JP2022035123A - Notification device of forklift - Google Patents

Abstract

To notify an operator of the existence of an obstacle in a rear side.SOLUTION: A notification device of a forklift includes a main control device, a detection device, and a lamp. The detection device detects an obstacle existing in a detection region behind the forklift. The main control device blinks the lamp when notification conditions are satisfied. The notification conditions are such that the forklift is traveling rearward while an obstacle exists in the detection region, and the vehicle speed of the forklift is in a low speed operation range.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a forklift notification device.

The forklift that performs cargo handling work includes a vehicle body and a cargo handling device provided in front of the vehicle body. The forklift may be equipped with a notification device that notifies the operator of the forklift. The notification device disclosed in Patent Document 1 notifies the operator when the load to be carried by the forklift may collapse.

Japanese Unexamined Patent Publication No. 2008-156093

By the way, the forklift may work between two obstacles. For example, there are two shelves, and the forklift may work between these two shelves. A shelf is a member on which a load is placed. The forklift performs the loading work of placing the load on the shelf and the loading work of removing the load from the shelf. One of the two shelves is the first shelf and the other is the second shelf. When placing a load on the first shelf, the forklift operator puts the load on the first shelf by the forklift and then moves the forklift backward. When taking a load from the first shelf, the forklift operator moves the forklift backward after taking the load from the first shelf by the forklift. In this way, the forklift is moved backward when the forklift is separated from the first shelf regardless of whether the loading work is performed or the loading work is performed. At this time, the second shelf is located behind the forklift. Since the cargo handling device is located in front of the forklift, the operator's consciousness is often directed to the front (cargo handling device). Therefore, it may be required to notify the operator when the forklift approaches an obstacle behind.

An object of the present disclosure is to provide a forklift notification device capable of notifying an operator that an obstacle is present behind.

The forklift notification device that solves the above problems is a forklift notification device, which is a detection device that detects an obstacle existing in a detection area behind the forklift in the front-rear direction of the forklift, and an operator of the forklift. A notification unit for notifying the presence of the obstacle, an acquisition unit for acquiring the vehicle speed of the forklift, and the forklift traveling backward in a state where the obstacle is present in the detection area. Further, when the notification condition is that the vehicle speed of the forklift truck acquired by the acquisition unit is in the low speed operating range, the notification control unit is provided to notify the notification unit when the notification condition is satisfied. ..

When the forklift performs cargo handling work between two obstacles, the obstacle may be located behind the forklift when the forklift is moved backward. When the forklift approaches an obstacle behind and the notification condition is satisfied by the presence of this obstacle, the notification unit notifies. Therefore, it is possible to notify the operator that an obstacle exists behind.

Regarding the notification device of the forklift, the notification unit includes a lamp, and the lamp may be arranged in front of the boarding position of the operator.
Regarding the notification device of the forklift, the notification control unit sends the notification unit to the notification unit when a specific condition different from the notification condition and at least when the obstacle is present in the detection area is satisfied. The notification control unit may make the notification different depending on whether the notification condition is satisfied or the specific condition is satisfied.

Regarding the forklift notification device, the detection device includes a person determination unit for determining whether or not the obstacle is a person, and the notification by the notification unit includes a deceleration notification for notifying by deceleration of the forklift and the deceleration. The notification control unit includes the non-deceleration notification for notifying without performing the above, and when the notification condition is satisfied and the obstacle is not a person, the notification control unit notifies the notification unit of the non-deceleration. You may only do it.

Regarding the forklift notification device, the forklift is traveling backward in a state where the obstacle is present in the detection area, and the vehicle speed of the forklift acquired by the acquisition unit operates at the low speed. If it is higher than the upper limit of the range, the notification control unit may cause the notification unit to perform the deceleration notification.

According to the present invention, it is possible to notify the operator that an obstacle exists behind.

The schematic diagram which shows the workplace where a forklift is used. Perspective view of a forklift. Schematic diagram of the forklift. A flowchart showing the processing performed by the obstacle detection device. The figure which shows typically the detectable area and the detection area. A flowchart showing the processing performed by the main control unit. The figure which shows the forklift in the state where there is no obstacle in the detection area. The figure which shows the forklift in the state where an obstacle exists in the detection area. The figure which shows the modification of the notification device of a forklift.

Hereinafter, an embodiment of the forklift notification device will be described. In the following description, front / rear / left / right are front / rear / left / right with respect to the forward direction of the forklift.
As shown in FIG. 1, the forklift 10 is used in a workplace such as a warehouse, a factory, a public facility, or a commercial facility. A plurality of shelves SH1 and SH2 are arranged in the work place. The shelves SH1 and SH2 are arranged so as to be spaced apart from each other. As an example, a case where two shelves SH1 and SH2 are arranged in the work place will be described, but three or more shelves may be arranged in the work place. One of the two shelves SH1 and SH2 is the first shelf SH1, and the other is the second shelf SH2. Cargo handling work is carried out in the workplace. The cargo handling work includes a loading operation of placing the load W on the shelves SH1 and SH2 and a loading operation of taking the load W from the shelves SH1 and SH2.

As shown in FIG. 2, the forklift 10 includes a vehicle body 11, two drive wheels 12 arranged at the front lower portion of the vehicle body 11, two steering wheels 14 arranged at the rear lower portion of the vehicle body 11, and a driver's seat 19. And a cargo handling device 20. The vehicle body 11 includes a head guard 15, two front pillars 16, and two rear pillars 17. The two front pillars 16 are provided apart from each other in the left-right direction of the forklift 10. The two rear pillars 17 are provided behind the front pillar 16. The two rear pillars 17 are provided apart from each other in the left-right direction of the forklift 10. The head guard 15 is supported by two front pillars 16 and two rear pillars 17. The area surrounded by the two front pillars 16, the two rear pillars 17, and the head guard 15 is the driver's cab 18 on which the operator can board. The driver's seat 19 is arranged in the driver's cab 18. In this embodiment, the driver's seat 19 is the boarding position. The front pillar 16 is arranged in front of the driver's seat 19.

The cargo handling device 20 includes a mast 21 provided at the front portion of the vehicle body 11, a pair of forks 22 provided so as to be able to move up and down together with the mast 21, and a lift cylinder 23 for raising and lowering the mast 21. The load W is loaded on the fork 22. The lift cylinder 23 is a hydraulic cylinder. When the mast 21 moves up and down due to the expansion and contraction of the lift cylinder 23, the fork 22 moves up and down accordingly. The forklift 10 of the present embodiment is operated by an operator to perform a traveling operation and a cargo handling operation.

As shown in FIG. 3, the forklift 10 includes a forklift notification device 30, an accelerator sensor 34, a direction sensor 35, a tire angle sensor 36, an accelerator pedal 37, a direction lever 38, a traveling motor 41, and the like. It includes a rotation speed sensor 42, a traveling control device 43, and a bus 60. The forklift notification device 30 includes a main control device 31 and a detection device 51.

The main control device 31 includes a processor 32 and a storage unit 33. As the processor 32, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a DSP (Digital Signal Processor) is used. The storage unit 33 includes a RAM (Random access memory) and a ROM (Read Only Memory). The storage unit 33 stores a program for operating the forklift 10. It can be said that the storage unit 33 stores a program code or a command configured to cause the processor 32 to execute the process. The storage unit 33, i.e., a computer-readable medium, includes any available medium accessible by a general purpose or dedicated computer. The main control device 31 may be configured by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The main control unit 31, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs and FPGAs, or a combination thereof.

The detection device 51 includes a stereo camera 52, an obstacle detection device 55 that detects an obstacle from an image captured by the stereo camera 52, a lamp 58, and a buzzer 59. Obstacles include humans and non-human obstacles. In the following description, obstacles other than humans are referred to as objects.

The stereo camera 52 may be arranged so as to take an image of the rear of the forklift 10, and can be arranged at an arbitrary position. In this embodiment, the stereo camera 52 is arranged on the head guard 15. The stereo camera 52 is arranged so that the road surface on which the forklift 10 travels can be seen 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 use, for example, a CCD image sensor or a CMOS image sensor. 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 separated from each other, the same obstacle is shifted in the image captured by the two cameras 53 and 54. More specifically, when the same obstacle is imaged, the obstacles in the image captured by the two cameras 53 and 54 have pixel shifts according to the distance between the two cameras 53 and 54. Become. As the stereo camera 52 of the present embodiment, a wide-angle stereo camera 52 having a horizontal angle of view of 100 ° or more is used, but as the stereo camera 52, a non-wide-angle stereo camera 52 may be used.

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

The obstacle detection device 55 detects an obstacle existing behind the forklift 10 by repeating the following processing in a predetermined control cycle. Further, the obstacle detection device 55 derives the position of the detected obstacle. The position of the obstacle is the relative position between 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 acquires a parallax image by performing stereo processing. The parallax image is a pixel associated with a parallax [px]. The parallax image does not necessarily require display, and indicates data in which parallax is associated with each pixel in the parallax image. The parallax is obtained by comparing the images captured by the two cameras 53 and 54 included in 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 pixels of the most similar 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 parallax. As a result, it is possible to acquire a parallax image in which the parallax is associated with each pixel of the reference image. The feature point is a part that can be recognized as a boundary, such as the edge of an obstacle. The feature points can be detected from the luminance information and 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 the coordinate system in the real space. In the world coordinate system, when the forklift 10 is located on the horizontal plane, the axis extending in the vehicle width direction of the forklift 10 in the horizontal direction is the X axis, the axis orthogonal to the X axis in the horizontal direction is the Y axis, and the vertical direction. It is a coordinate system with the extending axis as the Z axis. To derive the coordinates of the feature points, after deriving the coordinates of the feature points in the camera coordinate system from the baseline length of the stereo camera 52, the focal distance of the stereo camera 52, and the disparity image obtained in step S110, the coordinates are used as world coordinates. It is done by converting to the coordinates in the system. Note that, in FIGS. 2 and 5, the X-axis, Y-axis, and 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 feature points. The obstacle detection device 55 uses a set of feature points that are assumed to represent the same obstacle among the feature points that represent a part of the obstacle as one point cloud, and the point cloud as an obstacle. Extract. The obstacle detection device 55 performs clustering in which the feature points located within a predetermined range are regarded as one point cloud from the coordinates of the feature points in the world coordinate system derived in step S120. The obstacle detection device 55 regards a clustered point cloud as one obstacle. The feature point clustering 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. More specifically, among the coordinates of obstacles in the world coordinate system, the X coordinate represents the distance from the origin to the obstacle in the left-right direction, and the Y coordinate represents the distance from the origin to the obstacle in the front-back direction. .. The origin is, for example, the coordinates where the X coordinate and the Y coordinate are the arrangement positions of the stereo camera 52 and the Z coordinate is the road surface. It is also possible to derive the Euclidean distance from the arrangement position of the stereo camera 52 to the obstacle from the X coordinate and the Y coordinate. Of the coordinates of obstacles in the world coordinate system, the Z coordinate represents the height of the obstacle from the road surface.

As shown in FIG. 5, the obstacle detection device 55 can derive the position of the obstacle existing in the detectable region AA1. The detectable area AA1 is a range in which the obstacle detection device 55 can detect an obstacle. The detectable region AA1 is determined by, for example, 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 region AA1 can be said to be a range that can be captured by the stereo camera 52.

As shown in FIG. 4, in step S150, the obstacle detection device 55 determines whether or not the obstacle is a person. Whether or not an obstacle is a person can be determined by various methods. In the present embodiment, the obstacle detection device 55 performs a person determination 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 the camera coordinates, and converts the camera coordinates into the coordinates of the image captured by the cameras 53 and 54. In the present embodiment, the obstacle detection device 55 converts the coordinates of the obstacle in the world coordinate system into the coordinates of the reference image. The obstacle detection device 55 performs a person determination process on the coordinates of the obstacle in the reference image. The person determination process is performed using, for example, feature quantity extraction and a person determination device that has been machine-learned in advance. Examples of the feature amount extraction include a method of extracting the feature amount of a local region in an image such as HOG: Histogram of Oriented Gradients feature amount and Haar-Like feature amount. As the human judgment device, for example, a machine learning using a supervised learning model is used. As a supervised learning model, for example, a support vector machine, a neural network, naive bays, deep learning, a decision tree, or the like can be adopted. As the teacher data used for machine learning, image-specific components such as human shape elements and appearance elements extracted from the image are used. Examples of the shape element include the size and contour of a person. Examples of the appearance element include light source information, texture information, camera information, and the like. The light source information includes information on reflectance, shading, and the like. The texture information includes color information and the like. The camera information includes information on image quality, resolution, angle of view, and the like. By performing the process of step S150, it can be said that the obstacle detection device 55 includes a person determination unit for determining whether or not the obstacle is a person.

The detection result by the obstacle detection device 55 is acquired by the main control device 31. As a result, the main control device 31 can recognize an obstacle existing behind the forklift 10.
The lamp 58 may be singular or plural. In this embodiment, a plurality of lamps 58 are provided. The lamp 58 may be arranged at any position as long as it is arranged at a position that can be visually recognized by the operator of the forklift 10.

As shown in FIG. 2, one lamp 58 is provided for each of the two front pillars 16 and the two rear pillars 17. The lamp 58 is arranged at a height so as to enter the field of view of the operator seated in the driver's seat 19. The lamp 58 is arranged above the driver's seat 19. Since the front pillar 16 is arranged in front of the driver's seat 19, it can be said that the lamp 58 provided in the front pillar 16 is arranged in front of the driver's seat 19.

The buzzer 59 can be arranged arbitrarily. In this embodiment, the buzzer 59 is provided in one of the two rear pillars 17.
The lamp 58 and the buzzer 59 are operated by a command from the main control device 31. The main control device 31 can operate the lamp 58 by transmitting a command to the detection device 51 via the bus 60. The operation of the lamp 58 means that the lamp 58 is lit or the lamp 58 is blinking. The main control device 31 can select whether to turn on the lamp 58 or blink the lamp 58. The main control device 31 can operate the buzzer 59 by transmitting a command to the detection device 51 via the bus 60. The operation of the buzzer 59 means that the buzzer 59 emits a sound.

The accelerator sensor 34 detects the amount of operation of the accelerator pedal 37, that is, the accelerator opening degree. The accelerator sensor 34 outputs an electric signal corresponding to the accelerator opening degree to the main control device 31. The main control device 31 can recognize the accelerator opening degree by the electric signal from the accelerator sensor 34.

The direction sensor 35 detects the operating direction of the direction lever 38 that indicates the traveling direction. The direction sensor 35 detects whether the direction lever 38 is operated in the direction instructing forward or the direction lever 38 is operated in the direction instructing reverse, with reference to neutrality. The direction sensor 35 outputs an electric signal corresponding to the operation 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 by an electric signal from the direction sensor 35. The main control device 31 can grasp whether the operator has instructed to move forward, has been instructed to move backward, or has not been instructed to move forward.

The tire angle sensor 36 detects the steering angle of the steering wheel 14. The tire angle sensor 36 outputs an electric signal corresponding to the steering angle to the main control device 31. The main control device 31 can recognize the steering angle by the electric signal from the tire angle sensor 36.

The traveling motor 41 is a driving device for traveling the forklift 10. The forklift 10 travels by rotating the drive wheels 12 by driving the traveling motor 41.
The rotation speed sensor 42 detects the rotation speed of the traveling motor 41. As the rotation speed sensor 42, for example, a rotary encoder can be used. 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 travel control device 43 is a motor driver that controls the rotation speed of the travel motor 41. The travel control device 43 can recognize the rotation speed and the rotation direction of the travel motor 41 from the electric signal of the rotation speed sensor 42.

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

The main control device 31, the travel control device 43, and the detection device 51 are configured so that information can be acquired from each other by the bus 60. The main control device 31, the travel control device 43, and the detection device 51 acquire information from each other by communicating according to a communication protocol for a vehicle such as CAN: Controller Area Network or LIN: Local Interconnect Network.

The main control device 31 derives the vehicle speed of the forklift 10 by acquiring the rotation speed and the rotation direction of the traveling motor 41 from the traveling control device 43. The vehicle speed of the forklift 10 can be derived by using the rotation speed and rotation direction of each of the traveling motors 41 provided for each drive wheel 12, the gear ratio, the outer diameter of the drive wheel 12, and the like. The main control device 31 derives the traveling direction of the forklift 10 as well as the vehicle speed. The traveling direction of the forklift 10 is either a forward direction or a reverse direction. It can be said that the main control device 31 includes an acquisition unit for acquiring the vehicle speed of the forklift 10.

The main control device 31 calculates the target vehicle speed from the accelerator opening degree detected by the accelerator sensor 34. The main control device 31 calculates the target rotation speed from the target vehicle speed. The target rotation speed is a rotation speed for bringing the vehicle speed of the forklift 10 to reach the target vehicle speed. The target rotation speed is individually derived for each of the two traveling motors 41. Further, the main control device 31 determines whether to move the forklift 10 forward or backward from the operating 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 gives the command to the traveling control device 43. The travel control device 43 controls the travel motor 41 so as to follow the target rotation speed according to the command. The travel control device 43 controls the travel motor 41 so that the travel motor 41 rotates in the rotation direction according to the command. The forklift 10 travels at a vehicle speed corresponding to the amount of operation of the accelerator pedal 37 by the operator. In the forklift 10 that can independently control the rotation speeds of the two drive wheels 12 as in the present embodiment, the turning operation by the operator, that is, the rotation speeds of the two traveling motors 41 according to the angle of the handle. The forklift 10 can be turned by adjusting the rotation direction. Therefore, in the case of the forklift 10 that makes a turn by utilizing the difference in the rotation speeds of the two traveling motors 41, the main control device 31 derives the target rotation speed according to the target vehicle speed and the angle of the steering wheel.

The main control device 31 can impose a vehicle speed limit by setting a vehicle speed upper limit value. When the vehicle speed upper limit value is set, the main control device 31 controls so that the vehicle speed of the forklift 10 does not exceed the vehicle speed upper limit value. For example, when the target vehicle speed calculated from the accelerator opening is less than the vehicle speed upper limit value, the main control device 31 calculates the target rotation speed from the target vehicle speed calculated from the accelerator opening, while calculating from the accelerator opening. When the calculated target vehicle speed is equal to or higher than the vehicle speed upper limit value, the target rotation speed is calculated using the vehicle speed upper limit value instead of the target vehicle speed. Then, a command is given to the traveling control device 43 so that the target rotation speed and the rotation speed of the traveling motor 41 match.

In addition, the state in which the vehicle speed limit is not imposed means that, in addition to the mode in which the vehicle speed upper limit value is not set, the vehicle speed upper limit value higher than the maximum reachable speed of the forklift 10 is set. Includes an aspect of setting a vehicle speed upper limit.

Next, the notification control performed by the main control device 31 will be described. The main control device 31 performs the following notification control in a predetermined control cycle to make the operator recognize an obstacle existing behind the forklift 10.

As shown in FIG. 6, in step S10, the main control device 31 determines whether or not the forklift 10 is moving backward. If the determination result in step S10 is affirmative, the main control device 31 performs the process of step S11. If the determination result in step S10 is negative, the main control device 31 performs the process of step S31.

In step S11, the main control device 31 determines whether or not an obstacle exists in the detection area AA2. A detection area AA2 is set in the detectable area AA1 by the obstacle detection device 55. The detection area AA2 is also a narrow area for the detectable area AA1. The detection area AA2 is an area behind the forklift 10. The detection area AA2 is defined by world coordinates. In the present embodiment, the detection area AA2 is defined by the X coordinate Xw and the Y coordinate Yw of the world coordinate system, but the detection area AA2 is defined by the Z coordinate Zw in addition to the X coordinate Xw and the Y coordinate Yw of the world coordinate system. May be done. In the following description, the X-axis is the X-axis of the world coordinate system, and the Y-axis is the Y-axis of the world coordinate system.

The size of the detection area AA2 used in step S11 is preset. The dimension of the detection area AA2 in the Y-axis direction is set based on the dimension between the shelves SH1 and SH2 in the work place. The dimension of the detection area AA2 in the Y-axis direction is shorter than the dimension between the shelves SH1 and SH2. The longer the dimension between the shelves SH1 and SH2, the longer the dimension of the detection area AA2 in the Y-axis direction is set. When three or more shelves are arranged, the dimension of the detection area AA2 in the Y-axis direction is set based on the shortest dimension among the dimensions between the shelves.

Considering the operation of the forklift 10 when performing cargo handling work including loading and unloading work, the forklift 10 travels between the shelves SH1 and SH2 along the shelves SH1 and SH2, and then turns to the shelves. Turn to SH1. Then, it advances toward the shelf SH1. After finishing the cargo handling work, the forklift 10 moves backward. By moving backward, the forklift 10 is separated from the shelf SH1 in front of the forklift 10. When the distance between the shelves SH1 in front of the forklift 10 and the forklift 10 becomes equal to or greater than the distance at which the forklift 10 can turn, the forklift 10 turns and travels between the shelves SH1 and SH2. As described above, when the forklift 10 performs the loading work and the loading work, a step of moving backward to separate from the shelf SH1 in front of the forklift 10 occurs. The dimension of the detection area AA2 in the Y-axis direction is when the forklift 10 moves backward and is separated from the shelf SH1 in front of the forklift 10, and is separated from the shelf SH1 in front of the forklift 10 by a distance longer than the forklift 10 can turn. , The shelf SH2 behind the forklift 10 is set to enter the detection area AA2. In other words, the dimension of the detection area AA2 in the Y-axis direction is the rear of the forklift 10 when the distance between the forklift 10 and the shelf SH1 in front of the forklift 10 is less than the distance required for turning the forklift 10. Shelf SH2 is set so as not to enter the detection area AA2.

The dimensions of the detection area AA2 in the X-axis direction can be arbitrarily set. The dimension of the detection region AA2 in the X-axis direction is set to, for example, a dimension equal to or larger than the vehicle width of the forklift 10. The dimension of the detection area AA2 in the X-axis direction may be a constant value or may be a different value depending on the position of the detection area AA2 in the Y-axis direction. When the dimension in the X-axis direction is set to a different value depending on the position of the detection region AA2 in the Y-axis direction, for example, the dimension in the X-axis direction may be increased as the distance from the forklift 10 increases.

The detection region AA2 used in step S11 may be a region that always extends linearly behind the forklift 10, or may be a region that bends in the direction in which the forklift 10 is expected to turn. When the detection area AA2 is bent according to the direction in which the forklift 10 is expected to turn, the main controller 31 bends the detection area AA2 to the right when the forklift 10 is expected to turn to the right, and the forklift 10 is left. When it is expected to turn to the left, the detection area AA2 is bent to the left. The direction in which the forklift 10 is expected to turn can be grasped from, for example, the detection result of the tire angle sensor 36.

If the determination result in step S11 is affirmative, the main control device 31 performs the process of step S12. If the determination result in step S11 is negative, the main control device 31 performs the process of step S31.

In step S12, the main control device 31 determines whether or not the vehicle speed of the forklift 10 is within the low speed operating range. The low speed operating range is a predetermined range. The lower limit of the low speed operation range is a value higher than 0 [km / h]. The lower limit value of the low speed operation range can be set to an arbitrary value as long as it can detect that the forklift 10 is traveling. Even when the forklift 10 is not traveling, if vibration is applied to the forklift 10, a vehicle speed of 0 [km / h] or more may be detected. The lower limit of the low-speed operating range is set to a value higher than the vehicle speed that can be detected by the influence of vibration. The upper limit of the low speed operating range is a value lower than the maximum reachable speed of the forklift 10. The low-speed operating range can be arbitrarily set by the administrator of the forklift 10. The low-speed operation range is, for example, 0.5 [km / h] to 3.0 [km / h].

If the determination result in step S12 is affirmative, the main control device 31 performs the process of step S13. If the determination result in step S12 is negative, the main control device 31 performs the process of step S21.

In step S13, the main control device 31 determines whether the obstacle is a person or an object. When the obstacle is an object, the main control device 31 performs the process of step S14. When the obstacle is a person, the main control device 31 performs the process of step S15.

In step S14, the main control device 31 gives a notification. The notification in step S14 is an approach notification. The approach notification is a notification for notifying the operator that an obstacle exists behind the forklift 10. The main control device 31 blinks the lamp 58. The main control device 31 does not activate the buzzer 59 when the approach notification is performed. When giving an approach notification, the main control device 31 does not impose a vehicle speed limit. The approach notification is a notification only by blinking the lamp 58. By visually recognizing that the lamp 58 is blinking, the operator can recognize that an obstacle exists behind the forklift 10. The approach notification is a non-deceleration notification that does not decelerate the forklift 10. The approach notification is a notification set assuming a situation in which the operator recognizes that an obstacle exists behind the forklift 10. For example, when the cargo handling work is performed between the shelves SH1 and SH2, it is expected that the operator recognizes that the shelves SH1 and SH2 exist behind. If deceleration is performed at this time, deceleration is performed even though the operator recognizes that an obstacle exists behind the vehicle, resulting in a decrease in work efficiency. The approach notification can be said to be a notification performed in order to improve work efficiency by making the operator recognize that the forklift 10 has approached an obstacle. In the approach notification, the notification unit is the lamp 58. The main control device 31 is a notification control unit.

In step S15, the main control device 31 gives a notification. The notification in step S15 is a warning notification. The warning notification is a notification for notifying the operator that the forklift 10 needs to be stopped or decelerated. The warning notification is a notification that makes it easier for the operator to recognize the existence of an obstacle than the approach notification. The warning notification assumes a situation in which the operator does not recognize that an obstacle exists behind the forklift 10, and is a notification for the operator to recognize that an obstacle exists. Is. The warning notification is a notification for suppressing contact between the obstacle and the forklift 10.

The main control device 31 blinks the lamp 58. The blinking speed of the lamp 58 when giving a warning notification is faster than the blinking speed of the lamp 58 when giving an approach notification (the cycle of repeating turning on and off is short). The main control device 31 activates the buzzer 59. The main control device 31 imposes a vehicle speed limit by setting the vehicle speed upper limit value to 0. When the upper limit of the vehicle speed is 0, it can be said that the forklift 10 is prohibited from traveling. When the upper limit of the vehicle speed is set to 0, the forklift 10 decelerates. The warning notification is a notification by blinking the lamp 58, operating the buzzer 59, and limiting the vehicle speed. By visually recognizing that the lamp 58 is blinking, the operator can recognize that an obstacle exists behind the forklift 10. The operator can recognize that an obstacle exists behind the forklift 10 by the sound emitted by the buzzer 59. The operator can recognize that an obstacle exists behind the forklift 10 by decelerating the forklift 10. The warning notification is a deceleration notification that is notified by decelerating the forklift 10. In the warning notification, in addition to the ramp 58 and the buzzer 59, the main control device 31 that causes the forklift 10 to decelerate by imposing a vehicle speed limit is the notification unit.

When all the determinations in steps S10 to S12 are affirmative, the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2, and the vehicle speed of the forklift 10 is in the low speed operating range. It can be said that. The notification condition is that the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2, and the vehicle speed of the forklift 10 is in the low speed operating range. It can be said that the notification is given when all the determinations in steps S10 to S12 are affirmative, and the notification is given when the notification condition is satisfied.

In step S21, the main control device 31 determines whether or not the vehicle speed of the forklift 10 is equal to or higher than the threshold value. The threshold value is a value higher than the upper limit value of the low speed operating range and lower than the maximum reachable speed of the forklift 10.

If the determination result in step S21 is affirmative, the main control device 31 performs the process of step S22. If the determination result in step S21 is negative, the main control device 31 performs the process of step S31.

In step S22, the main control device 31 gives a notification. The notification in step S22 is a warning notification. The warning notification performed in step S22 is performed in a manner different from the approach notification performed in step S14 and the warning notification performed in step S15. The warning notification in step S22 is a notification including at least a deceleration notification. The main control device 31 causes the forklift 10 to decelerate by setting the vehicle speed upper limit value to a value of 0 or more. As the vehicle speed upper limit value, for example, a threshold value used for the determination in step S21 can be mentioned. The main control device 31 may blink the lamp 58. The blinking speed of the lamp 58 may be different from the blinking speed of the lamp 58 when the approach notification in step S14 and the warning notification in step S15 are given. The main control device 31 may operate the buzzer 59. The volume of the buzzer 59 may be different from the volume of the buzzer 59 at the time of giving the warning notification in step S15.

When the determinations of step S10, step S11, and step S21 are all affirmative, the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2, and the vehicle speed of the forklift 10 operates at a low speed. It can be said that it is higher than the upper limit of the range. It is a specific condition that the forklift 10 is traveling backward in a state where an obstacle exists in the detection region AA2, and the vehicle speed of the forklift 10 is not in the low speed operating range. By notifying when the determinations of steps S10, S11 and S21 are all affirmative, it can be said that when the specific condition is satisfied, the notification is performed in a different notification mode from the case where the notification condition is satisfied. The size of the detection area AA2 may be different depending on whether or not the notification condition is satisfied and whether or not the specific condition is satisfied. The specific condition may be satisfied when an obstacle exists in the same area as the detection area AA2 set in step S12, or in an area having a size different from the detection area AA2 set in step S12. It may be established when an obstacle exists. For example, when the main control device 31 determines whether or not a specific condition is satisfied, the faster the vehicle speed of the forklift 10, the longer the dimension of the detection region AA2 in the Y-axis direction, and the obstacle in the detection region AA2. A specific condition may be satisfied when is present.

In step S31, the main control device 31 cancels the notification. When the main control device 31 has given a notification by satisfying a notification condition or a specific condition in the past control cycle, the main control device 31 cancels the notification so that the notification is not performed. The main control device 31 maintains this state when the processing of step S31 is performed and the notification is not performed.

The operation of this embodiment will be described.
As shown in FIG. 7, when the forklift 10 performs a loading operation of taking a load W from the shelves SH1 and SH2, the operation is performed between the two shelves SH1 and SH2. When the forklift 10 takes the load W from the first shelf SH1, the forklift 10 advances toward the first shelf SH1. In the state where the forklift 10 is performing the loading work, the second shelf SH2 does not enter the detection area AA2, and the presence of the second shelf SH2 suppresses the establishment of the notification condition. After the forklift 10 finishes the loading work, the forklift 10 moves backward. When the cargo is being picked up, the forklift 10 is often stopped. Therefore, when the forklift 10 is separated from the first shelf SH1, the vehicle speed of the forklift 10 is within the low speed operating range. As the forklift 10 moves backward, the forklift 10 approaches the rear second shelf SH2.

As shown in FIG. 8, when the second shelf SH2 enters the detection area AA2, the notification condition is satisfied by the presence of the second shelf SH2. As a result, the approach notification is performed. In the present embodiment, the approach notification is performed by blinking the lamp 58. The operator of the forklift 10 recognizes that he / she has approached the second shelf SH2 by the approach notification. The operator of the forklift 10 turns the forklift 10 when he / she recognizes that he / she has approached the second shelf SH2 by the approach notification.

The operator can grasp the timing of turning by blinking the lamp 58. If the dimension of the detection area AA2 in the Y-axis direction is excessively long, the approach notification may be performed in a state where the distance from the first shelf SH1 is not sufficient. If the dimension of the detection area AA2 in the Y-axis direction is excessively short, the forklift 10 and the second shelf SH2 may be excessively close to each other before the approach notification is performed. The dimension of the detection area AA2 in the Y-axis direction is such that the distance from the first shelf SH1 is a distance that allows turning, and the forklift 10 can notify the approach in a state where the forklift 10 is not excessively close to the second shelf SH2. Is set to.

In the above example, the case where the forklift 10 performs the loading work has been described, but even when the forklift 10 performs the loading work of placing the load W on the shelves SH1 and SH2, the approach notification is performed in the same manner. ..

In the embodiment, the case where the cargo handling work is performed between the shelves SH1 and SH2 has been described as an example, but the forklift 10 has two obstacles even if it is not between the shelves SH1 and SH2. Cargo handling work may be performed between them. For example, when two loading positions are set in the work place and cargo handling work is performed between the two loading positions, the forklift 10 handles the cargo between the loads W placed in the two loading positions. Work may be done. Further, the forklift 10 may perform cargo handling work between the shelves SH1 and SH2 and the wall. When the forklift 10 performs cargo handling work between two obstacles, the approach notification is given in the same manner even when the obstacles are other than the shelves SH1 and SH2.

The effect of this embodiment will be described.
(1) The main control device 31 gives an approach notification when the notification condition is satisfied. When the forklift 10 approaches the rear shelves SH1 and SH2, the operator can be notified. The operator can recognize that he / she has approached the rear shelves SH1 and SH2 by the approach notification.

When the operator of the forklift 10 recognizes that he / she has approached the rear shelves SH1 and SH2 by the approach notification, the forklift 10 is turned. It can be said that the approach notification notifies the operator of the timing for turning the forklift 10. The approach notification can assist the operator and improve work efficiency.

(2) The lamp 58 that blinks at the time of approach notification is arranged in front of the driver's seat 19. Since the cargo handling device 20 is provided in front of the vehicle body 11, the operator often faces forward. By arranging the lamp 58 in front of the driver's seat 19, the operator can recognize that he / she has approached the rear shelves SH1 and SH2 while visually recognizing the cargo handling device 20.

(3) The notification mode is different between the notification given when the notification condition is satisfied and the notification given when the specific condition is satisfied. As a result, it is possible to give a notification according to the situation.
(4) The main control device 31 decelerates the forklift 10 when the notification condition is satisfied and the obstacle existing in the detection area AA2 is a person. When the notification condition is satisfied, the main control device 31 does not decelerate the forklift 10 if the obstacle existing in the detection area AA2 is an object. When the obstacle existing in the detection area AA2 is a person, it is preferable to decelerate the forklift 10. On the other hand, when the obstacle existing in the detection area AA2 is an object, the operator may move the forklift 10 backward after recognizing the existence of the obstacle, and decelerating the forklift 10 reduces the work efficiency. May be invited. When the obstacle is an object, the decrease in work efficiency can be suppressed by not decelerating.

(5) When the notification condition is satisfied and the obstacle existing in the detection area AA2 is an object, the approach notification is performed. In the approach notification, only the lamp 58 blinks. The approach notification is intended to make the operator recognize that the shelves SH1 and SH2 are present behind without deteriorating the work efficiency. The blinking of the lamp 58 is less likely to hinder the work than when the buzzer 59 is operated or the forklift 10 is decelerated. Therefore, it is possible to suppress a decrease in work efficiency.

(6) The warning notification is a notification for notifying the operator that the forklift 10 needs to be stopped or decelerated. Therefore, in the warning notification, the notification is performed so that the operator can easily recognize that an obstacle exists behind the approach notification. If excessive notification is given by the approach notification, the operator may become accustomed to the notification, and the operator may not be able to recognize that the forklift 10 needs to be stopped or decelerated when the warning notification is given. By limiting the approach notification to only the blinking of the lamp 58 and not performing excessive notification, it is possible to suppress the accustomed to the notification.

(7) When the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2 and the vehicle speed of the forklift 10 is higher than the threshold value, the main control device 31 of the forklift 10 Decelerate. When cargo handling work is being carried out between obstacles, there is inevitably an obstacle behind the forklift 10. When the vehicle speed of the forklift 10 is higher than the threshold value, it seems that there is inevitably an obstacle behind the forklift 10, such as a situation where the forklift 10 is traveling in a place different from the space between the two obstacles. It is not considered to be the situation. In a situation where an obstacle is inevitably present behind the forklift 10, the operator often recognizes that the obstacle is behind the forklift 10, and in this case, the work. Notify without slowing down in order to suppress the decrease in efficiency. On the other hand, when the vehicle speed of the forklift 10 is higher than the threshold value, the operator may not recognize the obstacle behind the forklift 10, so that the notification including deceleration is given. As a result, contact between the obstacle behind the forklift 10 and the forklift 10 can be suppressed.

The embodiment can be modified and implemented as follows. The embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.
○ The main control device 31 does not notify when the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2 and the vehicle speed of the forklift 10 is higher than the threshold value. You may.

○ The main control device 31 has a lamp 58 or a buzzer 59 when the forklift 10 is traveling backward in a state where an obstacle exists in the detection area AA2 and the vehicle speed of the forklift 10 is higher than the threshold value. It is not necessary to give a notification by deceleration.

○ The main control device 31 does not have to perform different control depending on whether the obstacle is a person or an object. More specifically, the main control device 31 does not have to perform the process of step S13. In this case, the main control device 31 may give an approach notification when the notification condition is satisfied. That is, the main control device 31 may give an approach notification regardless of whether the obstacle is an object or a person. Similarly, the main control device 31 may give the warning notification in step S15 when the notification condition is satisfied. In this case, the obstacle detection device 55 does not have to determine whether or not the obstacle is a person.

○ As the specific condition, any condition can be set as long as it is a condition that is satisfied when an obstacle exists in the detection area AA2. The notification condition is a condition set for the operator to recognize the approach to the obstacle behind when the cargo handling work is performed between the two obstacles. On the other hand, the specific conditions can be set assuming various situations such as when the forklift 10 is traveling in a place different from that between the two obstacles. By setting specific conditions, notification can be given in various situations. A plurality of specific conditions may be set. In this case, the notification mode that is performed when the conditions are satisfied may be different for each of a plurality of specific conditions.

○ Specific conditions do not have to be set.
○ The notification mode may be the same for the notification when the notification condition is satisfied and the notification when the specific condition is satisfied. In this case, the notification when the specific condition is satisfied may be the approach notification in step S14 or the warning notification in step S15.

○ The notification unit may be provided with at least one of a vehicle speed limiting function by the lamp 58, the buzzer 59, and the main control device 31. Further, the notification unit may be any as long as it can notify the operator. For example, the notification may be given by displaying on a display unit that can be visually recognized by the operator.

○ The notifications given in steps S14, S15 and S22 can be given in any manner. For example, the notification may be given only by deceleration, or the notification may be given by turning on the lamp 58.

○ The mounting position of the lamp 58 is arbitrary. The lamp 58 may be provided only on the front pillar 16 or may be provided only on the rear pillar 17. The lamp 58 may be provided at any position as long as it can be visually recognized by the operator, such as the cargo handling device 20.

○ At least one lamp 58 may be provided. In this case, the lamp 58 is preferably provided on either of the two front pillars 16.
○ As shown in FIG. 9, the lamp 70 may be provided on the shelves SH1 and SH2. In this case, when the notification condition is satisfied, the main control device 31 blinks the lamps 70 of the shelves SH1 and SH2. When the lamp 70 is provided on the shelves SH1 and SH2, the shelves SH1 and SH2 are provided with a control device for blinking the lamp 70. When the lamp 70 is provided on the shelves SH1 and SH2, the forklift 10 and the shelves SH1 and SH2 each include a wireless unit capable of communicating with each other. Examples of the wireless unit include those that perform short-range wireless communication. As an example, a case where Bluetooth (registered trademark) is used will be described.

The wireless communication unit can detect the RSSI value of the wireless signal. The RSSI (Received Signal Strength Indication) value is a value indicating the reception strength of the radio signal. The wireless communication units provided on the shelves SH1 and SH2 periodically transmit connection request signals. When the wireless unit provided in the forklift 10 receives the connection request signal, it detects the RSSI value of the connection request signal. The RSSI value becomes larger as the wireless communication unit of the forklift 10 and the wireless communication units of the shelves SH1 and SH2 are closer to each other. Therefore, it can be said that the RSSI value of the connection request signal represents the separation distance between the forklift 10 and the shelves SH1 and SH2.

When the wireless communication unit of the forklift 10 receives a connection request signal having an RSSI value equal to or higher than a threshold value, it pairs with the wireless communication unit that transmitted the connection request signal. As the threshold value of the RSSI value, when the forklift 10 approaches the shelves SH1 and SH2 for cargo handling work, the pairing between the wireless communication unit provided on the shelves SH1 and SH2 and the wireless communication unit of the forklift 10 is set. It is set to be done.

When the notification condition is satisfied, the main control device 31 transmits a command from the wireless communication unit of the forklift 10 to the wireless communication units of the shelves SH1 and SH2. This command is a command instructing the blinking of the lamp 70. When the wireless communication unit of the shelves SH1 and SH2 receives the command, the control device provided on the shelves SH1 and SH2 blinks the lamp 70. As a result, the lamps 70 of the shelves SH1 and SH2 existing in front of the forklift 10 can be blinked. After blinking the lamps 70 of the shelves SH1 and SH2, the main control device 31 can cancel the pairing at an arbitrary timing.

○ The detection device 51 may include a ToF (Time of Flight) camera, LIDAR (Laser Imaging Detection and Ranging), or a millimeter-wave radar instead of the stereo camera 52. The TOF camera includes a camera and a light source that irradiates light, and derives the distance in the depth direction for each pixel of the image captured by the camera from the time until the reflected light of the light emitted from the light source is received. It is a thing. LIDAR is a rangefinder that can recognize the surrounding environment by irradiating a laser while changing the irradiation angle and receiving the reflected light reflected from the part hit by the laser. The millimeter wave radar is capable of recognizing the surrounding environment by irradiating the surroundings with radio waves in a predetermined frequency band. The stereo camera 52, the ToF camera, the LIDAR, and the millimeter wave radar are sensors capable of measuring three-dimensional coordinates in the world coordinate system. The detection device 51 preferably includes a sensor capable of measuring three-dimensional coordinates. When the detection device 51 includes a sensor capable of measuring three-dimensional coordinates, the obstacle detection device 55 can determine whether an obstacle is a person or an object by using a human determination device that has been machine-learned in advance. .. The detection device 51 may include a combination of a plurality of sensors such as a stereo camera 52 and LIDAR.

Further, the detection device 51 may include a sensor capable of measuring the coordinates of an obstacle on the XY plane, which is a coordinate plane representing a horizontal plane, instead of the stereo camera 52. That is, as the sensor, a sensor capable of measuring the two-dimensional coordinates of the obstacle may be used. As this type of sensor, for example, a two-dimensional LIDAR that irradiates a laser while changing the irradiation angle in the horizontal direction can be used.

○ An ultrasonic sensor may be used as the detection device 51.
○ The obstacle detection device 55 may determine whether or not the obstacle is a person by using a comparative image among the images captured by the stereo camera 52. Since the coordinates of the obstacle are derived from the reference image, if the coordinates of the obstacle on the comparison image are derived from the coordinates of the obstacle, a deviation according to the baseline length occurs. Therefore, the obstacle detection device 55 corrects the coordinates of the obstacle on the comparative image according to the baseline length, and performs a person determination process on the corrected coordinates.

○ The main control device 31 may have a function as an obstacle detection device 55. In this case, the forklift notification device 30 does not have to include the obstacle detection device 55.
○ The stereo camera 52 may include three or more cameras.

○ The lamp 58 and the buzzer 59 may be directly operated by the main control device 31.
○ The forklift 10 may be driven by the drive of an engine which is a drive device. In this case, the travel control device 43 is a device that controls the fuel injection amount to the engine and the like.

○ The forklift 10 may be a standing type. In this case, the forklift 10 does not have a driver's seat 19. The boarding position in this case is a position where the operator operates the forklift 10.

○ The forklift 10 may rotate two drive wheels 12 with one traveling motor.
○ The notification control unit may be a device different from the main control device 31. The notification control unit may be, for example, an obstacle detection device 55.

AA2 ... Detection area, 10 ... Forklift, 30 ... Forklift notification device, 31 ... Acquisition unit, Notification unit and main control device as notification control unit, 51 ... Detection device, 58 ... Lamp as notification unit, 59 ... Notification unit Buzzer as.

Claims (5)

It is a notification device for forklift trucks.
A detection device that detects obstacles existing in the detection area behind the forklift in the front-rear direction of the forklift, and
A notification unit that notifies the operator of the forklift of the existence of the obstacle, and
The acquisition unit that acquires the vehicle speed of the forklift and
The notification condition is that the forklift is traveling backward in a state where the obstacle is present in the detection area, and the vehicle speed of the forklift acquired by the acquisition unit is within the low speed operating range. If so, a forklift notification device including a notification control unit that causes the notification unit to notify when the notification condition is satisfied. The notification unit includes a lamp.
The forklift notification device according to claim 1, wherein the lamp is arranged in front of the boarding position of the operator. The notification control unit causes the notification unit to notify when a specific condition is satisfied, which is a condition different from the notification condition and at least when the obstacle is present in the detection area.
The forklift notification device according to claim 1 or 2, wherein the notification control unit differs in the notification mode by the notification unit depending on whether the notification condition is satisfied or the specific condition is satisfied. The detection device includes a person determination unit that determines whether or not the obstacle is a person.
The notification by the notification unit includes a deceleration notification for notifying by decelerating the forklift and a non-deceleration notification for notifying without decelerating.
The notification control unit is any one of claims 1 to 3 in which the notification unit is made to perform only the non-deceleration notification when the notification condition is satisfied and the obstacle is not a person. The forklift notification device described in paragraph 1. The forklift is traveling backward in a state where the obstacle is present in the detection region, and the vehicle speed of the forklift acquired by the acquisition unit is higher than the upper limit of the low speed operating range. In this case, the forklift notification device according to claim 4, wherein the notification control unit causes the notification unit to notify the deceleration.

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