JP6444243B2 - Transport device - Google Patents

Description

  The present invention relates to a transfer device used in a warehouse, a factory, or the like.

  In factories that manufacture electronic devices and distribution centers that handle daily necessities, sundries, foods, and the like, conveying devices that automatically carry in, carry out, and move articles are used. As such a conveying device, a stacker crane is used that drives a servo motor by feedback control to move an article in a horizontal direction and a vertical direction to convey the article to a target position.

  Since the stacker crane has a mast extending in the vertical direction, the mast vibrates due to a change in speed in the horizontal direction from the start to the stop of the movement of the article, which may affect the conveyance of the article. As a vibration suppression control that suppresses vibration caused by such a speed change, for example, there is a control method in which a predetermined constant speed period is provided during acceleration and deceleration of the stacker crane (see, for example, Patent Document 1).

JP 2009-23769 A

  If a constant speed period is provided during acceleration and deceleration of the stacker crane, the time required for acceleration and deceleration becomes long, and the conveyance time required for moving the article to the target position becomes long. If vibration suppression control is not performed, it may be possible to shorten the time taken to move the article, but it may be necessary to wait for the article to be unloaded until the vibration during stoppage is alleviated, which may increase the overall conveyance time. Absent. Therefore, it is desirable that the article can be conveyed in a shorter time while performing vibration suppression control.

  SUMMARY An advantage of some aspects of the invention is to provide a conveyance device that can convey an article in a shorter time.

  A conveying device according to an aspect of the present invention includes a traveling carriage that is movable in the horizontal direction, a traveling motor that moves the traveling carriage, a lifting platform that is movable in a vertical direction along a mast fixed to the traveling carriage, Based on the vibration suppression control unit that determines the parameter value used for filtering according to the loading state of the lifting platform, including the vibration suppression filter that filters the position command value that specifies the position of the carriage, and the filtered position command value And a travel control unit that outputs a first torque command value for driving the travel motor.

  According to an aspect of the present invention, an article can be conveyed in a shorter time.

It is a figure which shows the conveyance system which concerns on embodiment. It is a control block diagram regarding operation | movement of a stacker crane.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  FIG. 1 is a diagram showing a transport system 1 according to the present embodiment. The transport system 1 includes a stacker crane 10 that is a transport device, and a ground control panel 40 that controls the stacker crane 10.

  The stacker crane 10 includes a traveling rail 12, a traveling carriage 14, a traveling device 16, a mast 18, a lifting platform 20, a lifting device 22, a fork platform 24, an onboard control panel 30, and an optical communication device 32. The traveling rail 12 is laid along the rack 8 installed on the ground. The traveling carriage 14 is movable along the traveling rail 12. Hereinafter, the horizontal direction in which the traveling rail 12 extends is defined as the X direction, the vertical direction is defined as the Z direction, and the direction from the traveling rail 12 toward the rack 8 is defined as the Y direction.

  The traveling device 16 controls traveling of the traveling carriage 14 based on a control command from the ground control panel 40. The mast 18 is installed on the traveling carriage 14 and moves along the traveling rail 12 together with the traveling carriage 14. The lifting platform 20 is attached to the mast 18 so as to be movable in the vertical direction (Z direction). The lifting device 22 changes the position of the lifting platform 20 based on a control command from the ground control panel 40.

  The elevator 20 has a brake for temporarily fixing the vertical position. The lifting device 22 operates a brake when the vertical position of the lifting platform 20 is fixed, and releases the brake when starting the movement of the lifting platform 20. The lifting device 22 controls the position of the lifting platform 20 while preventing the lifting platform 20 from falling when the brake is released.

  The fork stand 24 is provided to place a load (not shown) on the rack 8 or take out the load from the rack. The fork base 24 is attached to the lift base 20 so as to be movable in the Y direction. The position of the fork base 24 is also controlled in the Y direction based on a control command from the ground control panel 40. In addition, the stacker crane 10 includes a camera and various sensors (not shown).

  Each of the stacker crane 10 and the ground control panel 40 includes optical communication devices 32 and 42, and transmits a control command from the ground control panel 40 to the stacker crane 10 through optical communication. The control command received by the optical communication device 32 is input to the onboard control panel 30, and the onboard control panel 30 controls the traveling device 16, the lifting device 22 and the like based on the control command from the ground control panel 40. . The onboard control panel 30 transmits an acknowledgment of receipt of a control command, a notification of completion of the command, and the like to the ground control panel 40 via optical communication.

  FIG. 2 is a control block diagram relating to the operation of the stacker crane 10. The stacker crane 10 receives a first position command value Xa that specifies the position of the traveling carriage 14 and a second position command value Za that specifies the position of the elevating device 22 as control commands from the ground control panel 40. The stacker crane 10 mainly controls the operations of the traveling device 16 and the lifting device 22 with the first position command value Xa and the second position command value Za as inputs.

The traveling device 16 includes a first drive unit 52, a traveling motor 54, and a first encoder 56. The first drive unit 52 is, for example, a servo driver, and drives the travel motor 54 based on the first torque command value T ₁ output from the travel control unit 70. The first encoder 56 detects the driving state of the traveling motor 54 and transmits signals necessary for calculating the horizontal position _Xr and the traveling speed V _r1 of the traveling carriage 14 to the traveling control unit 70.

The lifting device 22 includes a second driving unit 62, a lifting motor 64, and a second encoder 66. The second drive unit 62 is, for example, a servo driver, and drives the travel motor 54 based on the second torque command value T ₂ output from the elevation control unit 90. The second encoder 66 detects the driving state of the lifting motor 64 and transmits signals necessary for calculating the vertical position _Zr and the lifting speed _Vr2 of the lifting device 22 to the lifting control unit 90.

  The stacker crane 10 includes a travel control unit 70, a lift control unit 90, and a vibration suppression control unit 110. The traveling control unit 70 is mounted on the onboard control panel 30, for example, and the elevation control unit 90 and the vibration suppression control unit 110 are mounted. In the modified example, the traveling control unit 70 may be included in the traveling device 16, and the lifting control unit 90 may be included in the lifting device 22.

The elevation controller 90 includes a second position controller 92, a second speed controller 94, a second position detector 96, a second speed detector 98, a subtracter 100, and a subtracter 102. The second position detector 96 calculates the vertical position Z _r of the elevator platform 20 by using a signal from the second encoder 66. The second speed detector 98 calculates the lifting speed V _r2 of the lifting platform 20 using the signal from the second encoder 66.

The second position controller 92, the difference between the vertical position Z _r and a second position command value Za generates a second velocity command value V ₂ to be eliminated. A subtracter 100 is provided at the input of the second position controller 92. Subtractor 100 inputs the difference obtained by subtracting the vertical position Z _r from the second position command value Za in the second position controller 92.

The second speed controller 94, the difference between the second speed command value V ₂ and the elevating velocity V _r2 to generate a second torque command value T ₂ as is eliminated. A subtracter 102 is provided at the input of the second speed controller 94. The subtractor 102 inputs a value obtained by subtracting the lifting speed V _r2 from the second speed command value V ₂ to the second speed controller 94. The generated second torque command value T ₂ is output to the lifting device 22.

The vibration suppression control unit 110 includes a vibration suppression filter 112, a speed feedforward unit 114, a torque feedforward unit 116, and a parameter determination unit 120. The damping filter 112 multiplies the first position command value Xa by the transfer function G ₁ = (P ₁ / P ₂ ) M, and filters the first position command value Xa. The transfer function G ₁ can be expressed as a reference model × anti-resonance, and can be realized by a combination of a notch filter and a phase advance filter.

Here, P ₁ is a transfer function having the first torque command value T ₁ as an input and the horizontal position _Xr of the traveling carriage 14 as an output. The P ₂ are a first torque command value T ₁ as input, the horizontal position of the elevation frame 20, that is, transfer function and outputting a vibration amplitude of the mast 18. The transfer functions P ₁ and P ₂ can be described, for example, by modeling the traveling carriage 14, the mast 18, and the lifting platform 20 using a two-inertia vibration system model in which two objects are connected via a spring. . At this time, P ₁ can be expressed as second order integral × antiresonance × resonance, and P ₂ can be expressed as second order integral × resonance. However, the model describing the stacker crane 10 and the transfer functions P ₁ and P ₂ are not particularly limited, and can be realized using other models.

  The parameter M is a reference model. When the stacker crane 10 is represented by a two-inertia vibration system model, it is described by a second-order lag system. The value of the parameter M is a value determined by the weight of the traveling carriage 14, the mast 18, and the lifting platform 20 and the weight of the luggage loaded on the lifting platform 20. In the present embodiment, the value of the parameter M is dynamically determined by the parameter determination unit 120 described later.

The speed feedforward unit 114 differentiates the filtered position command value Xb to generate a speed feedforward value _Vf . The generated speed feedforward value V _f is added to the first velocity command value V ₁ generated by the travel control unit 70.

The torque feedforward unit 116 multiplies the first position command value Xa by the transfer function G ₂ = (1 / P ₂ ) M to generate a torque feedforward value _Tf . The transfer function G ₂ is expressed using the above-described transfer function P ₂ and the parameter M, and can be expressed by, for example, reference model × resonance inverse characteristic × second-order pseudo differentiation. The generated torque feedforward value T _f is added to the torque command value T _c generated by the travel control unit 70, is reflected in the first torque command value T _1.

Parameter determination unit 120 uses the second torque command value T ₂ output from the elevation controller 90 to the elevating device 22, it determines the parameters M to be used in the vibration damping filter 112 and torque feedforward section 116. The parameter M can be a value that is optimal for vibration suppression control according to the weight of the load loaded on the lifting platform 20. Parameter determination unit 120, by the load on the elevating motor 64 from the second torque command value T ₂ is estimated, estimates the weight of the load to be stacked on the elevator platform 20 from the motor load, the loading state of the elevator platform 20 The value of the corresponding parameter M is calculated.

When the lifting platform 20 is stopped by the driving force of the lifting motor 64, the output of the lifting motor 64 is a work rate for supporting the total weight of the lifting platform 20 including luggage, power loss of the lifting motor 64, This is in proportion to the value obtained by adding mechanical loss such as friction of the device 22. Since the addition weight of the load is previously can be grasped values, by acquiring the second torque command value T ₂ which is output to the time of stopping the elevator platform 20, estimate the weight of the elevation frame 20 in consideration of the loading state Thus, the optimum value of the parameter M can be calculated. The second torque command value T ₂ used for determining the parameter M is output when the brake is released before the movement of the lifting platform 20 is started and the lifting platform 20 is supported and stopped by the driving force of the lifting motor 64. It is calculated with reference to the second torque command value T ₂ that.

The parameter determination unit 120 calculates the parameter M according to the magnitude of the second torque command value T ₂ by using the function f that satisfies the relational expression of M = f (T ₂ ). This function f is determined in advance using the weight of the lifting platform 20, the power loss and the mechanical loss of the lifting device 22, and is stored in the parameter determination unit 120.

The parameter determination unit 120 may round the value of the parameter M by incorporating a filter in the function f (T ₂ ). Also, previously preparing a plurality of fixed value as a parameter M, to determine the value of the parameter M by referring to a table storing relationships between the fixed value and the magnitude of the second torque command value T ₂ of the parameters M May be. For example, providing a value of three stages as a fixed value for the parameter M, the value of the parameter M may be switched stepwise according to the magnitude of the second torque command value T _2.

The travel control unit 70 includes a first position controller 72, a first speed controller 74, a first position detector 76, a first speed detector 78, a subtracter 80, an adder / subtractor 82, and an adder 84. The first position detector 76 calculates the horizontal position _Xr of the traveling carriage 14 using the signal from the first encoder 56. The first speed detector 78 calculates the traveling speed V _r1 of the traveling carriage 14 using the signal from the first encoder 56.

The first position controller 72 receives the first speed command value V so that the difference between the position command value Xb filtered by the damping filter 112 and the horizontal position _Xr calculated by the first position detector 76 is eliminated. ₁ is generated. A subtracter 80 is provided at the input of the first position controller 72. Subtracter 80 inputs the difference obtained from the filtered position command value Xb subtracts the horizontal position X _r in the first position controller 72.

The first speed controller 74 eliminates the difference between the speed command value obtained by adding the speed feedforward value V _f to the first speed command value V ₁ and the traveling speed V _r1 calculated by the first speed detector 78. Thus, the torque command value _Tc is generated. The input of the first speed controller 74 subtractor 82 is provided, adder-subtracter 82, the first speed command value V ₁ by adding the speed feedforward value Vf, obtained by subtracting the running speed V _r1 The value is input to the first speed controller 74.

The adder 84 generates a first torque command value T ₁ by adding the torque feed forward value T _f to the torque command value T _c of the first speed controller 74 generates. The generated first torque command value T ₁ is output to the traveling device 16.

Next, the operation of the stacker crane 10 according to the present embodiment will be described.
The stacker crane 10 loads a load on the lifting platform 20 at the position of the transfer source. The lifting device 22 releases the brake of the lifting platform 20 before starting the movement of the lifting platform 20 and temporarily stops the lifting platform 20 by the driving force of the lifting motor 64. Damping control unit 110 obtains the lifting platform second torque command value T ₂ which is output when stopping 20 determines the parameter M, filtering the first position command value Xa based on the determined parameter M. Travel control unit 70 outputs a first torque command value T ₁ based on the filtered position command value Xb, it moves the traveling vehicle 14 to the position of the transport destination.

  According to the present embodiment, the first position command value Xa from the ground control panel 40 is filtered by the damping filter 112. Therefore, even when the first position command value Xa including the frequency component that is the natural frequency of the stacker crane 10 is input, the traveling carriage 14 is caused to travel and be stopped so as to suppress the vibration of the stacker crane 10. be able to. Moreover, the effect of vibration suppression can be further enhanced by the speed feedforward by the speed feedforward unit 114 and the torque feedforward by the torque feedforward unit 116.

  Further, according to the present embodiment, since the parameter M of the vibration suppression filter 112 is optimized according to the loading state of the lifting platform 20, vibration suppression control suitable for the loading weight of the lifting platform 20 can be realized. If the parameter M is a fixed value, the vibration is not appropriately suppressed unless the load weight corresponds to the parameter M, and the next operation must be waited until the vibration generated when the traveling carriage 14 stops is settled. As a result, it is necessary to design the operation of the stacker crane 10 in consideration of the longest shaking time until the vibration is settled. In this case, even if the vibration is not so large, the next operation is performed after waiting for the longest shaking time, which hinders shortening of the conveyance time.

  On the other hand, according to the present embodiment, the vibration suppression control parameter M is dynamically changed according to the loading weight of the lifting platform 20, so that the time until the vibration is reduced is shortened even if the loading weight changes. Can do. Thereby, shortening of conveyance time is realizable. In addition, by realizing the vibration suppression control according to the loaded weight, it is possible to suppress the vibration while reducing the rigidity of the stacker crane 10. By reducing the rigidity of the stacker crane 10 to reduce the weight, the manufacturing cost of the stacker crane 10 can be reduced, and the amount of electric power necessary for the operation of the stacker crane 10 can be reduced.

Further, according to this embodiment, for determining the parameters M by using the second torque command value T ₂ which is output to the elevator unit 22, loading without providing a separate weighing scale in elevation frame 20 and the traveling carriage 14 The weight can be estimated. In addition, since the parameter M is determined using a state where the elevator 20 is temporarily stopped immediately before the movement of the elevator 20, it is necessary to determine the parameter M without adding an additional operation to a series of transfer processes. Information can be obtained.

  In the above, this invention was demonstrated based on the Example. It is understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, and various modifications are possible, and such modifications are within the scope of the present invention. It is a place.

  In the above-described embodiment, the vibration suppression control is realized by the combined use of filtering by the vibration suppression filter 112 and feedforward. In the modification, only the damping filter 112 may be used, or the stacker crane 10 may be configured using a combination of the damping filter 112 and the speed feedforward unit 114 or a combination of the damping filter 112 and the torque feedforward unit 116. You may suppress the vibration of.

DESCRIPTION OF SYMBOLS 10 ... Stacker crane, 14 ... Traveling cart, 18 ... Mast, 20 ... Lifting table, 54 ... Traveling motor, 64 ... Lifting motor, 70 ... Traveling control unit, 90 ... Lifting control unit, 110 ... Damping control unit, 112 ... Damping filter, T _1, first torque command value, T _2, second torque command value, M, parameter.

Claims (5)

A traveling cart that can move horizontally,
A travel motor for moving the travel carriage;
A lifting platform movable in a vertical direction along a mast fixed to the traveling carriage;
A damping control unit that includes a damping filter that filters a position command value that specifies a position of the traveling carriage, and that determines a parameter value used for the filtering according to a loading state of the lifting platform;
And a travel control unit that outputs a first torque command value for driving the travel motor based on the filtered position command value. A lifting motor for moving the lifting platform;
The said vibration suppression control part determines the value of the said parameter according to the load of the said raising / lowering motor, The conveying apparatus of Claim 1 characterized by the above-mentioned. An elevating control unit that outputs a second torque command value for driving the elevating motor;
The said vibration suppression control part determines the value of the said parameter using the magnitude | size of a said 2nd torque command value, The conveying apparatus of Claim 2 characterized by the above-mentioned. The vibration suppression control unit is output when the lifting / lowering table brake is released and the lifting / lowering motor is stopped in the vertical direction by the driving force of the lifting / lowering motor before the movement of the lifting / lowering table is started. The transport device according to claim 3, wherein the parameter value is determined using a magnitude of the second torque command value. Transfer function G of the damping filter ₁ Is a first transfer function P having the first torque command value of the traveling motor as an input and the horizontal position of the traveling carriage as an output. ₁ The second transfer function P having the first torque command value of the traveling motor as an input and the horizontal position of the elevator as an output. ₂ , Using the normative model M when the transfer device is described by a two-inertia vibration system model, ₁ = (P ₁ / P ₂ ) M,
The vibration suppression control unit determines a value of the reference model M as the parameter according to a loading state of the lifting platform, and uses the determined value of the reference model M to specify a position of the traveling carriage 5. The transport apparatus according to claim 1, wherein the value is filtered.

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