Stacker walking positioning structure and positioning method thereof

Abstract

The present application relates to a stacker walking positioning structure and a positioning method thereof, the positioning structure comprising a walking wheel, an encoder, a controller and a magnetic reed switch, the walking wheel being arranged at the lower end of the stacker, the walking wheel comprising a driving wheel and a driven wheel, a driving motor being connected to the rotation shaft of the driving wheel; the encoder being arranged on the rotation shaft of the driven wheel and used for detecting the action information thereof; the input end of the controller being connected to the output end of the encoder, the output end of the controller being connected to the input end of the driving motor, the both ends of the walking track of the stacker being provided with magnetic bodies with magnetic fields, the walking being positioned by the encoder, and according to the characteristics of the track stacker, the encoder being installed on the side of the driven wheel, so as to avoid the calculation error of the walking position due to the slippage of the walking wheel, the magnetic reed switch being able to be used as the origin detection and the wear error detection of the walking wheel, thereby providing the guarantee for the accurate and stable operation of the stacker, and the controller realizing the calculation of the walking position of the stacker, the origin correction, the wear detection of the walking wheel and the adjustment of the data of the warehouse position through the logic algorithm.

Description

Technical Field

[0001] This invention relates to the field of intelligent material handling system technology, and in particular to the stacker crane walking positioning structure and positioning method. Background Technology

[0002] Currently, global manufacturers of stacker cranes range from well-known international brands like Dematic and Swiss-made to leading domestic companies such as Yinfei and Zhongding. The primary methods for stacker crane positioning are laser positioning systems and barcode positioning systems. Laser positioning systems involve vertically mounting a reflector at the end of the stacker crane's running track. An optical distance sensor mounted on the stacker crane emits a laser beam that shines perpendicularly onto the reflector, measuring the distance between the sensor and the reflector in real time and feeding this data back to the stacker crane to calculate its real-time position. Barcode positioning systems involve installing a barcode strip along one side of the stacker crane's running track. A barcode recognition sensor mounted on the stacker crane identifies the barcode on the strip, calculates the corresponding position value, and feeds this data back to the stacker crane to calculate its current position. These methods obtain the position value of the stacker crane in its traveling direction, achieving proper positioning.

[0003] While the two aforementioned ranging and positioning methods are simple in design and easy to use, they are subject to stringent environmental requirements in practical applications, and some special scenarios cannot meet their usage conditions. For example, in outdoor environments with dust, fog, or condensation, light cannot penetrate, causing the optical ranging sensors to malfunction. In certain low-temperature (<-30℃) or high-temperature (>50℃) scenarios, these two ranging sensors may also malfunction and shut down due to exceeding their operating temperature range. Furthermore, industries such as petrochemicals have explosion-proof requirements for their equipment, in which case these two sensors cannot meet the explosion-proof requirements and cannot be used.

[0004] Existing stacking mechanisms that use encoders for positioning, such as Chinese patents [CN206757381U] and [CN115097873A], all achieve positioning and ranging functions using encoders. However, encoder ranging has two problems: wheel slippage and position calculation errors caused by wheel wear. These problems have not been completely solved in the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a stacker crane walking positioning structure and its positioning method, which solves the problem that the error caused by wear of the walking wheels is difficult to eliminate when using encoder positioning in existing stacker cranes.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a stacker crane travel positioning structure, including

[0008] The traveling wheels are located at the lower end of the stacker crane. The traveling wheels include a driving wheel and a driven wheel that is linked to it. A drive motor is connected to the rotating shaft of the driving wheel.

[0009] An encoder is mounted on the rotating shaft of the driven wheel and is used to detect its motion information;

[0010] The controller has its input terminal connected to the output terminal of the encoder to receive information data from the encoder, and its output terminal connected to the input terminal of the drive motor.

[0011] A reed switch is installed on the side wall of the stacker crane. Magnetic bodies with magnetic fields are installed at both ends of the stacker crane's travel track. The output end of the reed switch is connected to the input end of the controller.

[0012] Preferably, the connection between the input terminal of the reed switch and the output terminal of the controller is a dry connection, and the connection between the output terminal of the encoder and the input terminal of the controller is a communication connection.

[0013] Preferably, the encoder is an absolute encoder, and the encoder pulses are fourth-harmonic pulses. A stacker crane walking and positioning method includes at least:

[0014] S1. Before initial use, record the initial diameter R0 of the driven wheel. Perform position verification by running the stacker crane at a constant speed along both ends of the magnetic object on the travel track, and record the positions of the magnetic objects as follows: Point A, Position X. a0 and point B's position X b0 And calculate the position X of point A. a0 and point B's position X b0 The initial difference between them is L0;

[0015] S2. Calculate and record the position data of the shelves on one side of the track. Take point A as the base point. The distance from point A to the first column of shelves is X1, the distance to the second column is X2, ..., and the distance to the nth column is X... n ;

[0016] S3. During operation, the stacker crane performs a position check at fixed intervals, runs on the track at a constant speed, and the controller records the displayed value X when passing points A and B. an and X bn And calculate the distance L between points A and B at this time. n ;

[0017] S4. Set the origin deviation range W0, i.e., |X a0 -X an If the value of | is not greater than W0, then the position data of point A will not be adjusted; otherwise, if | X a0 -Xan If the value of | is greater than W0, then when the stacker crane is at position A, the value displayed on the controller will be adjusted to X. a0 ;

[0018] S5. Set the distance deviation range W1, when |L n If the value of L0| is not greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn; otherwise, if |L0| is greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn. n If the value of -L0| is greater than W1, the controller assumes that the stacker crane's traveling wheels are worn; and based on L... n And L0 determines the deviation rate σ=L n / L0, and re-label and record the position data of the shelves on one side of the track, using point A as the base point, and the distance from point A to the first column of shelves as X. 11 = X1*(1+σ) Distance to the second shelf X 12 = X2*(1+σ)… The distance to the nth shelf is X 1n = X n *(1+σ)

[0019] S6. Calculate the wear amount M1 of the travel wheel diameter, limit the deviation range M0 of the wear amount, and compare them. If M1 is greater than M0, replace the travel wheel; otherwise, proceed to the next step.

[0020] S7, The controller, based on the recalculated data X 11 X 12 X 1n The number of rotations required for the driven wheel at the positions of the first, second, and Nth shelves is recalculated based on the initial diameter of the driven wheel. n This information is then transmitted to the drive motor.

[0021] Preferably, the calculation method in S6 is as follows: Ln in S3 divided by the circumference of the driven wheel is equal to the number of revolutions N0 of the driven wheel from point A to point B; the value of |Ln-L0| in S5 divided by N0 is equal to the deviation W2 that occurs per revolution; and W2 divided by pi is equal to the wear amount M of the initial diameter of the driven wheel.

[0022] Due to the application of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art:

[0023] This invention relates to a stacker crane traveling and positioning structure and its positioning method.

[0024] 1. The walking mechanism uses encoder positioning, and based on the characteristics of the rail stacker crane, the encoder is installed on the driven wheel side to avoid errors in walking position calculation due to wheel slippage.

[0025] 2. A reed switch is installed on the lower crossbeam, which can be used for both origin detection and wear error detection of the traveling wheels, ensuring the accurate and stable operation of the stacker crane;

[0026] 3. The controller calculates the stacker crane's travel position based on the values ​​fed back from the encoder, performs origin correction, detects wear on the traveling wheels, and promptly readjusts the rack data. Attached Figure Description

[0027] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0028] Figure 1 This is a schematic diagram of the positioning structure in this embodiment;

[0029] Figure 2 This is a side view of the positioning structure in this embodiment;

[0030] Figure 3 This is a schematic diagram of signal transmission among the components in the positioning structure.

[0031] The reference numerals in the attached figures are explained as follows:

[0032] 1. Stacker crane; 11. Lower crossbeam;

[0033] 31. Driving wheel; 32. Driven wheel; 33. Drive motor;

[0034] 4. Encoder; 5. Reed switch. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] like Figure 1As shown, the stacker crane 1 walking positioning structure of the present invention is set on the lower crossbeam 11 of the stacker crane 1 and is used to detect the walking trajectory of the stacker crane 1.

[0038] The stacker crane 1 includes a crossbeam, columns, a loading platform, wheels, and an electrical control cabinet. The electrical control cabinet houses the electrical control components of the stacker crane 1, mainly including a controller, a frequency converter, and low-voltage components. The wheels are located at the lower end of the crossbeam of the stacker crane 1. Each wheel includes a drive wheel 31 and a driven wheel 32 linked to it. A drive motor 33 is connected to the rotating shaft of the drive wheel 31. The drive wheel 31 is driven to rotate by the drive motor 33. The driven wheel 32 is rigidly connected to the drive wheel 31. The driven wheel 32 rotates under the action of the drive wheel 31. The rotation of the drive wheel 31 and the driven wheel 32 can be used to drive the stacker crane 1 to move.

[0039] like Figure 2 As shown, encoder 4 is mounted on the rotating shaft of the driven wheel and is used to detect its motion information. Encoder 4 detects the number of rotations of the driven wheel's rotating shaft, thereby detecting the number of rotations of the driven wheel. Since the driven wheel and the driving wheel 31 are rigidly connected, the rotation of the traveling wheel can be detected by detecting the number of rotations of the driven wheel's rotating shaft. Then, by using the circumference of the traveling wheel, the distance traveled by the stacker crane 1 on the traveling track 2 can be calculated. At the same time, the speed of the traveling wheel can also be monitored.

[0040] like Figure 3 As shown, the controller's input terminal is connected to the output terminal of encoder 4, receiving information data from encoder 4, calculating, collecting, and displaying the information fed back by encoder 4. The controller's output terminal is connected to the input terminal of drive motor 33, and is connected via a frequency converter to achieve variable frequency speed control of the drive motor. After calculating the input information from encoder 4, the controller controls drive motor 33 to rotate the walking wheels to a specific shelf position, forming an effective information closed loop. The controller uses a PLC control system, which can record, calculate, and store multiple sets of data.

[0041] A reed switch 5 is installed on the side wall of the lower crossbeam of the stacker crane 1. Magnetic bodies with magnetic fields are installed at both ends of the travel track 2 of the stacker crane 1. When the stacker crane 1 runs along the track from A to B, the state of the reed switch 5 switches from 0 to 1 when passing point A, and from 1 to 0 when passing point B. Similarly, when the stacker crane 1 runs along the track from B to A, the state of the reed switch 5 switches from 0 to 1 when passing point B, and from 1 to 0 when passing point A. At the same time, the output terminal of the reed switch 5 is connected to the input terminal of the controller. In this way, the switching process information of the reed switch 5 is transmitted to the controller to confirm that the stacker crane 1 is running and has passed the end position of the track.

[0042] The input terminal of the reed switch 5 and the output terminal of the controller are connected in a dry connection, so that the state switching can be quickly fed back to the controller.

[0043] The output of encoder 4 is connected to the input of controller via a communication connection. This is because encoder 4 outputs a lot of information and continuously inputs data.

[0044] When the stacker crane 1 is moving, the current position of the stacker crane 1 is calculated based on feedback from the encoder 4. Two problems that need to be addressed with this solution are slippage of the traveling wheels and wear of the traveling wheels, which lead to errors in the calculation of the actual position of the stacker crane 1. Traveling wheel slippage occurs when the static friction between the traveling wheel and the track is broken, causing relative sliding between the wheel and the track, resulting in a discrepancy between the change in the actual position of the stacker crane 1 and the rotation angle of the wheel. Wear of the traveling wheels gradually occurs over the service life of the stacker crane 1, with the diameter of the traveling wheels decreasing over time. To address traveling wheel slippage, this embodiment installs the encoder 4 on the driven wheel axle. During normal operation, the driven wheel moves passively and does not deviate from the track, thus avoiding interference from slippage. Wear of the traveling wheels is detected and compensated for by the signal status of the reed switch 5 and the calculations of the controller.

[0045] The specific implementation method is as follows:

[0046] S1. Before initial use, record the initial diameter R0 of the driven wheel 32. Perform position verification by running the stacker crane 1 at a constant speed along both ends of the magnetic object on the travel track 2. Repeat this process multiple times to avoid errors. Record the positions of the magnetic objects as follows: Point A, Position X a0 and point B's position X b0 And calculate the position X of point A. a0 and point B's position X b0 The initial difference L0 between the two; the position data is obtained by multiplying the circumference of the walking wheel by the number of revolutions.

[0047] S2. Using the same calculation method as in S1, calculate and record the position data of the shelves on one side of the track. Take point A as the origin, the distance from point A to the first column of shelves is X1, the distance to the second column is X2, ..., the distance to the nth column is X... n ;

[0048] S3. During operation, the stacker crane 1 performs a position check at fixed intervals. The position check method is the same as in S1 and S2, which involves running at a constant speed on the track. The controller records the displayed value X when passing points A and B. an and X bn And calculate the distance L between points A and B at this time. n ;

[0049] S4. Set the origin deviation range W0, i.e., |X a0 -X an If the value of | is not greater than W0, then the position data of point A will not be adjusted; otherwise, if | X a0 -X an If the value of | is greater than W0, it indicates that the position of point A tested in S1 is deviated. Therefore, when the stacker crane is at position A, it should be reset to zero, and the value X displayed on the controller should be changed. an Adjust to X a0 ;

[0050] S5. Set the distance deviation range W1, when |L n If the value of L0| is not greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn; otherwise, if |L0| is greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn. n If the value of -L0| is greater than W1, the controller considers that the stacker crane's traveling wheels have a wear problem; at this time, the deviation rate σ=L is determined based on Ln and L0. n / L0, and re-label and record the position data of the shelves on one side of the track, using point A as the base point, and the distance from point A to the first column of shelves as X. 11 = X1*(1+σ) Distance to the second shelf X 12 = X2*(1+σ)… The distance to the nth shelf is X 1n = X n *(1+σ)

[0051] S6. Calculate the wear amount M1 of the travel wheel diameter, limit the deviation range M0 of the wear amount, and compare them. If M1 is greater than M0, replace the travel wheel; otherwise, proceed to the next step. Since the wear of the travel wheel is within a certain range, it can still continue to operate.

[0052] S7, The controller, based on the recalculated data X 11 X 12 X 1n The number of rotations required for the driven wheel at the positions of the first, second, and Nth shelves is recalculated based on the initial diameter of the driven wheel. n This information is then transmitted to the drive motor. Upon receiving the information, the drive motor drives the wheels to rotate.

[0053] L in S3 above n Dividing by the circumference of the driven wheel equals the number of revolutions N0 of the driven wheel over the distance from point A to point B after the traveling wheel begins to wear out, in S5| L n The value of -L0| divided by N0 equals the deviation W2 that occurs per revolution, and W2 divided by pi equals the wear amount M1 of the diameter of the driven wheel after wear occurs.

[0054] Suppose the total length of the aisles in a certain automated warehouse is 50000mm, the distance L0 between positions A and B of the ground-mounted magnets is 40000mm, and the initial diameter R0 of the stacker crane's traveling wheels is 400mm; the origin deviation error range W0 is set to 5mm, and the allowable range W1 for deviations in the distance between A and B due to wear of the stacker crane's traveling wheels is 10mm. Before use, the position of point A is set to 0, the position of point B is set to 40000, the distance from point A to the first column of the rack is X1=1000, the distance to the second column is X2=2000, ..., the distance to the nth column is X... n During the operation of =n*1000, when the stacker crane performs position verification, if it finds that the position value is not 0 when passing point A and the error exceeds W0, it will reset to zero. That is, when the stacker crane passes point A, the current position will be changed and recorded as 0 again. When measuring the distance between A and B, L1 = 40011mm, i.e., L1 - L0 = 40011 - 40000 = 11, which is greater than the allowable error W1 (10mm). At this time, the warehouse location data needs to be recalculated, and the deviation rate σ = L n / L0=40011 / 40000=.000275, then the updated shelf location data X 11 = X1*(1+σ)=1000*1.000275=1000.275,X 12 = X2*(1+σ)=1000*1.000275=1000.275…and so on to calculate other shelf location data;

[0055] During operation, an 11mm deviation occurred, meaning the calculated distance between A and B was 40011mm. The traveling wheel rotated 31.839742 times, with a deviation of 11mm / 31.839742≈0.34548mm per rotation. The wear on the traveling wheel diameter was 0.34548 / 3.1415926≈0.11mm. Based on the above hypothetical case, this invention can detect a wear of 0.11mm on the traveling wheel diameter. This wear is compared with M0. If it exceeds the limit, the wheel is replaced; otherwise, it continues to be used. When continuing to use the wheel, the controller records the new shelf position and recalculates the required number of traveling wheel rotations before transmitting the calculation to the drive motor. The drive motor then drives the traveling wheel to the corresponding position.

[0056] In this invention, all deviation ranges are determined based on actual usage requirements, as well as specific products and usage environments. Detection accuracy can be improved by reducing errors.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A stacker crane travel positioning method, characterized in that: The stacker crane adopts a walking and positioning structure, which includes: The traveling wheels are located at the lower end of the stacker crane. The traveling wheels include a driving wheel and a driven wheel that is linked to it. A drive motor is connected to the rotating shaft of the driving wheel. An encoder is mounted on the rotating shaft of the driven wheel and is used to detect the number of rotations of the driven wheel; The controller has its input terminal connected to the output terminal of the encoder to receive information data from the encoder, and its output terminal connected to the input terminal of the drive motor. A reed switch is installed on the side wall of the stacker crane. Magnetic bodies with magnetic fields are installed at both ends of the stacker crane's travel track. The output end of the reed switch is connected to the input end of the controller, which can confirm that the stacker crane is running and has passed the end position of the track. Stacker crane travel positioning methods should include at least the following: S1. Before initial use, record the initial diameter R0 of the driven wheel. Perform position verification by running the stacker crane at a constant speed along both ends of the magnetic object on the travel track, and record the positions of the magnetic objects as follows: Point A, Position X. a0 and point B's position X b0 And calculate the position X of point A. a0 and point B's position X b0 The initial difference between them is L0; S2. Using the same calculation method as in S1, calculate and record the position data of the shelves on one side of the track. Take point A as the base point. The distance from point A to the first column of shelves is X1, the distance to the second column is X2, and so on until the nth column is X... n ; S3. During operation, the stacker crane performs a position check at fixed intervals, runs on the track at a constant speed, and the controller records the displayed value X when passing points A and B. an and X bn And calculate the distance L between points A and B at this time. n ; S4. Set the origin deviation range W0, i.e., |X a0 -X an If the value of | is not greater than W0, then the position data of point A will not be adjusted; otherwise, if | X a0 -X an If the value of | is greater than W0, then when the stacker crane is at position A, the value displayed on the controller will be adjusted to X. a0 ; S5. Set the distance deviation range W1, when |L n If the value of L0| is not greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn; otherwise, if |L0| is greater than W1, the controller assumes that the stacker crane's traveling wheels are not worn. n If the value of -L0| is greater than W1, the controller considers that there is a wear problem with the stacker crane's traveling wheels; and determines the deviation rate σ=L based on Ln and L0. n / L0, and re-label and record the position data of the shelves on one side of the track, using point A as the base point, and the distance from point A to the first column of shelves as X. 11 = X1*(1+σ) Distance to the second shelf X 12 = X2*(1+σ)… The distance to the nth shelf is X 1n = X n *(1+σ) S6. Calculate the wear amount M1 of the travel wheel diameter, limit the deviation range M0 of the wear amount, and compare them. If M1 is greater than M0, replace the travel wheel; otherwise, proceed to the next step. S7, The controller, based on the recalculated data X 11 X 12 …X 1n The number of rotations required for the driven wheel at the positions of the first, second, and Nth shelves is recalculated based on the initial diameter of the driven wheel. n This information is then transmitted to the drive motor.

2. A stacker crane travel positioning method according to claim 1, characterized in that: The method for calculating the wear of the walking wheels in S6 is as follows: L in S3 n Dividing by the circumference of the driven wheel equals the number of revolutions N0 of the driven wheel from point A to point B, in S5 | L n The value of -L0| divided by N0 equals the deviation W2 that occurs per revolution, and W2 divided by pi equals the wear amount M1 of the driven wheel diameter.

3. The stacker crane travel positioning method according to claim 1, characterized in that: The connection between the input terminal of the reed switch and the output terminal of the controller is a dry connection, while the connection between the output terminal of the encoder and the input terminal of the controller is a communication connection.

4. The stacker crane travel positioning method according to claim 1, characterized in that: The encoder is an absolute encoder, and the encoder pulses are quadruple frequency pulses.

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