Attitude angle estimation device of vehicle

Abstract

To estimate an attitude of a vehicle, even if the vehicle travels on a roughened road surface.SOLUTION: A start lacquer (20) having a camera and an inertia sensor (21) are mounted on a vehicle (1). When a variation amount of an attitude angle of the vehicle (1) is smaller than a preset variation amount, starry sky is photographed by the camera and image data of the starry sky is generated, and when the variation amount of the attitude angle of the vehicle (1) exceeds the preset variation amount, the photographing of the starry sky by the camera is canceled. The attitude angle of the vehicle (1) is estimated on the basis of the arrangement of stars obtained from the generated image data and a fixed star catalog.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an attitude angle estimation device for a vehicle. [Background technology]

[0002] A known position identification system is equipped on a vehicle with a star tracker that outputs image data of the starry sky captured by a camera and an acceleration sensor, and identifies the vehicle's position based on the image data output from the star tracker and information obtained from the acceleration sensor (see, for example, Patent Document 1). By using a star tracker in this way, it is possible to estimate the position and attitude of a vehicle equipped with the star tracker by performing a pattern matching process between the arrangement of stars obtained from the image data output from the star tracker and a prepared star catalog. This star tracker is often used when the vehicle is stationary. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-144063 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle is driven at high speeds off-road in areas such as the desert, it can be difficult to accurately determine the vehicle's attitude, especially at night. In this case, if a star tracker is installed on the vehicle, it can be used to estimate the vehicle's attitude. However, when a star tracker is installed on a vehicle, if the vehicle travels on a rough road, causing the body to vibrate violently and the vehicle's attitude to fluctuate rapidly and continuously, the camera will not be able to accurately capture star photographs, making it impossible to estimate the vehicle's attitude. [Means for solving the problem]

[0005] In order to solve such problems, according to the present invention, a vehicle-mounted star tracker for outputting image data of a starry sky photographed by a camera, an inertial sensor mounted on the vehicle, and a processor are provided, The processor The amount of change in the attitude angle of the vehicle is calculated from the angular velocity signal output from the inertial sensor. When the amount of change in the attitude angle of the vehicle is smaller than a preset amount of change, the camera is used to photograph the starry sky and generate image data of the starry sky; When the amount of change in the attitude angle of the vehicle exceeds a preset amount of change, the camera stops photographing the starry sky, A vehicle attitude angle estimation device is provided that estimates the vehicle attitude angle based on the star arrangement and star catalog obtained from the generated image data. [Effects of the Invention]

[0006] The vehicle's posture can be estimated even when the vehicle is traveling on a rough road surface. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the functional configuration of a vehicle. [Figure 2] FIG. 2 is a schematic side view of a star tracker. [Figure 3] FIG. 3 is a time chart showing changes in the roll angular velocity and pitch angular velocity. [Figure 4] FIG. 4 is a flowchart for executing the vehicle attitude angle estimation process. [Figure 5] FIG. 5 is a flowchart for executing the vehicle attitude angle estimation process. DETAILED DESCRIPTION OF THE INVENTION

[0008] FIG. 1 shows the functional configuration of vehicle 1. Vehicle 1 can be driven either manually or automatically. Referring to FIG. 1, reference numeral 10 denotes a vehicle drive unit for applying drive force to the drive wheels of vehicle 1, 11 denotes a braking device for braking vehicle 1, 12 denotes a steering device for steering vehicle 1, and 13 denotes an electronic control unit mounted in vehicle 1. As shown in FIG. 2, electronic control unit 13 is a digital computer and includes a CPU (processor) 15, memory 16 consisting of ROM and RAM, and input / output ports 17, all connected to each other by a bidirectional bus 14. A communication device 18 is also connected to electronic control unit 13.

[0009] Meanwhile, as shown in FIG. 1 , a star tracker 20 capable of photographing the starry sky is mounted on the roof of the vehicle 1. The vehicle 1 is also equipped with an inertial sensor 21 capable of detecting longitudinal acceleration, lateral acceleration, vertical acceleration, roll angular velocity, pitch angular velocity, and yaw angular velocity. The vehicle 1 is also equipped with various other sensors 22. These various sensors 22 include sensors that detect the state of the vehicle 1 and sensors that detect the periphery of the vehicle 1. In this case, sensors that detect the state of the vehicle 1 include speed sensors, azimuth sensors, geomagnetic sensors, etc., and sensors that detect the periphery of the vehicle 1 include cameras that photograph the front, sides, and rear of the vehicle 1, and LIDAR, radar, clearance sonar, etc. that detect the front, sides, and rear of the vehicle 1.

[0010] 1, the vehicle 1 is equipped with a GNSS (Global Navigation Satellite System) receiver 23, a map data storage device 24, a navigation device 25, and a display device 26 that displays the attitude of the vehicle 1. The GNSS receiver 23 can detect the current position of the vehicle 1 (e.g., the latitude and longitude of the vehicle 1) based on information obtained from a plurality of artificial satellites, and a GPS receiver, for example, is used as the GNSS receiver 23. The map data storage device 24 stores map data and the like necessary for the vehicle 1 to travel. The star tracker 20, the inertial sensor 21, the various sensors 22, the GNSS receiver 23, the map data storage device 24, the navigation device 25, and the display device 26 are connected to the electronic control unit 13.

[0011] In the example shown in Fig. 1, vehicle 1 can be manually driven, and when a request for automatic driving control is made to vehicle 1, vehicle 1 can be made to perform automatic driving control. In the example shown in Fig. 1, vehicle drive unit 10 of vehicle 1 is composed of an electric motor driven by a secondary battery or an electric motor driven by a fuel cell, and the drive wheels are driven and controlled by these electric motors in accordance with output signals from electronic control unit 13. In the example shown in Fig. 1, when a request for automatic driving control is made to vehicle 1, braking control of vehicle 1 is performed by braking device 11 in accordance with output signals from electronic control unit 13, and steering control of vehicle 1 is also performed by steering device 12 in accordance with output signals from electronic control unit 13.

[0012] FIG. 2 is a schematic diagram of the star tracker 20 shown in FIG. 1. Referring to FIG. 2, the star tracker 20 is equipped with a camera consisting of a lens 30, a shutter 31, and a photodetector 32 that receives light incident through the lens 30. The star tracker 20 is also equipped with a shutter speed control device 33 for controlling the speed of the shutter 31. The star tracker 20 is further equipped with an output adjustment circuit 34 that increases the output signal value from the photodetector 32 to increase the exposure sensitivity, or decreases the output signal value from the photodetector 32 to decrease the exposure sensitivity. The output adjustment circuit 34 is controlled by an output signal from the electronic control unit 13. The output adjustment of the output signal value from the photodetector 32 can also be performed within the electronic control unit 13.

[0013] When the starry sky is photographed by the camera of the star tracker 20, output image data showing the photographed starry sky is output from the output adjustment circuit 34 to the electronic control unit 13. Inside the electronic control unit 13, a pattern matching process is performed between the arrangement of stars obtained from the output image data showing the photographed starry sky and a star catalog pre-stored in memory 16, thereby calculating the inclination of the vehicle body relative to the vertical axis of the road surface, i.e., the roll angle and pitch angle. In other words, the attitude angle of the vehicle 1 is estimated.

[0014] However, when the starry sky is photographed with the camera of star tracker 20 in this manner and the attitude angle of vehicle 1 is estimated using output image data showing the photographed starry sky, if vehicle 1 travels on a rough road surface and the vehicle body 1 vibrates violently, causing the attitude angle of vehicle 1 to fluctuate significantly, the camera of star tracker 20 will be unable to photograph the starry sky correctly. As a result, a problem arises in that the attitude of vehicle 1 cannot be accurately estimated. Therefore, in the present invention, while vehicle 1 is traveling, the amount of variation in the attitude angle of vehicle 1 is calculated from the angular velocity signal output from inertial sensor 21, and when the amount of variation in the attitude angle of vehicle 1 is smaller than a preset amount of variation, the camera of star tracker 20 will photograph the starry sky, but when the amount of variation in the attitude angle of vehicle 1 exceeds the preset amount of variation, the camera of star tracker 20 will stop photographing the starry sky.

[0015] In this case, the amount of variation in the attitude angle of vehicle 1 corresponds to the amount of variation in the roll angular velocity X of vehicle 1, i.e., the amplitude of variation, or the amount of variation in the pitch angular velocity Y of vehicle 1, i.e., the amplitude of variation. Therefore, in an embodiment according to the present invention, when the amount of variation in the roll angular velocity X of vehicle 1 or the amount of variation in the pitch angular velocity Y of vehicle 1 is smaller than a preset amount of variation, the camera of star tracker 20 photographs the starry sky, but when the amount of variation in the roll angular velocity X of vehicle 1 or the amount of variation in the pitch angular velocity Y of vehicle 1 exceeds the preset amount of variation, photographing of the starry sky by the camera of star tracker 20 is stopped.

[0016] In this case, even if the amount of variation in either the roll angular velocity X or the pitch angular velocity Y becomes smaller than a preset amount of variation, if the amount of variation in the other is large, the starry sky cannot be properly photographed by the camera of star tracker 20. Therefore, in this embodiment of the present invention, when the amounts of variation in both the roll angular velocity X and the pitch angular velocity Y detected by inertial sensor 21 are smaller than the preset amount of variation, that is, when the amplitudes of variation in the roll angular velocity X and the pitch angular velocity Y are smaller than the preset amplitudes, the camera of star tracker 20 photographs the starry sky.

[0017] Next, an embodiment of the vehicle attitude angle estimation method according to the present invention will be described with reference to the time chart shown in Fig. 3. Fig. 3 shows the temporal changes in the roll angular velocity X and the pitch angular velocity Y detected by the inertial sensor 21 while the vehicle 1 is traveling. Fig. 3 also shows the timing of photographing by the camera of the star tracker 20, the shutter speed, and the exposure sensitivity. Referring to Fig. 3, the periods S1 and S2 in Fig. 3 Period S2 indicates a period during which the amounts of fluctuation in both the roll angular velocity X and the pitch angular velocity Y detected by the inertial sensor 21 are smaller than preset amounts of fluctuation, i.e., a period during which the amplitudes of fluctuation in the roll angular velocity X and the pitch angular velocity Y are smaller than preset amplitudes. As shown by the shooting timing in FIG. 3 , during these periods S1 and S2, the camera of the star tracker 20 photographs the starry sky, and outside of these periods S1 and S2, the camera of the star tracker 20 stops photographing the starry sky.

[0018] When the vehicle 1 is traveling on a road with a small surface roughness, the fluctuations in both the roll angular velocity X and the pitch angular velocity Y are maintained smaller than the preset fluctuations. In contrast, when the vehicle 1 is traveling on a road with a large surface roughness, the fluctuations in both the roll angular velocity X and the pitch angular velocity Y may momentarily become smaller than the preset fluctuations, but the fluctuations in both the roll angular velocity X and the pitch angular velocity Y are not continuously maintained smaller than the preset fluctuations. Therefore, in this embodiment of the present invention, the starry sky is photographed by the camera of the star tracker 20 when the fluctuations in both the roll angular velocity X and the pitch angular velocity Y remain smaller than the preset fluctuations for a certain period of time TT, as shown by the photographing timing in FIG. 3 , so that the starry sky can be photographed by the camera of the star tracker 20 when there is a high probability that the fluctuations in both the roll angular velocity X and the pitch angular velocity Y will become smaller than the preset fluctuations.

[0019] On the other hand, if the amount of change in the attitude angle of vehicle 1 is not small, that is, the amount of change in both roll angular velocity X and pitch angular velocity Y is not smaller than the preset amount of change, but adjustments make it possible to photograph the starry sky with the camera of star tracker 20, then it is preferable to photograph the starry sky with the camera of star tracker 20 by adjusting the camera of star tracker 20 or the output image data showing the photographed starry sky. In this case, even if the amount of change in the attitude angle of vehicle 1 becomes somewhat large, if the shutter speed is increased and the output signal value from light receiving element 32 is increased to compensate for the resulting decrease in the amount of received light, that is, if the exposure sensitivity is increased, then it will be possible to photograph the starry sky with the camera of star tracker 20.

[0020] Therefore, in an embodiment of the present invention, the preset variation amount is composed of a first variation amount and a second variation amount that is a variation amount of the vehicle's attitude angle that is larger than the first variation amount, and as shown in period S1 in Figure 3, when the variation amount of the vehicle's attitude angle is less than the preset first variation amount, the camera of the star tracker 20 photographs the starry sky at a reference shutter speed and generates image data of the starry sky at a reference exposure sensitivity, and as shown in period S2 in Figure 3, when the variation amount of the vehicle's attitude angle is equal to or greater than the first variation amount and equal to or less than the second variation amount, the camera of the star tracker 20 photographs the starry sky at a speed faster than the reference shutter speed and generates image data of the starry sky at an exposure sensitivity higher than the reference exposure sensitivity, as shown by the shutter speed and exposure sensitivity in Figure 3, and when the variation amount of the vehicle's attitude angle exceeds the second variation amount, the camera stops photographing the starry sky.

[0021] 4 and 5 show a routine for executing the vehicle attitude angle estimation process. This routine is executed by interruption at regular intervals in the electronic control unit 13 of the vehicle 1.

[0022] 4 and 5, first, in step 40, the roll angular velocity X and pitch angular velocity Y output from the inertial sensor 21 are acquired. Next, in step 41, it is determined whether the roll angular velocity X is between a lower limit value −X1 and an upper limit value X1. If it is determined that the roll angular velocity X is between the lower limit value −X1 and the upper limit value X1, the process proceeds to step 42, where it is determined whether the pitch angular velocity Y is between a lower limit value −Y1 and an upper limit value Y1. If it is determined that the pitch angular velocity Y is between the lower limit value −Y1 and the upper limit value Y1, that is, if the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y are less than a preset first fluctuation amount, the process proceeds to step 43, where the duration t1 is incremented by the interrupt time interval Δt. Next, the process proceeds to step 45.

[0023] On the other hand, when it is determined in step 41 that the roll angular velocity X is not between the lower limit value −X1 and the upper limit value X1, or when it is determined in step 42 that the pitch angular velocity Y is not between the lower limit value −Y1 and the upper limit value y1, that is, when the amount of variation in at least one of the roll angular velocity X and the pitch angular velocity Y is equal to or greater than a first amount of variation set in advance, the process proceeds to step 44, where the duration t1 is cleared, and then the process proceeds to step 45.

[0024] In step 45, it is determined whether the roll angular velocity X is between a lower limit value −X2 and an upper limit value X2 (X2 is a value greater than X1). If it is determined that the roll angular velocity X is between the lower limit value −X2 and the upper limit value X2, the process proceeds to step 46, where it is determined whether the pitch angular velocity Y is between a lower limit value −Y2 and an upper limit value Y2 (Y2 is a value greater than Y1). If it is determined that the pitch angular velocity Y is between the lower limit value −Y2 and the upper limit value Y2, that is, if the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y are equal to or less than a preset second fluctuation amount, the process proceeds to step 47, where the duration t2 is incremented by the interrupt time interval Δt. Next, the process proceeds to step 49.

[0025] On the other hand, when it is determined in step 45 that the roll angular velocity X is not between the lower limit value −X2 and the upper limit value X2, or when it is determined in step 46 that the pitch angular velocity Y is not between the lower limit value −Y2 and the upper limit value Y2, that is, when the amount of variation in at least one of the roll angular velocity X and the pitch angular velocity Y exceeds a preset second amount of variation, the process proceeds to step 48, where the duration t2 is cleared, and then the process proceeds to step 49.

[0026] That is, the duration t1 is increased as long as the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y remain less than a predetermined first fluctuation amount, and the duration t2 is increased as long as the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y remain less than a predetermined second fluctuation amount.

[0027] In step 49, it is determined whether the duration t1 exceeds a certain period TT that determines the timing of shooting. Note that when the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y are less than a predetermined first fluctuation amount, the fluctuation amounts of both the roll angular velocity X and the pitch angular velocity Y are less than or equal to a predetermined second fluctuation amount, so when the duration t1 exceeds the certain period TT, the duration t2 also exceeds the certain period TT. If it is determined in step 49 that the duration t1 has exceeded the certain period TT, the process proceeds to step 50, where the shutter speed is set, and then to step 51, where the exposure sensitivity is set. At this time, in step 50, the shutter speed is set to a reference shutter speed, and in step 51, the exposure sensitivity is set to the reference exposure sensitivity. Next, the process proceeds to step 55.

[0028] On the other hand, if it is determined in step 49 that the duration t1 has not exceeded the fixed period TT, the process proceeds to step 52, where it is determined whether the duration t2 has exceeded the fixed period TT. If it is determined that the duration t2 has not exceeded the fixed period TT, the process ends. On the other hand, if it is determined in step 52 that the duration t2 has exceeded the fixed period TT, the process proceeds to step 53, where the shutter speed is set, and then to step 54, where the exposure sensitivity is set. At this time, in step 53, the shutter speed is set to a shutter speed faster than the reference shutter speed, and in step 51, the exposure sensitivity is set to an exposure sensitivity higher than the reference exposure sensitivity. Next, the process proceeds to step 55.

[0029] In step 55, both duration t1 and duration t2 are cleared. Next, in step 56, the starry sky is photographed by the camera of the star tracker 20. Next, in step 57, a pattern matching process is performed between the arrangement of stars obtained from the output image data showing the photographed starry sky and a star catalog pre-stored in memory 16, and the inclination of the vehicle body with respect to the vertical axis of the road surface, i.e., the roll angle and pitch angle, are calculated. In other words, the attitude angle of the vehicle 1 is estimated. Next, in step 58, the estimated attitude angle of the vehicle 1 is displayed on the display device 26.

[0030] As described above, the vehicle attitude angle estimation device according to the present invention comprises a star tracker 20 mounted on the vehicle to output image data of the starry sky photographed by the camera, an inertial sensor 21 mounted on the vehicle 1, and a processor 15. This processor 15 calculates the amount of variation in the attitude angle of the vehicle 1 from the angular velocity signal output from the inertial sensor 21, and when the amount of variation in the attitude angle of the vehicle 1 is smaller than a preset amount of variation, it causes the camera to photograph the starry sky and generate image data of the starry sky, and when the amount of variation in the attitude angle of the vehicle 1 exceeds the preset amount of variation, it stops photographing the starry sky with the camera, and estimates the attitude angle of the vehicle 1 based on the arrangement of stars obtained from the generated image data and the star catalog.

[0031] In this case, in an embodiment according to the present invention, the amount of change in the attitude angle of the vehicle 1 is determined from the amounts of change in both the roll angular velocity and the pitch angular velocity detected by the inertial sensor 21. Also, in this case, in an embodiment according to the present invention, when the amount of change in the attitude angle of the vehicle 1 is continuously smaller than a preset amount of change for a preset period of time, an image of the starry sky is captured by a camera and image data of the starry sky is generated.

[0032] On the other hand, in an embodiment according to the present invention, the preset variation amount is composed of a preset first variation amount and a preset second variation amount that is larger than the preset first variation amount, and when the variation amount of the attitude angle of the vehicle 1 is less than the preset first variation amount, the camera photographs the starry sky at a reference shutter speed and generates image data of the starry sky at a reference exposure sensitivity, and when the variation amount of the attitude angle of the vehicle 1 is equal to or greater than the preset first variation amount and equal to or less than the preset second variation amount, the camera photographs the starry sky at a speed faster than the reference shutter speed and generates image data of the starry sky at an exposure sensitivity higher than the reference exposure sensitivity, and when the variation amount of the attitude angle of the vehicle 1 exceeds the preset second variation amount, the camera stops photographing the starry sky.

[0033] In this case, in an embodiment according to the present invention, when the amount of change in the attitude angle of vehicle 1 is continuously less than a predetermined first amount of change for a predetermined time, the camera photographs the starry sky at a standard shutter speed and generates image data of the starry sky at a standard exposure sensitivity, and when the amount of change in the attitude angle of vehicle 1 is continuously greater than or equal to the predetermined first amount of change and less than or equal to a predetermined second amount of change for a predetermined time, the camera photographs the starry sky at a speed faster than the standard shutter speed and generates image data of the starry sky at an exposure sensitivity higher than the standard exposure sensitivity. [Explanation of symbols]

[0034] 1 vehicle 15 processors 20 Star Tracker 21 Inertial Sensor

Claims

1. The system includes a star tracker mounted on a vehicle to output image data of a starry sky photographed by a camera, an inertial sensor mounted on the vehicle, and a processor; The processor determining a variation in the attitude angle of the vehicle from the angular velocity signal output from the inertial sensor; When the amount of change in the attitude angle of the vehicle is smaller than a preset amount of change, a starry sky is photographed by a camera to generate image data of the starry sky; When the amount of change in the attitude angle of the vehicle exceeds a preset amount of change, the camera stops photographing the starry sky, A vehicle attitude angle estimation device that estimates the vehicle attitude angle based on the star arrangement and star catalog obtained from the generated image data.

2. 2. The vehicle attitude angle estimation device according to claim 1, wherein the amount of change in the vehicle attitude angle is determined from the amounts of change in both the roll angular velocity and the pitch angular velocity detected by the inertial sensor.

3. The processor 2. The vehicle attitude angle estimation device according to claim 1, wherein when the amount of change in the vehicle attitude angle is continuously smaller than a predetermined amount for a predetermined time, a starry sky is photographed with a camera to generate image data of the starry sky.

4. the predetermined fluctuation amount is configured by a predetermined first fluctuation amount and a predetermined second fluctuation amount that is greater than the predetermined first fluctuation amount, The processor When the amount of change in the attitude angle of the vehicle is less than a predetermined first amount of change, the camera captures an image of the starry sky at a reference shutter speed and generates image data of the starry sky at a reference exposure sensitivity; when the amount of change in the attitude angle of the vehicle is equal to or greater than the predetermined first amount of change and equal to or less than the predetermined second amount of change, photographing the starry sky with a camera at a speed faster than a reference shutter speed and generating image data of the starry sky at an exposure sensitivity higher than a reference exposure sensitivity; 2. The vehicle attitude angle estimation device according to claim 1, wherein when the amount of change in the vehicle attitude angle exceeds the second predetermined amount of change, the camera stops photographing the starry sky.

5. The processor When the amount of change in the attitude angle of the vehicle is continuously less than a predetermined first amount of change for a predetermined time, the camera captures an image of the starry sky at a reference shutter speed and generates image data of the starry sky at a reference exposure sensitivity; 2. The vehicle attitude angle estimation device according to claim 1, wherein when a variation amount of the vehicle attitude angle is continuously equal to or greater than the predetermined first variation amount and equal to or less than the predetermined second variation amount for a predetermined time, the device photographs the starry sky with a camera at a speed faster than a reference shutter speed and generates image data of the starry sky with an exposure sensitivity higher than the reference exposure sensitivity.

Images