Switch cabinet maintenance trolley and hole alignment and leveling method based on small current measurement

Abstract

The present invention discloses a switch cabinet maintenance trolley and a hole alignment and leveling method based on small current measurement, and relates to the field of power detection technology. The present invention includes an autonomous cruise drive module, a hole identification module and a leveling module. The present invention adopts an AC current sampling circuit to collect small currents. On the basis of a unipolar power supply, an equipotential method is adopted to connect one end of the secondary coil of a clamp-on current transformer to a DC bias, and one end to a reverse input end of an operational amplifier. The DC voltages at both ends of the clamp-on current transformer are of equal potential, and no DC current is generated, so that the original AC signal can be accurately collected. The present invention uses a machine vision system to locate the fixed hole position of the switch cabinet, and realizes the leveling of the maintenance trolley through a small current measurement circuit, so as to prevent the uneven maintenance trolley from causing the circuit breaker to roll over after being pulled onto the maintenance trolley, effectively improving the efficiency of on-site circuit breaker maintenance operations, and improving on-site operation safety.

Description

Technical Field

[0001] The invention belongs to the technical field of electric power detection, and relates to a switch cabinet maintenance trolley and a hole alignment and leveling method based on small current measurement. Background Art

[0002] Most of the 10kV switch cabinets used in the high-voltage room of the substation are center-mounted cabinets. The circuit breakers of the center-mounted cabinets are located in the middle of the cabinet and are designed to be removable. When the circuit breaker is inspected, the circuit breaker needs to be removed by an inspection trolley. In actual use, the inspection trolley has the following problems.

[0003] The operation efficiency of the maintenance trolley is low. There is a height difference between the switch cabinet and the maintenance trolley platform. The height of the maintenance trolley needs to be slightly adjusted to align the mounting bolts of the maintenance trolley with the fixing holes of the switch cabinet to ensure that the maintenance trolley is firm and reliable and does not move during the movement of the circuit breaker. During the alignment of the maintenance trolley with the positioning holes of the switch cabinet, the switch cabinet door will hinder the operation and maintenance personnel from aligning, reducing the efficiency of the on-site positioning hole alignment operation.

[0004] The circuit breaker weighs several hundred kilograms. The operation and maintenance personnel have to manually pull the circuit breaker onto the maintenance cart, which is prone to rollover and poses a safety hazard to on-site personnel.

[0005] The driving direction of the maintenance trolley wheels is perpendicular to the switch cabinet. During the alignment process, the angle of the maintenance trolley needs to be constantly adjusted, and on-site operation is time-consuming and laborious. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, the present invention provides a switch cabinet maintenance trolley and a hole alignment and leveling method based on small current measurement, uses a machine vision system to locate the fixed holes of the switch cabinet, and uses a small current detection circuit to achieve leveling of the maintenance trolley to prevent the circuit breaker from tipping over after being pulled onto the maintenance trolley due to the unevenness of the maintenance trolley, thereby effectively improving the efficiency of on-site circuit breaker maintenance operations and improving on-site operation safety. The present invention is implemented through the following technical solutions. The present invention provides a switch cabinet maintenance trolley, including an autonomous cruise drive module, a hole position recognition module and a leveling module;

[0007] The autonomous cruise drive module includes a vehicle control unit VCU; the vehicle control unit VCU is respectively connected to a two-in-one motor controller, a BMS battery management system, a touch screen, a magnetic navigation sensor, a brake system and an RFID induction sensor;

[0008] The hole position recognition module installs an embedded camera at the end of the maintenance trolley mounting bolt 1, adjusts its angle so that the embedded camera can observe the switch cabinet fixing hole position 1, and uses a machine vision system to recognize the hole position; uses the OpenCV recognition library to recognize the circular hole image, firstly selects the region of interest ROI for the image collected by the camera; then performs threshold processing on the image to segment the hole position part to be recognized, and uses a binarization method to separate the target and the background, and then uses a histogram to analyze the distribution of the grayscale value of the pixel points in the region of interest, performs circular detection on the image, and recognizes the circular contour of the hole position;

[0009] The leveling module includes: a limit module 1 connected to a vertical adjustment block, and the vertical adjustment block is connected to a small current detection circuit 1; a limit module 2 is connected to a horizontal adjustment block, and the horizontal adjustment block is connected to a small current detection circuit 3; a maintenance trolley mounting bolt 1 is connected to a DC electric push rod 1 and a DC electric push rod 3, and the DC electric push rod 1 is connected to a small current detection circuit 1, and the DC electric push rod 3 is connected to a small current detection circuit 3; the DC electric push rod 1 controls the maintenance trolley mounting bolt 1 to move in the vertical direction; the DC electric push rod 3 controls the maintenance trolley mounting bolt 1 to move in the horizontal direction; the leveling module also includes an ultrasonic ranging sensor and a leveling control unit installed on the maintenance trolley.

[0010] The switch cabinet maintenance trolley hole alignment and leveling method based on small current measurement includes:

[0011] An embedded camera is installed at the end of the mounting bolt 1 of the maintenance trolley, and its angle is adjusted so that the embedded camera can observe the fixing hole 1 of the switch cabinet; a machine vision system is used to identify the fixing hole 1 of the switch cabinet, and the circular contour of the fixing hole 1 of the switch cabinet is identified;

[0012] The machine vision system calculates the center coordinates of the switch cabinet fixing hole position 1;

[0013] Assume (x 01 ,y 01 ,z 01 ) is the camera center coordinate, (x 1 ,y 1 ,z 1 ) is the coordinate of the center point of the switch cabinet fixing hole;

[0014] The distance d measured by the ultrasonic ranging sensor is the straight-line distance between the camera and the center point of the switch cabinet fixing hole on the x-axis; the camera coordinates and the switch cabinet fixing hole coordinates are projected onto the xy plane and the xz plane respectively;

[0015] The y-axis offset between the camera and the switch cabinet fixing hole position 1 is calculated as shown in formula (1);

[0016] Δy=y1 -y 01 (1)

[0017] In formula (1), Δy is the horizontal offset between the camera and the switch cabinet fixing hole in the xy plane;

[0018] Similarly, the offset formula in the xz coordinate system is shown in formula (2);

[0019] Δz=z 1 -z 01 (2)

[0020] In formula (2), Δz is the vertical offset between the camera and the switch cabinet fixing hole in the xz plane;

[0021] The offset in the image coordinate system is converted into the offset in the world coordinate system. Assuming that the conversion coefficient of the pixel size in the fixed hole position image to the actual physical size is k, the offsets k*Δy and k*Δz are the displacements of the horizontal DC electric linear actuator and the vertical DC electric linear actuator;

[0022] According to the offsets k*Δy and k*Δz, the leveling control unit controls the DC electric push rod 1 and the DC electric push rod 3 to adjust the horizontal and vertical directions; so that the mounting bolt 1 of the maintenance trolley is aligned with the fixing hole 1 of the switch cabinet;

[0023] The leveling module uses a DC electric push rod for vertical or horizontal adjustment. For vertical adjustment, a limit module is installed on the DC electric push rod. The limit module is fixed to the vertical adjustment block, and the vertical adjustment block moves as the DC electric push rod rises or falls.

[0024] A copper column is connected below the vertical adjustment block, and a multi-contact resistance circuit is connected below the copper column. The rise and fall of the copper column will adjust the connection method of the multi-contact resistance. After the connection method of the multi-contact resistance changes, the small current in the circuit changes. The vertical adjustment result of the maintenance trolley mounting bolt 1 on the platform is obtained through the small current detection circuit. The maintenance trolley mounting bolt 2 is adjusted in the vertical direction according to this resistance value. When the circuit current of the maintenance trolley mounting bolt 2 is consistent with that of the maintenance trolley mounting bolt 1, the vertical adjustment is completed; the horizontal direction is adjusted in the same way.

[0025] The beneficial effects of the present invention are:

[0026] The present invention uses machine vision to locate the fixing hole position of the switch cabinet, and realizes the leveling of the maintenance trolley through a small current detection circuit, so as to prevent the circuit breaker from tipping over after being pulled onto the maintenance trolley due to the unevenness of the maintenance trolley, thereby effectively improving the efficiency of on-site circuit breaker maintenance operations and improving on-site operation safety.

[0027] (1) The present invention uses one camera to align multiple maintenance trolley mounting bolts with the switch cabinet fixing holes, thereby reducing the use of multiple cameras and reducing the cost of the entire device.

[0028] (2) The multi-contact measurement circuit of the present invention can be adapted to maintenance carts of different specifications, which is convenient for the alignment and adjustment of hole positions within different height ranges and for rapid installation on site.

[0029] (3) Based on the traditional manual hole alignment operation of the maintenance trolley, the present invention designs a resistance measurement circuit and a hole alignment system based on a multi-contact loop, so that the maintenance trolley can autonomously cruise to the corresponding switch cabinet. The maintenance trolley can automatically adjust and align the installation bolts, thereby improving the efficiency of the on-site positioning hole alignment operation.

[0030] (4) The present invention adopts an AC current sampling circuit to collect small currents. Based on a unipolar power supply, the equipotential method is adopted to connect one end of the secondary coil of the clamp-type current transformer to a DC bias and the other end to a reverse input terminal of an operational amplifier. The DC voltages at both ends of the clamp-type current transformer are of equal potential, and no DC current is generated, so the original AC signal can be accurately collected.

[0031] (5) The present invention is aimed at collecting small AC currents in a narrow space where a small circuit is required. An operational amplifier powered by a unipolar power supply and a bipolar AD conversion chip are used to reduce the volume of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings;

[0033] Figure 1 This is a working diagram of the maintenance trolley of the present invention;

[0034] Figure 2 This is a connection diagram of the autonomous cruise drive module of the present invention;

[0035] Figure 3 This is a connection diagram of the hole position identification and leveling module of the present invention;

[0036] Figure 4 This is a structural diagram of the hole position identification module of the present invention;

[0037] Figure 5 This is a process diagram for realizing the hole position recognition algorithm of the present invention;

[0038] Figure 6 This is a schematic diagram of the xy coordinate system mapping of the present invention;

[0039] Figure 7 It is a mathematical model diagram of hole positions in the xy image coordinate system of the present invention;

[0040] Figure 8A conversion diagram between the image coordinate system and the world coordinate system of the present invention;

[0041] Fig. 9 This is a side structural diagram of the maintenance trolley of the present invention;

[0042] Fig.10 A multi-contact measurement circuit of the present invention;

[0043] Fig.11 This is a contact structure diagram of the present invention;

[0044] Fig.12 It is a diagram of the fusion process between the contacts of the present invention;

[0045] Fig.13 This is a small current collection flow chart of the present invention;

[0046] Fig.14 It is the principle diagram of IV conversion operational amplifier circuit and low-pass RC filter circuit of the present invention;

[0047] Fig.15 This is the schematic diagram of the ADC conversion circuit of the present invention;

[0048] Fig.16 This is a schematic diagram of a DC bias circuit of the present invention;

[0049] In the figure, 1 is a vertical adjustment block, 2 is a copper column, and 3 is a contact conductor. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0051] The accompanying drawings are specific embodiments of the switch cabinet maintenance trolley and hole alignment and leveling method based on small current measurement of the present invention.

[0052] As attached Figure 1 As shown in the figure, the working process of the maintenance trolley is:

[0053] Step 1: The maintenance personnel enter the switch cabinet number that needs to be repaired on the touch screen, click start on the touch display, and the trolley starts to move.

[0054] Step 2: The vehicle control unit VCU obtains the signal of the magnetic navigation sensor installed at the bottom of the vehicle through RS485. The magnetic navigation sensor and the existing magnetic strip in the high-voltage switch cabinet form a weak magnetic field, and the path is cruised by detecting the presence or absence of magnetic field signals. The vehicle VCU controls the two-in-one motor controller to drive the motor according to the signal of the magnetic navigation sensor.

[0055] Step 3: During driving, the vehicle control unit VCU obtains the RFID tag information of the switch cabinet number installed under the magnet through the RFID sensing sensor installed. When the tag information is consistent with the maintenance switch cabinet number entered by the maintenance personnel on the touch screen in step 1, the vehicle control unit VCU activates the brake system through a switch signal to stop the vehicle in front of the corresponding switch cabinet; the maintenance cart is driven by the rear wheel hub motor, and the two-in-one motor controller controls the two motors. The switch cabinets in the switch cabinet room are arranged in a straight line, and the maintenance cart can move forward and backward to meet maintenance needs.

[0056] Step 4: The ultrasonic distance sensor installed on the side of the vehicle body is used to obtain the distance information between the vehicle and the switch cabinet plane, which is used in the coordinate calculation for hole position identification and alignment. The ultrasonic distance sensor plane is aligned with the vehicle body plane.

[0057] Step 5: Hole alignment. Based on hole identification and positioning, the position information of the switch cabinet fixed hole position 1 is obtained. The position data of the switch cabinet fixed hole position 2 is obtained through geometric calculation. Through the leveling module, the mounting bolts of the maintenance trolley are aligned with the switch cabinet fixed holes. After alignment, the maintenance trolley gives an alignment pop-up window on the touch screen to remind on-site maintenance personnel.

[0058] Step 6: The maintenance personnel manually push the installation bolts of the maintenance trolley into the fixed holes of the switch cabinet according to the pop-up window prompt of the maintenance trolley. After pushing the bolts into the fixed holes of the switch cabinet, the maintenance personnel tighten the bolts.

[0059] Step 7: After the maintenance trolley hole is locked, the maintenance personnel pull out the circuit breaker.

[0060] Step 8: The circuit breaker is fully pulled out.

[0061] Step 9: The maintenance personnel release the fixing holes of the switch cabinet and pull the bolts out of the fixing holes of the switch cabinet.

[0062] Step 10: The maintenance personnel operate on the touch screen and issue the return command, and the maintenance trolley automatically returns to the starting position.

[0063] The maintenance trolley includes an autonomous cruise drive module, a hole position recognition module, and a leveling module. The wheels of the maintenance trolley are parallel to the direction of the switch cabinet.

[0064] As attached Figure 2As shown, the autonomous cruise drive module includes a vehicle control unit VCU, a two-in-one motor controller, a battery pack, a BMS battery management system, a motor one, a motor two, a touch screen, a magnetic navigation sensor, a brake system, and an RFID induction sensor; the vehicle control unit VCU is respectively connected to the two-in-one motor controller, the BMS, the touch screen, the magnetic navigation sensor, the brake system, and the RFID induction sensor; the vehicle control unit VCU is connected to the two-in-one motor controller and the BMS through CAN communication; the BMS is connected to the battery pack and collects the voltage and current of the battery pack; the two-in-one motor controller is connected to the battery pack through a DC bus, and the two-in-one motor controller is connected to the motor through three-phase AC power, and the motor transmits the resolver signal to the two-in-one motor controller; the vehicle control unit VCU controls the switch of the brake system; the vehicle control unit VCU is connected to the magnetic navigation sensor and the RFID induction sensor through RS485 communication.

[0065] The hole position recognition module installs an embedded camera at the end of the maintenance trolley mounting bolt one, adjusts its angle so that the embedded camera can observe the switch cabinet fixed hole position one, and uses a machine vision system to recognize the hole position; the main goal of the hole position recognition of the high-voltage switch cabinet is to obtain the center position information of the switch cabinet fixed hole position one; the OpenCV recognition library is used to recognize the circular hole image, firstly, the region of interest ROI (Region of interest) is selected for the image collected by the camera to avoid interference from other irrelevant areas and reduce processing time; then the image is thresholded to segment the hole position part that needs to be identified, and after the binarization method is used to separate the target and the background, the histogram is used to analyze the distribution of the grayscale value of the pixel points in the region of interest, and the image is detected for a circle to identify the circular contour of the hole position.

[0066] In locating the switch cabinet fixing hole, the main function of the machine vision system is to calculate the coordinates of the hole center. In the image coordinate system, the distance of the switch cabinet fixing hole center point in the axial direction is obtained by the ultrasonic ranging sensor.

[0067] Install an embedded camera at the end of the maintenance trolley mounting bolt 1, and adjust its angle so that the embedded camera can observe the switch cabinet fixing hole 1. Since the camera is installed in the maintenance trolley mounting bolt 1, the coordinates of the fixed camera are the coordinates of the maintenance trolley mounting bolt.

[0068] Project the camera coordinates and the switch cabinet fixing hole coordinates to the xy plane and xz plane respectively. The distance d measured by the ultrasonic ranging sensor is the straight-line distance between the camera and the center point of the switch cabinet fixing hole on the x-axis. The position of the distance d on the x-axis remains unchanged. The xy coordinate system mapping diagram is shown in the figure below. Figure 6 As shown. Assume (x 01 ,y 01 ,z01 ) is the camera center coordinate, (x 1 ,y 1 ,z 1 ) is the coordinate of the center point of the switch cabinet fixing hole.

[0069] The mathematical model of hole position in the image xy coordinate system is as follows: Figure 7 As shown, the position of the camera center in the image coordinate system is known, and the center point of the switch cabinet fixed hole position 1 can be calculated in the image coordinate system. Therefore, the y-axis offset between the camera and the switch cabinet fixed hole position 1 can be calculated as shown in Formula 1.

[0070] Δy=y 1 -y 01 (1)

[0071] In formula (1), Δy is the horizontal offset between the camera and the switch cabinet fixing hole in the xy plane.

[0072] Similarly, the offset formula in the xz coordinate system is shown in formula (2).

[0073] Δz=z 1 -z 01 (2)

[0074] In formula (2), Δz is the vertical offset between the camera and the switch cabinet fixing hole in the xz plane.

[0075] The offset in the image coordinate system is converted into the offset in the world coordinate system. Assuming that the conversion coefficient from the pixel size in the switch cabinet fixed hole image to the actual physical size is k, the offsets k*Δy and k*Δz are the displacements of the horizontal DC electric push rod and the vertical DC electric push rod.

[0076] As attached Fig. 9 As shown, the leveling module includes: a limit module 1 connected to a vertical adjustment block, and the vertical adjustment block is connected to a small current detection circuit 1; a limit module 2 is connected to a horizontal adjustment block, and the horizontal adjustment block is connected to a small current detection circuit 3; a maintenance trolley mounting bolt 1 is connected to a DC electric push rod 1 and a DC electric push rod 3, and the DC electric push rod 1 is connected to a small current detection circuit 1, and the DC electric push rod 3 is connected to a small current detection circuit 3; the DC electric push rod 1 controls the maintenance trolley mounting bolt 1 to move in a vertical direction; the DC electric push rod 3 controls the maintenance trolley mounting bolt 1 to move in a horizontal direction; similarly, the maintenance trolley mounting bolt 2 is respectively connected to a DC electric push rod 2 and a DC electric push rod 4, and the DC electric push rod 2 is connected to a small current detection circuit 2, and the DC electric push rod 4 is connected to a small current detection circuit 4; the leveling module also includes an ultrasonic ranging sensor and a leveling control unit installed on the maintenance trolley.

[0077] As attached Figure 3As shown, the leveling control unit is connected to the vehicle VCU, the camera and the ultrasonic ranging sensor; the leveling control unit is respectively connected to the small current detection circuits one to four; the leveling control unit is connected to control the DC electric push rods one to four; the leveling control unit is connected to the camera through the network port to TTL module.

[0078] The leveling module is used to level the maintenance trolley platform after hole position identification. The maintenance trolley has multiple maintenance trolley mounting bolts, as shown in the attached Fig. 9 As shown, there are two maintenance trolley mounting bolts in this embodiment; after obtaining the coordinates of the fixed hole position 1 for installing the switch cabinet through hole position identification, the leveling control unit controls the DC electric push rod 1 and the DC electric push rod 3 to adjust the horizontal and vertical directions according to the offsets k*Δy and k*Δz; when the DC electric push rods 1 and 3 are adjusted, the small current detection circuits 1 and 3 will measure the current changes accordingly. After the maintenance trolley mounting bolt 1 is aligned with the fixed hole position 1 of the switch cabinet, the DC electric push rods 2 and 4 of the maintenance trolley mounting bolt 2 are adjusted accordingly according to the current change values ​​of the small current detection circuits 1 and 3. By adjusting the DC electric push rods 2 and 4 of the maintenance trolley mounting bolt 2, the current change of the small current detection circuit is made the same as the change value of the small current detection circuits 1 and 3, that is, the position change of the maintenance trolley mounting bolt 2 and the maintenance trolley mounting bolt 1 is achieved to be the same. The leveling module adopts a DC electric push rod for vertical and horizontal adjustment. A limit module is installed on the DC electric push rod. Limit module one is installed on DC electric push rod one, and limit module three is installed on DC electric push rod three. The limit module is fixed to the vertical adjustment block or the horizontal adjustment block. The vertical adjustment block moves as the DC electric push rod rises or falls, and the horizontal adjustment block moves as the DC electric push rod moves horizontally.

[0079] As attached Fig.10 As shown, the maintenance trolley is powered by direct current, which is converted into alternating current through an inverter. A copper column is connected below the vertical adjustment block, and a multi-contact resistor circuit is connected below the copper column. The copper column can adjust the connection mode of the multi-contact resistor by rising and falling. After the connection mode of the multi-contact resistor changes, the small current in the circuit changes. The small current detection circuit is used to obtain the vertical adjustment result of the maintenance trolley mounting bolt 1 on the platform. The maintenance trolley mounting bolt 2 is adjusted in the vertical direction according to this resistance value. When the circuit current of the maintenance trolley mounting bolt 2 is consistent with that of the maintenance trolley mounting bolt 1, the vertical adjustment is completed. Similarly, adjust the horizontal direction of the maintenance trolley mounting bolt 1.

[0080] When the vertical adjustment block of the maintenance trolley is displaced in the vertical direction, the resistance wire between the contacts will be displaced, and the resistance wires between the upper and lower parts will fit to different degrees, thus short-circuiting part of the resistance. The sampling resistor between the contacts is made of constantan wire, which can be made into a micro resistor for easy expansion and contraction.

[0081] Contact structure such as Fig.11As shown, the middle of the contact is hollow, the contact conductor is located below the contact, the inside of the contact conductor is also hollow, and the contact conductor is a cylinder. Through the short-circuit method, different resistances of the short-circuit loop are achieved.

[0082] During the downward movement of the contact, when the upper contact conductor touches the lower contact conductor and is completely in contact with the lower contact conductor, the two contacts are completely connected, and the resistance between the two contacts is completely short-circuited.

[0083] The sampling resistor has a small resistance and a weak current Ic. The present invention uses alternating current for current sampling. The small alternating current collection process based on the equipotential method is as follows: Fig.13 As shown, the small AC signal outputs an analog signal after passing through the clamp-on current transformer, and then enters the AD chip after passing through the operational amplifier acquisition follower circuit and the filter circuit. After being processed by the AD chip, it enters the microcontroller through the communication interface for processing.

[0084] The acquisition circuit includes a small-sized clamp-shaped current transformer, a unipolar current-voltage IV conversion operational amplifier circuit, a DC bias circuit, an RC low-pass filter circuit and a single-chip microcomputer processing circuit.

[0085] The principle of unipolar IV conversion operational amplifier circuit is as follows Fig.14 As shown, the small AC signal enters the unipolar current and voltage IV conversion operational amplifier circuit through a small pointed clamp-shaped current transformer. The unipolar current and voltage IV conversion operational amplifier circuit amplifies the small AC signal. The amplified signal is a voltage signal in the range of 0 to 3.3V that can be measured by the single-chip microcomputer. After the voltage signal is filtered by the voltage follower and the RC low-pass filter circuit, the output impedance of the signal is reduced and the high-frequency noise is filtered out to ensure more accurate ADC sampling. The output signal of the RC low-pass filter circuit enters the ADC acquisition pin of the single-chip microcomputer. The sampling loop current is provided by the unipolar current and voltage IV conversion operational amplifier circuit, which makes up for the signal accuracy problem caused by the small internal resistance of the current transformer and the small sampling resistance. The feedback capacitor is connected in parallel with the output of the operational amplifier to reduce environmental noise and restore the initial signal more closely.

[0086] By using the transformer equipotential method, the DC potential at both ends of the clamp-on current transformer is equal, thus avoiding the generation of DC current. Fig.14 As shown, one end of the secondary coil of the clamp-on current transformer is connected to a DC bias of 1.5V, and the other end is connected to the reverse input of the op amp. The DC voltages at both ends of the transformer are equal in potential, and no DC current is generated. The output can restore the original AC signal. A DC bias of 1.5V is input to the same-direction transmission end of the RS6332 unipolar operational amplifier. TS5A3160 is a chip select chip. The sampling resistor at the back end of the op amp is selected through SCALE_EN, which is suitable for different current ranges.

[0087] ADC conversion circuit such as Fig.15As shown, the AC voltage signal output by the unipolar current-voltage IV conversion operational amplifier circuit is connected to the AD conversion chip input, and the collected signal is transmitted to the single-chip microcomputer circuit through SPI communication.

[0088] The principle of DC bias circuit is as follows Fig.16 As shown, the voltage reference chip REF3030 and the low voltage drop linear regulator RT9063-1.5 are used to generate 3.0V and 1.5V DC bias voltages respectively.

Claims

1. The switch cabinet maintenance trolley is characterized by: Including autonomous cruise drive module, hole position recognition module and leveling module; The autonomous cruise drive module includes a vehicle control unit VCU; the vehicle control unit VCU is respectively connected to a two-in-one motor controller, a BMS battery management system, a touch screen, a magnetic navigation sensor, a brake system and an RFID induction sensor; The hole position recognition module installs an embedded camera at the end of the maintenance trolley mounting bolt 1, adjusts its angle so that the embedded camera can observe the switch cabinet fixing hole position 1, and uses a machine vision system to recognize the hole position; uses the OpenCV recognition library to recognize the circular hole image, firstly selects the region of interest ROI for the image collected by the camera; then performs threshold processing on the image to segment the hole position part to be recognized, and uses a binarization method to separate the target and the background, and then uses a histogram to analyze the distribution of the grayscale value of the pixel points in the region of interest, performs circular detection on the image, and recognizes the circular contour of the hole position; The leveling module includes: a limit module 1 connected to a vertical adjustment block, and the vertical adjustment block is connected to a small current detection circuit 1; a limit module 2 connected to a horizontal adjustment block, and the horizontal adjustment block is connected to a small current detection circuit 3; a maintenance trolley mounting bolt 1 is connected to a DC electric push rod 1 and a DC electric push rod 3, and the DC electric push rod 1 is connected to a small current detection circuit 1, and the DC electric push rod 3 is connected to a small current detection circuit 3; the DC electric push rod 1 controls the maintenance trolley mounting bolt 1 to move in the vertical direction; the DC electric push rod 3 controls the maintenance trolley mounting bolt 1 to move in the horizontal direction; the limit module 1 is installed on the DC electric push rod 1, and the limit module 3 is installed on the DC electric push rod 3. The leveling module also includes an ultrasonic ranging sensor and a leveling control unit installed on the maintenance trolley; the leveling control unit is connected to the vehicle VCU, the camera and the ultrasonic ranging sensor; the leveling control unit is respectively connected to the small current detection circuit 1 and the small current detection circuit 3; the leveling control unit is connected to control the DC electric push rod 1 and the DC electric push rod 3; the leveling control unit is connected to the camera through the network port to TTL module.

2. The switch cabinet maintenance trolley according to claim 1, characterized in that: The vehicle control unit VCU connects the two-in-one motor controller and BMS through CAN communication; the BMS connects the battery pack and collects the voltage and current of the battery pack; the two-in-one motor controller connects the battery pack through the DC bus, and the two-in-one motor controller connects the motor through three-phase AC power, and the motor transmits the resolver signal to the two-in-one motor controller; the vehicle control unit VCU controls the switch of the brake system; the vehicle control unit VCU connects the magnetic navigation sensor and the RFID induction sensor through RS485 communication.

3. The switch cabinet maintenance trolley according to claim 2, characterized in that: Similarly, the maintenance trolley mounting bolt 2 of the leveling module is respectively connected to the DC electric push rod 2 and the DC electric push rod 4, the DC electric push rod 2 is connected to the small current detection circuit 2, and the DC electric push rod 4 is connected to the small current detection circuit 4; the leveling control unit is respectively connected to the small current detection circuit 2 and the small current detection circuit 4; the leveling control unit is connected to control the DC electric push rod 2 and the DC electric push rod 4.

4. The hole alignment and leveling method of the switch cabinet maintenance trolley according to claim 3 based on small current measurement is characterized in that: include, An embedded camera is installed at the end of the mounting bolt 1 of the maintenance trolley, and its angle is adjusted so that the embedded camera can observe the fixing hole 1 of the switch cabinet; a machine vision system is used to identify the fixing hole 1 of the switch cabinet, and the circular contour of the hole is identified; the machine vision system calculates the center coordinates of the fixing hole 1 of the switch cabinet; Assume (x 01 ,y 01 ,z 01 ) is the center coordinate of the camera, (x1, y1, z1) is the center coordinate of the switch cabinet fixing hole; The distance d measured by the ultrasonic ranging sensor is the straight-line distance between the camera and the center point of the switch cabinet fixing hole on the x-axis; the camera coordinates and the switch cabinet fixing hole coordinates are projected onto the xy plane and the xz plane respectively; The y-axis offset between the camera and the switch cabinet fixing hole position 1 is calculated as shown in formula (1); Δy=y1-y 01 (1) In formula (1), Δy is the horizontal offset between the camera and the switch cabinet fixing hole in the xy plane; Similarly, the offset formula in the xz coordinate system is shown in formula (2); Δz=z1-z 01 (2) In formula (2), Δz is the vertical offset between the camera and the switch cabinet fixing hole in the xz plane; The offset in the image coordinate system is converted into the offset in the world coordinate system. Assuming that the conversion coefficient of the pixel size in the fixed hole position image to the actual physical size is k, the offsets k*Δy and k*Δz are the displacements of the horizontal DC electric linear actuator and the vertical DC electric linear actuator; According to the offsets k*Δy and k*Δz, the leveling control unit controls the DC electric push rod 1 and the DC electric push rod 3 to adjust the horizontal and vertical directions; so that the mounting bolt 1 of the maintenance trolley is aligned with the fixing hole 1 of the switch cabinet; For the adjustment in the vertical direction, a limit module 1 is installed on the DC electric push rod 1, and the limit module 1 is fixed to the vertical adjustment block, and the vertical adjustment block moves as the DC electric push rod 1 rises or falls; A copper column is connected below the vertical adjustment block, and a multi-contact resistance circuit is connected below the copper column. The rise and fall of the copper column will adjust the connection method of the multi-contact resistance. After the connection method of the multi-contact resistance changes, the small current in the circuit changes. The vertical adjustment result of the maintenance trolley mounting bolt 1 on the platform is obtained through the small current detection circuit. The maintenance trolley mounting bolt 2 is adjusted in the vertical direction according to this resistance value. When the circuit current of the maintenance trolley mounting bolt 2 is consistent with that of the maintenance trolley mounting bolt 1, the vertical adjustment is completed; the horizontal direction is adjusted in the same way.

5. The hole alignment and leveling method according to claim 4, characterized in that: The contact is hollow in the middle, the contact conductor is located below the contact, the inside of the contact conductor is also hollow, the contact conductor is a cylinder, and different resistances of the short-circuit loop are achieved through the short-circuit method; the sampling resistor between the contacts uses constantan wire to make a micro-resistance, which is easy to expand and contract.

6. The hole alignment and leveling method according to claim 4, characterized in that: AC current is used for current sampling, and small AC current is collected based on the equipotential method; the collection circuit includes a pointed small clamp-shaped current transformer, a unipolar current-voltage IV conversion operational amplifier circuit, a DC bias circuit, an RC low-pass filter circuit and a single-chip microcomputer processing circuit; the small AC signal enters the unipolar current-voltage IV conversion operational amplifier circuit through the pointed small clamp-shaped current transformer, and the unipolar current-voltage IV conversion operational amplifier circuit amplifies the small AC signal. The amplified signal is a voltage signal in the range of 0 to 3.3V that can be measured by the single-chip microcomputer. After the voltage signal is filtered by a voltage follower and an RC low-pass filter circuit, the output impedance of the signal is reduced and high-frequency noise is filtered out, so that ADC sampling is more accurate, and the output signal of the RC low-pass filter circuit enters the ADC collection pin of the single-chip microcomputer.

7. The hole alignment and leveling method according to claim 4, characterized in that: The transformer equipotential method is adopted, and the DC potential at both ends of the clamp-on current transformer is equal. One end of the secondary coil of the clamp-on current transformer is connected to a DC bias of 1.5V, and the other end is connected to the reverse input terminal of the operational amplifier, so that the DC voltage at both ends of the transformer is of equal potential.

8. The hole alignment and leveling method according to claim 4, characterized in that: The AC voltage signal output by the unipolar current-voltage IV conversion operational amplifier circuit is connected to the AD conversion chip input, and the collected signal is transmitted to the single-chip microcomputer circuit through SPI communication.

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