value ω
_{When off} is reset, the true angular velocity (ω _T = ω−ω _off ) becomes “0” by the offset process in the next step S7.

If the vehicle is traveling in the determination in step S3, it is determined from the road data of the map information (vector information) whether the road currently in progress is a straight road (step S8). ), If the road is a straight road, then the current speed data is obtained from the travel distance sensor 3 and the travel speed V is set to a predetermined threshold level V.
It is determined whether _k or more (step S9). Then, when the traveling speed V is equal to or higher than the threshold level V _k , the offset reset determination process from step S4 is performed as in the case of the stop. That is, even when the vehicle is traveling, when the traveling road is a straight road and the traveling speed is equal to or higher than the threshold level V _k , the change rate of the angular velocity ω and the change rate of the absolute azimuth angle θ are calculated, and the respective threshold levels are calculated. If it is within the range, offset reset is performed.

On the other hand, if the angular acceleration dω / dt is greater than the threshold level in the determination in step S4 even when the vehicle is stopped, or the rate of change in absolute azimuth angle dθ / dt is greater than the threshold level in the determination in step S5. If large, the offset value goes to step S7 without being reset, the offset value omega _off which is set previously, the offset processing (ω _T = ω-
ω _off ) to obtain the true angular velocity ω _T. Further, even if the vehicle is running, the road in progress is not a straight road in the determination in step S8, the traveling speed V is less than the threshold level V _k in the determination in step S9, or the rate of change is in steps S4 and S5. If each larger threshold level, the offset value goes to step S7 without being reset, the offset value omega _off which is set previously, the offset processing (omega _T
= Ω-ω _off ) to obtain the true angular velocity ω _T.

In addition, in the above embodiment, the offset reset is performed even during traveling, and the road and the traveling speed during traveling are determined based on the map information in order to increase the certainty. Similarly to when stopped, the output ω of the gyro 2 in steps S4 and S5
It is also possible to make only the determination based on the change rate of the above and the change rate of the output θ of the geomagnetic sensor 1. In this case, steps S3, S8, and S9 are unnecessary.

Further, in the offset certification in step S6, the output angular velocity ω of the gyro 2 at that time is set as the offset value ω _off , but as shown below, the offset value up to that time and the current offset value ω _offn are set. On the other hand, by weighting each of them and obtaining them from both, it is possible to reduce the influence when the offset is reset by mistake. That is, the offset value of the present (n-th); omega _OFFN Until the offset value; Omega _n-1 weighting constants; α (0 ≦ α ≦ 1 ) the offset value to be obtained; When Omega _n, the offset value Omega _n is , Ω _n = αΩ _n-1 + (1-α) ω _n , and the true angular velocity ω _Tn is calculated by ω _Tn = ω _n −Ω _n .

The offset value Ω_nThe formula smell for
If α = 0, the offset reset in step S6 is performed.
Processing is the same. Also, the offset value Ω_nIs α
By Ω_n-1From ω_offTo take values up to
The effect of offset reset gradually diminishes as you make it
Eventually, the effect of an incorrect offset reset
Will be less. FIG. 4 shows the offset reset process.
A flow chart is shown. In the flowchart, D
Is the delay process, and the certified offset value Ω _nNext
Offset value up to that time at offset reset of Ω
_n-1Indicates the processing.

In the above embodiment, an example in which an angular velocity sensor such as a gyro is configured as the angular velocity detection sensor is shown, but the present invention is not limited to this. For example, the azimuth is detected by the rotational speed difference of the wheels or the optical fiber method. The same can be done by the sensor.

[0030]

As described above, according to the present invention,
Even when the vehicle travels without stopping for a long time, the linear traveling state is detected and the offset is reset in a timely manner.Therefore, it is possible to provide a navigation device capable of detecting an accurate angular velocity and always obtaining an accurate traveling direction. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vehicle-mounted navigation device that is an embodiment of the present invention.

FIG. 2 is a flowchart of angular velocity detection processing in the embodiment.

FIG. 3 is an explanatory diagram of angular velocity detection in the embodiment.

FIG. 4 is a flowchart of another process of offset reset in the embodiment.

FIG. 5 is a flowchart of a conventional angular velocity detection process.

[Explanation of symbols]

 1 ... Geomagnetic sensor 2 ... Gyro 3 ... Travel distance sensor 4 ... GPS positioning device 5 ... System controller 6 ... Interface 7 ... CPU 8 ... ROM 9 ... RAM 10 ... CD-ROM 11 ... Buffer memory 12 ... Graphic controller 13 ... Display control Circuit 14 ... Keyboard 15 ... Display

Claims (2)

[Claims] 1. An angular velocity sensor that detects an angular velocity associated with a change in direction of a moving body and outputs angular velocity data, and an azimuth detection sensor that outputs azimuth detection data corresponding to a change in direction of the moving body. A navigation device for detecting and indicating a traveling azimuth direction, and detecting a linear traveling state of a moving body from at least the angular velocity data and azimuth detection data, and in the linear traveling state, a reference of an output of the angular velocity sensor. A navigation device, comprising straight-line offset reset means for setting a value to an output value at that time. 2. An angular velocity sensor for detecting angular velocity associated with a change in direction of a moving body and outputting angular velocity data, and an azimuth detection sensor for outputting azimuth detection data corresponding to a change in direction of the moving body. A navigation device that detects a current position and a traveling direction and indicates and displays them together with map information, wherein at least the linear traveling state of the moving body is detected from the angular velocity data, the orientation detection data, and the map information, and the vehicle is in the linear traveling state. In addition, the navigation device is provided with a straight advance offset reset means for setting the reference value of the output of the angular velocity sensor to the output value at that time.