JP7488991B2 - Industrial Vehicles - Google Patents

Description

This disclosure relates to industrial vehicles.

The industrial vehicle disclosed in Patent Document 1 is equipped with an accelerator sensor, a main control device, a camera, and an obstacle detection device that detects obstacles. The accelerator sensor detects the amount of operation of the accelerator member. The obstacle detection device detects obstacles from the image captured by the camera. The main control device restricts the start of the industrial vehicle when an obstacle is detected by the obstacle detection device. When the amount of operation of the accelerator member exceeds a threshold, the main control device restricts the start of the industrial vehicle by prohibiting the start or imposing a vehicle speed limit. This makes it possible to prevent the industrial vehicle from coming into contact with an obstacle.

JP 2020-164316 A

Industrial vehicles are often used in environments where there are many obstacles around. For this reason, industrial vehicle operators may be aware of the presence of obstacles while operating the industrial vehicle. Even in such cases, if the start of the industrial vehicle is restricted, it will lead to a decrease in work efficiency.

The industrial vehicle that solves the above problem includes a driving motor, a driving control device that controls the driving motor according to the amount of operation of the accelerator member, a distance measuring device that measures the distance to an obstacle, an obstacle detection device that detects an obstacle from the measurement result of the distance measuring device, a departure determination unit that determines whether the industrial vehicle will start or not, a vehicle speed limiting unit that limits the vehicle speed when the industrial vehicle starts and the obstacle is present within a limited range, and a range changing unit that changes the size of the limited range in the traveling direction of the industrial vehicle in response to an indicator related to the operation of the accelerator member.

The manner in which the operator of the industrial vehicle operates the accelerator member differs depending on whether or not the operator recognizes the presence of an obstacle. The vehicle speed limiting unit changes the size of the restricted range in the traveling direction of the industrial vehicle in response to an indication of the operation of the accelerator member. This changes the size of the restricted range in the traveling direction of the industrial vehicle depending on whether or not the operator of the industrial vehicle recognizes the presence of an obstacle. If the size of the restricted range in the traveling direction of the industrial vehicle becomes shorter, it becomes more difficult for the vehicle speed limiting unit to limit the vehicle speed. This makes it possible to suppress a decrease in work efficiency.

In the above industrial vehicle, the indicator may be an operation amount of the accelerator member, and the range change unit may increase the dimension as the operation amount increases.
When the operator of the industrial vehicle is aware of the presence of an obstacle, the amount of operation of the accelerator member tends to be less than when the operator of the industrial vehicle is not aware of the presence of an obstacle. By making the dimension of the restricted range in the traveling direction of the industrial vehicle longer as the amount of operation of the accelerator member increases, it becomes more difficult for the obstacle to enter the restricted range when the operator of the industrial vehicle is aware of the presence of an obstacle. It becomes more difficult for the vehicle speed limiting unit to limit the vehicle speed. This makes it possible to suppress a decrease in work efficiency.

For the above industrial vehicle, the indicator may be an increase per unit time in the amount of operation of the accelerator member, and the range change unit may increase the dimension as the increase per unit time in the amount of operation increases.

When the operator of the industrial vehicle is aware of the presence of an obstacle, the increase per unit time in the operation amount of the accelerator member tends to be smaller than when the operator of the industrial vehicle is not aware of the presence of an obstacle. By making the dimension of the restricted range in the traveling direction of the industrial vehicle longer the greater the increase per unit time in the operation amount of the accelerator member, it becomes more difficult for the obstacle to enter the restricted range when the operator of the industrial vehicle is aware of the presence of an obstacle. It becomes more difficult for the vehicle speed limiting unit to limit the vehicle speed. This makes it possible to suppress a decrease in work efficiency.

The present invention can prevent a decline in work efficiency.

FIG. 1 is a schematic diagram showing a workplace where a forklift is used. FIG. FIG. 1 is a schematic diagram of a forklift. 4 is a flowchart showing a process performed by the obstacle detection device. FIG. 4 is a diagram illustrating a detectable range and a restricted range. 4 is a flowchart showing a process performed by a main control device. FIG. 4 is a diagram showing the correspondence relationship between a limit distance and a target vehicle speed. FIG. 13 is a diagram showing a forklift truck in a state where an obstacle is present within a restricted range. FIG. 13 is a diagram showing a forklift truck in a state where no obstacle exists within a restricted range. 6 is a graph showing an increase in accelerator pedal depression amount per unit time.

First Embodiment
Hereinafter, a first embodiment of the industrial vehicle will be described.
As shown in FIG. 1, a forklift 10 as an industrial vehicle is used in a work site such as a warehouse, a factory, a public facility, or a commercial facility. A plurality of shelves SH1, SH2 are arranged in the work site. The shelves SH1, SH2 are arranged at a distance from each other. As an example, a case where two shelves SH1, SH2 are arranged in the work site will be described, but three or more shelves may be arranged in the work site. One of the two shelves SH1, SH2 is a first shelf SH1, and the other is a second shelf SH2. Loading and unloading work is performed in the work site. The loading and unloading work includes a loading and unloading work of placing a load W on the shelves SH1, SH2, and a loading and unloading work of taking the load W from the shelves SH1, SH2.

As shown in FIG. 2, the forklift 10 is a counter-loading forklift. The forklift 10 includes a vehicle body 11, two drive wheels 12, two steering wheels 14, and a loading device 20. The vehicle body 11 includes a head guard 15. The two drive wheels 12 are disposed at the front of the vehicle body 11. The two steering wheels 14 are disposed at the rear of the vehicle body 11.

The loading/unloading device 20 comprises a mast 21 provided at the front of the vehicle body 11, a pair of forks 22 provided so as to be able to rise and fall together with the mast 21, and a lift cylinder 23 for raising and lowering the mast 21. A load W is loaded onto the forks 22. The lift cylinder 23 is a hydraulic cylinder. When the mast 21 is raised and lowered by the extension and contraction of the lift cylinder 23, the forks 22 are raised and lowered accordingly. The forklift 10 of this embodiment performs traveling and loading/unloading operations by being operated by an operator aboard the forklift 10. In the following description, the operator refers to the operator of the forklift 10.

As shown in FIG. 3, the forklift 10 includes a main control device 31, an accelerator sensor 34, a direction sensor 35, a tire angle sensor 36, an accelerator pedal 37, a direction lever 38, a driving motor 41, a rotation speed sensor 42, a driving control device 43, a detection device 51, and a bus 60.

The main control device 31 includes a processor 32 and a storage unit 33. The processor 32 may be, for example, a central processing unit (CPU), a graphics processing unit (GPU), or a digital signal processor (DSP). The storage unit 33 includes a random access memory (RAM) and a read only memory (ROM). The storage unit 33 stores a program for operating the forklift 10. The storage unit 33 stores program code or instructions configured to cause the processor 32 to execute processing. The storage unit 33, i.e., the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. The main control device 31 may be configured by a hardware circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The main control device 31, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as ASICs or FPGAs, or a combination thereof.

The accelerator sensor 34 detects the amount of depression of the accelerator pedal 37. The accelerator pedal 37 is an accelerator member for driving the forklift 10. The amount of depression of the accelerator pedal 37 can also be referred to as the accelerator opening. The amount of depression of the accelerator pedal 37 can also be referred to as the amount of operation of the accelerator pedal 37. The accelerator sensor 34 outputs an electrical signal corresponding to the accelerator opening to the main control device 31. The main control device 31 can recognize the accelerator opening from the electrical signal from the accelerator sensor 34. The amount of depression of the accelerator pedal 37 changes depending on the manner in which the accelerator pedal 37 is operated. Therefore, the amount of depression of the accelerator pedal 37 is an index related to the operation of the accelerator pedal 37.

The direction sensor 35 detects the direction of operation of the direction lever 38, which indicates the direction of travel. The direction sensor 35 detects whether the direction lever 38 is operated in a direction instructing forward movement or in a direction instructing reverse movement, based on the neutral position. The direction sensor 35 outputs an electrical signal according to the operating direction of the direction lever 38 to the main control device 31. The main control device 31 can recognize the operating direction of the direction lever 38 from the electrical signal from the direction sensor 35. The main control device 31 can know whether the operator has instructed forward movement, reverse movement, or neither.

The tire angle sensor 36 detects the steering angle of the steered wheels 14. The tire angle sensor 36 outputs an electrical signal corresponding to the steering angle to the main control unit 31. The main control unit 31 can recognize the steering angle from the electrical signal from the tire angle sensor 36.

The traveling motor 41 is a drive device for propelling the forklift 10. When the traveling motor 41 is driven, the drive wheels 12 rotate, causing the forklift 10 to propel.
The rotation speed sensor 42 detects the rotation speed of the traveling motor 41. For example, a rotary encoder can be used as the rotation speed sensor 42. The rotation speed sensor 42 outputs an electric signal corresponding to the rotation speed of the traveling motor 41 to the traveling control device 43.

The driving control device 43 is a motor driver that controls the rotation speed of the driving motor 41. The driving control device 43 can recognize the rotation speed and direction of the driving motor 41 from the electrical signal of the rotation speed sensor 42.

The driving motor 41, the rotation speed sensor 42, and the driving control device 43 are provided separately for each of the two driving wheels 12. By individually controlling the rotation speed and direction of the driving motor 41 provided for each of the two driving wheels 12 by the driving control device 43, the rotation speed and direction of the two driving wheels 12 can be controlled independently. The rotation speed of the driving motor 41 provided for each of the two driving wheels 12 can be detected individually by the rotation speed sensor 42.

The detection device 51 includes a stereo camera 52 and an obstacle detection device 55 that detects obstacles from images captured by the stereo camera 52. The stereo camera 52 is a distance measuring device.

The stereo camera 52 may be positioned anywhere as long as it is positioned to capture an image of the area around the forklift 10. In this embodiment, the stereo camera 52 is positioned to capture an image of the area behind the forklift 10. The stereo camera 52 is positioned on the head guard 15. The stereo camera 52 is positioned so that it can provide a bird's-eye view of the road surface on which the forklift 10 is traveling from above the forklift 10. The obstacle detected by the detection device 51 is an obstacle behind the forklift 10.

The stereo camera 52 includes two cameras 53 and 54. The cameras 53 and 54 are, for example, CCD image sensors or CMOS image sensors. The cameras 53 and 54 are arranged so that their optical axes are parallel to each other. Since the two cameras 53 and 54 are spaced apart from each other, the same obstacle will appear shifted in the images captured by the two cameras 53 and 54. In detail, when the same obstacle is captured, the obstacle will appear in the images captured by the two cameras 53 and 54 with a pixel shift corresponding to the distance between the two cameras 53 and 54. As the stereo camera 52 of this embodiment, a wide-angle stereo camera 52 with a horizontal angle of view of 100° or more is used, but a stereo camera that is not wide-angle may be used as the stereo camera 52.

The obstacle detection device 55 includes a processor 56 and a storage unit 57. The processor 56 may be, for example, a CPU, a GPU, or a DSP. The storage unit 57 includes a RAM and a ROM. The storage unit 57 stores various programs for detecting obstacles from images captured by the stereo camera 52. The storage unit 57 stores program codes or instructions configured to cause the processor 56 to execute processing. The storage unit 57, i.e., the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. The obstacle detection device 55 may be configured by a hardware circuit such as an ASIC or an FPGA. The obstacle detection device 55, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC or an FPGA, or a combination thereof.

The obstacle detection device 55 detects obstacles present behind the forklift 10 by repeatedly performing the following process at a predetermined control period. The obstacle detection device 55 also derives the position of the detected obstacle. The position of the obstacle is the relative position of the forklift 10 and the obstacle.

As shown in FIG. 4, in step S100, the obstacle detection device 55 acquires images from the cameras 53 and 54 of the stereo camera 52.
Next, in step S110, the obstacle detection device 55 performs stereo processing to obtain a parallax image. The parallax image is obtained by associating pixels with parallax [px]. The parallax image does not necessarily need to be displayed, but refers to data in which each pixel in the parallax image is associated with a parallax. The parallax is obtained by comparing images captured by the two cameras 53 and 54 of the stereo camera 52 and deriving the difference in the number of pixels between the images for the same feature point appearing in each image. The obstacle detection device 55 uses one of the images captured by the two cameras 53 and 54 as a reference image and the other as a comparison image, and extracts the most similar pixel of the comparison image for each pixel of the reference image. The obstacle detection device 55 calculates the difference in the number of pixels between the pixels of the reference image and the pixels of the comparison image as the parallax. This makes it possible to obtain a parallax image in which each pixel of the reference image is associated with a parallax. Note that a feature point is a part that can be recognized as a boundary, such as an edge of an obstacle. The feature point can be detected from brightness information or the like.

Next, in step S120, the obstacle detection device 55 derives the coordinates of the feature points in the world coordinate system, which is a coordinate system in real space. The world coordinate system is a coordinate system in which the axis extending in the vehicle width direction of the forklift 10 in the horizontal direction when the forklift 10 is located on a horizontal plane is the X axis, the axis perpendicular to the X axis in the horizontal direction is the Y axis, and the axis extending in the vertical direction is the Z axis. The Y axis can also be said to be an axis extending in the front-rear direction of the forklift 10. The Z axis can also be said to be an axis perpendicular to both the X axis and the Y axis. The coordinates of the feature points are derived by deriving the coordinates of the feature points in the camera coordinate system from the base line length of the stereo camera 52, the focal length of the stereo camera 52, and the parallax image obtained in step S110, and then converting the coordinates into coordinates in the world coordinate system. In addition, in FIG. 2 and FIG. 5, the X axis, the Y axis, and the Z axis are illustrated by arrows X, Y, and Z.

As shown in FIG. 4, in step S130, the obstacle detection device 55 extracts obstacles by clustering the feature points. The obstacle detection device 55 treats a set of feature points, which are points that represent parts of obstacles, that are assumed to represent the same obstacle as one point cloud, and extracts the point cloud as an obstacle. The obstacle detection device 55 performs clustering by regarding feature points located within a predetermined range from the coordinates of the feature points in the world coordinate system derived in step S120 as one point cloud. The obstacle detection device 55 regards the clustered point cloud as one obstacle. Note that the clustering of feature points performed in step S130 can be performed by various methods.

Next, in step S140, the obstacle detection device 55 derives the coordinates of the obstacle in the world coordinate system. The coordinates of the obstacle can be derived from the coordinates of the feature points that make up the point cloud. The coordinates of the obstacle in the world coordinate system represent the relative position between the forklift 10 and the obstacle. In detail, the X coordinate of the obstacle's coordinates in the world coordinate system represents the left-right distance from the origin to the obstacle, and the Y coordinate represents the front-rear distance from the origin to the obstacle. The origin is, for example, a coordinate in which the X coordinate and the Y coordinate represent the position of the stereo camera 52, and the Z coordinate represents the road surface. It is also possible to derive the Euclidean distance from the position of the stereo camera 52 to the obstacle from the X coordinate and the Y coordinate. The Z coordinate of the obstacle's coordinates in the world coordinate system represents the height of the obstacle from the origin.

As shown in FIG. 5, the obstacle detection device 55 can derive the position of an obstacle present within the detectable range AA1. The detectable range AA1 is the range in which the obstacle detection device 55 can detect an obstacle. The detectable range AA1 is determined, for example, by the horizontal angle of view of the stereo camera 52, the vertical angle of view of the stereo camera 52, and the mounting angle of the stereo camera 52. The detectable range AA1 can also be said to be the range that can be captured by the stereo camera 52.

The detection result by the obstacle detection device 55 is acquired by the main control device 31. In this way, the main control device 31 can recognize an obstacle present behind the forklift 10.
3, the main control device 31, the driving control device 43, and the detection device 51 are configured to be able to obtain information from one another via a bus 60. The main control device 31, the driving control device 43, and the detection device 51 obtain information from one another by communicating according to a vehicle communication protocol such as a Controller Area Network (CAN) or a Local Interconnect Network (LIN).

The main control device 31 derives the vehicle speed of the forklift 10 by acquiring the rotation speed and rotation direction of the travel motor 41 from the travel control device 43. The vehicle speed of the forklift 10 can be derived using the rotation speed and rotation direction of each travel motor 41 provided for each drive wheel 12, the gear ratio, the outer diameter of the drive wheel 12, etc. The main control device 31 also derives the traveling direction of the forklift 10 along with the vehicle speed. The traveling direction of the forklift 10 is either the forward direction or the reverse direction.

The main control device 31 calculates the target vehicle speed from the accelerator opening detected by the accelerator sensor 34. The larger the accelerator opening, the higher the target vehicle speed. It can be said that the greater the depression of the accelerator pedal 37, the higher the target vehicle speed. Note that the target vehicle speed and the accelerator opening need not be proportional as long as there is a correspondence relationship such that the target vehicle speed increases as the accelerator opening increases. For example, the greater the accelerator opening, the greater the change in the target vehicle speed relative to the change in the accelerator opening.

The main control device 31 calculates the target rotation speed from the target vehicle speed. The target rotation speed is the rotation speed for making the vehicle speed of the forklift 10 reach the target vehicle speed. The target rotation speed is derived separately for each of the two traveling motors 41. The main control device 31 also determines whether the forklift 10 should move forward or backward based on the operation direction of the direction lever 38. The main control device 31 generates a command including information indicating the target rotation speed and information indicating the rotation direction of the traveling motor 41, and issues the command to the traveling control device 43. The traveling control device 43 controls the traveling motor 41 so that it follows the target rotation speed according to the command. The traveling control device 43 controls the traveling motor 41 so that the traveling motor 41 rotates in the rotation direction according to the command. The forklift 10 travels at a vehicle speed according to the amount of depression of the accelerator pedal 37 by the operator. Since the target rotation speed changes according to the amount of depression of the accelerator pedal 37, it can be said that the traveling control device 43 controls the traveling motor 41 according to the amount of depression of the accelerator pedal 37.

The main control device 31 can impose a vehicle speed limit by setting an upper vehicle speed limit. When an upper vehicle speed limit is set, the main control device 31 controls the vehicle speed of the forklift 10 so that it does not exceed the upper vehicle speed limit. For example, when the target vehicle speed calculated from the accelerator opening is less than the upper vehicle speed limit, the main control device 31 calculates the target rotation speed from the target vehicle speed calculated from the accelerator opening, whereas when the target vehicle speed calculated from the accelerator opening is equal to or greater than the upper vehicle speed limit, the main control device 31 calculates the target rotation speed using the upper vehicle speed limit instead of the target vehicle speed. Then, the main control device 31 issues a command to the driving control device 43 so that the target rotation speed matches the rotation speed of the driving motor 41.

Note that a state in which no vehicle speed limit is imposed includes not only a state in which no upper vehicle speed limit is set, but also a state in which a vehicle speed limit that is not actually functional is set, such as a state in which a vehicle speed limit that is higher than the maximum speed that the forklift 10 can reach is set.

Next, the control performed by the main control device 31 will be described. The main control device 31 performs the following start control when the forklift 10 starts. The start of the forklift 10 means that the forklift 10 transitions from a stopped state to a traveling state. The stopped state is a state in which the speed of the forklift 10 is equal to or lower than the stop threshold. The traveling state is a state in which the speed of the forklift 10 is higher than the stop threshold. The stop threshold can be set to any value, for example, between 0 [km/h] and 0.5 [km/h]. In this embodiment, the main control device 31 also performs start control when starting backward.

As shown in FIG. 6, in step S10, the main control device 31 determines whether the forklift 10 will start backward. Whether the forklift 10 will start can be determined by various methods. The main control device 31 may determine that the forklift 10 will start when the speed of the forklift 10 becomes higher than the stop threshold from a state where it is equal to or lower than the stop threshold. The main control device 31 may determine that the forklift 10 will start when the depression amount of the accelerator pedal 37 is detected from a state where it is not detected. The main control device 31 may determine that the forklift 10 will start when the target vehicle speed becomes higher than 0 from a state where the target vehicle speed is 0.

The starting direction of the forklift 10 can be determined from the detection result of the direction sensor 35. In addition, since the main control device 31 derives the traveling direction of the forklift 10, when the forklift 10 is traveling at a speed equal to or lower than the stop threshold, the traveling direction of the forklift 10 may be set as the starting direction of the forklift 10.

If the determination result of step S10 is positive, the main control device 31 performs the process of step S11. If the determination result of step S10 is negative, the main control device 31 performs the process of step S21. By performing the determination of step S10, the main control device 31 can be said to be equipped with a departure determination unit.

In step S11, the main control unit 31 acquires the target vehicle speed. The main control unit 31 calculates the target vehicle speed from the amount of depression of the accelerator pedal 37 detected by the accelerator sensor 34. In this way, the main control unit 31 acquires the target vehicle speed.

Next, in step S12, the main control device 31 determines the limit range.
As shown in Fig. 5, the limited range AA2 is an area narrower than the detectable range AA1. The limited range AA2 is set within the detectable range AA1. The limited range AA2 is an area extending rearward from the forklift 10. The limited range AA2 is defined in world coordinates. In this embodiment, the limited range AA2 is defined by the X coordinate and the Y coordinate of the world coordinate system, but the limited range AA2 may be defined by the Z coordinate in addition to the X coordinate and the Y coordinate of the world coordinate system. In the following description, the X axis refers to the X axis of the world coordinate system, and the Y axis refers to the Y axis of the world coordinate system.

The dimension of the restricted range AA2 in the Y-axis direction changes in response to the target vehicle speed. The dimension of the restricted range AA2 in the Y-axis direction is the dimension of the restricted range AA2 in the direction of travel of the forklift 10. In the following description, the dimension of the restricted range AA2 in the Y-axis direction is referred to as the restricted distance L.

The higher the target vehicle speed, the longer the limit distance L. Since the target vehicle speed increases the greater the depression of the accelerator pedal 37, it can be said that the greater the depression of the accelerator pedal 37, the longer the limit distance L. In this embodiment, the higher the target vehicle speed, the longer the limit distance L becomes. In other words, the target vehicle speed is divided into a number of speed ranges, and a limit distance L is associated with each speed range.

As shown in FIG. 7, the target vehicle speed is divided into a first speed range SR1, a second speed range SR2, a third speed range SR3, and a fourth speed range SR4. The first speed range SR1 is a speed range including 0 [km/h]. The second speed range SR2 is a speed range including a target vehicle speed higher than the upper limit of the first speed range SR1. The third speed range SR3 is a speed range including a target vehicle speed higher than the upper limit of the second speed range SR2. The fourth speed range SR4 is a speed range including a target vehicle speed higher than the upper limit of the third speed range SR3. In the example shown in FIG. 7, the first speed range SR1 is a range of 0 [km/h] or more and less than 1.0 [km/h]. The second speed range SR2 is a range of 1.0 [km/h] or more and less than 2.0 [km/h]. The third speed range SR3 is a range of 2.0 [km/h] or more and less than 3.0 [km/h]. The fourth speed range SR4 is the range between 3.0 km/h and 4.0 km/h.

The first speed range SR1 is associated with the first limit distance L1 as the limit distance L. The second speed range SR2 is associated with the second limit distance L2 as the limit distance L. The third speed range SR3 is associated with the third limit distance L3 as the limit distance L. The fourth speed range SR4 is associated with the fourth limit distance L4 as the limit distance L. The second limit distance L2 is longer than the first limit distance L1. The third limit distance L3 is longer than the second limit distance L2. The fourth limit distance L4 is longer than the third limit distance L3. In the example shown in FIG. 7, the first limit distance L1 is 0 [m]. The second limit distance L2 is 1.0 [m]. The third limit distance L3 is 2.0 [m]. The fourth limit distance L4 is 3.0 [m]. Each of the limit distances L1 to L4 is set based on the environment in which the forklift 10 is used. For example, in an environment where loading and unloading operations are performed between shelves SH1 and SH2, the shorter the distance between the two shelves SH1 and SH2, the shorter the limit distances L1 to L4 are set.

For target vehicle speeds of 4.0 km/h or more, a speed range and a corresponding limit distance L may be set. Also, without setting an upper limit for the fourth speed range SR4, the fourth speed range SR4 may be the entire range in which the target vehicle speed is 3.0 km/h or more.

The correspondence between each of the speed ranges SR1 to SR4 and each of the limit distances L1 to L4 is stored in a storage medium that can be read by the main control device 31. For example, the correspondence between each of the speed ranges SR1 to SR4 and each of the limit distances L1 to L4 is stored in the storage unit 33.

In this embodiment, the dimension of the restricted range AA2 in the X-axis direction is constant, but the dimension of the restricted range AA2 in the X-axis direction may be increased as the target vehicle speed increases. In addition, the dimension of the restricted range AA2 in the X-axis direction may vary depending on a factor other than the target vehicle speed. In other words, the dimension of the restricted range AA2 in the X-axis direction can be set arbitrarily.

The restricted range AA2 may be an area that always extends in a straight line behind the forklift 10, or an area that bends in the direction in which the forklift 10 is expected to turn. When bending the restricted range AA2 according to the direction in which the forklift 10 is expected to turn, the main control device 31 bends the restricted range AA2 to the right when the forklift 10 is expected to turn to the right, and bends the restricted range AA2 to the left when the forklift 10 is expected to turn to the left. The direction in which the forklift 10 is expected to turn can be determined, for example, from the detection result of the tire angle sensor 36. By performing the process of step S12, it can be said that the main control device 31 is equipped with a range change unit.

As shown in FIG. 5, in step S13, the main control device 31 acquires the position of the obstacle. More specifically, the main control device 31 acquires the coordinates of the obstacle in the world coordinate system from the obstacle detection device 55.

Next, in step S14, the main control device 31 determines whether or not an obstacle is present in the restricted range AA2. Whether or not an obstacle is present in the restricted range AA2 can be determined from the restricted range AA2 determined in step S12 and the position of the obstacle acquired in step S13. Since the restricted range AA2 is defined in world coordinates and the position of the obstacle is also defined in world coordinates, whether or not an obstacle is present in the restricted range AA2 can be determined from the positional relationship between the two. If the determination result in step S14 is positive, the main control device 31 performs the process of step S15. If the determination result in step S14 is negative, the main control device 31 performs the process of step S21.

In step S15, the main control device 31 restricts the start of the forklift 10. In this embodiment, the start of the forklift 10 is prohibited. The main control device 31 sets the upper vehicle speed limit to 0 [km/h]. Even if the accelerator pedal 37 is operated, the target vehicle speed is prevented from exceeding 0 [km/h], and therefore the start of the forklift 10 is prohibited. By performing the processing of step S15, it can be said that the main control device 31 is equipped with a vehicle speed limiting unit.

In step S21, the main control device 31 does not restrict the start of the forklift 10. The main control device 31 does not limit the vehicle speed. This allows the forklift 10 to start at a speed that corresponds to the amount of depression of the accelerator pedal 37.

In this embodiment, when the process of step S15 is performed, the limit distance L is maintained until the accelerator pedal 37 is released. When the accelerator pedal 37 is released, the limit distance L is reset.

The operation of the first embodiment will be described.
When starting the forklift 10, the amount of depression of the accelerator pedal 37 differs depending on whether or not the operator recognizes the presence of an obstacle. The main control device 31 changes the limit distance L in accordance with the amount of depression of the accelerator pedal 37.

When the operator is aware of the presence of an obstacle, the amount of depression of the accelerator pedal 37 tends to be less than when the operator is not aware of the presence of an obstacle. In this embodiment, the greater the amount of depression of the accelerator pedal 37, the longer the limit distance L is. This makes it difficult for the obstacle to enter the limit range AA2 when the operator is aware of the presence of an obstacle.

An example will be described in which the forklift 10 performs cargo handling operations between two shelves SH1, SH2.
As shown in FIG. 8, when the forklift 10 performs an unloading operation to take a load W from the shelf SH1, the unloading operation is performed between the two shelves SH1 and SH2. After the forklift 10 has completed the unloading operation, the forklift 10 moves backward. When the forklift 10 performs a depositing operation to place a load W on the shelf SH1, the depositing operation is performed between the two shelves SH1 and SH2. After the forklift 10 has completed the depositing operation, the forklift 10 moves backward. In this manner, the forklift 10 moves backward whether the forklift 10 has performed an unloading operation or a depositing operation. When the forklift 10 is performing an unloading operation, the forklift 10 is often stopped. Similarly, when the forklift 10 is performing a depositing operation, the forklift 10 is often stopped. For this reason, the forklift 10 starts backward whether the forklift 10 has performed an unloading operation or a depositing operation is completed.

The forklift 10 is performing cargo handling operations between the two shelves SH1 and SH2, so when the forklift 10 starts moving backwards, the shelf SH2 is present behind the forklift 10. The obstacle detection device 55 detects at least one of the shelf SH2 and the load W placed on the shelf SH2 as an obstacle.

When the operator is not aware of the existence of shelf SH2, the operator does not anticipate that the forklift 10 will come into contact with shelf SH2 when the forklift 10 starts moving. As a result, the operator presses the accelerator pedal 37 more than when the operator is aware of the existence of shelf SH2. Because the accelerator pedal 37 is pressed more, the restricted distance L is also longer. This causes shelf SH2 to enter restricted range AA2. When shelf SH2 enters restricted range AA2, the starting of the forklift 10 is restricted.

As shown in FIG. 9, when the operator is aware of the presence of shelf SH2, the operator is aware that there is a risk of contact between the forklift 10 and shelf SH2. The operator starts the forklift 10 gently to prevent contact between the forklift 10 and shelf SH2. As a result, the operator depresses the accelerator pedal 37 less than when the operator is not aware that shelf SH2 is present behind the forklift 10. Because the operator depresses the accelerator pedal 37 less, the restricted distance L is also short. Because shelf SH2 does not fall within restricted range AA2, the start of the forklift 10 is not restricted.

In the above example, shelf SH2 was given as an example of an obstacle, but the same control is performed for any obstacle that is detected as an obstacle by the obstacle detection device 55.

When the start of the forklift 10 is restricted, the operator becomes aware of the presence of an obstacle due to the restriction on the start of the forklift 10. When the operator recognizes the presence of an obstacle, he releases the operation of the accelerator pedal 37. When the operator operates the accelerator pedal 37 again, the main control device 31 performs start-up control. At this time, the operator adjusts the amount of depression of the accelerator pedal 37 so that the forklift 10 starts gently. This shortens the restricted distance L, making it difficult for an obstacle to enter the restricted range AA2. If there is no obstacle in the restricted range AA2, the forklift 10 starts.

The effects of the first embodiment will be described.
(1-1) The main control unit 31 changes the limit distance L in accordance with the depression amount of the accelerator pedal 37 (an index related to the operation of the accelerator member). The depression amount of the accelerator pedal 37 differs depending on whether or not the operator recognizes the presence of an obstacle. For this reason, the limit distance L is changed depending on whether or not the operator recognizes the presence of an obstacle. When the limit distance L is shortened, it becomes more difficult for an obstacle to enter the restricted range AA2. Because it becomes more difficult for the main control unit 31 to limit the vehicle speed, a decrease in work efficiency can be suppressed.

(1-2) The main control device 31 lengthens the limit distance L the greater the depression of the accelerator pedal 37. By lengthening the limit distance L the greater the depression of the accelerator pedal 37, it becomes more difficult for an obstacle to enter the limit range AA2 when the operator is aware of the presence of an obstacle. By making it more difficult for the vehicle speed to be limited, it is possible to suppress a decrease in work efficiency.

(1-3) When the accelerator pedal 37 is depressed deeply, the limit distance L is increased, which tends to restrict starting. If the operator is not familiar with operating the forklift 10, there is a risk that the operator will depress the accelerator pedal 37 too much, even if he or she is aware of the presence of an obstacle. Even in such a case, the limit distance L is increased to restrict the starting of the forklift 10, so assistance can be given to the operator.

Second Embodiment
A second embodiment of the industrial vehicle will be described below, focusing on differences from the industrial vehicle of the first embodiment.

The main control device 31 increases the limit distance L as the increase per unit time in the depression amount of the accelerator pedal 37 increases. The increase per unit time in the depression amount of the accelerator pedal 37 is an index related to the operation of the accelerator member.

As shown in FIG. 10, the accelerator sensor 34 outputs a higher voltage as the depression amount of the accelerator pedal 37 increases. The main control device 31 can recognize the increase in the depression amount of the accelerator pedal 37 per unit time from the voltage output by the accelerator sensor 34. Any time can be set as the unit time.

The main control device 31 may increase the limit distance L in stages, as in the first embodiment. For example, the increase per unit time in the depression amount of the accelerator pedal 37 is divided into multiple ranges, and the limit distance L is associated with these ranges. The main control device 31 sets the limit distance L corresponding to the increase per unit time in the depression amount of the accelerator pedal 37.

The operation of the second embodiment will be described.
When the operator is aware of the presence of an obstacle, the increase per unit time in the depression amount of the accelerator pedal 37 tends to be smaller than when the operator is not aware of the presence of an obstacle. The main control device 31 lengthens the limit distance L the greater the increase per unit time in the depression amount of the accelerator pedal 37. This makes it more difficult for the obstacle to enter the limit range AA2 when the operator is aware of the presence of an obstacle.

As in the first embodiment, a case in which the forklift 10 performs cargo handling operations between two shelves SH1, SH2 will be described as an example.
As shown in Fig. 8, when the operator is not aware of the existence of shelf SH2, the operator does not anticipate that the forklift 10 will come into contact with shelf SH2. For this reason, the operator attempts to start the forklift 10 with a higher acceleration than when the operator is aware of the existence of shelf SH2. The increase in the depression amount of the accelerator pedal 37 per unit time becomes larger. As a result, shelf SH2 enters the restricted range AA2. When shelf SH2 enters the restricted range AA2, the start of the forklift 10 is restricted.

As shown in FIG. 9, when the operator recognizes the presence of shelf SH2, the operator starts the forklift 10 so as to prevent contact between the forklift 10 and shelf SH2. The operator tries to accelerate the forklift 10 gently. As a result, the increase per unit time in the depression of the accelerator pedal 37 is smaller than when the operator is not aware that shelf SH2 is present behind the forklift 10. The increase per unit time in the depression of the accelerator pedal 37 can also be referred to as the depression speed of the accelerator pedal 37. Because the increase per unit time in the depression of the accelerator pedal 37 is small, the restricted distance L is also short. Because shelf SH2 does not enter restricted range AA2, the start of the forklift 10 is not restricted.

The effects of the second embodiment will be described.
(2-1) The main control device 31 lengthens the limit distance L the greater the increase per unit time in the depression amount of the accelerator pedal 37. By lengthening the limit distance L the greater the increase per unit time in the depression amount of the accelerator pedal 37, it becomes more difficult for an obstacle to enter the limit range AA2 when the operator recognizes the presence of an obstacle. By making it more difficult for the vehicle speed to be limited, it is possible to suppress a decrease in work efficiency.

Each embodiment can be modified as follows: The embodiments and the following modifications can be combined with each other to the extent that there is no technical contradiction.
In each embodiment, the main control device 31 may set the upper vehicle speed limit to a value greater than 0 when restricting starting. In this case, it can be said that the main control device 31 allows the forklift 10 to start at or below the upper vehicle speed limit. The forklift 10 is restricted from traveling at a speed higher than the upper vehicle speed limit, and contact between the forklift 10 and an obstacle can be restricted. In this case, when the obstacle is no longer present within the restricted range AA2 due to the movement of at least one of the forklift 10 and the obstacle, the vehicle speed limit is released. Restricting starting includes prohibiting starting and allowing starting at or below the upper vehicle speed limit.

In each embodiment, when restricting starting, prohibition of starting and permission of starting at or below the upper vehicle speed limit may be combined. If an obstacle is present within the restricted range AA2, the main control device 31 prohibits the forklift 10 from starting. In this state, if the accelerator pedal 37 is released, the main control device 31 assumes that the operator has recognized the presence of an obstacle. If the operator recognizes the presence of an obstacle, the main control device 31 allows the forklift 10 to start even if an obstacle is present within the restricted range AA2. In this case, the main control device 31 prevents contact between the forklift 10 and the obstacle by setting an upper vehicle speed limit. In this way, whether to prohibit the forklift 10 from starting or to allow the forklift 10 to start at or below the upper vehicle speed limit may be determined depending on whether the operator is assumed to recognize the presence of an obstacle.

In the first embodiment, the depression amount of the accelerator pedal 37 and the limit distance L may have a corresponding relationship such that the greater the depression amount of the accelerator pedal 37, the longer the limit distance L. The limit distance L may be determined by the depression amount of the accelerator pedal 37 itself instead of the target vehicle speed. The limit distance L may be longer in proportion to the target vehicle speed.

Similarly, in the second embodiment, the increase in the depression amount of the accelerator pedal 37 per unit time and the limit distance L may have a corresponding relationship such that the greater the increase in the depression amount of the accelerator pedal 37 per unit time, the longer the limit distance L.

In the first embodiment, the main control device 31 may restrict the start of the forklift 10 when the depression amount of the accelerator pedal 37 is equal to or greater than a threshold value during the start control.
In the second embodiment, the main control device 31 may restrict the start of the forklift 10 when the increase in the depression amount of the accelerator pedal 37 per unit time is equal to or greater than a threshold value during the start control.

○ In each embodiment, the obstacle detection device 55 may determine whether the obstacle is a person or not. The determination of whether the obstacle is a person or not can be performed in various ways. For example, the obstacle detection device 55 performs a human detection process on an image captured by one of the two cameras 53 and 54 of the stereo camera 52. The obstacle detection device 55 converts the coordinates of the obstacle in the world coordinate system obtained in step S140 into camera coordinates, and converts the camera coordinates into coordinates of the image captured by the cameras 53 and 54. The obstacle detection device 55 performs a human detection process on the coordinates of the obstacle in the image. The human detection process is performed, for example, using feature extraction and a human determiner that has performed machine learning in advance. Examples of feature extraction include a method of extracting features of local regions in an image, such as HOG (Histogram of Oriented Gradients) features and Haar-Like features. For example, a human determiner that has performed machine learning using a supervised learning model is used. Examples of supervised learning models that can be used include support vector machines, neural networks, naive Bayes, deep learning, and decision trees. The training data used in machine learning are image-specific components such as shape elements and appearance elements of a person extracted from an image. Examples of shape elements include the size and contours of a person. Examples of appearance elements include light source information, texture information, and camera information. Light source information includes information on reflectance, shading, and the like. Texture information includes color information, and the like. Camera information includes information on image quality, resolution, angle of view, and the like.

The main control device 31 may perform different controls depending on whether the obstacle is a person or not. For example, the main control device 31 may vary the manner of restricting the start depending on whether a person is present in the restricted range AA2. The main control device 31 prohibits the start of the forklift 10 when a person is present in the restricted range AA2. On the other hand, the main control device 31 may allow the start of the forklift 10 at or below the upper vehicle speed limit value of the forklift 10 when an obstacle other than a person is present in the restricted range AA2. Note that, when both a person and an obstacle other than a person are present in the restricted range AA2, the main control device 31 prohibits the start of the forklift 10. The main control device 31 may restrict the start of the forklift 10 when the obstacle present in the restricted range AA2 is a person, and may not restrict the start of the forklift 10 when the obstacle present in the restricted range AA2 is not a person.

The main control device 31 may change the limit distance L depending on whether or not the obstacle detection device 55 detects a person. The main control device 31 may make the limit distance L longer when the obstacle detection device 55 detects a person than when the obstacle detection device 55 does not detect a person. In this case, the limit distance L becomes longer depending on the depression amount of the accelerator pedal 37, and becomes longer when the obstacle detection device 55 detects a person.

○ In each embodiment, the detection device 51 may be equipped with a ToF (Time of Flight) camera, LIDAR (Laser Imaging Detection and Ranging), or millimeter wave radar as a distance measuring device. The TOF camera is equipped with a camera and a light source that emits light, and derives the distance in the depth direction for each pixel of the image captured by the camera from the time it takes to receive the reflected light of the light emitted from the light source. The LIDAR is a distance meter that can recognize the surrounding environment by emitting a laser while changing the irradiation angle and receiving the reflected light reflected from the part where the laser hits. The millimeter wave radar is capable of recognizing the surrounding environment by emitting radio waves of a predetermined frequency band to the surroundings. The stereo camera 52, the ToF camera, the LIDAR, and the millimeter wave radar are distance measuring devices that can measure three-dimensional coordinates in a world coordinate system. It is preferable that the detection device 51 is equipped with a distance measuring device that can measure three-dimensional coordinates. If the detection device 51 is equipped with a distance measuring device capable of measuring three-dimensional coordinates, the obstacle detection device 55 can determine whether an obstacle is a human or a non-human object by using a human determiner that has undergone machine learning in advance. The distance measuring device may be a combination of multiple devices, such as the stereo camera 52 and LIDAR.

Instead of the stereo camera 52, the detection device 51 may be provided with a distance measuring device capable of measuring the coordinates of an obstacle on the XY plane, which is a coordinate plane representing a horizontal plane. That is, the distance measuring device may be one capable of measuring the two-dimensional coordinates of an obstacle. For example, a two-dimensional LIDAR that irradiates a laser while changing the irradiation angle in the horizontal direction may be used as this type of distance measuring device. Also, instead of the stereo camera 52, the detection device 51 may be provided with a distance measuring device capable of measuring the distance to an obstacle on the XY plane, which is a coordinate plane representing a horizontal plane. That is, the distance measuring device may be one capable of measuring the relative distance to an obstacle. For example, an ultrasonic sensor may be used as this type of distance measuring device.

In each embodiment, the detection device 51 may detect the position of an obstacle present in the forward direction of the forklift 10. In this case, the stereo camera 52 is positioned facing forward of the forklift 10. When the detection device 51 detects the position of an obstacle present in the forward direction of the forklift 10, the restricted range AA2 becomes an area extending forward from the forklift 10. In addition, the main control device 31 performs start control when the forklift 10 starts moving forward.

The detector 51 may be capable of detecting the position of an obstacle present in either the backward or forward direction of the travel direction of the forklift 10. In this case, one detector 51 may be capable of detecting an obstacle present in either the backward or forward direction of the travel direction of the forklift 10, or a detector 51 for the forward direction and a detector 51 for the backward direction may be provided. When detecting the position of an obstacle present in either the backward or forward direction of the travel direction of the forklift 10, the restricted range AA2 is set to the range in front of the forklift 10 when the forklift 10 starts forward. When the forklift 10 starts backward, the restricted range AA2 is set to the range behind the forklift 10. In other words, it can be said that the main control device 31 restricts the start of the forklift 10 when the travel direction of the forklift 10 is a direction approaching the obstacle detected by the detector 51.

In the first embodiment, the main control device 31 may change the limit distance L even if the accelerator pedal 37 is not released. That is, the main control device 31 does not have to maintain the limit distance L. In this case, the limit distance L is changed according to the amount of depression of the accelerator pedal 37 even if the accelerator pedal 37 is not released. If the starting of the forklift 10 is restricted due to the presence of an obstacle in the restricted range AA2, the limit distance L is shortened by reducing the amount of depression of the accelerator pedal 37. As a result, when there is no obstacle in the restricted range AA2, the forklift 10 can be started.

In each embodiment, the stereo camera 52 may include three or more cameras.
In each embodiment, the forklift 10 may be a reach-type forklift. In the case of a reach-type forklift, the main control device 31 calculates the target vehicle speed according to the amount of operation of the direction lever. The amount of operation of the direction lever is the amount of tilt of the direction lever from the neutral position of the direction lever. The amount of operation of the direction lever is detected by a direction sensor. The main control device 31 can recognize the amount of operation of the direction lever from the detection result of the direction sensor. The main control device 31 can perform the same control as in each embodiment from the detection result of the direction sensor. In this case, the direction lever is the accelerator member. The amount of operation of the direction lever is an index related to the operation of the accelerator member.

○ In each embodiment, the forklift 10 may be remotely operated. In this case, the operator operates the forklift 10 at a remote location away from the forklift 10. The operator operates an operation terminal provided at a remote location. As the operation terminal, a dedicated device or a mobile communication terminal such as a tablet terminal can be used. The operation terminal includes an accelerator member, an accelerator sensor that detects the operation amount of the accelerator member, and a communication device that transmits information indicating the operation amount of the accelerator member to the forklift 10. When the operation terminal includes a physical accelerator member such as an operation lever, the accelerator sensor detects the operation amount of the accelerator member. When the operation terminal displays a symbol that functions as an accelerator member on a touch panel, the forklift 10 is driven by operating the touch panel. For example, when the forklift 10 is driven by the operator's sliding operation on the touch panel, the sliding amount may be the operation amount of the accelerator member. In this case, the touch panel functions as the accelerator member. The communication device generates data in a predetermined format and transmits the data to the forklift 10. The main control device 31 recognizes the amount of accelerator operation from the data sent from the communication device, and operates the forklift 10 according to this amount of operation.

In each embodiment, the industrial vehicle may be an industrial vehicle other than the forklift 10. For example, the industrial vehicle may be a towing tractor or an order picker.

AA2...restricted range, L...restricted distance, 10...forklift, 31...main control device as starting determination unit, vehicle speed limiting unit, and range changing unit, 37...accelerator pedal as accelerator member, 41...travel motor, 43...travel control device, 52...stereo camera as distance measuring device, 55...obstacle detection device.

Claims (3)

A driving motor;
a travel control device that controls the travel motor in response to an operation amount of an accelerator member;
A distance measuring device for measuring the distance to an obstacle;
an obstacle detection device that detects an obstacle based on the measurement result of the distance measuring device;
a start determination unit that determines whether or not the industrial vehicle starts;
a vehicle speed limiting unit that prohibits the industrial vehicle from starting by limiting the vehicle speed when the industrial vehicle starts and the obstacle is present within a limited range;
and a range change unit that changes the size of the restricted range in the traveling direction of the industrial vehicle in response to an indicator related to the operation of the accelerator member. the indicator is an operation amount of the accelerator member,
The industrial vehicle according to claim 1 , wherein the range change unit increases the dimension as the amount of operation increases. the index is an increase per unit time in the operation amount of the accelerator member,
The industrial vehicle according to claim 1 , wherein the range change unit increases the dimension as an increase in the amount of operation per unit time increases.