Lower control system of door machine

Abstract

The utility model provides a door machine under-machine control system. The lower control system of the door machine comprises a control box, multiple control signal input circuits are arranged in the control box, one control signal input circuit comprises a change-over switch SA1, the first end and the second end of the change-over switch SA1 are both grounded, the fourth end of the change-over switch SA1 is connected with a first power source through a pull-up resistor, and the second end of the change-over switch SA1 is connected with a second power source through a pull-up resistor. The fourth end of the change-over switch SA1 is connected to the first signal input end of the on-board controller, and the on-board controller is configured to control a door machine to work. The problem that time and labor are wasted during under-machine control of an existing door machine can be solved.

Description

Technical Field

[0001] This disclosure relates to the field of automatic control technology, and in particular to the control system of a gantry crane. Background Technology

[0002] Gantry cranes, also known as portal cranes, are used in port operations for loading and unloading containers, bulk cargo, and general cargo. When a gantry crane operator needs to perform under-crane movement, they must first go to the operator's cab to engage the main contactor and rotate the rotary switch to the "under-crane movement" position. This entire process requires getting on and off the gantry crane, engaging the main contactor, and selecting the movement control position, which is time-consuming and limits the gantry crane's responsiveness, resulting in low efficiency in wind protection and vessel avoidance. Utility Model Content

[0003] This disclosure provides a gantry crane bottom control system to solve the problem of time-consuming and labor-intensive existing gantry crane bottom control systems.

[0004] This disclosure provides a gantry crane control system, including a control box. The control box contains multiple control signal input circuits, one of which includes a switch SA1. The first and second terminals of the switch SA1 are both grounded, and the fourth terminal of the switch SA1 is connected to a first power supply via a pull-up resistor.

[0005] The fourth terminal of the switching switch SA1 is connected to the first signal input terminal of the on-board controller, which is configured to control the operation of the gantry crane.

[0006] In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes an RS trigger.

[0007] The fourth terminal of the switching switch SA1 is connected to the reset input terminal of the RS flip-flop, the third terminal of the switching switch SA1 is connected to the set input terminal of the RS flip-flop, and the output terminal of the RS flip-flop is connected to the signal input terminal of the on-board controller.

[0008] In one exemplary embodiment of this disclosure, the door operator's lower control system further includes an anti-electric shock circuit, which comprises a voltage acquisition circuit, a switching transistor Q1, a potentiometer RP1, a thyristor SCR, and a contactor K1.

[0009] The voltage acquisition circuit is configured to detect the voltage between the control box casing and ground. The control terminal of the switching transistor Q1 is connected to the output terminal of the voltage acquisition circuit. The first terminal of the switching transistor Q1 is connected to a first power supply through potentiometer RP1, and the second terminal of the switching transistor Q1 is grounded.

[0010] The first terminal of the switching transistor Q1 is connected to the control terminal of the thyristor SCR. The anode of the thyristor SCR is connected to one end of the coil of contactor K1, and the other end of the coil of contactor K1 is connected to a second power supply. The cathode of the thyristor SCR is grounded.

[0011] The normally open contact of the contactor K1 is connected in series in the power supply line of the control box.

[0012] In one exemplary embodiment of this disclosure, the voltage acquisition circuit includes resistors R17 and R18.

[0013] The first end of the resistor R17 is connected to the casing of the control box, the second end of the resistor R17 is grounded through the resistor R18, and the second end of the resistor R17 is the output terminal of the voltage acquisition circuit.

[0014] In one exemplary embodiment of this disclosure, the door operator's control system further includes an alarm circuit. The alarm circuit includes a switch Q3, a resistor R12, an oscillation circuit, another switch Q2, and a speaker. The control terminal of switch Q3 is connected to the first terminal of switch Q1. The first terminal of switch Q3 is connected to a first power supply through resistor R12. The second terminal of switch Q3 is grounded. The first terminal of switch Q3 is connected to the control terminal of the oscillation circuit.

[0015] The output terminal of the oscillation circuit is connected to the control terminal of the switching transistor Q2. The first terminal of the switching transistor Q2 is connected to the first power supply terminal of the speaker. The second power supply terminal of the speaker is connected to the first power supply. The second terminal of the switching transistor Q2 is grounded.

[0016] In one exemplary embodiment of this disclosure, the oscillation circuit includes a time base chip U4, resistor R7, resistor R8, and capacitor C1.

[0017] The first terminal of resistor R8 is connected to a first power supply, and the second terminal of resistor R8 is connected to the first terminal of capacitor C1 through resistor R7. The second terminal of capacitor C1 is grounded.

[0018] The second end of the resistor R8 is connected to the discharge terminal of the time base chip U4, and the first end of the capacitor C1 is connected to the threshold input terminal and the trigger input terminal of the time base chip U4.

[0019] The reset terminal of the time base chip U4 is the control terminal of the oscillation circuit, and the output terminal of the time base chip U4 is the output terminal of the oscillation circuit.

[0020] In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes:

[0021] A surge protector is installed at the power input terminal of the control box, and the surge protector is configured to introduce the overcurrent signal of a lightning strike to the ground.

[0022] In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes:

[0023] The arc detection circuit is configured to detect arc signals within the control box.

[0024] The working principle and beneficial effects of the gantry crane control system provided in this embodiment are as follows:

[0025] In this embodiment of the disclosure, by setting up a control box under the machine and setting up a multi-channel control signal input circuit in the control box, control commands such as closing / opening the switch, lifting / moving under the machine, switching between high / low speeds for movement under the machine, and moving left / right (ascending / descending) can be input under the machine. The gantry crane operator can complete a whole set of under-machine movement operations, including power supply under the machine, moving the gantry crane under the machine, controlling the lifting and lowering of the grab bucket under the machine, and resetting the machine under the machine, which greatly improves the efficiency of the gantry crane avoidance operation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the control signal input circuit provided in an embodiment of this disclosure;

[0028] Figure 2 This is the power supply procedure provided in the embodiments of this disclosure;

[0029] Figure 3 This is the onboard lifting operation procedure provided in the embodiments of this disclosure;

[0030] Figure 4 This is the driver's cab travel condition program provided in the embodiments of this disclosure;

[0031] Figure 5 This is the ground walking operation program provided in the embodiments of this disclosure;

[0032] Figure 6 This is the ground lifting operation procedure provided in the embodiments of this disclosure;

[0033] Figure 7 This is the hook working mode program provided in the embodiments of this disclosure;

[0034] Figure 8This is the upshift and downshift procedure provided in the embodiments of this disclosure;

[0035] Figure 9 This is the speed reference program provided in the embodiments of this disclosure;

[0036] Figure 10 This is the walking speed program provided in the embodiments of this disclosure;

[0037] Figure 11 This is a schematic diagram of the anti-electric shock circuit provided in the embodiments of this disclosure;

[0038] Figure 12 This is a schematic diagram of the alarm circuit provided in an embodiment of this disclosure. Detailed Implementation

[0039] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0040] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0041] The implementation of this disclosure will be described in detail below with reference to the specific accompanying drawings:

[0042] In this embodiment, the gantry crane's lower control system includes a control box, which contains multiple control signal input circuits. (Refer to...) Figure 1 One of the control signal input circuits includes a switch SA1. The first and second terminals of switch SA1 are both grounded, and the fourth terminal of switch SA1 is connected to the first power supply through a pull-up resistor.

[0043] The fourth terminal of the switch SA1 is connected to the signal input terminal of the on-board controller, which is then configured to control the operation of the gantry crane.

[0044] In this embodiment, the on-machine controller can be a PLC controller. The control box is equipped with five control signal input circuits. Among them, the switching switch SA1 is used for switching the machine's lower closing / opening, the switching switch SA2 is used for switching the machine's lower lifting / lower traveling, the switching switch SA3 is used for switching the machine's lower traveling high / low speed. In the machine traveling mode, the switching switch SA4 is used to control the left travel button, and the switching switch SA5 is used to control the right travel button. In the machine lifting mode, the switching switch SA4 is used for the machine's lowering, and the switching switch SA5 is used for the machine's lowering.

[0045] Taking the switch SA1 as an example, the working principle of the control signal input circuit is as follows: When the switch SA1 is not pressed, the fourth terminal and the second terminal of the switch SA1 are connected, and the fourth terminal of the switch SA1 is grounded; when it is necessary to close the circuit breaker on the machine, the switch SA1 is pressed, the fourth terminal and the second terminal of the switch SA1 are disconnected, the fourth terminal of the switch SA1 is connected to the first power supply VCC, the fourth terminal of the switch SA1 is at a high level, and the controller on the machine receives the high level signal and controls the circuit breaker to close.

[0046] Correspondingly, the power supply cabinet on the machine needs to be equipped with contactor KM and relay KA to power the main contactor ZC from below.

[0047] The control program for the PLC controller is as follows:

[0048] (1) Power supply from below the machine. (Refer to...) Figure 2 The power supply signal to the machine is input through the "closing / opening" switch in the machine's lower travel control box (wire number C12D61) and then connected to the PLC controller. The output module of the PLC controller on the machine (wire number C9D42) outputs a control signal to drive the KA to close.

[0049] (2) Switching between working modes: Use the "underground hoisting / underground travel switching switch" added to the under-machine maintenance box to switch between ground travel and ground hoisting modes. Distinguish from the ground travel gear signal on the machine: the under-machine ground travel gear is called ground travel 2, signal address I00433, wire number C13D11; ground hoisting, signal address I00430, wire number C12d72.

[0050] Once the machine enters the ground walking working state, the other three working states will be disabled until the changeover switch is switched or the power supply to the machine is disconnected.

[0051] Reference Figure 3 The onboard lifting procedure has been updated with an interlock for the normally closed contacts used for ground lifting. (Refer to...) Figure 4 The operator's cab lifting procedure has been updated with an interlock for the normally closed contact of the ground lifting mechanism. (Refer to...) Figure 5The ground travel operation program has added an interlock to the normally closed contact of the ground lifting mechanism, and also added a control signal path for ground travel 2 under the machine control. Additionally, protection for the inverter's operating status has been added here. If the inverter is running (support or switch), the operating status will not change until the inverter stops running, preventing equipment damage. (Refer to...) Figure 6 Add a selection program segment for ground lifting operation mode. This includes interlocking with other operation modes and inverter operation signal protection.

[0052] (3) Modification of hoisting control mode

[0053] Reference Figure 7 Considering that the opening, closing, and support mechanisms operate simultaneously during the lifting and lowering of the grab bucket from below the machine, in order to achieve the lifting bucket operation requirements from below the machine as simply and reliably as possible, the working mode of the lifting mechanism is directly locked in the hook mode when switching to the ground lifting mode. This ensures that the opening, closing, and support mechanisms operate synchronously, eliminating interference from the gear selection on the machine.

[0054] (4) Modification of gear control program

[0055] Reference Figure 8 The up and down gears have added control signals from below the engine, which can be controlled by the left and right buttons below the engine, respectively, and are effective in ground lifting conditions.

[0056] (5) Reference Figure 9 The lifting speed signal of the handle is read in the ground lifting condition and locked at the minimum speed (the program can be modified to increase the speed appropriately).

[0057] (6) Reference Figure 10 The walking speed switching program uses a high / low speed switching switch added to the under-machine maintenance box, signal address I00436, wire number C13D22, to switch between high and low walking speed states. Low level signal means low speed, and high level signal means high speed.

[0058] As can be seen from the above, this embodiment, by setting up a control box under the machine and setting up a multi-channel control signal input circuit in the control box, can input control commands such as closing / opening the switch, lifting / moving under the machine, switching between high / low speeds for movement under the machine, and moving left / right (ascending / descending) from under the machine. The gantry crane operator can complete a whole set of under-machine movement operations, including power supply under the machine, moving the gantry crane under the machine, controlling the lifting and lowering of the grab bucket under the machine, and resetting the machine from under the machine, which greatly improves the efficiency of gantry crane avoidance operations.

[0059] Reference Figure 1 In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes an RS trigger.

[0060] The fourth terminal of the switch SA1 is connected to the reset input terminal of the RS flip-flop, the third terminal of the switch SA1 is connected to the set input terminal of the RS flip-flop, and the output terminal of the RS flip-flop is connected to the first signal input terminal of the controller on the machine.

[0061] In this embodiment, an RS flip-flop is installed between the fourth terminal of the switch SA1 and the first signal input terminal of the on-board controller to filter out key bounce. Its working principle is as follows: When the switch SA1 is not pressed, the first and fourth terminals of the switch SA1 are connected, the reset input terminal of the RS flip-flop is low, and the output terminal of the RS flip-flop is low. During the pressing of the switch SA1, a bounce signal may be generated at the fourth terminal of the switch SA1. At this time, since the third terminal of the switch SA1 is high, the output terminal of the RS flip-flop remains unchanged until the third terminal of the switch SA1 is connected to the first terminal. At this point, the third terminal of the switch SA1 is low, and the output terminal of the RS flip-flop switches to high.

[0062] Similarly, RS triggers are provided between the fourth terminal of switch SA2 and the second signal input terminal of the onboard controller, between the fourth terminal of switch SA3 and the third signal input terminal of the onboard controller, between the fourth terminal of switch SA4 and the fourth signal input terminal of the onboard controller, and between the fourth terminal of switch SA5 and the fifth signal input terminal of the onboard controller.

[0063] As can be seen from the above, the setting of the RS trigger in this embodiment can prevent the on-board controller from receiving a jitter signal during the button press process, thereby avoiding malfunction of the on-board controller.

[0064] Reference Figure 11 In one exemplary embodiment of this disclosure, the door operator's lower control system further includes an anti-electric shock circuit, which comprises a voltage acquisition circuit, a switching transistor Q1, a potentiometer RP1, a thyristor SCR, and a contactor K1.

[0065] The voltage acquisition circuit is configured to detect the voltage between the control box chassis and ground. The control terminal of the switching transistor Q1 is connected to the output terminal of the voltage acquisition circuit. The first terminal of the switching transistor Q1 is connected to the first power supply through potentiometer RP1, and the second terminal of the switching transistor Q1 is grounded.

[0066] The first terminal of the switching transistor Q1 is connected to the control terminal of the thyristor SCR. The anode of the thyristor SCR is connected to one end of the coil of contactor K1, and the other end of the coil of contactor K1 is connected to a second power supply. The cathode of the thyristor SCR is grounded.

[0067] The normally open contact of contactor K1 is connected in series in the power supply line of the control box.

[0068] In this embodiment, considering the complexity of the door operator's electrical system, if the insulation of the electrical equipment is damaged or the grounding is poor, an electric shock accident may occur. To avoid the above problems, this embodiment is equipped with an anti-electric shock circuit.

[0069] Its working principle is as follows: The control terminal of the switch Q1 is connected to the casing of the control box. Under normal circumstances, the casing is not energized, the control terminal of the switch Q1 is at a low level, the switch Q1 is cut off, the first terminal of the switch Q1 is at a high level, the thyristor SCR is turned on, the coil of the contactor K1 is energized, the contactor K1 is closed, and the external power supply supplies power to the control box through the contactor K1.

[0070] When the insulation of the electrical equipment in the control box is damaged or the grounding is poor, resulting in a high voltage between the casing and the ground, the control terminal of the switch Q1 is at a high level, the switch Q1 is turned on, the first terminal of the switch Q1 is at a low level, the thyristor SCR is cut off, the coil of contactor K1 is de-energized, and contactor K1 is disconnected, thus disconnecting the power supply to the control box in time to avoid electric shock accidents caused by the high voltage on the casing.

[0071] As can be seen from the above, the voltage acquisition circuit, switching transistor Q1, and thyristor SCR in this embodiment can promptly disconnect the power supply to the control box when the chassis voltage exceeds the set voltage, thus preventing electric shock accidents caused by the high voltage of the chassis.

[0072] Reference Figure 11 In one exemplary embodiment of this disclosure, the voltage acquisition circuit includes resistor R17 and resistor R18.

[0073] The first end of resistor R17 is connected to the casing of the control box, and the second end of resistor R17 is grounded through resistor R18. The second end of resistor R17 is the output terminal of the voltage acquisition circuit.

[0074] In this embodiment, resistors R17 and R18 form a series voltage divider circuit. The voltage across resistor R18 is proportional to the chassis voltage. The chassis voltage can be obtained by detecting the voltage across resistor R18. The circuit structure is simple and easy to implement.

[0075] Reference Figure 12 In one exemplary embodiment of this disclosure, the door operator's control system further includes an alarm circuit. The alarm circuit includes a switch Q3, a resistor R12, an oscillation circuit, a switch Q2, and a speaker. The control terminal of switch Q3 is connected to the first terminal of switch Q1. The first terminal of switch Q3 is connected to a first power supply through resistor R12. The second terminal of switch Q3 is grounded. The first terminal of switch Q3 is connected to the control terminal of the oscillation circuit.

[0076] The output terminal of the oscillation circuit is connected to the control terminal of the switching transistor Q2. The first terminal of the switching transistor Q2 is connected to the first power supply terminal of the speaker. The second power supply terminal of the speaker is connected to the first power supply. The second terminal of the switching transistor Q2 is grounded.

[0077] In this embodiment, the first terminal of switch Q1 can be connected to the control terminal of switch Q2. When the chassis voltage is too high, the first terminal of switch Q1 is at a low level, switch Q3 is cut off, and the first terminal of switch Q3 is at a high level. The first terminal of switch Q3 is connected to the control terminal of the oscillation circuit. The oscillation circuit starts and outputs a square wave pulse signal to the control terminal of switch Q2, controlling switch Q2 to periodically turn on or off, thereby causing the speaker to output intermittent alarm sounds.

[0078] Conversely, when the casing is not powered, the first terminal of switch Q1 is at a high level, switch Q3 is turned on, the first terminal of switch Q3 is grounded, and the first terminal of switch Q3 is connected to the control terminal of the oscillation circuit. The oscillation circuit does not work, and the speaker will not emit an alarm signal.

[0079] As can be seen from the above, the configuration of the switching transistor Q3, resistor R12, oscillation circuit, switching transistor Q2, and speaker in this embodiment can promptly issue alarm information when the chassis voltage is too high, providing timely maintenance for the staff.

[0080] Reference Figure 12 In one exemplary embodiment of this disclosure, the oscillation circuit includes a time base chip U4, resistor R7, resistor R8, and capacitor C1.

[0081] The first terminal of resistor R8 is connected to the first power supply, and the second terminal of resistor R8 is connected to the first terminal of capacitor C1 through resistor R7. The second terminal of capacitor C1 is grounded.

[0082] The second terminal of resistor R8 is connected to the discharge terminal of timer chip U4, and the first terminal of capacitor C1 is connected to the threshold input terminal and trigger input terminal of timer chip U4.

[0083] The reset terminal of the time base chip U4 is the control terminal of the oscillation circuit, and the output terminal of the time base chip U4 is the output terminal of the oscillation circuit.

[0084] In this embodiment, the function of the oscillation circuit is realized by using the time base chip U4 and its peripheral circuit. The first end of the capacitor C1 is connected to the threshold input terminal and the trigger input terminal of the time base chip U4. As the capacitor C1 is charged and discharged, a square wave signal is output at the output terminal of the time base chip U4.

[0085] The reset terminal of the timer chip U4 is also the control terminal of the oscillation circuit. When the reset terminal of the timer chip U4 is high, the timer chip U4 outputs a square wave signal normally. When the reset terminal of the timer chip U4 is low, the timer chip U4 stops outputting.

[0086] As can be seen from the above, this embodiment is based on the output of a square wave signal by the time base chip U4. The circuit structure is simple, the stability is good, and the cost is low. According to actual needs, the duty cycle of the square wave signal can be adjusted by adjusting the resistance value of resistor R7 or the capacitance value of capacitor C1.

[0087] In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes:

[0088] A surge protector is installed at the power input terminal of the control box. The surge protector is configured to direct the overcurrent signal of a lightning strike to the ground.

[0089] In this embodiment, considering that the gantry crane is usually located in an open area, it is susceptible to lightning strikes during thunderstorms. Lightning strikes may damage the electrical equipment inside the control box, or even cause serious accidents such as fires or explosions.

[0090] To address the aforementioned issues, this embodiment incorporates a surge protector at the power input terminal of the control box. In the event of a lightning strike, the surge protector can quickly direct the overcurrent signal generated by the lightning strike to the ground, preventing the overcurrent from flowing through the equipment inside the control box. This protects the equipment from high-current impacts, extends the equipment's lifespan, and reduces maintenance and replacement costs due to equipment damage.

[0091] In one exemplary embodiment of this disclosure, the gantry crane's lower control system further includes:

[0092] The arc detection circuit is configured to detect arc signals within the control box.

[0093] In this embodiment, it is considered that aging, short circuits, overloads, and other faults in the electrical wiring within the control box can cause the current flowing through the equipment to exceed the rated value, leading to overheating. Excessive temperature will accelerate the aging and damage of the insulation material, reducing its insulation performance. When the insulation resistance drops to a certain level, it may cause the air between conductors or between the conductor and the grounding body to break down, which could potentially ignite surrounding flammable materials or cause an explosion of combustible gases, dust, etc.

[0094] To avoid the above problems, this embodiment is equipped with an arc light detection circuit in the control box. The arc light detection circuit can detect the arc light signal in time and issue an early warning or take measures, such as cutting off the power supply, in the early stage of an accident, thereby avoiding the occurrence of explosions and fires and protecting the safety of port facilities, cargo and personnel.

[0095] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A gantry crane control system, characterized in that, The system includes a control box containing multiple control signal input circuits. One of these circuits includes a switch SA1, with its first and second terminals grounded. The fourth terminal of the switch SA1 is connected to a first power supply via a pull-up resistor. The fourth terminal of the switching switch SA1 is connected to the first signal input terminal of the on-board controller, which is configured to control the operation of the gantry crane.

2. The gantry crane control system as described in claim 1, characterized in that, It also includes RS triggers, The fourth terminal of the switching switch SA1 is connected to the reset input terminal of the RS flip-flop, the third terminal of the switching switch SA1 is connected to the set input terminal of the RS flip-flop, and the output terminal of the RS flip-flop is connected to the signal input terminal of the on-board controller.

3. The gantry crane control system as described in claim 1, characterized in that, It also includes an electric shock protection circuit, which comprises a voltage acquisition circuit, a switching transistor Q1, a potentiometer RP1, a thyristor SCR, and a contactor K1. The voltage acquisition circuit is configured to detect the voltage between the control box casing and ground. The control terminal of the switching transistor Q1 is connected to the output terminal of the voltage acquisition circuit. The first terminal of the switching transistor Q1 is connected to a first power supply through potentiometer RP1, and the second terminal of the switching transistor Q1 is grounded. The first terminal of the switching transistor Q1 is connected to the control terminal of the thyristor SCR. The anode of the thyristor SCR is connected to one end of the coil of contactor K1, and the other end of the coil of contactor K1 is connected to a second power supply. The cathode of the thyristor SCR is grounded. The normally open contact of the contactor K1 is connected in series in the power supply line of the control box.

4. The gantry crane control system as described in claim 3, characterized in that, The voltage acquisition circuit includes resistors R17 and R18. The first end of the resistor R17 is connected to the casing of the control box, the second end of the resistor R17 is grounded through the resistor R18, and the second end of the resistor R17 is the output terminal of the voltage acquisition circuit.

5. The gantry crane under-machine control system as described in claim 3, characterized in that, It also includes an alarm circuit, which comprises a switch Q3, a resistor R12, an oscillation circuit, a switch Q2, and a speaker. The control terminal of the switch Q3 is connected to the first terminal of the switch Q1. The first terminal of the switch Q3 is connected to a first power supply through the resistor R12. The second terminal of the switch Q3 is grounded. The first terminal of the switch Q3 is connected to the control terminal of the oscillation circuit. The output terminal of the oscillation circuit is connected to the control terminal of the switching transistor Q2. The first terminal of the switching transistor Q2 is connected to the first power supply terminal of the speaker. The second power supply terminal of the speaker is connected to the first power supply. The second terminal of the switching transistor Q2 is grounded.

6. The gantry crane control system as described in claim 5, characterized in that, The oscillation circuit includes a timer chip U4, resistor R7, resistor R8, and capacitor C1. The first terminal of resistor R8 is connected to a first power supply, and the second terminal of resistor R8 is connected to the first terminal of capacitor C1 through resistor R7. The second terminal of capacitor C1 is grounded. The second end of the resistor R8 is connected to the discharge terminal of the time base chip U4, and the first end of the capacitor C1 is connected to the threshold input terminal and the trigger input terminal of the time base chip U4. The reset terminal of the time base chip U4 is the control terminal of the oscillation circuit, and the output terminal of the time base chip U4 is the output terminal of the oscillation circuit.

7. The gantry crane control system as described in claim 1, characterized in that, Also includes: A surge protector is installed at the power input terminal of the control box, and the surge protector is configured to introduce the overcurrent signal of a lightning strike to the ground.

8. The gantry crane control system as described in claim 1, characterized in that, Also includes: The arc detection circuit is configured to detect arc signals within the control box.

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