Cargo handling vehicles and cargo handling programs

Abstract

Compared to conventional methods, this allows for simpler and more efficient detection of surrounding objects. [Solution] The cargo handling vehicle 20 comprises a vehicle body 11, a gimbal 291 positioned on the vehicle body 11, a laser scanner 29 tiltably supported by the gimbal 291, and a control unit 27. The control unit 27 corrects the measurement results of the laser scanner 29 based on the measurement results of the vehicle body 11 by the laser scanner 29.

Description

Technical Field

[0001] The present invention relates to a loading vehicle and a loading program.

Background Art

[0002] Conventionally, loading vehicles such as automated guided forklifts (AGF) for performing loading work are known. As this type of loading vehicle, there is known one that detects surrounding obstacles by a distance sensor such as a laser scanner with a scanning area set horizontally to ensure driving safety.

[0003] When detecting such surrounding objects, it is necessary to grasp the position of environmental objects on a horizontal plane in order to suppress detection delay and false detection. For this purpose, it is necessary to accurately attach the distance sensor to the vehicle body so that the scanning plane is horizontal. In addition, when there is a bias in the weight distribution of the load or the road surface is bad, etc., the posture of the vehicle body may change and the distance sensor may tilt, and countermeasures are required. For example, in the technologies described in Patent Documents 1 and 2, the amount of tilt of the vehicle body is grasped and the distance to an obstacle on a horizontal plane is corrected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to attach the distance sensor to the vehicle body so that the scanning plane is horizontal, complicated adjustment work such as projecting the scanning plane in a wide work space is required, and the manufacturing cost increases. Furthermore, especially when the laser scanner is mounted at a low position, there is a risk of the floor surface being mistakenly detected as an obstacle due to the tilt of the vehicle body. The technologies described in the above-mentioned Patent Documents 1 and 2 only correct for distance changes due to tilt, and therefore cannot suppress the false detection itself.

[0006] This invention has been made in view of the above circumstances, and aims to provide a simpler and more suitable method for detecting surrounding objects compared to conventional methods. [Means for solving the problem]

[0007] The cargo handling vehicle according to the present invention is The car body and, A gimbal positioned on the vehicle body, A distance sensor supported so as to be tiltable by the gimbal, A correction unit corrects the measurement result of the distance sensor based on the measurement result of the vehicle body by the distance sensor, It is equipped with. [Effects of the Invention]

[0008] According to the present invention, the detection of surrounding objects can be performed more easily and effectively than in the conventional method. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram showing a cargo handling vehicle according to an embodiment. [Figure 2] This is a block diagram showing a schematic control configuration of a cargo handling system according to an embodiment. [Figure 3] This diagram illustrates an example of measurement data acquired by a cargo handling vehicle under normal conditions. [Figure 4] This is a flowchart showing the flow of the sensor measurement process according to the embodiment. [Figure 5] This figure shows a cargo handling vehicle according to the embodiment in a forward-tilted state. [Figure 6] This figure shows an example of measurement data acquired by a cargo handling vehicle in a forward-tilted position. [Figure 7] This figure shows a modified example of a cargo handling vehicle according to an embodiment. [Figure 8] This is a diagram showing the state in which the cargo handling vehicle in FIG. 7 is tilted.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] [Configuration of Cargo Handling System] FIG. 1 is a diagram showing a cargo handling vehicle 20 according to this embodiment, and FIG. 2 is a block diagram showing a schematic control configuration of a cargo handling system 1 including the cargo handling vehicle 20. As shown in these figures, the cargo handling system 1 performs predetermined cargo handling operations (such as loading and unloading, transporting, stacking, picking, sorting, aligning loads, etc. and operations associated therewith) in a work area by the cargo handling vehicle 20. The cargo handling system 1 is a system including, for example, a WMS (Warehouse Management System), a WES (Warehouse Execution System), a WCS (Warehouse Control System), etc.

[0012] Specifically, the cargo handling system 1 includes at least one cargo handling vehicle 20 and a management server 30.

[0013] The cargo handling vehicle 20 is a vehicle that performs cargo handling operations, such as a forklift that can travel on the road without using rails or the like. The cargo handling vehicle 20 holds a load or a pallet by a pair of left and right forks (cargo handling parts) 12 and performs various cargo handling operations. The cargo handling vehicle 20 of this embodiment is an automated guided forklift (AGF) that can operate automatically (unattended) and operates based on an operation command or the like from the management server 30.

[0014] Specifically, the cargo handling vehicle 20 includes a vehicle body drive unit 21, a fork drive unit 28, an operation unit 22, a display unit 23, a communication unit 24, a position measurement device 25, a laser scanner 29, a storage unit 26, and a control unit 27.

[0015] The vehicle body drive unit 21 includes a traveling motor and a steering motor (both not shown), which are the drive sources of the material handling vehicle 20. The traveling motor drives the drive wheels among the wheels 15. The steering motor rotates (steers) the steering wheels among the wheels 15. Each motor is supplied with power from a battery not shown. Note that the drive source is not limited to a motor, and an internal combustion engine or the like may be used.

[0016] The fork drive unit 28 is a drive source for operating a pair of forks 12 protruding forward. The fork drive unit 28 of the present embodiment includes a tilt cylinder, a lift cylinder, and a reach cylinder (all not shown) for tilting, lifting and lowering, and extending and retracting (expanding and contracting) a pair of forks 12 with respect to the vehicle body 11. These cylinders are piston cylinders driven by hydraulic pressure (for example, oil pressure). The tilt cylinder tilts the lift body 13 or the mast 14 supporting a pair of forks 12 back and forth with respect to the vehicle body. The lift cylinder raises and lowers the lift body 13 holding a pair of forks 12 along the mast 14. The reach cylinder extends and retracts (expands and contracts) a pair of forks 12 back and forth (substantially perpendicular to the mast 14) of the material handling vehicle 20.

[0017] The operation unit 22 is an operation means for a driver to perform various operations during manned (manual) driving. The operation unit 22 includes, for example, a steering wheel, pedals, levers, various buttons, etc., and outputs an operation signal corresponding to these operation contents to the control unit 27. The display unit 23 is, for example, a liquid crystal display, an organic electro luminescence display, or other displays, and displays various information based on a display signal input from the control unit 27. Note that the display unit 23 may be a touch panel that also serves as a part of the operation unit 22, or may include a speaker capable of voice display (output). The communication unit 24 is a communication device capable of transmitting and receiving various information between the management server 30, other material handling vehicles 20, and the like.

[0018] The position measuring device 25 measures the position of the cargo handling vehicle 20 itself. The self-position information acquired by the position measuring device 25 is transmitted, for example, to the management server 30 and used for position control of the cargo handling vehicle 20 itself. The specific configuration of the position measuring device 25 is not particularly limited and may utilize, for example, GNSS (Global Navigation Satellite System), SLAM (Simultaneous Localization and Mapping) technology, indoor positioning (indoor mapping) technology, or other technologies.

[0019] The laser scanner 29 is an example of a distance sensor according to the present invention. It detects objects around the vehicle body by acquiring distance information within a predetermined scan area (measurement area) N, and outputs the result to the control unit 27. The laser scanner 29 in this embodiment is a two-dimensional distance sensor (for example, a two-dimensional LiDAR (Laser Imaging Detection and Ranging)) having a planar scan area N that is substantially orthogonal to the vertical direction of the vehicle body 11. The planar viewing range of the scan area N is not particularly limited, but is for example 270 to 360°. The laser scanner 29 is positioned on the vehicle body 11 such that the scan area N includes a desired measurement target range (direction) outside the vehicle and the vehicle body 11.

[0020] The laser scanner 29 is positioned on the vehicle body 11 via a gimbal 291. In this embodiment, the laser scanner 29 is positioned on the reach leg 112 that covers the wheel 15 within the vehicle body 11. The gimbal 291 is fixed to the tip of the left reach leg 112 and supports the laser scanner 29 so that it can tilt. The gimbal 291 tilts the laser scanner 29 so that the scanning area N of the laser scanner 29 remains horizontal regardless of the attitude of the vehicle body 11. The specific configuration of the gimbal 291 is not particularly limited as long as it tilts the laser scanner 29 so that the scanning area N remains horizontal. For example, it may be electrically implemented using a tilt measuring instrument, an attitude correction motor, and a control device that performs horizontal holding control. In this embodiment, the "vehicle body" to which the gimbal 291 is fixed refers to the frame portion of the cargo handling vehicle 20 whose relative position to the gimbal 291 does not change. Therefore, for example, parts whose relative position to the gimbal 291 may change due to the driving of the forks 12 are not included in the "vehicle body" with respect to the placement of the gimbal 291 (laser scanner 29).

[0021] The memory unit 26 is a memory composed of, for example, RAM (Random Access Memory) or ROM (Read Only Memory), and stores various programs and data, as well as functioning as a workspace for the control unit 27. In this embodiment, the memory unit 26 stores not only the program for executing the sensor measurement processing described later (see Figure 4), but also reference data 261. Reference data 261 is data used to calculate the horizontal movement amount of the laser scanner 29 in the sensor measurement processing described later. Specifically, as shown in Figure 3, the reference data 261 in this embodiment is data obtained by pre-measuring the distance to the vehicle body 11 using the laser scanner 29 in a reference posture (reference state) of the cargo handling vehicle 20 that is not holding a load L, and includes, for example, measured vehicle body measurement data (point cloud data) D0.

[0022] As shown in Figure 2, the control unit 27 is composed of, for example, a CPU (Central Processing Unit) and controls the operation of each part of the cargo handling vehicle 20. Specifically, the control unit 27 operates each part based on control commands from the management server 30 and the operation content of the operation unit 22, and also deploys programs pre-stored in the storage unit 26 and executes various processes in cooperation with the deployed programs.

[0023] The management server 30 centrally controls the cargo handling system 1 and is configured to control the operation of the cargo handling vehicles 20. The management server 30 may be a personal computer, smartphone, tablet terminal, or the like. Specifically, the management server 30 includes an operation unit 31, a display unit 32, a communication unit 34, a storage unit 36, and a control unit 37.

[0024] The operation unit 31 is an operating means that allows the operator to perform various operations to operate the management server 30, and includes, for example, a pointing device such as a mouse or keyboard. The display unit 32 is, for example, a liquid crystal display, an organic electroluminescent display, or other type of display. The display unit 32 displays various information based on display signals input from the control unit 37. The display unit 32 may also be a touch panel that also functions as at least a part of the operation unit 31. The communication unit 34 is a communication device capable of sending and receiving various types of information with each cargo handling vehicle 20.

[0025] The memory unit 36 ​​is a memory composed of, for example, RAM (Random Access Memory) or ROM (Read Only Memory), and stores various programs and data, as well as functioning as a workspace for the control unit 37. The control unit 37 is composed of, for example, a CPU (Central Processing Unit) and controls the operation of each part of the management server 30. Specifically, the control unit 37 deploys programs pre-stored in the storage unit 36 ​​based on the operation content of the operation unit 31, and performs various processes in cooperation with the deployed programs.

[0026] [Sensor measurement processing] Next, we will explain the sensor measurement process in which the cargo handling vehicle 20 detects surrounding objects using a laser scanner 29. Figure 4 is a flowchart illustrating the flow of the sensor measurement process. Figures 5 and 6 are diagrams illustrating the sensor measurement process; Figure 5 shows a cargo handling vehicle 20 in a tilted position, and Figure 6 shows an example of measurement data acquired by the cargo handling vehicle 20 in a tilted position.

[0027] The sensor measurement process is performed when the cargo handling vehicle 20 detects surrounding objects (measures distance) using the laser scanner 29. This sensor measurement process is performed by the control unit 27 of the cargo handling vehicle 20 reading the relevant program from the storage unit 26 and loading it. This program may be part of a cargo handling program executed for a predetermined cargo handling operation.

[0028] As shown in Figure 4, first the control unit 27 executes a predetermined cargo handling operation in the work area based on a command from the management server 30 (step S1). In cargo handling operations, for example, the management server 30 specifies a particular coordinate to the cargo handling vehicle 20 and instructs it to transport the cargo to that location. Here, for example, as shown in Figure 5, we assume that the cargo handling vehicle 20 holds a load L on its forks 12, and that the weight of this load L causes the cargo handling vehicle 20 to tilt forward overall. However, in Figure 5, the tilt of the cargo handling vehicle 20 is exaggerated for clarity.

[0029] Next, the control unit 27 performs measurements of the surroundings using the laser scanner 29 (step S2). Here, the control unit 27 performs measurements targeting, for example, the side of the cargo handling vehicle 20 and the cargo handling vehicle 20 itself (at least a part of the vehicle body 11), and acquires the measurement data. In this case, since the laser scanner 29 is tiltably supported by the gimbal 291, even if the posture of the cargo handling vehicle 20 changes from its normal state (reference state) due to the weight of the load L, the scanning area N of the laser scanner 29 is kept horizontal. Therefore, measurement data can be acquired in the same way as under normal conditions. Furthermore, since the scanning area N of the laser scanner 29 includes at least a portion of the vehicle body 11, the measurement data includes measurement points that capture the vehicle body 11. As a result, measurement data D is obtained, which includes, for example, first measurement data D1 measuring the vehicle body 11 and second measurement data D2 measuring parts other than the vehicle body 11, such as the cargo L, as shown in Figure 6.

[0030] Next, the control unit 27 extracts the first measurement data D1, which measures the vehicle body 11, from the measurement data D acquired in step S2 (step S3).

[0031] Next, the control unit 27 compares the first measurement data D1 extracted in step S3 with the vehicle body measurement data D0 of the reference data 261 and calculates the amount of horizontal movement of the laser scanner 29 (step S4). Specifically, in this step, the control unit 27 calculates the horizontal movement amount (movement amount in the horizontal plane) of the first measurement data D1 that has the highest degree of agreement with the vehicle body measurement data D0 of the reference data 261. The horizontal shift may also be estimated using a time-series processing method that incorporates the previously estimated value, such as a Kalman filter.

[0032] Next, the control unit 27 corrects the measurement data acquired in step S2 by the amount of horizontal movement calculated in step S4 (step S5). This allows for proper correction of the relative positional relationship between the laser scanner 29 and the vehicle body 11 in the horizontal plane, which changes as the gimbal 291 tilts.

[0033] Next, the control unit 27 determines whether or not to terminate the sensor measurement process (step S6). If it determines not to terminate the process (step S6; No), it proceeds to step S1 described above and continues the cargo handling operation. On the other hand, if the control unit 27 determines that the sensor measurement process should be terminated for reasons such as the completion of a predetermined cargo handling operation (step S6; Yes), the control unit 27 terminates the sensor measurement process.

[0034] [Technical effects of this embodiment] As described above, according to this embodiment, the laser scanner (distance sensor) 29 is tiltably supported by the gimbal 291 positioned on the vehicle body 11, and the measurement results of the laser scanner 29 are corrected based on the measurement results of the vehicle body 11 by the laser scanner 29. As a result, the gimbal 291 automatically maintains a constant orientation for the laser scanner 29, eliminating the need to manually mount the laser scanner 29 to the vehicle body 11 in a predetermined position. Furthermore, because the gimbal 291 automatically maintains a constant orientation for the laser scanner 29, misdetection of the road surface due to the tilt of the laser scanner 29 can be suppressed. Additionally, by utilizing the vehicle body 11, whose relative position to the gimbal 291 does not change, the measurement results of the laser scanner 29 can be appropriately corrected by detecting changes in the relative distance between the laser scanner 29 and the vehicle body 11 due to changes in the orientation of the cargo handling vehicle 20. Therefore, compared to conventional methods, the detection of surrounding objects can be performed more easily and effectively.

[0035] Furthermore, according to this embodiment, the measurement results of the vehicle body 11 by the laser scanner 29 in a standard posture of the loading / unloading vehicle 20 (vehicle body 11) are stored in advance as reference data 261, and the measurement results of the laser scanner 29 are corrected based on a comparison between the measurement results of the vehicle body 11 by the laser scanner 29 and the reference data 261. This allows for the appropriate detection of changes in the relative distance between the laser scanner 29 and the vehicle body 11 due to changes in the posture of the cargo handling vehicle 20, and enables proper correction of the measurement results of the laser scanner 29.

[0036] Furthermore, according to this embodiment, the amount of horizontal movement of the laser scanner 29 relative to the vehicle body 11 is calculated based on a comparison of the measurement result of the vehicle body 11 by the laser scanner 29 with the reference data 261, and the measurement result of the laser scanner 29 is corrected by the amount of this horizontal movement. This allows for simple two-dimensional correction of measurement results. Therefore, it can reduce computational costs compared to conventional techniques that performed three-dimensional correction calculations using trigonometric functions on all output data from a laser scanner (see, for example, Patent Documents 1 and 2).

[0037] [others] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments (including modifications). For example, in the above embodiment, a laser scanner 29 mounted on the side of the vehicle body 11 was given as an example of a distance sensor according to the present invention. However, the type and position of the distance sensor according to the present invention are not particularly limited, as long as it is mounted on the cargo handling vehicle 20 and measures the distance to surrounding objects. For example, the distance sensor may be placed on the overhead guard 16 located above the vehicle body 11. Furthermore, the application of the distance sensor is not particularly limited, and it may be used for self-position estimation rather than obstacle detection, for example.

[0038] Furthermore, in the above embodiment, the control unit 27 mounted on the cargo handling vehicle 20 performs various calculations. However, a control means (for example, a management server 30) located outside the cargo handling vehicle 20 may perform calculations based on information transmitted from the cargo handling vehicle 20 and transmit the results to the cargo handling vehicle 20. In addition, the cargo handling vehicle 20 and the management server 30 may cooperate to perform various controls in other ways.

[0039] Furthermore, in the above embodiment, the cargo handling vehicle 20 was assumed to be an unmanned vehicle (unmanned transport forklift) capable of operating without a driver. However, the cargo handling vehicle according to the present invention also includes those that can be operated by a driver (including remote operation) or those that can switch between operated by a driver and operated without a driver. Moreover, the present invention can also be used as an assist function for operated by a driver.

[0040] Furthermore, the cargo handling vehicle according to the present invention is not limited to forklifts as long as it holds and moves cargo, and includes, for example, autonomous mobile robots (AMRs) and automated guided vehicles (AGVs) that operate without a driver. For example, the present invention can be suitably applied to a cargo handling vehicle 20A as an autonomous mobile transport robot, as shown in Figures 7 and 8. In this case as well, similar to the above embodiment, the laser scanners 29 can be placed on the front and rear of the vehicle body 11A via the gimbal 291. This allows for easy and suitable detection of surrounding objects, similar to the above embodiment, even when the vehicle body 11A is tilted due to the loading of cargo L. Furthermore, details shown in the above embodiments can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0041] 20, 20A cargo handling vehicles 11, 11A Car body 26 Memory section 27 Control Unit (Correction Unit) 29. Laser scanner (distance sensor) 261 Reference Data 291 Gimbal D Measurement data D0 Vehicle Measurement Data D1 First measurement data D2 Second measurement data L load N scan area (measurement area)

Claims

1. The car body and, A gimbal positioned on the vehicle body, A distance sensor supported so as to be tiltable by the gimbal, A correction unit corrects the measurement result of the distance sensor based on the measurement result of the vehicle body by the distance sensor, A cargo handling vehicle equipped with the following features.

2. The vehicle body is equipped with a storage unit that pre-stores the measurement results of the vehicle body by the distance sensor in the vehicle body's reference posture as reference data. The correction unit corrects the measurement result of the distance sensor based on a comparison of the measurement result of the vehicle body by the distance sensor with the reference data. A cargo handling vehicle according to claim 1.

3. The correction unit, Based on a comparison of the measurement results of the vehicle body by the distance sensor and the reference data, the amount of horizontal movement of the distance sensor relative to the vehicle body is calculated. The measurement result of the distance sensor is corrected by the amount of the aforementioned horizontal movement. The cargo handling vehicle according to claim 2.

4. The distance sensor is positioned on the vehicle body such that its measurement area includes the vehicle body and the measurement target area outside the vehicle. A cargo handling vehicle according to claim 1.

5. The distance sensor has a planar measurement area, The gimbal tilts the distance sensor so that the measurement area remains horizontal. A cargo handling vehicle according to claim 1.

6. A computer for a cargo handling vehicle comprising a vehicle body, a gimbal positioned on the vehicle body, and a distance sensor tiltably supported by the gimbal, A correction unit corrects the measurement result of the distance sensor based on the measurement result of the vehicle body by the distance sensor. A cargo handling program designed to function as such.

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