Power control system and power control method

Abstract

A power control system 1 includes a peripheral camera 510 for detecting an object around a power cable 200 for supplying power to an electric excavator 100 operated by electric power, and an object detection computing machine 520 that limits the electric power supplied to the electric excavator 100 when the distance between the object detected by the peripheral camera 510 and the power cable 200 falls within a predetermined range. It is thereby possible to provide a power control system and a power control method with which contact of objects with a power cable can be minimized and a work machine can be operated more safely.

Description

Power control system and power control method

[0001] TECHNICAL FIELD The present invention relates to a power control system and a power control method that can be suitably used to control power supplied to a work machine through a power cable.

[0002] Recently, from an environmental perspective, electrically operated work machines have been increasingly used. One method of supplying power to a work machine is to connect a power cable to the work machine and supply power obtained from a power grid or the like to the work machine via the power cable.

[0003] Patent Document 1 discloses that a high-voltage cable for connecting an electric drive means, which is driven by power from a power generation means that generates power by driving an engine or a power storage means that stores the power generated by the power generation means, to the power storage means and supplying power is routed along the side of a frame structural member that protrudes vertically, so that the frame structural member acts as a standing wall to suitably protect the high-voltage cable, and that even if, for example, a construction machine collides with an obstacle or the like, the high-voltage cable is suitably protected by the frame structural member.

[0004] JP 2011-122307 A

[0005] However, for example, when the work machine is a construction machine, there is a possibility that the connected power cable may come into contact with an object such as a worker or equipment at the construction site, or the work machine itself, which is connected to the power cable, causing damage or disconnection. This may result in a fire or electric shock. The present invention aims to provide a power control system and a power control method that can prevent objects from coming into contact with the power cable and enable safer operation of the work machine.

[0006] In order to solve the above problems, the present invention provides a power control system that includes a first detection device that detects objects around a power cable that supplies power to an electrically operated work machine, and a control device that limits the power supplied to the work machine when the distance between the object detected by the first detection device and the power cable falls within a predetermined range. In this case, it is possible to provide a power control system that prevents objects from coming into contact with the power cable and allows the work machine to operate more safely.

[0007] Here, the power cable can be connected to the work machine and a cable container that straightens the power cable by winding it up, and power can be supplied to the work machine via the cable container. In this case, an excess length of power cable can be stored in the cable container. The predetermined range can be a predetermined width that encompasses the straight power cable. In this case, a more appropriate range can be set as the detection range. Furthermore, a second detection device that detects the position of the work machine and the position of the cable container can be provided, and the control device can estimate that the straight line connecting the position of the work machine and the position of the cable container detected by the second detection device is the position of the power cable, and set the predetermined range based on this position of the power cable. In this case, detection of the power cable is made easier. Furthermore, the first detection device is a camera arranged to be able to capture an image of the power cable, and the power cable is provided with a detection material on its outer surface, and the control device can determine the position of the detection material imaged by the camera as the position of the power cable. In this case, the position of the power cable can be determined based on the captured image. The work machine may also be equipped with a vehicle control device that is mounted on the work machine and that, when the power supplied to the work machine via the power cable is limited, operates the work machine using power supplied from a battery contained in the work machine. In this case, tipping over of the work machine or the like can be prevented. The work machine may also be equipped with a vehicle control device that is mounted on the work machine and that executes operation limiting control to limit the operation of the work machine when the power supplied to the work machine via the power cable is limited. In this case, contact with an object approaching the power cable can be prevented. Furthermore, the operation limiting control can be control that limits the operation of the work machine within a predetermined range. In this case, safety is improved. The operation limiting control can also be control that gradually slows and stops the operation of the work machine. In this case, tipping over of the work machine or the like can be prevented. Furthermore, the control device can be further equipped with an alarm device that issues an alarm, and the control device can issue an alarm using the alarm device when the distance between the object detected by the first detection device and the power cable falls within a predetermined range. In this case, it is possible to notify nearby workers or the like that an object is approaching.Furthermore, the alarm device can be configured to issue an alert using at least one of light and sound. In this case, the alert can be made more effective. The alarm device can also be a portable display terminal that displays the presence of an object around the power cable. In this case, the alert can be issued even if a worker is located remotely.

[0008] The present invention also provides a power control method in which a processor executes a program stored in memory to detect an object around a power cable that supplies power to an electrically operated work machine, and when the distance between the detected object and the power cable falls within a predetermined range, limits the power supplied to the work machine. In this case, it is possible to provide a power control method that prevents objects from coming into contact with the power cable and allows the work machine to be operated more safely.

[0009] According to the present invention, it is possible to provide a power control system and a power control method that can prevent objects from coming into contact with a power cable and operate a work machine more safely.

[0010] 1 is a diagram showing the overall configuration of a work site to which the present embodiment is applied. FIG. 1 is a block diagram showing a power control system when an object detection device is mounted on an electric shovel. FIG. 2 is a diagram showing information exchange when an object detection device is mounted on an electric shovel. FIG. 3 is a block diagram showing a power control system 1 when an object detection device is mounted on a reel-type cable container. FIG. 4 is a diagram showing information exchange when an object detection device is mounted on a reel-type cable container. FIG. 5 is a flowchart showing processing performed in the power control system. FIG. 6 is a flowchart showing processing performed in the power control system. FIG. 7 is a sequence diagram showing operations and information exchange of a peripheral camera, a vehicle control device, a power control computing unit, and an alarm device. FIG. 8 is a diagram showing the positional relationship between an electric shovel, a reel-type cable container, and a power cable. FIG. 9 is a diagram showing a detection range set when a peripheral camera is used. 10(a) to 10(b) are diagrams showing other examples of detection means.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0012] <Explanation of Overall Configuration of Work Site> FIG. 1 is a diagram showing the overall configuration of a work site to which this embodiment is applied. A plurality of work machines operate at the work site. The work site shown in the figure is a construction site. The example shows a case where an electric shovel 100 operates as a work machine at the construction site. Note that the work machine operating at the construction site is not limited to the electric shovel 100, and can be construction machinery such as a wheel loader, bulldozer, or crane truck. The work machine operating at the construction site can also be a truck that transports gravel or the like. Note that the work site is not limited to a construction site. For example, it can also be an agricultural work site where agricultural machinery operates as work machines. In this case, the agricultural machinery can be a felling machine, a timber processing machine, a tractor, a forestry work vehicle, a logging machine, or the like.

[0013] The electric shovel 100 shown in the figure is an example of a work machine that operates using electricity. The electric shovel 100 can also be said to be an example of an electric construction machine. A power cable 200 that supplies power to the electric shovel 100 is connected to the electric shovel 100. The power cable 200 is, for example, a high-voltage cable that is capable of transmitting three-phase alternating current. The power cable 200 is connected to the electric shovel 100 and a reel-type cable container 300, and supplies power to the electric shovel 100 via the reel-type cable container 300. That is, one end of the power cable 200 is connected to the electric shovel 100, and the other end is connected to the reel-type cable container 300. The reel-type cable container 300 is an example of a cable container, and reels up the power cable 200 and stores the excess length of the power cable 200. The reel-type cable container 300 straightens the power cable 200 by reeling up the power cable 200. That is, when the electric shovel 100 moves away from the reel-type cable container 300, the wound power cable 200 is pulled out from the reel-type cable container 300. On the other hand, when the electric shovel 100 moves toward the reel-type cable container 300, the power cable 200 is wound into the reel-type cable container 300. The reel-type cable container 300 provides tension for winding the power cable 200, and as a result, the power cable 200 maintains a linear shape between the electric shovel 100 and the reel-type cable container 300.

[0014] Electric power is supplied to the reel-type cable container 300 from a power grid 400. The power grid 400 is also called a commercial power source, and is power generated by a power plant and supplied by an electric power company. Fig. 1 shows that power is supplied from the power grid 400 via a switchboard 410 and a cable 420.

[0015] As described above, not only the electric shovel 100 but also other work machines operate at a construction site. Furthermore, in addition to the work machines, workers also move around the construction site. Therefore, there is a risk that the other work machine or the worker may get between the electric shovel 100 and the reel-type cable container 300. In this case, there is a risk that the work machine or the worker may come into contact with the power cable 200. If the other work machine comes into contact with the power cable 200, the power cable 200 may be damaged or cut, which may result in a fire or electric shock. Furthermore, it is dangerous for the worker to come into contact with the power cable 200.

[0016] For this reason, in this embodiment, an object detection device is provided that detects objects such as work machines and workers approaching the power cable 200. The object detection device then avoids the above problem by performing control to limit the power supplied to the electric shovel 100 on the upstream side of the power cable 200. In this embodiment, the object detection device is provided in either the electric shovel 100 or the reel-type cable container 300.

[0017] <Explanation of the configuration of the power control system 1> Fig. 2 is a block diagram showing the power control system 1 in the case where the object detection device 500 is mounted on the electric shovel 100. Fig. 3 is a diagram showing the exchange of information in the case where the object detection device 500 is mounted on the electric shovel 100. In the power control system 1 shown in Fig. 2, power is supplied from the system power supply 400 to the reel-type cable container 300, and power is also supplied from the reel-type cable container 300 to the electric shovel 100 via the power cable 200.

[0018] The electric shovel 100 includes a high-voltage circuit 110, a vehicle control device 120, a hydraulic circuit 130, an operation system 140, and an object detection device 500. The electric shovel 100 shown in the figure controls the high-voltage circuit 110 using power supplied from a power cable 200 via the vehicle control device 120 to drive a drive motor 118, which is a power source. The high-voltage circuit 110 includes an AC / DC converter 111 that converts the AC power supplied from the power cable 200 into DC, a high-voltage storage battery 112 that is an example of a battery and stores power, a pre-charge relay 113 and a main relay 114 that control the ON / OFF of the high-voltage circuit 110, a resistor 115, a capacitor 116, an inverter 117 that converts the DC power into AC power for driving the drive motor 118, and the drive motor 118.

[0019] When the high-voltage circuit 110 is turned on, the pre-charge relay 113 is first turned on. This causes charge to accumulate in the capacitor 116. Then, the main relay 114 is turned on. This prevents an inrush current from occurring when the high-voltage circuit 110 is turned on. It also prevents the terminals of the high-voltage circuit 110 from welding. The high-voltage circuit 110 supplies power to the drive motor 118 using power generated by the AC / DC converter 111 and the high-voltage storage battery 112. In other words, when the load on the drive motor 118 is small, the drive motor 118 is driven by power from the AC / DC converter 111. At this time, if there is a surplus of power supplied from the AC / DC converter 111, the high-voltage storage battery 112 is charged. On the other hand, when the load on the drive motor 118 increases and the power from the AC / DC converter 111 becomes insufficient, the shortfall in power is supplied from the high-voltage storage battery 112. The power supplied from the AC / DC converter 111 and the high-voltage storage battery 112 is converted into stable direct current by repeated charging and discharging by a capacitor 116. Then, an inverter 117 converts the direct current into alternating current at a desired frequency and voltage, and controls the rotation speed of a drive motor 118. This controls the amount of hydraulic pressure generated by a hydraulic pump 131, and operates the electric excavator 100.

[0020] The vehicle control device 120 includes a control and calculation function unit 121, a data recording unit (memory) 122, and a communication function unit 123. The control and calculation function unit 121 performs calculations to control the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117. The AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 are provided with control units (controllers) 111C, 112C, and 117C, respectively. The control units 111C, 112C, and 117C transmit data representing the states of the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 to the control and calculation function unit 121. The control and calculation function unit 121 performs calculations based on the transmitted data and transmits control signals for controlling the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 to the control units 111C, 112C, and 117C. The data recording unit (memory) 122 records program data used by the control and calculation function unit 121 to perform calculations. The communication function unit 123 is a communication interface used to transmit control signals to the control units 111C, 112C, and 117C. The communication function unit 123 also receives object detection information, which is information transmitted when the object detection device 500 detects an object. As shown in FIG. 3 , when the object detection information is received, the control and calculation function unit 121 outputs a motor stop signal to the inverter 117. The inverter 117 further outputs a motor stop signal to the drive motor 118, stopping the hydraulic pump 131. A vehicle monitor 124 is also connected to the vehicle control device 120. The vehicle monitor 124 can display the status of the electric excavator 100. The vehicle monitor 124 is, for example, a touch panel, and the operator can input settings for the electric excavator 100 through the vehicle monitor 124.

[0021] The hydraulic circuit 130 includes a hydraulic pump 131 that generates hydraulic pressure, a hydraulic oil tank 132 that stores hydraulic oil, a first directional control valve 133, and a second directional control valve 134. The hydraulic pump 131 is a variable displacement hydraulic pump that is driven by the drive motor 118. This hydraulic pump 131 draws hydraulic oil from the hydraulic oil tank 132 and supplies the hydraulic oil to the swing motor (not shown) and arm cylinders 14, 16, and 17 of the electric excavator 100 via the first directional control valve 133 and the second directional control valve 134, thereby operating the electric excavator 100.

[0022] The operation system 140 is provided in the driver's cab of the electric shovel 100, and is used by the operator when operating the electric shovel 100. The operation system 140 includes a work mode selection switch, a motor control dial (not shown) for setting the rotation speed of the drive motor 118, operation levers 141A, 141B, etc. The operation levers 141A, 141B correspond to the respective swing motors and arm cylinders, and use, for example, electric levers that output an electric operation signal (lever signal Lv) according to the amount of operation.

[0023] The object detection device 500 includes a surrounding camera 510, an object detection calculator 520, a data transmitter / receiver 530, and an alarm device 540. The surrounding camera 510 is an example of a first detection device that detects objects around the power cable 200. The surrounding camera 510 is also an example of a second detection device that detects the position of a work machine and the position of a cable container. The surrounding camera 510 is a camera that is attached to, for example, the upper part of the electric excavator 100 and captures images of the area around the electric excavator 100. The surrounding camera 510 is, for example, a single camera that captures images behind the electric excavator 100 as shown in FIG. 3 . However, the present invention is not limited to this, and multiple cameras may be used to capture images of the entire side or circumferential direction of the electric excavator 100.

[0024] The object detection computer 520 extracts an object approaching the power cable 200 based on the image captured by the surrounding camera 510. This can be done by using existing image processing technology. Then, when an object enters a predetermined detection range, the object detection computer 520 transmits object detection information to the reel-type cable container 300. As a result, the reel-type cable container 300 limits the power sent to the power cable 200, thereby limiting the power supplied to the electric shovel 100. In practice, it is preferable that the reel-type cable container 300 cuts off the power sent to the power cable 200, thereby cutting off the power supplied to the electric shovel 100. In this case, the object detection computer 520 functions as a control device that limits the power supplied to the electric shovel 100 when the distance between the object detected by the surrounding camera 510 and the power cable 200 falls within a predetermined range.

[0025] The data transmitter / receiver 530 is a communication interface used when transmitting object detection information from the object detection computer 520 to the reel-type cable container 300. Here, the case where the object detection information is transmitted to the reel-type cable container 300 via wireless communication is illustrated, but the object detection information may also be transmitted via wired communication. In this case, for example, a communication cable may be installed in association with the power cable 200, and the object detection information may be transmitted via this communication cable. Furthermore, the object detection information may also be transmitted using power line communication (PLC). That is, the object detection information is transmitted using the power cable 200.

[0026] The alarm device 540 is a device that issues an alert when an object enters a predetermined detection range. The alarm device 540 is an example of an alarm device that issues an alert. It can also be said that the object detection computing unit 520 issues an alert using the alarm device 540 when the distance between the object detected by the surrounding camera 510 and the power cable 200 falls within a predetermined range. As shown in FIG. 3 , the alarm device 540 issues an alert when it receives an alarm ON signal from the object detection computing unit 520. The alarm device 540 can be, for example, a warning light or a flashing lamp. In this case, the alert is issued by light. The alarm device 540 can also be, for example, a speaker or a buzzer. In this case, the alert is issued by sound, such as a voice or a warning sound. The alarm device 540 is installed, for example, on the electric excavator 100. This makes it easier for the operator to hear and notice a dangerous situation, allowing them to take a safe posture or other preparations. Furthermore, it is easy to identify which of multiple work machines the power cable belongs to. However, the installation location is not limited to a work machine such as the electric shovel 100, and the alarm device 540 may be installed in the reel-type cable container 300 or elsewhere at a work site. Furthermore, the alarm device 540 may be, for example, a portable display terminal that displays information that an object is present around the power cable 200. In this case, for example, the alarm information is displayed on the display of a terminal display device carried by the worker.

[0027] The reel-type cable container 300 includes a breaker 310, a power control computer 320, and a data transmitter / receiver 330. The breaker 310 cuts off the power sent to the power cable 200 when it receives object detection information from the object detection device 500. When it receives the object detection information from the object detection device 500, the power control computer 320 sends a power limiting signal to the breaker 310 to shut off the breaker 310, as shown in Fig. 3 . The data transmitter / receiver 330 is a communication interface that exchanges data such as object detection information with the object detection device 500.

[0028] Although the embodiment described in FIGS. 2 and 3 shows the case where the object detection device 500 is mounted on the electric excavator 100, the present invention is not limited to this. For example, the object detection device 500 may be mounted on the reel-type cable container 300. FIG. 4 is a block diagram showing the power control system 1 when the object detection device 500 is mounted on the reel-type cable container 300. FIG. 5 is a diagram showing the exchange of information when the object detection device 500 is mounted on the reel-type cable container 300. Note that the following description of FIGS. 4 and 5 will focus on differences from FIGS. 2 and 3, and other descriptions will be omitted. When the object detection device 500 is mounted on the reel-type cable container 300, the data transmitter / receiver 330 that receives object detection information from the vehicle control device 120 is unnecessary. However, it is necessary to transmit the object detection information from the object detection device 500 to the electric excavator 100. In this case, a data transmitter / receiver 125 connected to the vehicle control device 120 of the electric excavator 100 is provided. Then, the object detection information is transmitted from the data transmitter / receiver 530 of the object detection device 500 to the data transmitter / receiver 125 .

[0029] <Explanation of Processing Performed by Power Control System 1> FIGS. 6A and 6B are flowcharts showing processing performed by the power control system 1. FIG. 7 is a sequence diagram showing the operations and information exchange between the surrounding camera 510, the vehicle control device 120, the power control computing device 320, and the alarm device 540. First, the operator of the electric excavator 100 turns the key ON (S601). This turns ON the high-voltage circuit 110, allowing the operator to operate the electric excavator 100. Next, the surrounding camera 510 of the object detection device 500 starts object detection (S602). That is, the surrounding camera 510 starts capturing images. Next, the object detection computing device 520 of the surrounding camera 510 captures images captured by the surrounding camera 510 (S603) and performs image processing (S604, S701). The object detection computing device 520 then detects the position of the power cable 200 (S605). A method for detecting the position of the power cable 200 will be described later.

[0030] Furthermore, the object detection computer 520 determines whether or not the position of the power cable 200 has been detected (S606). As a result, if the position of the power cable 200 has not been detected (No in S606), the object detection computer 520 transmits a message to the vehicle control device 120 of the electric excavator 100 that the cable position cannot be detected (S607). Next, the vehicle control device 120 notifies the operator that the position of the power cable 200 should be confirmed (S608). Then, the operator corrects the position of the power cable 200 or the vehicle body position (S609). After this, the process returns to S603.

[0031] On the other hand, if the position of the power cable 200 can be detected in S606 (Yes in S606), the object detection computer 520 determines whether or not an object is present within a predetermined distance from the power cable 200 (S610). That is, the object detection computer 520 determines whether or not the distance between the object detected by the surrounding camera 510 and the power cable 200 is within a predetermined range. As a result, if there is no object within the predetermined distance (No in S610), the object detection computer 520 turns off the alarm function and turns off the warning sound and warning display of the alarm device 540 (S611). After this, the process returns to S603.

[0032] On the other hand, if an object is present within the predetermined distance (Yes in S610), the following processing is performed. First, in the object detection device 500, the object detection computer 520 turns on the alarm function and turns on the alarm sound and warning display of the alarm device 540 (S612, S703 to S704). Furthermore, the object detection computer 520 transmits object detection information to the vehicle control device 120 of the electric excavator 100 (S613, S702). In the electric excavator 100, the vehicle control device 120 receives the object detection information (S614, S702). Furthermore, the object detection computer 520 transmits the object detection information to the power control computer 320 of the reel-type cable container 300 (S615, S706 to S707). In the reel-type cable container 300, the power control computer 320 receives the object detection information (S616, S707). In the electric excavator 100, the vehicle control device 120 changes the power supply means (S617, S705). Specifically, the power supply means is switched to the high-voltage storage battery 112 (battery-powered). Furthermore, in the reel-type cable container 300, the power control computer 320 turns on the power limit (S618, S708). This causes the breaker 310 to cut off the power sent to the power cable 200. Then, in the electric excavator 100, the vehicle control device 120 turns on the operation limit of the electric excavator 100, safely stopping the electric excavator 100 (S619, S709).

[0033] Next, the object detection computer 520 determines whether or not an object is present within a predetermined distance from the power cable 200 (S620). As a result, if an object is present within the predetermined distance (Yes in S620), the process returns to S610. On the other hand, if no object is present within the predetermined distance (No in S620), the object detection computer 520 notifies the electric excavator 100 and the reel-type cable container 300 of this fact. Then, in the reel-type cable container 300, the power control computer 320 turns off the power restriction (S621). This resumes the power supply to the power cable 200. Furthermore, in the electric excavator 100, the vehicle control device 120 turns off the operational restriction on the electric excavator 100 (S622). This resumes the operation of the electric excavator 100.

[0034] 6B, when determining whether or not an object is present within a predetermined distance from the power cable 200, it is necessary to detect the position of the power cable 200 as described in S605. In this embodiment, the position of the power cable 200 is detected by, for example, the following method.

[0035] In the first method, the object detection computer 520 estimates that the straight line connecting the position of the electric shovel 100 detected by the surrounding camera 510 and the position of the reel-type cable container 300 is the position of the power cable 200, and sets a predetermined range based on the position of the power cable 200. FIG. 8 is a diagram showing the positional relationship between the electric shovel 100, the reel-type cable container 300, and the power cable 200. The reel-type cable container 300 is in a fixed position, and the electric shovel 100 moves to various positions depending on the type of work. Here, the electric shovel 100 moves to three different positions. However, the power cable 200 is reeled in by the reel-type cable container 300, and maintains a linear shape between the electric shovel 100 and the reel-type cable container 300 regardless of the position of the electric shovel 100. Therefore, if the object detection computer 520 detects the positions of the electric shovel 100 and the reel-type cable container 300, it is determined that a linear power cable 200 exists between them. Therefore, by estimating that the straight line connecting the position of the electric shovel 100 and the position of the reel-type cable container 300 is the position of the power cable 200, the object detection calculator 520 can determine the position of the power cable 200.

[0036] A second method is to provide a detection material on the outer surface of the power cable 200. The detection material is, for example, a fluorescent agent. To provide the fluorescent agent, for example, the fluorescent agent is applied to the power cable 200. Note that the fluorescent agent does not need to be applied to the entire power cable 200, and may be applied to only a portion of the power cable 200. The object detection calculator 520 then detects the fluorescent agent captured by the surrounding camera 510 and determines the position of the fluorescent agent as the position of the power cable 200. Because the fluorescent agent emits color at a specific wavelength, the object detection calculator 520 determines the position of the power cable 200 as a linear object that emits color at this specific wavelength from within the captured image.

[0037] <Method for Determining Whether an Object is Present Within a Predetermined Distance from the Power Cable 200> In S610 of FIG. 6B , the object detection computer 520 uses the following method to determine whether the distance between the object detected by the peripheral camera 510 and the power cable 200 is within a predetermined range. That is, the object detection computer 520 defines the predetermined range as an area that is within a predetermined width of the straight power cable 200. In other words, the predetermined range is the predetermined width of the straight power cable 200. This range may be hereinafter referred to as the detection range. FIG. 9 is a diagram showing the detection range Rk set when the peripheral cameras 510 are used. Here, three peripheral cameras 510 are used to capture images of the rear and side directions of the electric excavator 100. In this case, the angle of view of the capture range Rc is, for example, 270°. The power cable 200 is linearly present between the electric excavator 100 and the reel-type cable container 300. The figure also shows that the range of width L, which sandwiches the power cable 200, is the detection range Rk. This width L can be, for example, 4 m. Note that this width L is set as a predetermined length on the image, and whether the distance between the object and the power cable 200 is within the predetermined range can be determined based on whether the object has entered the detection range Rk defined by the width L. Therefore, the object detection calculator 520 does not need to specifically calculate the distance between the object and the power cable 200.

[0038] In the above example, the peripheral camera 510 is used as a detection means for detecting an object approaching the power cable 200, but this is not limiting. FIGS. 10( a) and 10(b) are diagrams showing other examples of detection means. Of these, FIG. 10(a) illustrates a case in which a laser scanner such as a LiDAR (Light Detection and Ranging) 511 is used. The LiDAR 511 scans the surface of an object approaching the power cable 200 to measure its three-dimensional shape. LiDAR is a device that measures the distance to an object by irradiating the object with a laser and receiving the reflected light. Due to its principle, the accuracy of distance measurement is relatively high, ranging from several millimeters to several centimeters. LiDAR uses a single linearly propagating laser as its basic unit and periodically changes the direction of irradiation at a high speed of several tens of hertz to capture the surface shape of the object as a collection of minute points (point cloud). In this case, the information obtained is data representing the three-dimensional shape of the object as a point cloud. Then, based on the positions of the point cloud, it can be determined whether or not an object is present within a predetermined distance from the power cable 200. Note that the LiDAR 511 can also detect the position of the power cable 200. Here, the laser irradiation range Rr of the LiDAR 511 is shown. The detection range is an area that is within a predetermined width and sandwiches the power cable 200.

[0039] 10(b) is a diagram showing a case where a transmission type infrared sensor is used. Here, a projector 512 that emits infrared rays is installed on the reel-type cable container 300. A photoreceiver 513 that receives the infrared rays is installed on the electric shovel 100. The width of the range in which the projector 512 and the photoreceiver 513 are installed is defined as a detection range Rk. When an object blocks the infrared rays and is no longer detected by the photoreceiver, it can be determined that an object has entered the detection range Rk.

[0040] <Explanation of Operation Restriction of the Electric Excavator 100> In S619 of FIG. 6B , the vehicle control device 120 restricts the operation of the electric excavator 100. In this embodiment, when the power supplied to the electric excavator 100 via the power cable 200 is restricted, the vehicle control device 120 operates the electric excavator 100. In this case, the electric excavator 100 can operate using power supplied from the high-voltage storage battery 112. In the absence of the high-voltage storage battery 112, the electric excavator 100 will suddenly stop when the power supplied from the power cable 200 is cut off. In this case, depending on the operating state of the electric excavator 100, for example, the inertia of the arm or the like may cause the electric excavator 100 to lose balance and tip over. Therefore, in this embodiment, even if the power supplied to the electric excavator 100 via the power cable 200 is restricted, the electric excavator 100 is configured to operate using power supplied from the high-voltage storage battery 112, thereby preventing such an event from occurring. On the other hand, if the electric shovel 100 is operated without any restrictions, there is a risk that the arm or the like may come into contact with an approaching object. Therefore, in this embodiment, the vehicle control device 120 executes operation restriction control to restrict the operation of the electric shovel 100 when the power supplied to the electric shovel 100 by the power cable 200 is restricted.

[0041] Specifically, the operation limit control is control that limits the operation of the electric shovel 100 within a predetermined range. More specifically, it is control that limits the driving operation of the work implements, such as the boom, arm, and bucket, the swinging operation of the electric shovel 100, and the traveling operation of the electric shovel 100. In other words, the vehicle control device 120 limits the operation range so that the arm, etc. does not come into contact with approaching objects. Furthermore, the operation limit control is control that gradually slows down and stops the operation of the electric shovel 100. In other words, the vehicle control device 120 stops the electric shovel 100 so that the power cable 200, the arm, etc. do not come into contact with approaching objects, but stops the electric shovel 100 gradually. This makes it possible to prevent the electric shovel 100 from losing balance due to the inertia of the arm, etc., and tipping over. It also makes it possible to prevent the electric shovel 100 from damaging or cutting the power cable 200 by itself.

[0042] In the above-described embodiment, a case where an object other than the electric excavator 100 approaches the power cable 200 has been described. However, the present invention is not limited to this and can also be applied to a case where the electric excavator 100 itself approaches the power cable 200. For example, a case where the arm of the electric excavator 100 approaches the power cable 200 can be considered. In addition, in the above-described embodiment, the surrounding camera 510 is used as the second detection device, but the present invention is not limited to this. For example, the second detection device may be another camera installed in the work site, rather than a camera that detects objects around the power cable 200. In addition, for example, the second detection device may be configured such that the electric excavator 100 or the reel-type cable container 300 is equipped with a position transmitter such as a GNSS (Global Navigation Satellite System) antenna, and the second detection device is configured with a position receiver that acquires position information obtained by the position transmitter. In this case, as in the case where the surrounding camera 510 is used as the second detection device, the object detection calculator 520 can grasp the position of the power cable 200 by estimating that the straight line connecting the position of the electric shovel 100 and the position of the reel-type cable container 300 is the position of the power cable 200.

[0043] <Explanation of Power Control Method> The processing performed by the object detection device 500 in this embodiment described above is realized by cooperation between software and hardware resources. That is, a processor such as a CPU (Central Processing Unit) (not shown) provided in the object detection device 500 loads into memory and executes a program that realizes each function of the object detection device 500, thereby realizing each function performed by the object detection device 500.

[0044] Therefore, the processing performed by the object detection device 500 described above can be considered to be a power control method in which a processor executes a program recorded in memory to detect objects around a power cable that supplies power to a work machine that operates on electricity, and when the distance between the detected object and the power cable falls within a predetermined range, the power supplied to the work machine is restricted.

[0045] The program for realizing this embodiment can be provided not only by communication means but also by being stored on a recording medium such as a CD-ROM.

[0046] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention.

[0047] 1...power control system, 100...electric shovel (work machine), 110...high voltage circuit, 111...AC / DC converter, 112...high voltage storage battery (battery), 120...vehicle control device, 121...control calculation function unit, 130...hydraulic circuit, 200...power cable, 300...reel-type cable container (cable container), 310...breaker, 320...power control calculator, 400...system power supply, 500...object detection device, 510...surrounding camera (first detection device, second detection device), 520...object detection calculator (control device), 540...alarm device (alarm device), Rk...detection range

Claims

1. A power control system comprising: a first detection device that detects objects around a power cable that supplies power to a work machine that operates using electricity; and a control device that limits the power supplied to the work machine when the distance between the object detected by the first detection device and the power cable falls within a predetermined range.

2. The power control system according to claim 1, wherein the power cable is connected to the work machine and a cable container that straightens the power cable by winding it up, and supplies power to the work machine via the cable container.

3. The power control system according to claim 2, wherein the predetermined range is a predetermined width that encompasses the straight power cable.

4. A power control system as described in claim 3, further comprising a second detection device which detects the position of the work machine and the position of the cable container, wherein the control device estimates that a straight line connecting the position of the work machine detected by the second detection device and the position of the cable container is the position of the power cable, and sets the predetermined range based on the position of the power cable.

5. The power control system of claim 3, wherein the first detection device is a camera arranged so as to be able to image the power cable, the power cable has a detection material on its outer surface, and the control device determines the position of the detection material imaged by the camera as the position of the power cable.

6. The power control system according to claim 1, further comprising a vehicle control device that is mounted on the work machine and operates the work machine using power supplied from a battery contained in the work machine when the power supplied to the work machine by the power cable is limited.

7. The power control system according to claim 1, further comprising a vehicle control device mounted on the work machine and executing operation limiting control for limiting the operation of the work machine when the power supplied to the work machine by the power cable is limited.

8. An electric power control system according to claim 7, wherein the operation limiting control is a control that limits the operation of the work machine within the predetermined range.

9. The power control system according to claim 7, wherein the operation limiting control is a control for gradually slowing down and stopping the operation of the work machine.

10. The power control system of claim 1, further comprising an alarm device for issuing an alarm, wherein the control device issues an alarm using the alarm device when the distance between the object detected by the first detection device and the power cable falls within the predetermined range.

11. The power control system according to claim 10, wherein the alarm device issues an alarm using at least one of light and sound.

12. The power control system according to claim 10, wherein the notification device is a portable display terminal that displays the presence of the object around the power cable.

13. A power control method comprising: a processor executing a program recorded in a memory, detecting an object around a power cable that supplies power to a work machine operated by electricity; and limiting the power supplied to the work machine when the distance between the detected object and the power cable falls within a predetermined range.

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