A shuttle positioning method based on encoder and hole counting

Abstract

The present application belongs to the field of factory logistics and storage, and particularly relates to a shuttle positioning method based on an encoder and hole counting. Specifically, a hole position is arranged on each column of racks where the shuttle is located, each hole position corresponds to a coordinate, and a preset position value of the coordinate is stored in an array Row[]. When the shuttle starts positioning operation, the preset position value Row[n] of the target position is written into a target position value Pos_target of a servo controller, and a compensation algorithm is used to compensate the actual walking path of the shuttle, and the servo controller controls the shuttle to reach the target position according to the compensation amount. The shuttle positioning method based on the encoder and hole counting provided by the present application is convenient to install and debug, has a high cost performance, overcomes the influence of the slipping of the walking wheels on the walking performance, achieves good control performance, simplifies the device, and improves the flexibility and robustness of the system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of factory logistics and storage, in particular to a shuttle positioning method based on an encoder and hole counting. BACKGROUND

[0002] The multi-layer shuttle-to-goods system has the advantages of low energy consumption, high efficiency, flexible layout, high cost performance, etc. After years of technical accumulation, the technology has become very mature and is increasingly favored by customers.

[0003] Under the premise of reducing the manufacturing cost of the shuttle, how to improve the performance of the shuttle has become a problem faced by various equipment suppliers. As the length of the multi-layer shuttle three-dimensional warehouse design is getting larger and larger, the walking performance requirements of the shuttle are getting higher and higher, and how to provide a walking control mode with higher cost performance is becoming more and more important.

[0004] Although the shuttle has the advantages of low energy consumption, high efficiency, flexible layout, high cost performance, etc., there are interference factors such as machining errors and slipping between the wheels and the track in the actual use process, which will seriously affect the control performance and repeatability. SUMMARY

[0005] The shuttle positioning method based on the encoder and hole counting provided by the application well solves the influence of the above factors and achieves good control effect in actual use.

[0006] The technical scheme adopted by the application to achieve the above purpose is:

[0007] A shuttle positioning method based on an encoder and hole counting, specifically: a hole position is arranged on each column of racks where the shuttle is located, each hole position corresponds to a coordinate, and the preset position value of the coordinate is stored in an array Row[], the preset position value corresponding to the nth column is Row[n], when the shuttle starts positioning operation, the preset position value Row[n] of the target position is written into the target position value Pos_target of the servo controller, and a compensation algorithm is used to compensate the actual walking path of the shuttle, and the servo controller controls the shuttle to reach the target position according to the compensation amount.

[0008] The compensation algorithm includes the following steps:

[0009] The actual slipping amount of the shuttle from the nth column to the n+1th column is calculated;

[0010] The absolute value of the actual slipping amount is compared with the allowed slipping amount δ1, if it is greater than δ1, it is abnormal slipping, and the shuttle is repaired; otherwise, it is normal slipping, the target position value is revised, and the revised value is written into the servo controller;

[0011] When the shuttle vehicle reaches the target position, the distance of the total travel is checked, and the deviation value obtained by the checking is compared with the total slip δ2, if greater than δ2, the slip of the total travel is out of tolerance, and the shuttle vehicle is maintained, otherwise it is normal slip.

[0012] The actual slip γ-η is specifically:

[0013] γ-η=(Pos_Actual-POS1)-(Row[n+1]-Row[n])

[0014] Wherein, γ represents the actual rotation distance of the train wheel from the nth column to the n+1th column, η represents the distance between the nth column and the n+1th column, Pos_Actual represents the real-time position value of the encoder at the n+1th column; POS1 represents the real-time position value of the encoder at the nth column; Row[n] represents the preset position value of the nth column.

[0015] The revision of the shuttle vehicle is specifically:

[0016] Pos_target=Pos_target+(γ-η).

[0017] The deviation value obtained by the checking is specifically:

[0018] Pos_target-ρ-Row(target)

[0019] Wherein, ρ represents the cumulative slip when passing through each column, and Row(target) represents the hole distance between the starting position and the target position of the shuttle vehicle.

[0020] The present application has the following beneficial effects and advantages:

[0021] The shuttle vehicle positioning method based on the encoder and the hole counting provided by the application has the advantages of convenient installation and debugging, high equipment cost performance, overcoming the influence of the walking wheel slip on the walking performance, achieving good control performance, simplifying the device, and improving the system flexibility and robustness. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a hardware structure diagram of the shuttle vehicle walking control;

[0023] Figure 2 It is a hole address recognition principle diagram of the shuttle vehicle;

[0024] Figure 3 It is a position compensation algorithm;

[0025] Figure 4 It is a shuttle vehicle walking speed curve. DETAILED DESCRIPTION

[0026] The application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] As shown in the drawings, Figure 1 The shuttle vehicle walking mechanism is composed of a servo motor, an encoder, a servo controller, a PLC and a photoelectric switch.

[0028] The shuttle vehicle walking adopts a position closed-loop control mode, and the target position value of the servo controller can be changed in real time during positioning.

[0029] The PLC corrects the target position value sent to the servo controller in real time according to the position information returned by the encoder and the number of holes calculated based on the photoelectric switch, so that the shuttle vehicle walking realizes position closed-loop control and improves the running performance of the shuttle vehicle.

[0030] As shown in the drawings, Figure 1 Two photoelectric sensors with background suppression function are installed on the shuttle vehicle, and two high-level rising edge output signals are provided when the two sensors pass through each hole.

[0031] As shown in the drawings, Figure 2 If photoelectric 1 has a high-level signal before photoelectric 2 has a high-level signal during the running of the shuttle vehicle, it can be judged that the shuttle vehicle is running in the forward direction, and the hole count n (column value) of the shuttle vehicle at present should be increased by 1. Conversely, if photoelectric 2 has a high-level signal before photoelectric 1 has a high-level signal, it can be judged that the shuttle vehicle is running in the reverse direction, and the hole count n (column value) of the shuttle vehicle at present should be reduced by 1. In this way, the column value n corresponding to the current shuttle vehicle can be accurately calculated.

[0032] The shuttle vehicle walking adopts a position closed-loop mode control. The target position value of the servo controller can be changed in real time during positioning. The encoder installed at the tail of the motor can provide the walking distance and linear speed of the walking wheel.

[0033] Each hole on the rack where the shuttle vehicle is located corresponds to a unique coordinate, and the preset position value corresponding to the coordinate is stored in the array Row[]. The preset position value corresponding to the nth column is Row[n]. When starting the positioning operation, the preset position value Row[n] of the target position is written into the target position value Pos_target of the servo. Due to the problem of slippage between the wheel and the track during walking, the actual driving distance of the shuttle vehicle is less than the linear distance of the walking wheel rotation. In order to solve this problem, the application introduces a walking track compensation algorithm.

[0034] The compensation algorithm is as shown in the drawings, Figure 3 First, the actual slippage from the nth column to the nth+1 column is calculated

[0035] γ-η = (Pos_Actual-POS1)-(Row[n+1]-Row[n])

[0036] 1.γ is the actual distance the wheel rotates from column n to column n+1

[0037] 2.η The distance between the nth hole and the n+1th hole

[0038] 3.Pos_Actual The real-time position value of the car encoder at the n+1th column

[0039] 4. Real-time position value of the trolley encoder at POS1 column n

[0040] 5.Row[n] preset position value of the nth column

[0041] Compare the absolute value of the actual slip with the allowable slip δ1. If it is greater than δ1, it is considered abnormal slip, and the photoelectric switch or travel wheel needs to be repaired. If it is less than δ1, it is considered normal slip. In this case, the target position value Pos_target = Pos_target + (γ - η) needs to be revised and the revised value should be written to the servo.

[0042] After the travel position loop positioning is completed, the total travel distance needs to be verified. The specific formula is as follows

[0043] Pos_target-ρ-Row(target)>δ2

[0044] 1.Pos_target sends the target position value to the servo

[0045] 2.ρ The accumulated slippage when passing each column

[0046] 3. Row (target) hole distance between the starting position and the target position

[0047] 4.δ2 deviation

[0048] When the deviation exceeds δ2, it is considered that the slippage of the total stroke is out of tolerance and an alarm is required.

[0049] like Figure 4 As shown in the figure, there is an actual distance difference offset between the target position value Pos_target sent to the servo and the target hole, which can eliminate the influencing factors such as cargo weight difference, cumulative error and manufacturing tolerance.

Claims

1. A shuttle positioning method based on encoder and hole counting, characterized in that: Specifically, a hole position is arranged on each column of the rack where the shuttle vehicle is located, each hole position corresponds to a coordinate, and a preset position value of the coordinate is stored in an array Row[], the preset position value corresponding to the nth column is Row[n], when the shuttle vehicle starts positioning operation, the preset position value Row[n] of the target position is written into a target position value Pos_target of a servo controller, a compensation algorithm is used to compensate an actual walking path of the shuttle vehicle, and the shuttle vehicle reaches the target position according to the compensation amount controlled by the servo controller; two photoelectric sensors are installed on the shuttle vehicle; The compensation algorithm comprises the following steps: an actual slip amount of the shuttle vehicle from the nth column to the n+1th column is calculated; an absolute value of the actual slip amount is compared with an allowed slip amount δ1, if the absolute value is greater than δ1, it is an abnormal slip, and the shuttle vehicle is maintained; otherwise, it is a normal slip, the target position value is revised, and the revised value is written into the servo controller; after the shuttle vehicle reaches the target position, distance verification of a total travel is performed, and a deviation value obtained through the verification is compared with a total slip amount δ2, if the deviation value is greater than δ2, the total travel slip amount is out of tolerance, and the shuttle vehicle is maintained; otherwise, it is a normal slip; the revision of the shuttle vehicle is specifically: Pos_target =Pos_target+(γ-η); the actual slip amount γ-η is specifically: γ-η=(Pos_Actual-POS1)-(Row[n+1]-Row[n]) wherein γ represents an actual rotation distance of a wheel of the shuttle vehicle from the nth column to the n+1th column, η represents an interval between the nth column and the n+1th column, Pos_Actual represents a real-time position value of an encoder at the n+1th column, POS1 represents a real-time position value of the encoder at the nth column, and Row[n] represents the preset position value of the nth column; the deviation value obtained through the verification is specifically: Pos_target-ρ-Row(target) wherein ρ represents a cumulative slip amount when passing through each column, and Row(target) represents a hole distance between a starting position and a target position of the shuttle vehicle.

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