Obstacle detection device

Abstract

To prevent deterioration in the positional accuracy of an obstacle.SOLUTION: An obstacle detection device includes a camera and a control unit. The control unit acquires a captured image from the camera. The control unit calculates a position of the obstacle, based on a feature portion of the captured image and an angle of an optical axis. The control unit does not correct the angle of the optical axis when a specific condition is satisfied and corrects the angle of the optical axis when the specific condition is not satisfied.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an obstacle detection device. [Background technology]

[0002] The obstacle detection device disclosed in Patent Document 1 includes a camera and a detection unit. The detection unit acquires straight lines from an image captured by the camera. The detection unit estimates the position of the vanishing point based on the straight lines that may form the vanishing point. The detection unit calculates the tilt of the camera from the distance between the vanishing point and the center of the captured image and the focal length of the camera. By estimating the position of an obstacle taking the tilt of the camera into consideration, errors due to the tilt of the camera can be corrected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-132153 Summary of the Invention [Problem to be solved by the invention]

[0004] When an obstacle detection device is mounted on a moving body, correcting the tilt can result in a decrease in the accuracy of the obstacle position, and further improvements in the obstacle detection device are needed. [Means for solving the problem]

[0005] An obstacle detection device that solves the above problem is an obstacle detection device mounted on a moving body, and includes a camera and a control unit. The control unit acquires an image from the camera, calculates the position of an obstacle based on characteristic features of the image and the angle of the optical axis of the camera, and does not correct the angle of the optical axis if certain conditions are met, and corrects the angle of the optical axis if the certain conditions are not met.

[0006] When the specific condition is met, the angle of the optical axis is not corrected. Therefore, when the specific condition is met, the angle of the optical axis is corrected, and it is possible to prevent a decrease in the accuracy of the obstacle position.

[0007] In the obstacle detection device, the camera may be a monocular camera, and the optical axis may extend in a direction intersecting with the ground on which the moving object is traveling. In the obstacle detection device, the specific condition may include that the moving object is being operated.

[0008] In the obstacle detection device, the moving body may include an engine, and the specific condition may include vibrations occurring in the moving body not being in a steady state. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent the accuracy of the obstacle position from decreasing. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a forklift. [Figure 2] FIG. 2 is a schematic diagram of the forklift and the obstacle detection device. [Figure 3] FIG. 3 is a diagram showing the optical axis of a camera. [Figure 4] FIG. 4 is a flowchart showing the obstacle position calculation control. [Figure 5] FIG. 5 is a flowchart showing the correction control. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the obstacle detection device will be described. 1, a forklift 10 includes a vehicle body 11, drive wheels 12, steering wheels 13, and a cargo handling device 21. The forklift 10 is an example of a mobile object. The mobile object may be an industrial vehicle, such as a forklift or a towing tractor, or may be a passenger vehicle.

[0012] The vehicle body 11 is provided with a head guard 14. The head guard 14 is provided, for example, above the driver's seat. The cargo handling device 21 includes a mast 22 and a fork 23. The fork 23 moves up and down as the mast 22 moves up and down. The fork 23 tilts as the mast 22 tilts. A load is placed on the fork 23.

[0013] As shown in FIG. 2, the forklift 10 includes an accelerator operating member 31, an accelerator sensor 32, a direction lever 33, a direction switch 34, a vehicle control device 41, an engine 51, a travel control device 52, a power transmission mechanism 53, a hydraulic pump 54, a hydraulic mechanism 55, a load handling lever 56, and a vehicle speed sensor 57.

[0014] The accelerator operating member 31 is, for example, an accelerator pedal. The accelerator operating member 31 may also be, for example, a lever. The accelerator sensor 32 detects the amount of operation of the accelerator operating member 31.

[0015] The direction lever 33 determines the direction of travel of the forklift 10. The direction lever 33 is operated by the rider of the forklift 10. The direction lever 33 is operated to a forward position that commands forward travel or a reverse position that commands reverse travel, with the neutral position being used as a reference. For example, the forward position is a position where the direction lever 33 is tilted further forward than the neutral position. The reverse position is a position where the direction lever 33 is tilted further rearward than the neutral position.

[0016] The direction switch 34 switches depending on the operating direction of the direction lever 33. The direction switch 34 has, for example, three contacts. The contacts of the direction switch 34 switch depending on whether the direction lever 33 is in the neutral position, forward position, or reverse position.

[0017] The vehicle control device 41 includes a processor 42 and a storage unit 43. The processor 42 is, for example, a central processing unit (CPU), a graphics processing unit (GPU), and a digital signal processor (DSP). The storage unit 43 includes a random access memory (RAM) and a read-only memory (ROM). The storage unit 43 stores program code or instructions configured to cause the processor 42 to execute processing. The storage unit 43, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. The vehicle control device 41 may be configured with a hardware circuit such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The vehicle control device 41, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as an ASIC or an FPGA, or a combination thereof.

[0018] The engine 51 is a power source for driving the forklift 10 in its traveling and loading / unloading operations. The cruise control device 52 is an engine control unit that controls the engine 51. The cruise control device 52 adjusts, for example, the throttle opening. By adjusting the throttle opening, the driving force of the engine 51 is adjusted.

[0019] The power transmission mechanism 53 transmits the driving force of the engine 51 to the driving wheels 12. The power transmission mechanism 53 includes, for example, a torque converter and a transmission. The hydraulic pump 54 is driven by the engine 51. The hydraulic pump 54 draws hydraulic oil from an oil tank.

[0020] The hydraulic mechanism 55 distributes the hydraulic oil pumped up by the hydraulic pump 54. For example, the hydraulic mechanism 55 distributes the hydraulic oil to hydraulic cylinders such as tilt cylinders and lift cylinders provided in the cargo handling device 21. The tilt cylinder is a hydraulic cylinder that tilts the mast 22. The lift cylinder is a hydraulic cylinder that raises and lowers the mast 22.

[0021] The loading levers 56 are operated by the rider of the forklift 10. The loading levers 56 include a lift lever that is operated to move the forks 23 up and down, and a tilt lever that is operated to tilt the mast 22. In response to the operation of the loading levers 56, hydraulic oil is supplied from the hydraulic mechanism 55 to the loading device 21, thereby causing the loading device 21 to operate.

[0022] The vehicle speed sensor 57 is a sensor for detecting the vehicle speed of the forklift 10. The vehicle speed sensor 57 outputs a pulse signal corresponding to the vehicle speed of the forklift 10. The detection result of the vehicle speed sensor 57 is acquired by the travel control device 52. As a result, the travel control device 52 can acquire the vehicle speed of the forklift 10.

[0023] The vehicle control device 41 is configured to be able to communicate with the travel control device 52. The vehicle control device 41 can acquire the vehicle speed of the forklift 10 from the travel control device 52. The vehicle control device 41 acquires the operation amount of the accelerator operation member 31 from the accelerator sensor 32. The vehicle control device 41 issues a command to the travel control device 52 so that the forklift 10 travels at a speed corresponding to the operation amount of the accelerator operation member 31.

[0024] The vehicle control device 41 recognizes the position of the direction lever 33 by recognizing which of the contacts of the direction switch 34 is in. The vehicle control device 41 recognizes the load handling state of the forklift 10. The load handling state of the forklift 10 is, for example, whether or not the load handling device 21 is operating. The operation of the load handling device 21 includes tilting of the mast 22 and raising and lowering of the forks 23.

[0025] <Obstacle detection device> The forklift 10 is equipped with an obstacle detection device 61. The forklift 10 may be equipped with one obstacle detection device 61 or a plurality of obstacle detection devices 61.

[0026] The obstacle detection device 61 includes a camera 62, an inertial measurement unit 71, and a control unit 81. The camera 62 and the inertial measurement unit 71 are integrated into a single unit. Therefore, when the camera 62 tilts, the inertial measurement unit 71 also tilts in the same manner as the camera 62. The control unit 81 may also be integrated into a single unit with the camera 62 and the inertial measurement unit 71.

[0027] The camera 62 is a digital camera. The camera 62 includes an imaging element. The imaging element is, for example, a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. The camera 62 is a monocular camera.

[0028] As shown in FIG. 3, the optical axis 63 of the camera 62 extends in a direction intersecting with the ground G on which the forklift 10 travels. The camera 62 is attached to, for example, the head guard 14. The camera 62 is attached facing downward. The camera 62 may be attached facing in the direction in which obstacle detection is desired. If it is desired to detect obstacles behind the forklift 10, the camera 62 may be attached facing backward. If it is desired to detect obstacles on the left and right, the camera 62 may be attached facing left and right.

[0029] As shown in Fig. 2, the inertial measurement unit 71 includes an acceleration sensor 72 and a gyro sensor 73. The acceleration sensor 72 is a triaxial acceleration sensor having three axes that are orthogonal to each other. The acceleration sensor 72 detects acceleration acting on each axis. The gyro sensor 73 is a triaxial gyro sensor having three axes that are orthogonal to each other. The gyro sensor 73 detects angular velocity acting on each axis.

[0030] The control unit 81 has, for example, the same hardware configuration as the vehicle control device 41. The control unit 81 has a processor 82 and a storage unit 83. The control unit 81 is configured to be able to communicate with the vehicle control device 41 using a vehicle communication protocol. This allows the control unit 81 to acquire various information from the vehicle control device 41.

[0031] The control unit 81 calculates the position of the obstacle. The position of the obstacle is a position relative to the forklift 10, that is, the relative position between the forklift 10 and the obstacle. The obstacle position calculation control will be described.

[0032] <Obstacle position calculation control> As shown in FIG. 4, the control unit 81 acquires a captured image from the camera 62 in step S1.

[0033] Next, in step S2, the control unit 81 calculates the position of the obstacle based on the characteristic part of the captured image and the angle of the optical axis 63. The characteristic part is a part for extracting an object from the captured image. The characteristic part can be detected, for example, from the brightness gradient of the captured image. The control unit 81 may extract obstacles by distinguishing between people and non-people objects.

[0034] The control unit 81 converts the coordinates of the obstacle in the captured image into the coordinates of the obstacle in real space based on the angle of the optical axis 63. Converting the coordinates of the obstacle in the captured image into the coordinates of the obstacle in real space based on the angle of the optical axis can be performed using known technology. The angle of the optical axis 63 is the angle of the optical axis 63 with respect to the ground G on which the forklift 10 travels. In other words, it is the angle formed between the optical axis 63 and a plane parallel to the ground G on which the forklift 10 travels. The coordinates in real space may be represented by Cartesian coordinates or polar coordinates. The coordinates in real space may be two-dimensional coordinates or three-dimensional coordinates.

[0035] As described above, the control unit 81 calculates the position of the obstacle using the angle of the optical axis 63. The angle of the optical axis 63 can be known in advance. Therefore, by storing the angle of the optical axis 63 in a storage medium such as the storage unit 83, the position of the obstacle can be calculated. As shown in FIG. 3, when the angle of the optical axis 63 changes from a known angle θ1 to an unknown angle θ2, a difference occurs between the actual position of the obstacle and the position of the obstacle calculated by the obstacle position calculation control. In other words, there is a risk that the accuracy of the calculated position of the obstacle will decrease.

[0036] When the angle of the optical axis 63 changes from the known angle θ1, the control unit 81 corrects the angle of the optical axis 63. This makes it possible to reduce errors in the position of the obstacle even when the angle of the optical axis 63 changes from the known angle θ1.

[0037] <Correction control> The correction control for correcting the angle of the optical axis 63 will be described. As shown in FIG. 5, in step S11, the control unit 81 determines whether the forklift 10 is traveling. Whether the forklift 10 is traveling can be determined from the vehicle speed of the forklift 10. If the vehicle speed of the forklift 10 is equal to or greater than the travel determination threshold, the control unit 81 determines that the forklift 10 is traveling. If the vehicle speed of the forklift 10 is less than the travel determination threshold, the control unit 81 determines that the forklift 10 is stopped. The vehicle speed of the forklift 10 can be obtained from the detection result of the vehicle speed sensor 57 from the vehicle control device 41. The travel determination threshold is set, for example, within the range of 0 km / h to 0.5 km / h. If the determination result of step S11 is negative, the control unit 81 proceeds to step S12. If the determination result of step S11 is positive, the control unit 81 proceeds to step S17.

[0038] In step S12, the control unit 81 determines whether the forklift 10 is currently handling a load. Whether the forklift 10 is currently handling a load can be determined from the load handling status. The load handling status can be acquired from the vehicle control device 41. The vehicle control device 41 determines that loading is currently being performed when the loading device 21 is operating. The vehicle control device 41 determines that loading is not currently being performed when the loading device 21 is not operating. If the determination result in step S12 is negative, the control unit 81 proceeds to step S13. If the determination result in step S12 is positive, the control unit 81 proceeds to step S17.

[0039] In step S13, the control unit 81 determines whether the vibration occurring in the forklift 10 is in a steady state. Vibrations occurring even when the moving body is not traveling are considered to be steady state vibrations. For a moving body equipped with a loading device 21, such as the forklift 10, vibrations occurring even when the moving body is neither traveling nor handling a load are considered to be steady state vibrations. In contrast, vibrations occurring when an external shock or vibration is applied to the forklift 10 and the resulting vibrations have not yet subsided are considered to be non-steady state vibrations. Vibrations that are not in a steady state are considered to be non-steady state vibrations. For example, steady state vibrations are vibrations that occur when the engine 51 is idling. Whether the vibrations are in a steady state can be determined from the detection results of the inertial measurement unit 71.

[0040] The control unit 81 determines that the vibration is in a steady state if the amplitude of the vibration detected by the inertial measurement unit 71 is equal to or less than the vibration threshold value for consecutive designated frames within the most recent designated frame. The control unit 81 determines that the vibration is in a non-steady state if the amplitude of the vibration detected by the inertial measurement unit 71 becomes greater than the vibration threshold value within the most recent designated frame. The number of designated frames can be set arbitrarily. For example, the number of designated frames is set so that, when external vibration or impact is applied to the forklift 10, it can be determined whether the vibration caused by the vibration or impact has converged.

[0041] The amplitude of vibration detected by the inertial measurement unit 71 may be at least one of the amplitude of acceleration detected on each axis by the acceleration sensor 72 and the amplitude of angular velocity detected on each axis by the gyro sensor 73.

[0042] If the determination result in step S13 is positive, the control unit 81 proceeds to step S14. If the determination result in step S13 is negative, the control unit 81 proceeds to step S17. In step S14, the control unit 81 estimates the angle of the optical axis 63. Gravitational acceleration acts on each axis of the acceleration sensor 72. Each axis of the acceleration sensor 72 detects a component of gravitational acceleration according to its inclination relative to the direction of gravity. Because the camera 62 and the inertial measurement unit 71 tilt together, a change in the angle of the optical axis 63 causes a change in the magnitude of the gravitational acceleration detected on each axis of the acceleration sensor 72. When the forklift 10 is not traveling or handling a load, the acceleration acting on the acceleration sensor 72 can be considered to be gravitational acceleration. The control unit 81 estimates the angle of the optical axis 63 from the magnitude of the gravitational acceleration detected on each axis of the acceleration sensor 72.

[0043] The control unit 81 may correct the estimated angle of the optical axis 63 by using the detection result of the gyro sensor 73. The control unit 81 can also estimate the amount of change in the angle of the optical axis 63 from the acceleration detected on each axis of the acceleration sensor 72. For example, the amount of change in the angle of the optical axis 63 can be estimated from the difference between the acceleration detected on each axis of the acceleration sensor 72 when the tilt of the optical axis 63 does not change and the acceleration detected on each axis of the acceleration sensor 72 when the tilt of the optical axis 63 has changed.

[0044] When estimating the angle of the optical axis 63, the influence of vibration may be removed by a hardware filter or a software filter. When estimating the angle of the optical axis 63, steady-state vibration may be applied to the forklift 10. In this case, noise may be included in the acceleration detected by the acceleration sensor 72 and the angular velocity detected by the gyro sensor 73. This noise may be removed by a hardware filter or a software filter. Then, the angle of the optical axis 63 may be estimated from the acceleration and angular velocity after the noise has been removed.

[0045] Next, in step S15, the control unit 81 determines whether or not the forklift 10 is located on a slope. Whether or not the forklift 10 is located on a slope can be determined from the amount of change in the angle of the optical axis 63.

[0046] The angle of the optical axis 63 may change due to, for example, the following factors. Change in the mounting angle of the camera 62 due to loosening of the brackets and bolts that secure the camera 62 due to deterioration over time. Change in the mounting angle of the camera 62 due to load being applied to the camera 62, for example, when the occupant of the forklift 10 bumps into the camera 62. Change in the inclination of the vehicle body 11 due to wear of the tires on the drive wheels 12 and steering wheels 13. Change in the inclination of the vehicle body 11 due to a load being loaded onto the forks 23. Change in the inclination of the vehicle body 11 due to the forklift 10 riding over a step. Shaking of at least one of the camera 62 and the vehicle body 11 due to impact or vibration.

[0047] When the forklift 10 is located on a slope, the angle between the ground surface G and the optical axis 63 does not change. However, as the forklift 10 tilts according to the inclination of the slope, the magnitude of the gravitational acceleration detected by each axis of the acceleration sensor 72 changes. Therefore, even though the angle of the optical axis 63 with respect to the ground surface G does not change, the angle of the optical axis 63 with respect to the direction of gravity changes. As a result, when the angle of the optical axis 63 is estimated in step S14, a value different from the known angle θ1 is estimated.

[0048] If the amount of change in the angle of the optical axis 63 exceeds a threshold, the control unit 81 determines that the forklift 10 is located on a slope. The amount of change in the angle of the optical axis 63 is the difference between the known angle θ1 and the estimated angle of the optical axis 63. The amount of change in the angle of the optical axis 63 when the forklift 10 is located on a slope is greater than the amount of change in the angle of the optical axis 63 caused by the factors described above. For this reason, the threshold value is a value obtained by accumulating the amount of change in the angle of the optical axis 63 caused by the factors described above using the square root of the sum of the squares.

[0049] If the determination result in step S15 is negative, the control unit 81 proceeds to step S16. If the determination result in step S15 is positive, the control unit 81 proceeds to step S17. In step S16, the control unit 81 corrects the angle of the optical axis 63. For example, in the obstacle position calculation control, the control unit 81 calculates the obstacle position using the angle of the optical axis 63 estimated in step S14.

[0050] In step S17, the control unit 81 does not correct the angle of the optical axis 63. In this case, in the obstacle position calculation control, the control unit 81 may calculate the obstacle position using the known angle θ1 of the optical axis 63. The control unit 81 may calculate the obstacle position using the angle of the optical axis 63 that was most recently corrected in step S16.

[0051] After completing the process of step S16 or step S17, the control unit 81 returns to step S11. The correction control is repeatedly performed while the forklift 10 is in operation. As described above, the control unit 81 does not correct the angle of the optical axis 63 when the specific condition is met, and corrects the angle of the optical axis 63 when the specific condition is not met. When the forklift 10 is traveling and when the forklift 10 is handling a load, the forklift 10 is in operation. The specific condition includes the forklift 10 being in operation. The specific condition includes the vibration occurring in the forklift 10 not being in a steady state. The specific condition includes the forklift 10 being located on a slope. The specific condition may include at least one of these.

[0052] [Operation of this embodiment] When the control unit 81 corrects the angle of the optical axis 63, the correction by the control unit 81 may result in a decrease in the accuracy of the obstacle position. For example, when the forklift 10 is traveling or handling a load, the forklift 10 experiences large vibrations. These vibrations become disturbances, causing large noises in the acceleration detected by the acceleration sensor 72 and the angular velocity detected by the gyro sensor 73. Therefore, even if the angle of the optical axis 63 is estimated using the acceleration sensor 72 or the gyro sensor 73, there is a risk of a large deviation. The same applies when the vibration is not in a steady state.

[0053] As shown in Fig. 1, when the forklift 10 is located on a slope, the angle between the ground surface G and the optical axis 63 does not change. Therefore, by performing obstacle position calculation control without correcting the angle of the optical axis 63, the position of the obstacle O located on the ground surface G on which the forklift 10 is located can be correctly calculated. When the angle of the optical axis 63 is corrected, the correction is performed based on the acceleration of gravity. In other words, when the angle of the optical axis 63 is corrected, it is determined that the obstacle Oi is located on a plane Gi perpendicular to the acceleration of gravity.

[0054] As described above, the specific condition is when the detection results of the acceleration sensor 72 and the gyro sensor 73 contain large noise, or when the angle between the optical axis 63 and the direction of gravity changes even though the angle between the optical axis 63 and the ground G remains unchanged. If the specific condition is met, correcting the optical axis 63 would reduce the accuracy of the obstacle position, so the angle of the optical axis 63 is not corrected if the specific condition is met.

[0055] [Effects of this embodiment] (1) When a specific condition is met, the angle of the optical axis 63 is not corrected. Therefore, when the specific condition is met, the angle of the optical axis 63 is corrected, which can prevent the positional accuracy of the obstacle from decreasing.

[0056] (2) The camera 62 is a monocular camera. Compared to using a stereo camera as the camera 62, the manufacturing cost can be reduced. (3) The specific condition includes the forklift 10 being in operation. When the forklift 10 is in operation, there is a large amount of noise contained in the detection results of the acceleration sensor 72 and the gyro sensor 73. Therefore, by not correcting the optical axis 63 when the forklift 10 is in operation, it is possible to suppress a decrease in the accuracy of the obstacle position caused by correcting the angle of the optical axis 63.

[0057] (4) The specific condition includes a state in which the vibration occurring in the forklift 10 is not in a steady state. When the vibration occurring in the forklift 10 is not in a steady state, the noise contained in the detection results of the acceleration sensor 72 and the gyro sensor 73 is large. Therefore, when the vibration occurring in the forklift 10 is not in a steady state, the optical axis 63 is not corrected, thereby suppressing deterioration in the position accuracy of the obstacle caused by correcting the angle of the optical axis 63.

[0058] (5) The specific condition includes the forklift 10 being located on a slope. When the forklift 10 is located on a slope, the position of an obstacle located on the ground G on which the forklift 10 is located can be correctly calculated without correcting the angle of the optical axis 63. Therefore, by not correcting the optical axis 63 when the forklift 10 is located on a slope, it is possible to suppress a decrease in the accuracy of the obstacle position caused by correcting the angle of the optical axis 63.

[0059] [Example of change] The embodiment can be modified as follows: The embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0060] In step S11, the control unit 81 may determine whether the forklift 10 is traveling based on the amount of operation of the accelerator operating member 31. The amount of operation of the accelerator operating member 31 may be acquired from the vehicle control device 41. The control unit 81 determines that the forklift 10 is traveling when the amount of operation of the accelerator operating member 31 is equal to or greater than the accelerator operating amount threshold. The accelerator operating amount threshold is set to exclude minute operating amounts. The control unit 81 may make the determination in step S11 using both the vehicle speed and the amount of operation of the accelerator operating member 31.

[0061] If the accelerator operating member 31 is operated with the direction lever 33 in the neutral position, vibrations will occur in the forklift 10 even though the forklift 10 is not traveling. If the angle of the optical axis 63 is corrected in this case, the accuracy of the obstacle position may be reduced due to the influence of the vibrations. By performing the determination in step S11 using the operation amount of the accelerator operating member 31, it is possible to prevent the angle of the optical axis 63 from being corrected when the accelerator operating member 31 is operated with the direction lever 33 in the neutral position.

[0062] In step S12, the control unit 81 may determine whether the forklift 10 is currently handling a load based on the amount of operation of the load handling lever 56. In this case, the forklift 10 is equipped with a sensor that detects the amount of operation of the load handling lever 56. The control unit 81 determines that the forklift 10 is currently handling a load when the amount of operation of the load handling lever 56 is equal to or greater than the load handling operation amount threshold. The load handling operation amount threshold is set to exclude small amounts of operation. The control unit 81 may make the determination in step S12 using both the load state and the amount of operation of the load handling lever 56.

[0063] In step S13, the control unit 81 may estimate the angle of the optical axis 63 from the detection results of the inertial measurement unit 71, and determine that the vibration is in a steady state if the estimated angle of the optical axis 63 is equal to or less than the angle threshold for a specified number of consecutive frames. The angle threshold is a predetermined value. The angle threshold is set so that it can be determined whether the vibration is in a steady state or an unsteady state. If noise due to vibration is included in the detection results of the acceleration sensor 72 or the gyro sensor 73, the estimated angle of the optical axis 63 increases, causing the angle of the optical axis 63 to exceed the angle threshold. Therefore, using the angle threshold makes it possible to determine whether the vibration is in a steady state or not.

[0064] By providing a low-pass filter that removes large vibrations and shocks, the process of step S13 may be omitted. In this case, the processing speed of the correction control is improved and implementation is easier.

[0065] In step S15, the control unit 81 may determine whether the forklift 10 is located on a slope based on the result of self-location estimation. For example, the control unit 81 may compare map data recording slope locations in the location where the forklift 10 is operated with the self-location estimated on the map data by self-location estimation. The self-location estimation may be performed by the vehicle control device 41. The map data is stored in a storage device readable by the control unit 81 or the vehicle control device 41.

[0066] In step S15, the control unit 81 may determine whether the forklift 10 is located on a slope based on the detection results of the ground distance sensors. The ground distance sensors are provided, for example, at two locations spaced apart in the front-to-rear direction of the forklift 10. When the forklift 10 approaches a slope from flat ground, a difference occurs between the distances to the ground G detected by the two ground distance sensors. The control unit 81 may determine whether the forklift 10 is located on a slope based on the difference between the distances to the ground G detected by the two ground distance sensors.

[0067] When the forklift 10 is shipped, the angle of the optical axis 63 may be estimated with the forklift 10 positioned on a flat surface plate. Then, this angle of the optical axis 63 may be stored in the storage unit 83 as a known angle θ1. This can improve the efficiency of the work compared to when an operator measures the angle of the optical axis 63 manually.

[0068] The camera 62 may be a stereo camera. The forklift 10 may be driven by a motor. [Definition] The phrase "at least one" as used herein means "one or more" of the desired options. As an example, the phrase "at least one" as used herein means "only one option" or "both of two options" when the number of options is two. As another example, the phrase "at least one" as used herein means "only one option" or "any combination of two or more options" when the number of options is three or more. [Explanation of symbols]

[0069] 10...forklift as an example of a moving body, 61...obstacle detection device, 62...camera, 63...optical axis, 81...control unit.

Claims

1. An obstacle detection device mounted on a moving body, A camera and a control unit, The control unit Acquire a captured image from the camera; calculating a position of an obstacle based on a characteristic portion of the captured image and an angle of the optical axis of the camera; An obstacle detection device that does not correct the angle of the optical axis when a specific condition is met, and corrects the angle of the optical axis when the specific condition is not met.

2. the camera is a monocular camera, The obstacle detection device according to claim 1 , wherein the optical axis extends in a direction intersecting with a ground surface on which the moving object travels.

3. The obstacle detection device according to claim 1 , wherein the specific condition includes the moving object being in operation.

4. The moving body includes an engine, 2. The obstacle detection device according to claim 1, wherein the specific condition includes a condition in which vibrations occurring in the moving object are not in a steady state.

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