Speed calculation device

Abstract

To provide a speed calculation device capable of being hardly affected by a peripheral environment and a traveling environment.SOLUTION: The control unit 15 acquires a result of detection of a feature at time t0 by the front LIDAR 21a provided in the vehicle C and detecting the feature ahead of the vehicle, and acquires a result of detection of the same feature as the feature detected by the front LIDAR 21a at time t0 by the rear LIDAR 21b provided in the vehicle C and detecting the feature behind the vehicle at time t1 by the second acquiring unit 15b. Then, the calculating unit 15c calculates the moving speed of the vehicle C based on the result acquired by the first acquiring unit 15a and the result acquired by the second acquiring unit 15b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a velocity calculation device that calculates the velocity of a moving object. [Background technology]

[0002] Conventionally, there have been known techniques for estimating vehicle speed with high accuracy. For example, Patent Document 1 discloses a technique for measuring the distance and relative speed between a vehicle and a surrounding object using a measuring device such as a LiDAR (Light Detection and Ranging) and estimating the speed of the vehicle based on the measurement results. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-101944 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention described in Patent Document 1, a measurement device such as a lidar measures the same feature multiple times using a single measurement device, and calculates the speed of a moving object from the measured distance and time. However, if there are other moving objects around the moving object or if the moving object's own speed is high, it may be difficult to measure the same feature multiple times. In other words, conventional methods have been susceptible to the influence of the surrounding environment and the driving environment.

[0005] One example of a problem that the present invention aims to solve is to make the vehicle less susceptible to the influence of the surrounding environment and the driving environment. [Means for solving the problem]

[0006] The invention described in claim 1, which was made to solve the above problem, comprises a first acquisition unit that is provided on a moving body and acquires the results of features detected at a first time by a first detection device that detects features in front of the moving body; a second acquisition unit that is provided on the moving body and acquires the results of features detected at a second time by a second detection device that is provided on the moving body and detects features behind the moving body; and a calculation unit that calculates the movement speed of the moving body based on the results acquired by the first acquisition unit and the results acquired by the second acquisition unit, wherein the calculation unit determines whether the features detected in each result are the same based on the results acquired by the first acquisition unit and the results acquired by the second acquisition unit, and calculates the movement speed of the moving body if it is determined that they are the same.

[0007] Furthermore, the invention described in claim 7 is a speed calculation method executed by a speed calculation device that calculates the movement speed of a moving body, and includes: a first acquisition step of acquiring a result of a feature detected at a first time by a first detection device that is provided on the moving body and detects features in front of the moving body; a second acquisition step of acquiring a result of an identical feature detected at a second time by a second detection device that is provided on the moving body and detects features behind the moving body; and a calculation step of calculating the movement speed of the moving body based on the result acquired in the first acquisition step and the result acquired in the second acquisition step, wherein the calculation step determines whether the features detected in each result are the same based on the result acquired in the first acquisition step and the result acquired in the second acquisition step, and calculates the movement speed of the moving body if it is determined that they are the same.

[0008] The invention as set forth in claim 8 is characterized in that the velocity calculation method as set forth in claim 7 is executed by a computer.

[0009] The invention as set forth in claim 9 is characterized in that the speed calculation program as set forth in claim 8 is stored. [Brief explanation of the drawings]

[0010] [Figure 1]1 illustrates the configuration of a detection device having a velocity calculation device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram of the installation position of the rider shown in FIG. 1 on the vehicle. [Figure 3] 2 is an explanatory diagram of a speed calculation method in the control unit shown in FIG. 1. FIG. [Figure 4] 2 is a flowchart of a speed calculation method in the control unit shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] An information processing device according to one embodiment of the present invention will be described below. In a speed calculation device according to one embodiment of the present invention, a first acquisition unit is provided on a moving body and acquires a result of a first detection device detecting features ahead of the moving body at a first time, and a second acquisition unit is provided on the moving body and acquires a result of a second detection device detecting features behind the moving body at a second time, the second detection device detecting the same feature as the first detection device detected at the first time. The calculation unit then calculates the moving speed of the moving body based on the result acquired by the first acquisition unit and the result acquired by the second acquisition unit. In this manner, the speed can be calculated using the results of detection of the same feature by the two detection units, the first detection unit and the second detection unit. Therefore, the speed can be calculated even when the moving body has passed the feature to be measured, when there are other moving bodies nearby, or when the moving body's own speed is high, making it less susceptible to the influence of the surrounding environment and the traveling environment.

[0012] The calculation unit may calculate the moving speed of the moving object based on the results acquired by the first acquisition unit, the results acquired by the second acquisition unit, and the installation interval between the first detection device and the second detection device in the moving direction of the moving object. By doing so, the accuracy of the calculated speed can be further improved by using the installation interval.

[0013] The calculation unit may also identify the same feature based on the shape of the feature, thereby making it possible to identify that a feature detected in front and a feature detected behind are the same feature based on the shape of the feature.

[0014] The calculation unit may also identify the same feature by comparing the distance calculated based on the results detected by the other speed sensor with the distance based on the results acquired by the first acquisition unit and the results acquired by the second acquisition unit. In this way, the results detected by the other speed sensor can be used to identify the same feature.

[0015] Furthermore, a vehicle speed sensor correction device according to one embodiment of the present invention includes the above-described speed calculation device, a third acquisition unit that acquires an output signal of a vehicle speed sensor of a moving object, and a correction unit that corrects the output signal acquired by the third acquisition unit based on the moving speed calculated by the speed calculation device. In this way, the speed detected by the vehicle speed sensor can be corrected by the speed detected by the above-described speed calculation device.

[0016] Furthermore, in a speed calculation method according to one embodiment of the present invention, a first acquisition step involves a first detection device provided on the moving body for detecting features ahead of the moving body acquiring a result of feature detection at a first time, and a second acquisition step involves a second detection device provided on the moving body for detecting features behind the moving body acquiring a result of feature detection at a second time, the second detection device detecting the same feature as the first detection device detected at the first time. The calculation step then involves calculating the moving speed of the moving body based on the results acquired in the first acquisition step and the results acquired in the second acquisition step. This allows the speed to be calculated using the results of detection of the same feature by the first and second detection units. Therefore, the speed can be calculated even when the moving body has passed the feature to be measured, when there are other moving bodies nearby, or when the moving body's own speed is high, making it less susceptible to the influence of the surrounding environment and the traveling environment.

[0017] The above-described speed calculation method may also be implemented as a speed calculation program that causes a computer to execute the method. This allows the computer to calculate the speed using the results of detecting the same feature by the first and second detection units. Therefore, it is possible to increase the frequency of speed calculations even when the target feature has passed, when there are other moving objects nearby, or when the moving object itself is moving at a high speed.

[0018] The speed calculation program may be stored in a computer-readable recording medium, which allows the program to be distributed as a standalone program rather than being incorporated into a device, and allows for easy version upgrades. [Example]

[0019] A speed calculation device according to an embodiment of the present invention will be described with reference to Figures 1 to 4. The speed calculation device according to this embodiment is included in a detection device 1, and moves together with a vehicle as a moving object.

[0020] A schematic block diagram of a detection device 1 according to this embodiment is shown in Fig. 1. The detection device 1 includes a sensor group 11, a storage unit 12, a control unit 15, and an output unit 16.

[0021] The sensor group 11 includes a lidar 21 , a vehicle speed sensor 22 , an acceleration sensor 23 , a gyro sensor 24 , a traveling direction sensor 25 , and a GPS receiver 27 .

[0022] The lidar 21, which serves as a detection unit, measures the distance to an object in the external world in a discrete manner by emitting a pulsed laser beam. The lidar 21 outputs a point cloud of measurement points indicated by a pair of the distance to the object where the laser beam is reflected and the emission angle of the laser beam. In this embodiment, the lidar 21 is used to detect features present around the vehicle. The term "feature" encompasses all natural and artificial objects on the ground. Examples of features include route features located on the vehicle's route (i.e., road) and surrounding features located around the road. Examples of route features include road signs, traffic lights, guardrails, pedestrian bridges, etc., as well as the road itself. In other words, route features also include letters and figures drawn on the road surface and the shape of the road (road width and curvature). Examples of surrounding features include buildings (houses, stores) and signs located along the road.

[0023] In this embodiment, as shown in Fig. 2, the LIDAR 21 includes a front LIDAR 21a that detects features ahead of the vehicle C, and a rear LIDAR 21b that detects features behind the vehicle C. The front LIDAR 21a is provided, for example, at the front end of the vehicle C. The rear LIDAR 21b is provided, for example, at the rear end of the vehicle C. The number of LIDARs 21 installed is not limited to two. In other words, a plurality of LIDARs may correspond to the front LIDAR 21a, and a plurality of LIDARs may correspond to the rear LIDAR 21b. Measurement results may be selected and acquired from a plurality of LIDARs to calculate the speed.

[0024] In this embodiment, when road markings (such as letters and figures drawn on the road surface) are mainly used as features for speed calculation, it is preferable to provide the lidar 21 below the vehicle (for example, below the hood). Furthermore, when signs and the like provided above the road, such as guide signs indicating the direction and distance to the destination or passing points, are mainly used, it is preferable to provide the lidar 21 above the vehicle (for example, above the hood). Furthermore, the lidar 21 does not have to be dedicated to speed calculation, and may also be used for other purposes such as obstacle detection and self-location estimation.

[0025] The vehicle speed sensor 22 measures pulses (also called "axle rotation pulses") consisting of pulse signals generated in accordance with the rotation of the vehicle's wheels to detect the vehicle speed. The acceleration sensor 23 detects the acceleration in the vehicle's traveling direction. The gyro sensor 24 detects the angular velocity of the vehicle when changing direction. The traveling direction sensor 25 detects whether the vehicle is traveling forward or backward based on a reverse signal output, for example, when the vehicle's shift lever is placed in the reverse position. The GPS (Global Positioning System) receiver 27 detects the absolute position of the vehicle by receiving radio waves containing positioning data from multiple GPS satellites. The output of each sensor in the sensor group 11 is supplied to the control unit 15.

[0026] The storage unit 12 stores a speed calculation program executed by the control unit 15, information necessary for the control unit 15 to execute predetermined processing, and the like. In this embodiment, the storage unit 12 stores a map database (DB) 10 including road data and information on features. The map DB 10 may be updated periodically. In this case, for example, the control unit 15 receives partial map information related to the area to which the vehicle position belongs from an external server device that manages map information via a communication unit (not shown), and reflects the information in the map DB 10. Instead of the storage unit 12 storing the map DB 10, a server device that can communicate with the detection device 1 may store the map DB 10. In this case, the control unit 15 acquires necessary feature information and the like from the map DB 10 by communicating with the external server device.

[0027] The output unit 16 outputs, for example, the speed information calculated by the control unit 15 to an automatic driving control device or other in-vehicle devices such as meters.

[0028] The control unit 15 includes a CPU (Central Processing Unit) that executes programs and controls the entire detection device 1. The control unit 15 includes a first acquisition unit 15a, a second acquisition unit 15b, and a calculation unit 15c. In this embodiment, the control unit 15 calculates the speed of the vehicle based on the features detected by the lidar 21.

[0029] The first acquisition unit 15a acquires the detection results of the features detected by the front lidar 21a, and the second acquisition unit 15b acquires the detection results of the features detected by the rear lidar 21b.

[0030] The calculation unit 15c calculates the speed of the vehicle based on the results acquired by the first acquisition unit 15a and the results acquired by the second acquisition unit 15b.

[0031] The control unit 15 of the detection device 1 having the above-described configuration functions as the velocity calculation device according to this embodiment.

[0032] Next, a speed calculation method in the control unit 15 (speed calculation device) of the detection device 1 configured as described above will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram of the speed calculation method when the vehicle C moves from the bottom to the top of the figure.

[0033] As described above, the vehicle C is provided with the front lidar 21a and the rear lidar 21b. First, at time t0, the front lidar 21a detects a feature A (for example, a stop line). This detection detects the distance dt0 (m) from the front lidar 21a to the feature A at the point in time t0.

[0034] Next, at time t1 after the vehicle C has passed the feature A, the rear lidar 21b detects the feature A. Through this detection, the distance dt1 (m) from the rear lidar 21b to the feature A at the point in time t1 is detected.

[0035] Furthermore, the installation distance ds (m) between the front rider 21a and the rear rider 21b is a distance that is known in advance when the riders 21 are installed. Therefore, the speed S of the vehicle C can be calculated using the following equation (1) from these distances dt0, dt1, and ds and the time difference (seconds) between time t1 and time t0. S(m / s)=(dt0+dt1+ds) / (t1-t0)...(1)

[0036] That is, the speed S of the vehicle C is calculated based on the result (dt0) acquired by the first acquisition unit 15a, the result (dt1) acquired by the second acquisition unit 15b, and the installation distance (ds) between the front rider 21a and the rear rider 21b in the vehicle's traveling direction.

[0037] In addition, if the distance dt0 from the front rider 21a to the feature A or the distance dt1 from the rear rider 21b to the feature A at the point in time t1 is sufficiently larger than the installation interval ds between the front rider 21a and the rear rider 21b, the installation interval ds can be omitted.

[0038] Next, the operation (speed calculation method) of the above-mentioned control unit 15 (speed calculation device) is summarized in the flowchart of Fig. 4. The flowchart shown in Fig. 4 is configured as a computer program (speed calculation program) that runs on the CPU of the control unit 15. Furthermore, this program is not limited to being stored in a memory or the like that the control unit 15 has, but may also be stored in a storage medium such as a memory card or optical disk.

[0039] First, the first acquisition unit 15a acquires the detection result of the front rider 21a (step S1), and then the second acquisition unit 15b acquires the detection result of the rear rider 21b (step S2).

[0040] Next, it is determined whether the same feature is detected in the detection result of the front lidar 21a acquired in step S1 and the detection result of the rear lidar 21b acquired in step S2 (step S3). Whether the feature is the same can be determined by, for example, detecting the feature by the front lidar 21a and then the rear lidar 21b in that order when the vehicle C is moving forward, and comparing the shapes of the detected features. In addition, the range of the detection time may be limited, for example, to within how many seconds after detection by the front lidar 21a.

[0041] Regarding the shape of features, for example, in the case of road markings, it is easy to determine whether they are the same if they have a distinctive shape such as a speed limit sign or a sign indicating the presence of a pedestrian crossing or a bicycle crossing zone.

[0042] By executing step S3, the second acquisition unit 15b can identify and acquire the result of the rear lidar 21b detecting the same feature at the second time as the feature detected by the front lidar 21a at the first time.

[0043] Furthermore, the determination of whether the features are the same may be made based on the result of the vehicle speed sensor 22 or the speed detected by other methods, such as the trajectory of position information detected by the GPS receiver 27. For example, the distance can be calculated from the time difference between the speed detected by the vehicle speed sensor 22 and the detection time. This distance is approximately the same as the total distance from the front lidar 21a to the feature to be detected (dt0 in FIG. 3) and the distance from the rear lidar 21b to the feature to be detected (dt1 in FIG. 3). Therefore, when the distance based on the vehicle speed sensor 22 is compared with the distance actually detected by the front lidar 21a or the rear lidar 21b, it can be determined that the features are the same if the difference is within a predetermined range.

[0044] Then, using the detection results (distance and time) for the features determined to be the same feature in step S3, the speed is calculated according to equation (1) (step S4).

[0045] As is clear from the above description, step S1 functions as a first acquisition step, steps S2 and S3 function as a second acquisition step, and step S4 functions as a calculation step.

[0046] The speed calculated in this manner can be used, for example, to correct the speed detected by the vehicle speed sensor 22. A known method can be used to correct the speed detected by the vehicle speed sensor 22, such as the method described in Japanese Patent Application Laid-Open No. 2008-8783. In this case, the control unit 15 functions as a third acquisition unit that acquires the output signal of the vehicle speed sensor 22 and a correction unit that corrects the output signal acquired by the third acquisition unit based on the moving speed calculated by the speed calculation device.

[0047] According to this embodiment, the control unit 15 acquires a result of the front LIDAR 21a, which is provided on the vehicle C and detects features in front of the vehicle, detecting the feature at time t0, through the first acquisition unit 15a, and a result of the rear LIDAR 21b, which is provided on the vehicle C and detects features behind the vehicle, detecting the feature at time t1, through the rear LIDAR 21b, which is provided on the vehicle C and detects features behind the vehicle, detecting the same feature as the feature detected by the front LIDAR 21a at time t0, through the second acquisition unit 15b. The calculation unit 15c then calculates the travel speed of the vehicle C based on the result acquired by the first acquisition unit 15a and the result acquired by the second acquisition unit 15b. In this way, the speed can be calculated using the results of the detection of the same feature by the two LIDARs, the front LIDAR 21a and the rear LIDAR 21b. Therefore, it is possible to increase the frequency of speed calculation even when the vehicle C has passed the feature to be measured, when there are other vehicles around the vehicle C, or when the vehicle C's own speed is high.

[0048] Furthermore, the calculation unit 15c calculates the moving speed of the vehicle C based on the results acquired by the first acquisition unit 15a, the results acquired by the second acquisition unit 15b, and the installation interval ds between the front rider 21a and the rear rider 21b in the traveling direction of the vehicle C. In this way, by using the installation interval, the accuracy of the calculated speed can be further improved.

[0049] Furthermore, the calculation unit 15c may identify the same feature based on the shape of the feature, thereby making it possible to identify that a feature detected in front and a feature detected behind are the same feature based on the shape of the feature.

[0050] Furthermore, the calculation unit 15c may identify the same feature by comparing the distance calculated based on the result detected by the speed sensor 22 with the distance based on the result acquired by the first acquisition unit 15a and the result acquired by the second acquisition unit 15b. In this way, the result detected by the speed sensor 22, which is another sensor, can be used to identify the same feature.

[0051] Furthermore, the control unit 15 functions as the above-mentioned speed calculation device, a third acquisition unit that acquires the output signal of the vehicle speed sensor 22 of the vehicle C, and a correction unit that corrects the output signal acquired by the third acquisition unit based on the moving speed calculated by the speed calculation device. In this way, the speed detected by the vehicle speed sensor 22 can be corrected with the speed detected by the above-mentioned speed calculation device.

[0052] In the above description, the speed calculation method when the vehicle C is moving forward has been described, but it is also possible to calculate the speed when the vehicle C is moving backward. In this case, the result detected by the rear rider 21b may be obtained first, and then the result detected by the front rider 21a may be obtained.

[0053] Furthermore, in the above description, the first and second detection devices are described as lidars, but they may also be in-vehicle cameras.

[0054] Furthermore, the present invention is not limited to the above-described embodiments. That is, a person skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the gist of the present invention. As long as such modifications still include the configuration of the velocity calculation device of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0055] 1. Detection device 15 control unit (speed calculation device, third acquisition unit, correction unit, vehicle speed sensor correction device) 15a 1st acquisition part 15b 2nd Acquisition Part 15c Calculation part 21a Front lidar (first detection device) 21b Rear lidar (second detection device)

Claims

1. a first acquisition unit that acquires a result of a feature being detected at a first time by a first detection device that is provided on the moving body and detects a feature ahead of the moving body; a second acquisition unit that acquires a result of detection of a feature at a second time by a second detection device that is provided on the moving body and detects a feature behind the moving body; a calculation unit that calculates a moving speed of the moving object based on the result acquired by the first acquisition unit and the result acquired by the second acquisition unit, the calculation unit determines whether the features detected in the results acquired by the first acquisition unit and the results acquired by the second acquisition unit are the same, and calculates the moving speed of the moving object when it is determined that the features are the same. A velocity calculation device characterized by:

2. 2. The velocity calculation device according to claim 1, wherein the calculation unit calculates the moving velocity of the moving body based on the results acquired by the first acquisition unit, the results acquired by the second acquisition unit, and the installation interval between the first detection device and the second detection device in the direction of travel of the moving body.

3. 2. The velocity calculation device according to claim 1, wherein the calculation unit determines whether the features are identical based on the shape of the features.

4. The speed calculation device according to claim 1, characterized in that the calculation unit compares a distance calculated based on the results detected by another speed sensor with a distance based on the results acquired by the first acquisition unit and the results acquired by the second acquisition unit to determine whether the feature is the same.

5. 5. The speed calculation device according to claim 1, wherein the moving object is a vehicle traveling on a road.

6. A velocity calculation device according to any one of claims 1 to 5; a third acquisition unit that acquires an output signal of a vehicle speed sensor of the moving object; a correction unit that corrects the output signal acquired by the third acquisition unit based on the moving speed calculated by the speed calculation device; A vehicle speed sensor correction device comprising:

7. A velocity calculation method executed by a velocity calculation device that calculates a moving velocity of a moving object, comprising: a first acquisition step of acquiring a result of detection of a feature at a first time by a first detection device provided on the moving body and configured to detect a feature ahead of the moving body; a second acquisition step of acquiring a result of a second detection device provided on the moving body and configured to detect a feature behind the moving body detecting the same feature at a second time; a calculation step of calculating a moving speed of the moving object based on the result acquired in the first acquisition step and the result acquired in the second acquisition step, The calculation step determines whether the features detected in the results obtained in the first acquisition step and the results obtained in the second acquisition step are the same, and calculates the moving speed of the moving object when it is determined that the features are the same. A velocity calculation method characterized by:

8. A velocity calculation program for causing a computer to execute the velocity calculation method according to claim 7.

9. 9. A computer-readable recording medium storing the velocity calculation program according to claim 8.

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