Cargo collision prevention device

Abstract

To provide a collision prevention device capable of further reliably suppressing collision of a cargo.SOLUTION: A collision prevention device for a cargo includes a sensor for detecting an obstacle present in a lowering direction of a support mechanism and detecting a distance between a cargo supported by the support mechanism and the obstacle and a control unit, which sequentially acquires information about the distance from the sensor, sequentially acquires information about the lowering speed of the support mechanism from a main device, calculates a first moving distance until the support mechanism reaches the preset minimum speed based on the information about the lowering speed and the deceleration of the preset lowering speed, and outputs a deceleration command for reducing the lowering speed to the main device based on the first moving distance and the distance. The control unit sequentially determines whether the lowering speed is in an accelerating state or a constant speed state based on the sequentially obtained lowering speed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a collision prevention device for cargo such as containers. More specifically, the present invention relates to a collision prevention device for taking safety measures when, for example, containers for marine transport are moved within a container stack in a container yard. [Background technology]

[0002] For example, gantry cranes such as RTG (Rubber Tired Gantry Cranes) and RMG (Rail Mounted Gantry Cranes) are used to transfer containers in ports. Gantry cranes are used to stack containers in ports, change container positions, and load and unload containers onto trucks.

[0003] RMGs are rail-mounted, so they tend to be larger cranes than RTGs and have longer traverse distances. This means that the distance traveled after lifting the container also becomes longer, and the traverse speed also tends to become faster.

[0004] Crane operators operate with the utmost care to avoid collisions with containers, but occasionally a suspended container may hit the container stack, causing the stack to collapse, or a container may be placed too quickly, causing an impact.

[0005] Therefore, there is a demand for installing a collision prevention device on an existing crane. The collision prevention device includes a sensor such as a laser sensor or a camera, and a control unit that processes information from the sensor data.

[0006] When installing a collision prevention device, in order to minimize the number of modifications, the interface with the main unit that controls the motor drive may be limited to the minimum number of signals. In this case, the main signals from the collision prevention device to the main unit are, for example, deceleration and stop signals for lowering, and deceleration and stop signals for traversing, and they function as advanced limit switch signals.

[0007] The collision prevention device, for example, calculates a deceleration distance from the speed of the spreader suspending the container and the distance to the top of the container in the hoisting direction, and decelerates the spreader. In this way, the collision prevention device decelerates the spreader according to the distance to the obstacle before it collides with an obstacle such as a container, and stops the spreader in front of the obstacle. This makes it possible to suppress collisions of containers.

[0008] However, when calculating the deceleration distance, the calculation is based only on the spreader speed, which changes from moment to moment, and if the crane accelerated before the deceleration, the container may be placed at a speed faster than the calculated value, which may be dangerous.

[0009] For this reason, it is desirable for the collision prevention device to determine whether the crane's speed is constant or accelerating, and calculate the deceleration distance taking into account processing delays, so as to more reliably prevent collisions. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2020-007089 A Summary of the Invention [Problem to be solved by the invention]

[0011] An embodiment of the present invention provides a collision prevention device that can more reliably suppress collisions of cargo. [Means for solving the problem]

[0012] An embodiment of the present invention is used in a crane having a movable part movable in a horizontal direction, a support mechanism suspended from the movable part via a hoisting rope and configured to support a cargo, and a main device that controls the movement of the movable part and the hoisting and lowering of the support mechanism by the hoisting rope. This collision prevention device includes a sensor that detects an obstacle present in the direction of movement of the movable part and the lowering of the support mechanism and detects a distance from the support mechanism or the cargo supported by the support mechanism to the obstacle, and a control unit that sequentially acquires information on the distance from the sensor and sequentially acquires information on the lowering speed of the support mechanism from the main device, calculates a first moving distance until the support mechanism reaches a preset minimum speed based on the information on the lowering speed and a preset deceleration of the lowering speed, and outputs a deceleration command to the main device to decelerate the lowering speed based on the first moving distance and the distance. The control unit sequentially determines whether the lowering speed is accelerating or constant based on the lowering speed sequentially acquired, and when it determines that the lowering speed is constant, calculates the first movement distance as a second movement distance including the distance moved by the support mechanism during a response delay time including a control delay time of the control unit, and when it determines that the lowering speed is accelerating, calculates a third movement distance by adding the distance moved by the support mechanism in accordance with the acceleration of the lowering speed to the second movement distance. Effect of the Invention

[0013] A collision prevention device is provided that can more reliably suppress cargo collisions. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic side view illustrating a crane to which a cargo collision prevention device according to an embodiment is applied. [Diagram 2] 1 is a schematic block diagram illustrating a cargo collision prevention device according to an embodiment; [Diagram 3] 5 is a schematic graph for explaining the operation of the cargo collision prevention device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Each embodiment will be described below with reference to the drawings. In addition, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0016] FIG. 1 is a side view that diagrammatically illustrates a crane to which a cargo collision prevention device according to an embodiment is applied. As shown in FIG. 1 , the crane 10 includes, for example, a pair of legs 12 , a traverse rail 14 , a traverse trolley 16 , a spreader 18 , and a cab 20 .

[0017] The crane 10 is provided, for example, in a container yard in a port, and moves containers 2 (cargo) for marine transportation. The crane 10, for example, stacks the containers 2 in the port, changes the position of the containers 2, and loads and unloads the containers 2 onto trucks. The crane 10 is, for example, a gate-type gantry crane.

[0018] The pair of legs 12 are placed on the pair of traveling rails 4. The pair of traveling rails 4 are laid on, for example, the ground 6 of a container yard. The pair of traveling rails 4 are laid, for example, along a direction perpendicular to the plane of the paper in FIG. 1. The pair of legs 12 have wheels, a traveling motor, a brake, and the like, which are not shown, and are placed on and travel on the pair of traveling rails 4.

[0019] As a result, the crane 10 travels in a direction perpendicular to the plane of the paper in Fig. 1 by being driven by the travel motor. That is, in this example, the crane 10 is a so-called RMG. The crane 10 may also be, for example, an RTG that travels on the ground 6 via tires provided on a pair of legs 12.

[0020] The lateral rail 14 is provided so as to be suspended over the pair of legs 12. The pair of traveling rails 4 and the pair of legs 12 are aligned in a direction substantially perpendicular to the traveling direction, and the lateral rail 14 extends in a direction substantially perpendicular to the traveling direction. The crane 10 has, for example, a pair of lateral rails 14 aligned in the traveling direction. Hereinafter, the direction in which the lateral rails 14 extend is referred to as the "lateral direction."

[0021] The traverse trolley 16 is provided on the traverse rail 14. The traverse trolley 16 is provided, for example, between a pair of traverse rails 14. The traverse trolley 16 travels along the traverse rail 14 by being provided on the traverse rail 14 via wheels 16a, for example. In other words, the traverse trolley 16 travels traversely along the traverse rail 14. The traverse trolley 16 can move horizontally along the traverse rail 14. However, the configuration of the traverse trolley 16 is not limited to the above, and any configuration that allows it to travel traversely along the traverse rail 14 may be used.

[0022] The spreader 18 is suspended from the traverse trolley 16 via a head block 22, a hoist pulley 24, and a hoisting rope 26 such as a wire rope. The spreader 18 is configured to be able to grip and support the container 2. The spreader 18 moves up and down (hoists and lowers) by a hoisting motor 50 (see FIG. 2) around which the hoisting rope 26 is wound. The support mechanism configured to be able to support cargo such as the container 2 is not limited to the spreader 18, and may be tongs, a bucket, a hook, or the like.

[0023] The operator's cab 20 is provided on the traverse rail 14. The operator's cab 20 is provided, for example, substantially integral with the traverse trolley 16 and moves traversely together with the traverse trolley 16. The operator's cab 20 may be provided separately from the traverse trolley 16. The operator's cab 20 may be provided, for example, on the traverse rail 14 so as to be able to move traversely independently of the traverse trolley 16.

[0024] The crane 10 performs a hoisting operation for moving the spreader 18 in the vertical direction, a traverse operation for moving the traverse trolley 16 and the driver's cab 20 along the traverse rail 14, and a traveling operation for driving the wheels of a pair of legs 12 to move in the traveling direction on the traveling rail 4. This allows the stacking and positioning of containers 2 in the port to be changed.

[0025] FIG. 2 is a schematic block diagram illustrating a collision prevention device for cargo according to the embodiment. FIG. 2 shows the cargo collision prevention device 60 as well as a control system for controlling the traverse and lifting operations of the crane 10 as the crane 10. As shown in FIG. 2 , the crane 10 has a main device 40, a hoisting controller 42, a traverse controller 44, a hoisting drive 46, a traverse drive 48, a hoisting motor 50, a traverse motor 52, and a collision prevention device 60.

[0026] The main device 40 controls the operation of each part of the crane 10. The hoisting controller 42 and the traverse controller 44 are connected to the main device 40. The hoisting controller 42 and the traverse controller 44 are provided in the operator's cab 20.

[0027] The hoisting controller 42 inputs speed commands for hoisting and lowering the spreader 18 to the main unit 40. The traverse controller 44 inputs speed commands for traverse of the traverse trolley 16 to the main unit 40. The hoisting controller 42 and the traverse controller 44 have operating units such as levers. The hoisting controller 42 and the traverse controller 44 accept operations by an operator and input speed commands to the main unit 40 according to the operator's operations.

[0028] The hoisting drive 46 and the traverse drive 48 are connected to the main unit 40. The main unit 40 provides a speed reference to the hoisting drive 46 in response to a speed command input from the hoisting controller 42. The hoisting drive 46 inputs a current to the hoisting motor 50 so that the rotation speed of the hoisting motor 50 follows the input speed reference. The hoisting motor 50 winds up or lowers the hoisting rope 26 in response to the current input from the hoisting drive 46. As a result, the spreader 18 is wound up or lowered at the speed set by the hoisting controller 42.

[0029] Similarly, the main device 40 gives a speed reference to the traverse drive 48 in response to a speed command input from the traverse controller 44. The traverse drive 48 inputs a current to the traverse motor 52 so that the rotation speed of the traverse motor 52 follows the input speed reference. The traverse motor 52 moves the traverse trolley 16 and the operator's cab 20 in response to the current input from the traverse drive 48. As a result, the traverse trolley 16 and the operator's cab 20 move in a traverse manner at the speed set by the traverse controller 44.

[0030] The operator operates the hoist controller 42 and the traverse controller 44 while watching the position of the container 2 in the cab 20, and issues a speed command to the main unit 40 to perform traverse between the traverse trolley 16 and the cab 20, and hoisting and lowering of the spreader 18. In this way, the main unit 40 controls the movement of the traverse trolley 16 and the hoisting ropes 26 to hoist and lower the spreader 18.

[0031] The operator adjusts the hoisting height and traverse position of the spreader 18 relative to the container 2, and also adjusts the hoisting height and traverse position of the suspended container 2, by operating the hoisting controller 42 and the traverse controller 44. This allows the crane 10 to perform loading and unloading operations.

[0032] The collision prevention device 60 includes a sensor 62 and a control unit 64. The sensor 62 detects an obstacle present in the unwinding direction or lateral direction of the spreader 18 moving with the lateral trolley 16, and detects a distance DT (see FIG. 1) from the spreader 18 to the obstacle in the moving direction. In other words, the distance DT is the distance from the container 2 supported by the spreader 18 to the obstacle. The sensor 62 detects, for example, another container 2a stacked on a container pile as the obstacle. However, the obstacle is not limited to another container 2a, and may be any obstacle that may collide with the spreader 18 or the container 2 supported by the spreader 18, such as a building or an anchored ship.

[0033] The sensor 62 is connected to the control unit 64. The control unit 64 acquires and inputs information on the distance DT from the container 2 to the obstacle detected by the sensor 62. Note that communication between the sensor 62 and the control unit 64 may be wired or wireless. The sensor 62 does not necessarily have to be physically connected to the control unit 64 via a cable or the like.

[0034] The sensor 62 may be, for example, a photographing device that detects the distance DT to an obstacle by image processing, or a laser distance meter that detects the distance DT to an obstacle by using a laser beam. The sensor 62 is not limited to the above, and may be any sensor that can detect the distance DT to an obstacle. In this example, the distance DT is the distance in the hoisting or lowering direction from the lower end of the container 2 supported by the spreader 18 to the obstacle.

[0035] The control unit 64 is connected to the sensor 62 and also to the main device 40. The control unit 64 acquires and inputs information on the hoisting speed (lowering speed) of the hoisting drive 46 and information on the position of the spreader 18 from the main device 40. Note that communication between the control unit 64 and the main device 40 may be wired or wireless, similar to the sensor 62. The distance DT is calculated using information on the position of the obstacle detected by the sensor 62 and information on the position of the spreader 18. Alternatively, the distance DT may be calculated using information on the position of the obstacle detected by the sensor 62 and information on the position of the spreader 18 detected by the sensor 62.

[0036] The control unit 64 outputs a deceleration command to the main device 40 to start decelerating the lowering speed of the spreader 18 based on the input distance DT to the obstacle, the lowering speed of the spreader 18, and the preset deceleration of the spreader 18. More specifically, the control unit 64 monitors the speed and distance DT during lowering, and calculates the travel distance until the lowering operation stops. The control unit 64 calculates the travel distance based on the lowering speed and deceleration of the spreader 18. The control unit 64 outputs the deceleration command at a timing when the travel distance until the lowering operation stops is just before the obstacle. Here, the stopping position just before the obstacle is, for example, a position within a range of 5 cm or less above the obstacle.

[0037] When the main unit 40 receives the deceleration command, it starts decelerating the lowering speed of the spreader 18. In response to the input of the deceleration command, the main unit 40 decelerates the lowering speed from a lowering speed corresponding to a speed command input from the hoisting controller 42 to a predetermined minimum speed, for example, a minimum speed of 0 [m / s], that is, until the lowering of the spreader 18 stops. Note that the deceleration is a negative acceleration, and refers to a case where the speed is reduced as the spreader 18 is lowered to lower the container 2. Also, the minimum speed is not limited to 0, and may be, for example, a creep speed.

[0038] Through such an operation, the collision prevention device 60 can prevent the spreader 18 and the container 2 supported by the spreader 18 from colliding with an obstacle.

[0039] With regard to the lowering operation of the spreader 18, since there may be cases where the container 2 cannot be placed due to erroneous detection by the sensor 62, the operator may manually stop the spreader 18 regardless of the deceleration operation by the collision prevention device 60. Also, for example, when a command to stop lowering is input from the hoisting controller 42 to the main unit 40 during deceleration based on a deceleration command from the collision prevention device 60, the main unit 40 may decelerate and stop the spreader 18 in the same way as when a deceleration command is received from the collision prevention device 60, or may rapidly stop the spreader 18 in response to the operation of the hoisting controller 42.

[0040] The operation of the cargo collision prevention device 60 of the embodiment will be described. FIG. 3 is a schematic graph for explaining the operation of the cargo collision prevention device according to the embodiment. FIG. 3 is a schematic graph showing the lowering speed v of the spreader 18 versus time t, with the vertical axis representing the lowering speed v of the spreader 18 and the horizontal axis representing time t. In the following description, three types of deceleration operations will be described. One of the three types of deceleration operations is an ideal case where there is no control delay or transmission delay in the collision prevention device 60, the main device 40, the drive device, etc., and is called deceleration operation I, and is shown in FIG. 3 by a thick solid line. The remaining two deceleration operations are actual operations when there is a control delay or the like in the collision prevention device 60, etc., and are called deceleration operation II and deceleration operation III. The deceleration operation II is an operation in which a deceleration command is output during a period in which the lowering operation is performed at a constant speed, and is shown in FIG. 3 by a thin dashed line. The deceleration operation III is an operation in which a deceleration command is output during a period in which the lowering operation is accelerating, and is shown in FIG. 3 by a thick dashed line.

[0041] In the example described below, as shown in FIG. 1, the container 2 is supported on the spreader 18, and below the container 2 in the hoisting direction there is a container 2a placed on the ground 6 as an obstacle. In this case, the distance DT [m] from the bottom end of the container 2 to the top end of the container 2a is successively measured by the sensor 62. In each of the deceleration operations I to III, the deceleration is expressed as b [m / s 2 ], and in deceleration operation III, the acceleration before deceleration is a [m / s 2 The deceleration b is preset in the collision prevention device 60. The acceleration a can be a different value depending on the operation of the operator, but in the following explanation, it is assumed to be a constant value unless otherwise specified. In addition, the minimum speed at the end of the deceleration operation is 0 [m / s 2 ].

[0042] In the cargo collision prevention device 60 of the embodiment, the control unit 64 of the collision prevention device 60, as described in detail below, sequentially calculates the moving distance until the lowering speed v0 becomes the minimum speed, using the distance DT sequentially obtained from the sensor 62, the lowering speed v0 sequentially obtained from the main device 40, and a preset deceleration b. The control unit 64 outputs a deceleration command when the sequentially calculated moving distance reaches a predetermined threshold value that is equal to or greater than the distance DT between the container 2 and the container 2a sequentially obtained from the sensor 62. The collision prevention device 60 of the embodiment determines whether the lowering speed of the spreader 18 is in a constant speed state or an accelerating state, and calculates the deceleration distance according to the determined lowering operation.

[0043] First, for ease of understanding, an ideal deceleration operation I in which there is no control delay in the collision prevention device 60 or the like will be described. In the deceleration operation I, the travel distance s1 (first travel distance) [m] of the container 2 is calculated at the deceleration b during the period from time t0 to time t3. The travel distance of the container 2 is calculated by accumulating (integrating) the hoisting speed v obtained from the main device 40 for each acquisition time. In the collision prevention device 60 of the embodiment, since the deceleration b is constant, the travel distance s1 is calculated by calculating the area of ​​a triangle ABC having vertices at point A corresponding to the hoisting speed v0 at time t0, point B corresponding to the hoisting speed 0 at time t0, and point C corresponding to the hoisting speed 0 at time t3 in FIG. 3, and is calculated by the following formula (1).

[0044] s1=v0 2 / (2b)[m] (1)

[0045] The control unit 64 outputs a deceleration command to the main device 40 at a timing when the travel distance s1 calculated by equation (1) becomes greater than or equal to the distance DT [m] from the bottom end of the container 2 to the obstacle (equation (2)), thereby starting deceleration and preventing collision with the obstacle.

[0046] s1 ≥ DT (2)

[0047] In reality, there is a control delay in the collision prevention device 60, etc., and a delay occurs between the time when the control unit 64 outputs a deceleration command and the time when the deceleration operation actually starts. In the deceleration operations II and III, the travel distance is calculated taking into consideration the time delay that occurs between the time when the deceleration command is output and the time when the deceleration operation actually starts.

[0048] The additional movement distance s1' due to control delay, etc. is calculated as the area of ​​a parallelogram ACED whose vertices in Figure 3 are point A corresponding to the winding speed v0 at time t0, point C corresponding to the winding speed 0 at time t3, point E corresponding to the winding speed 0 at time t4, and point D corresponding to the winding speed v0 at time t1 (equation (3)).

[0049] s1'=v0×(t1-t0) (3)

[0050] Therefore, in the deceleration operation II, the collision prevention device 60 outputs a deceleration command when the following condition is satisfied (Equation (4)). For example, in the control unit 64, the threshold value sth for outputting the deceleration command is set as sth=DT+5 [cm].

[0051] s1+s1'(second moving distance)≧DT (4)

[0052] The time (t1-t0) of the control delay of the collision prevention device 60, etc. is determined, for example, by actual measurement, for each crane 10 in which a control system including the collision prevention device 60 is installed, and is set for each collision prevention device 60.

[0053] In the deceleration operation III, at time t0 when the deceleration command is output, the lowering operation is accelerated at the acceleration a. In this case, the lowering operation is accelerated until the deceleration operation starts at time t1, and after reaching time t1, the operation shifts to the deceleration operation. Therefore, the moving distance is further extended compared to the case of the deceleration operation II described above.

[0054] In the case of deceleration operation III, the sum of the areas of triangle ADF, triangle DGF, and parallelogram DEHG shown in Figure 3 is the movement distance s2 [m] extended by the acceleration a at time t0. Point D is the point of lowering speed v0 at time t1, point F is the point of lowering speed v1 at time t1, and point G is the point of lowering speed v0 at time t2. The movement distance s2 is the area of ​​the hatched region in Figure 3. Therefore, the movement distance s2 [m] is calculated by the following formula (5).

[0055] s2=(1 / 2)×a×(t1-t0) 2 +(1 / 2)×b×(t2-t1) 2 +(t2-t1)×v0 (5)

[0056] Therefore, in the deceleration operation III, the collision prevention device 60 outputs a deceleration command when the following condition is satisfied (Equation (6)). In this case, the threshold value sth' for outputting the deceleration command is set as sth'=DT+5 [cm].

[0057] s1+s1'+s2(3rd movement distance)≧DT (6)

[0058] The control unit 64 of the collision prevention device 60 sequentially acquires information on the lowering speed v from the main device 40, and judges whether the lowering speed v is in an accelerating state or a constant speed state based on the difference in the lowering speed v. For this judgment, for example, a threshold value related to acceleration is set in advance, and the control unit 64 judges the lowering speed v to be in an accelerating state when the difference in the lowering speed v sequentially acquired over time is equal to or greater than the threshold value, and judges the lowering speed v to be in a constant speed state when the difference in the lowering speed v over time is smaller than the threshold value. When the control unit 64 judges that the lowering speed is in an accelerating state, it uses equations (5) and (6) to determine the timing to output a deceleration command. When the control unit 64 judges that the lowering speed is in a constant speed state, it uses equations (1), (3), and (4) to determine the timing to output a deceleration command.

[0059] To determine whether the lowering speed is in an accelerating state or a constant speed state, the control unit 64 may monitor a notch signal output by the hoisting controller 42. The notch signal is a signal generated according to a notch for each speed setting, which is provided so that the hoisting controller 42 can set the speed in several stages. The control unit 64 determines that the lowering speed is in an accelerating state when the notch detection means detects that the notch signal output by the hoisting controller 42 has entered from a smaller notch to two or more larger notches. The notch from which the speed is determined to be in an accelerating state is set in advance.

[0060] In the above embodiments, the case of the lowering operation of the crane 10 has been described, but the present invention may be applied to the traverse operation. Also, the minimum speed is set to 0 [m / s], but an arbitrary creep speed may be set.

[0061] In the above specific example, the crane 10 is a gantry crane used in ports and the like, but the crane is not limited to a gantry crane and may be an overhead crane used in factories or other cranes. The crane 10 may be any crane that can move horizontally while suspending cargo and perform hoisting and lowering operations. The cargo supported by the crane 10 is not limited to containers 2 for marine transport and may be any cargo that can be hoisted by the crane 10.

[0062] The effects of the collision prevention device 60 according to the embodiment will be described. In the embodiment, the collision prevention device 60 uses information on the hoisting speed v acquired from the main device 40 to determine whether the hoisting operation of the spreader 18 is in a constant speed state or an accelerating state. When the hoisting operation of the spreader 18 is in an accelerating state, a deceleration command can be output taking into consideration the longer distance that the spreader 18 descends before decelerating to a predetermined minimum speed compared to when the hoisting operation is in a constant speed state. Therefore, it is possible to reliably prevent collision of cargo without depending on the operation of the operator of the crane 10.

[0063] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0064]

[0033] 2...container, 4...traveling rail, 6...ground, 10...crane, 12...leg, 14...traverse rail, 16...traverse trolley, 18...spreader, 20...operator's cab, 22...head block, 24...pulley, 26...hoisting rope, 40...main device, 42...hoisting controller, 44...traverse controller, 46...hoisting drive, 48...traverse drive, 50...hoisting motor, 52...traverse motor, 60...collision prevention device, 62...sensor, 64...control unit

Claims

1. A collision prevention device for use with a crane having a movable part that is movable in a horizontal direction, a support mechanism that is suspended from the movable part via a hoisting rope and configured to be able to support cargo, and a main device that controls the movement of the movable part and the hoisting and lowering of the support mechanism by the hoisting rope, a sensor that detects an obstacle present in the direction of movement of the movable part and the direction of lowering of the support mechanism, and detects a distance from the support mechanism or the cargo supported by the support mechanism to the obstacle; a control unit which sequentially acquires information on the distance from the sensor, sequentially acquires information on the lowering speed of the support mechanism from the main device, calculates a first moving distance until the support mechanism reaches a preset minimum speed based on the information on the lowering speed and a preset deceleration of the lowering speed, and outputs a deceleration command to the main device to decelerate the lowering speed based on the first moving distance and the distance; Equipped with The control unit is Based on the successively acquired lowering speed, it is successively determined whether the lowering speed is in an accelerating state or a constant speed state; When it is determined that the lowering speed is in a constant speed state, the first moving distance is calculated as a second moving distance including a distance moved by the support mechanism during a response delay time including a control delay time of the control unit, A cargo collision prevention device that, when it is determined that the lowering speed is accelerating, calculates a third moving distance by adding the distance moved by the support mechanism in accordance with the acceleration of the lowering speed to the second moving distance.

2. The cargo collision prevention device according to claim 1 , wherein the control unit calculates the third moving distance by successively calculating the acceleration based on the successively acquired hoisting speed.

3. The control unit is Sequentially monitoring notch signals output from a controller connected to the main device and generated in accordance with a plurality of notches for each speed setting set in the controller in order to set the lowering speed in a plurality of stages; 2. A cargo collision prevention device according to claim 1, wherein, when it is detected based on the notch signal that the notch becomes larger than a predetermined level, it is determined that the hoisting speed is accelerating.

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