Patent Description:
An example of such a stacker crane control system is disclosed in <CIT>. Hereinafter, in "Description of the Related Art", the reference numerals and names in <CIT> are cited in parentheses.

The stacker crane control system of <CIT> detects parameters that affect swaying of a stacker crane (<NUM>) before the stacker crane (<NUM>) stops, and estimates, based on the detected parameters, a swaying state that the stacker crane (<NUM>) will enter after it is stopped. Then, the stacker crane control system determines the waiting time until the estimated swaying state has an allowable swaying amount or less, and controls a transfer apparatus (fork apparatus (<NUM>)) to operate immediately once the waiting time has elapsed. Here, the weight of a lift (<NUM>) that includes an article (package (<NUM>)), and the lifting height of the lift (<NUM>) are used as the parameters that affect swaying of the stacker crane (<NUM>).

Furthermore, an article transport apparatus with an angle sensor for detecting the total sway amount of a lift mast is dislosed in <CIT>, this document discloses the preamble of claim <NUM>.

However, in the technique disclosed in <CIT>, the swaying state of the stacker crane that is used to determine the waiting time is merely theoretically estimated based on parameters such as the weight or the lifting height of the lift, and may be different from the actual swaying state. Also, if the actual swaying amount is greater than the estimated swaying amount, there may be cases where an article cannot be appropriately transferred. On the other hand, if a longer waiting time is set in order to avoid such a situation, the start of the article transfer operation will be delayed, and the operation efficiency of the stacker crane will be reduced.

Also, even if the actual swaying amount of the stacker crane is detected in order to avoid such situations, the swaying amount of the transfer apparatus varies according to the lifting height of the lift that varies with time, and thus a large number of sensors are required to detect the actual swaying amount along the entire height of the lift. In this case, an increase in the installation cost of the stacker crane is unavoidable.

Thus, there is a demand for realizing a technique that avoids an increase in the installation cost of a stacker crane, and can start a transfer operation at an appropriate time based on an actual swaying amount of the stacker crane.

According to the present disclosure, a stacker crane control system for controlling a stacker crane including: a travel carriage that travels along a travel route; a mast supported on the travel carriage in an orientation along a vertical direction; a lift that moves up and down within a predetermined lifting range along the mast; a lifting apparatus that raises and lowers the lift; and a transfer apparatus supported by the lift and including a holding unit for holding an article, the stacker crane being configured to perform a transfer operation of transferring the article between the holding unit and a transfer destination, the stacker crane control system including: a sway detection unit configured to detect a reference swaying amount that is a swaying amount of the mast at a detection height, the detection height being set greater than or equal to the height of a lowermost part of the transfer apparatus when the lift is located at an upper limit of the lifting range; a lifting height acquiring unit configured to acquire lifting height information that indicates a lifting height, which is the height of the lift, at a plurality of points in time; and a transfer control unit configured to control the transfer apparatus, wherein the transfer control unit converts the reference swaying amount detected by the sway detection unit into a lifting height swaying amount that is a swaying amount of the mast at the lifting height indicated by the lifting height information, and starts the transfer operation of the transfer apparatus if the lifting height swaying amount is stably smaller than or equal to a predetermined determination threshold.

According to the present configuration, it is possible to obtain a lifting height swaying amount that is a swaying amount of the mast at the actual lifting height, based on an actual swaying amount of the mast that is detected by the sway detection unit, and an actual lifting height of the lift at each point in time that is acquired by the lifting height acquiring unit. Then, if the lifting height swaying amount is stably smaller than or equal to a predetermined determination threshold, the transfer operation of the transfer apparatus is started. Since the transfer operation is started in this way based on a detection result of the actual swaying amount of the mast, the transfer operation of the transfer apparatus can be started at an appropriate time according to the actual swaying amount of the mast that varies depending on various operation conditions.

Further features and advantages of the stacker crane control system will become apparent from the following description of embodiments given with reference to the drawings.

Embodiments of a stacker crane control system will be described with reference to the drawings, wherein.

The following will describe a first embodiment of a stacker crane control system with reference to the drawings (<FIG>). The description is given taking an example where the stacker crane control system according to the present disclosure is applied to an article transport facility as exemplified in <FIG>. Note that, in the present embodiment, a control system <NUM> corresponds to the "stacker crane control system".

As shown in <FIG>, a stacker crane <NUM> that is controlled by the control system <NUM> (see <FIG>) includes a travel carriage <NUM>, masts <NUM>, a lift <NUM>, a lifting apparatus <NUM>, and a transfer apparatus <NUM>. The travel carriage <NUM> travels along a travel route <NUM>. The travel operation of the travel carriage <NUM> is controlled by a later-described travel control unit <NUM> (see <FIG>). The travel control unit <NUM> controls driving of a travel drive unit (for example, an electric motor such as a servomotor) included in the travel carriage <NUM> so as to control the travel operation of the travel carriage <NUM>. Here, the longitudinal direction of the travel route <NUM> (direction in which the travel route <NUM> extends) is defined as the "route longitudinal direction L", and the width direction of the travel route <NUM> is defined as the "route width direction W'. The route width direction W refers to a direction that is orthogonal to both the route longitudinal direction L and a vertical direction V. In the present embodiment, the route longitudinal direction L corresponds to a "direction along the travel route".

As shown in <FIG>, the travel route <NUM> is formed of a travel rail <NUM>. The travel rail <NUM> is provided on a floor part <NUM> (see <FIG>). The travel carriage <NUM> includes travel wheels that roll on a travel surface of the travel rail <NUM>, and as a result of the travel wheels being driven to rotate by the travel drive unit, the travel carriage <NUM> travels along the travel rail <NUM>. Note that, in <FIG>, the stacker crane <NUM> is shown in a simplified manner, and the travel rail <NUM> provided on the floor part <NUM> and a later-described guide rail <NUM> provided on a ceiling part <NUM> are omitted.

As shown in <FIG> and <FIG>, the masts <NUM> are supported on the travel carriage <NUM> in an orientation along the vertical direction V. The masts <NUM> stand upright from the travel carriage <NUM> so as to extend upward from the travel carriage <NUM>. In the present embodiment, two masts <NUM> are supported on the travel carriage <NUM> while being lined up in the route longitudinal direction L. Upper end portions of the two masts <NUM> are coupled to each other by a connection part <NUM> such as an upper frame. The connection part <NUM> includes guide wheels that are guided by the guide rail <NUM> provided on the ceiling side such as the ceiling part <NUM>, and the connection part <NUM> moves in the route longitudinal direction L while being guided by the guide rail <NUM>.

The lifting apparatus <NUM> raises and lowers the lift <NUM>. The operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM> is controlled by a later-described lifting control unit <NUM> (see <FIG>). The lifting control unit <NUM> controls driving of a lifting drive unit (for example, an electric motor such as a servomotor) included in the lifting apparatus <NUM> so as to control the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM>. The lifting apparatus <NUM> raises or lowers the lift <NUM> by, for example, using driving by the lifting drive unit to rotate a wind-up drum on which a wire connected to the lift <NUM> is wound, so that the wire is wound up or unwound.

The lift <NUM> moves up and down in a predetermined lifting range E (see <FIG>) that extends along the masts <NUM>. The lift <NUM> moves up and down between an upper limit E1 and a lower limit E2 of the lifting range E. The lift <NUM> includes guide wheels that are guided by the masts <NUM>, and moves up and down along the masts <NUM> while being guided by the masts <NUM>. In the present embodiment, the lift <NUM> moves up and down in a state of being arranged between the two masts <NUM> lined up in the route longitudinal direction L. The lift <NUM> is suspended by a wire and moves up and down along the masts <NUM>.

The transfer apparatus <NUM> is supported by the lift <NUM>. As shown in <FIG> and <FIG>, the transfer apparatus <NUM> includes a holding unit <NUM> for holding an article <NUM>, and performs a transfer operation of transferring the article <NUM> between the holding unit <NUM> and a transfer destination <NUM>. When the transfer apparatus <NUM> is located at a position that corresponds to a transfer destination <NUM> (specifically, a position at which the transfer apparatus <NUM> faces the transfer destination <NUM> in the route width direction W) according to the travel operation of the travel carriage <NUM> and the operation of raising and lowering the lift <NUM>, the transfer apparatus <NUM> performs the transfer operation. In the present embodiment, the holding unit <NUM> supports the article <NUM> (specifically, a central portion of the article <NUM> in the route longitudinal direction L) from below to hold the article <NUM>. In other words, the article <NUM> is placed on and supported by the holding unit <NUM>. The operation performed by the transfer apparatus <NUM> to transfer the article <NUM> is controlled by a later-described transfer control unit <NUM> (see <FIG>). The transfer control unit <NUM> controls driving of a transfer drive unit (for example, an electric motor such as a servomotor) included in the transfer apparatus <NUM> so as to control the transfer operation of the transfer apparatus <NUM>.

In the present embodiment, the transfer apparatus <NUM> is configured to advance and retract the holding unit <NUM> in the route width direction W (advancing movement away from the lift <NUM>, and retracting movement toward the lift <NUM>). As a result of the operation performed by the transfer apparatus <NUM> to advance and retract the holding unit <NUM>, and the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM>, the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>. That is to say, in the present embodiment, the transfer operation of the transfer apparatus <NUM> is the operation of advancing and retracting the holding unit <NUM>, and through cooperation between the transfer apparatus <NUM> and the lifting apparatus <NUM> (specifically, by performing the operation of raising and lowering the lift <NUM> in accordance with the transfer operation of the transfer apparatus <NUM>), the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>.

Specifically, when transferring the article <NUM> from the holding unit <NUM> to the transfer destination <NUM>, the transfer apparatus <NUM> performs the transfer operation and the lifting apparatus <NUM> performs the operation of raising and lowering the lift <NUM>, such that the holding unit <NUM> that holds the article <NUM> is advanced from a retracted position (position at which the holding unit <NUM> is retracted to the lift <NUM>) to an advanced position (position at which the holding unit <NUM> is advanced to the transfer destination <NUM>), then the lift <NUM> is lowered, and then the holding unit <NUM> is retracted from the advanced position to the retracted position. With this, the article <NUM> is unloaded from the holding unit <NUM> to the transfer destination <NUM>, and thus the article <NUM> is transferred from the holding unit <NUM> to the transfer destination <NUM>. Also, when transferring the article <NUM> from the transfer destination <NUM> to the holding unit <NUM>, the transfer apparatus <NUM> performs the transfer operation and the lifting apparatus <NUM> performs the operation of raising and lowering the lift <NUM> such that the holding unit <NUM> not holding any article <NUM> is advanced from the retracted position to the advanced position, then the lift <NUM> is raised, and then the holding unit <NUM> is retracted from the advanced position to the retracted position. With this, the article <NUM> is scooped by the holding unit <NUM>, and thus the article <NUM> is transferred from the transfer destination <NUM> to the holding unit <NUM>.

As shown in <FIG>, an article transport facility <NUM> includes at least one storage rack <NUM>. The storage rack <NUM> is arranged in an orientation such that its rack width direction matches the route longitudinal direction L and its rack depth direction matches the route width direction W. The travel route <NUM> is provided on the front side of the storage rack <NUM> (on the side on which the article <NUM> is loaded to and unloaded from the storage rack <NUM>). The storage rack <NUM> includes a plurality of storage spaces <NUM> for storing articles <NUM>. The plurality of storage spaces <NUM> are arranged in multiple rows in the vertical direction V and multiple columns in the route longitudinal direction L. In the example shown in <FIG>, each article <NUM> is stored in a storage space <NUM> with its side portions in the route longitudinal direction L supported from below. In the example shown in <FIG>, the storage racks <NUM> are provided on both sides of the travel route <NUM> in the route width direction W. In the present embodiment, the storage spaces <NUM> are included in the transfer destination <NUM>. The storage spaces <NUM> serve as transfer destinations <NUM> set at a plurality of positions determined in the route longitudinal direction L and the vertical direction V.

The article transport facility <NUM> includes a support unit <NUM> for supporting an article <NUM> (in the example shown in <FIG>, a pair of support units <NUM> that face each other in the route width direction W with the travel route <NUM> interposed therebetween). The support unit <NUM> is used as a loading unit that supports an article <NUM> to be loaded to the storage rack <NUM>. Also, the support unit <NUM> is used as an unloading unit that supports an article <NUM> unloaded from the storage rack <NUM>. In the present embodiment, the support units <NUM> are included in the transfer destination <NUM>.

As shown in <FIG>, the control system <NUM> includes an operation control unit <NUM> for controlling the operation of the stacker crane <NUM>. The control system <NUM> includes, in addition to the operation control unit <NUM>, a sway detection unit <NUM>, a lifting height acquiring unit <NUM>, and a storage unit <NUM>, which will be described in detail later. The functions of the control system <NUM> (specifically, the functions of the sway detection unit <NUM>, the lifting height acquiring unit <NUM>, and the operation control unit <NUM>) are realized by cooperation between hardware such as an arithmetic processing unit, and a program executed on the hardware. The storage unit <NUM> includes, for example, a storage medium such as a flash memory or a hard disk.

The plurality of constituent components of the control system <NUM> are configured to be able to exchange information with each other. Note that the constituent components of the control system <NUM> shown in <FIG> are distinguished from each other at least logically, but do not need to be physically distinguished from each other. Also, the constituent components of the control system <NUM> may be provided on the stacker crane <NUM> (for example, on a device controller included in the stacker crane <NUM>) or may be provided independently from the stacker crane <NUM>. Some of the constituent components of the control system <NUM> may be provided on the stacker crane <NUM>, and the remaining constituent components of the control system <NUM> may be provided independently from the stacker crane <NUM>.

The operation control unit <NUM> includes the travel control unit <NUM>, the lifting control unit <NUM>, and the transfer control unit <NUM>. The travel control unit <NUM> controls the travel operation of the travel carriage <NUM>, the lifting control unit <NUM> controls the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM>, and the transfer control unit <NUM> controls the transfer operation of the transfer apparatus <NUM>. In the present embodiment, as a result of the transfer control unit <NUM> controlling the transfer operation of the transfer apparatus <NUM> and the lifting control unit <NUM> controlling the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM>, the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>.

In response to an instruction from a superordinate control unit or the like, the operation control unit <NUM> controls the stacker crane <NUM> to perform a loading operation of loading an article <NUM> into a storage space <NUM>, or an unloading operation for unloading an article <NUM> from a storage space <NUM>.

When the operation control unit <NUM> controls the stacker crane <NUM> to load the article <NUM>, the travel control unit <NUM> controls the travel operation of the travel carriage <NUM> such that the transfer apparatus <NUM> is located at a position that corresponds to the support unit <NUM> (specifically, a position at which the transfer apparatus <NUM> faces the support unit <NUM> in the route width direction Wj, and the lifting control unit <NUM> controls the lifting apparatus <NUM> to raise and lower the lift <NUM>. Then, the transfer control unit <NUM> controls the transfer operation of the transfer apparatus <NUM> such that the article <NUM> is transferred from the support unit <NUM> to the holding unit <NUM>. Then, the travel control unit <NUM> controls the travel operation of the travel carriage <NUM> such that the transfer apparatus <NUM> is located at a position that corresponds to the storage space <NUM> serving as the loading destination for the article <NUM> (specifically, a position at which the transfer apparatus <NUM> faces the storage space <NUM> in the route width direction Wj, and the lifting control unit <NUM> controls the lifting apparatus <NUM> to raise and lower the lift <NUM>. Then, the transfer control unit <NUM> controls the transfer operation of the transfer apparatus <NUM> such that the article <NUM> is transferred from the holding unit <NUM> to the storage space <NUM>.

Also, when the operation control unit <NUM> controls the stacker crane <NUM> to unload the article <NUM>, the travel control unit <NUM> controls the travel operation of the travel carriage <NUM> such that the transfer apparatus <NUM> is located at a position that corresponds to the storage space <NUM> in which the article <NUM> is stored, and the lifting control unit <NUM> controls the lifting apparatus <NUM> to raise and lower the lift <NUM>. Then, the transfer control unit <NUM> controls the transfer operation of the transfer apparatus <NUM> such that the article <NUM> is transferred from the storage space <NUM> to the holding unit <NUM>. Then, the travel control unit <NUM> controls the travel operation of the travel carriage <NUM> such that the transfer apparatus <NUM> is located at a position that corresponds to the support unit <NUM>, and the lifting control unit <NUM> controls the lifting apparatus <NUM> to raise and lower the lift <NUM>. Then, the transfer control unit <NUM> controls the transfer operation of the transfer apparatus <NUM> such that the article <NUM> is transferred from the holding unit <NUM> to the support unit <NUM>.

In the present embodiment, the travel carriage <NUM> is controlled so as to be stopped at reference stop positions S (see <FIG>) that are preset at a plurality of locations in the route longitudinal direction L. A reference stop position S is set for each transfer destination <NUM>. Each reference stop position S is set such that, when the travel carriage <NUM> is stopped at the reference stop position S, the lift <NUM> can be located at a position that corresponds to a transfer destination <NUM> (the transfer destination <NUM> set for the reference stop position S). A common reference stop position S may be set at a plurality of transfer destinations <NUM> located at the same level in the route longitudinal direction L. For example, also when there is a small position shift in the route longitudinal direction L between a plurality of storage spaces <NUM> that belong to the same column, a common reference stop position S may be set for the plurality of storage spaces <NUM> that belong to the same column.

Meanwhile, as schematically shown in <FIG>, the masts <NUM> sway with their portions connected to the travel carriage <NUM> (i.e., lower ends of the masts <NUM>) serving as fulcrums for a while after the travel carriage <NUM> is stopped, due to inertia that occurs when the travel carriage <NUM> decelerates. In response to the swaying of the masts <NUM>, the lift <NUM> and the transfer apparatus <NUM> supported by the lift <NUM> sway in the route longitudinal direction L. Note that, in <FIG>, the stacker crane <NUM> in a static state in which the swaying of the masts <NUM> is stopped and the masts <NUM> are standing still is indicated by solid lines, and the masts <NUM> in a state in which the masts <NUM> are bent to one side (to the right in the drawing) in the route longitudinal direction L with respect to the static state are indicated by dotted lines. The masts <NUM> change to the static state while bending to both sides in the route longitudinal direction L with respect to the static state.

In order to prevent a decrease in the operation efficiency of the stacker crane <NUM>, it is desirable that, for example, the transfer operation can be started as soon as possible when the swaying amount is in a range in which no failure will occur in the transfer operation of the transfer apparatus <NUM>. In the present embodiment, by configuring the control system <NUM> in the following manner, it is possible to start the transfer operation at an appropriate time based on the actual swaying amount of the stacker crane <NUM> (it is possible to start the transfer operation as soon as possible when the swaying amount is in a range in which no failure will occur in the transfer operation of the transfer apparatus <NUM>), while suppressing an increase in the installation cost of the stacker crane <NUM>.

As shown in <FIG>, the control system <NUM> includes the sway detection unit <NUM>, the lifting height acquiring unit <NUM>, and the above-described transfer control unit <NUM> for controlling the transfer apparatus <NUM>. In the present embodiment, the control system <NUM> further includes the storage unit <NUM>. In the present embodiment, the sway detection unit <NUM> includes a position detection sensor <NUM> and a stop position acquiring unit <NUM>. In the present embodiment, the stop position acquiring unit <NUM> includes a stop-position detection sensor <NUM>.

The sway detection unit <NUM> detects a reference swaying amount X1 (see <FIG>), which is a swaying amount X of the masts <NUM> at a detection height H1. Here, as shown in <FIG>, the detection height H1 is set to at least the height of a lowermost part 26a of the transfer apparatus <NUM> when the lift <NUM> is located at the upper limit E1 of the lifting range E. In the example shown in <FIG>, the detection height H1 is set to the height of the upper ends (uppermost parts) of the masts <NUM>. In the present embodiment, the swaying amount X is the amount of swaying in the route longitudinal direction L, although the swaying amount X may include, in addition to the swaying amount in the route longitudinal direction L, the swaying amount in the vertical direction V.

As shown in <FIG>, in the present embodiment, the sway detection unit <NUM> includes the position detection sensor <NUM> that dynamically detects the positions of the masts <NUM> at the detection height H1 in the route longitudinal direction L. As shown in <FIG>, in the present embodiment, the position detection sensor <NUM> is an optical distance detection sensor. The position detection sensor <NUM> projects detection light D toward a first reflective plate <NUM>, and receives light reflected from the first reflective plate <NUM>, thereby detecting the distance between the position detection sensor <NUM> and the first reflective plate <NUM>. Based on the distance between the position detection sensor <NUM> and the first reflective plate <NUM>, the positions of the masts <NUM> at the detection height H1 in the route longitudinal direction L are derived.

Either the position detection sensor <NUM> or the first reflective plate <NUM> (in the example shown in <FIG>, the first reflective plate <NUM>) is fixed to a portion whose position in the route longitudinal direction L does not change, such as the ceiling part <NUM>. The remaining one of the position detection sensor <NUM> and the first reflective plate <NUM> (in the example shown in <FIG>, the position detection sensor <NUM>) is fixed to a fixation target portion of the stacker crane <NUM>. The fixation target portion is a portion that sways with the same swaying amount as the swaying amount X of the portion of the mast <NUM> (in the example of <FIG>, the upper end of the mast <NUM>) that is located at the detection height H1. In the example shown in <FIG>, the position detection sensor <NUM> is fixed to the connection part <NUM> serving as the fixation target portion. Note that the position detection sensor <NUM> may be a sensor (e.g., a rotary encoder) other than an optical distance detection sensor.

As shown in <FIG> that shows changes in the swaying amounts X of the masts <NUM> relative to time T, after the travel carriage <NUM> is stopped, the masts <NUM> vibrates around a reference position A, which is a position in the static state, and the vibration attenuates. In the present embodiment, the sway detection unit <NUM> detects a difference between the reference position A and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1. The method for deriving the reference position A will be described later.

The lifting height acquiring unit <NUM> acquires lifting height information that indicates a lifting height H2. Here, the lifting height H2 is a height (position in the vertical direction V) of the lift <NUM> at each point in time, as shown in <FIG> and <FIG>. The lifting height H2 varies between the upper limit E1 and the lower limit E2 of the lifting range E of the lift <NUM>. The lifting height acquiring unit <NUM> includes a height detection sensor <NUM> that detects the height of the lift <NUM>, and acquires a detection result of the height detection sensor <NUM> as lifting height information. A sensor that is used when the lifting control unit <NUM> controls the operation of raising and lowering the lift <NUM> may also be used as the height detection sensor <NUM>, or another sensor may be used as the height detection sensor <NUM>.

As shown in <FIG>, in the present embodiment, the height detection sensor <NUM> is an optical distance detection sensor. In the example shown in <FIG>, the height detection sensor <NUM> is fixed to a part of the stacker crane <NUM> whose position in the vertical direction V does not change. Then, the height detection sensor <NUM> projects detection light D toward the lift <NUM> (specifically, a reflective plate provided on the lift <NUM>), and receives light reflected from the lift <NUM>, thereby detecting the distance between the height detection sensor <NUM> and the lift <NUM>. Based on the distance between the height detection sensor <NUM> and the lift <NUM>, the height of the lift <NUM> is derived. In contrast to this configuration, a configuration is also possible in which the height detection sensor <NUM> is provided on the lift <NUM>. Also, the height detection sensor <NUM> may be a sensor (e.g., a rotary encoder) other than an optical distance detection sensor.

The transfer control unit <NUM> converts the reference swaying amount X1 detected by the sway detection unit <NUM> into a lifting height swaying amount X2 (see <FIG>), which is a swaying amount X of the masts <NUM> at the lifting height H2 that is indicated by the lifting height information. The lifting height swaying amount X2 corresponds to the swaying amount of the lift <NUM>. That is to say, the transfer control unit <NUM> converts the swaying amount X of the masts <NUM> at the detection height H1 into the swaying amount of the lift <NUM>. The conversion from the reference swaying amount X1 into the lifting height swaying amount X2 can be made based on, for example, a vibration model that approximates the displacement using a cubic function. In this case, the transfer control unit <NUM> can obtain the lifting height swaying amount X2 from the reference swaying amount X1 based on the following expression (<NUM>).

The conversion from the reference swaying amount X1 into the lifting height swaying amount X2 can also be made based on, for example, a vibration model that approximates the displacement using a linear function. In this case, the transfer control unit <NUM> can obtain the lifting height swaying amount X2 from the reference swaying amount X1 based on the following expression (<NUM>).

Note that the detection height H1 and the lifting height H2 (height of the lift <NUM>) in these expressions refer to heights from a common reference height, which can be the height of the connection part that connects the masts <NUM> and the travel carriage <NUM> (i.e., lower ends of the masts <NUM>).

The transfer control unit <NUM> performs the above-described conversion using an amplitude of swaying of the masts <NUM> at the detection height H1 (amplitude with the reference position A used as a reference) as the reference swaying amount X1. Therefore, the lifting height swaying amount X2 derived by the transfer control unit <NUM> indicates the amplitude (crest value) of swaying of the masts <NUM> at the lifting height H2. Accordingly, in the expressions (<NUM>) and (<NUM>), the reference swaying amount X1 is an amplitude of swaying of the masts <NUM> at the detection height H1, and the lifting height swaying amount X2 is an amplitude of swaying of the masts <NUM> at the lifting height H2.

The sway detection unit <NUM> acquires the reference swaying amount X1 repeatedly, and detects an amplitude of the swaying of the masts <NUM> at the detection height H1 based on time-series data of the reference swaying amount X1. The sway detection unit <NUM> subjects the time-series data of the reference swaying amount X1 to differential processing or the like to detect a peak of the swaying of the masts <NUM> (peak in vibration waveform), and detects the (absolute) value of the reference swaying amount X1 at the peak as the amplitude of the swaying of the masts <NUM> at the detection height H1. A peak of swaying of the masts <NUM> appears at a period of half of the natural period of the swaying of the masts <NUM>, and in the example shown in <FIG>, peaks of the swaying of the masts <NUM> appear at time T1, time T2, time T3, time T4, and time T5. The transfer control unit <NUM> converts the amplitude of the swaying of the masts <NUM> at the detection height H1 that was detected by the sway detection unit <NUM> in this way into the amplitude of the swaying of the masts <NUM> at the lifting height H2.

As described above, the transfer control unit <NUM> derives the lifting height swaying amount X2 by converting the reference swaying amount X1 into the lifting height swaying amount X2. Then, the transfer control unit <NUM> starts the transfer operation of the transfer apparatus <NUM> if the lifting height swaying amount X2 is stably smaller than or equal to a predetermined determination threshold ΔX. In this context, "stably" means a period of predetermined determination time or longer. As described above, in the present embodiment, by performing the above-described conversion, the transfer control unit <NUM> derives the amplitude of swaying of the masts <NUM> at the lifting height H2 as the lifting height swaying amount X2. Then, if the derived lifting height swaying amount X2 is smaller than or equal to the predetermined determination threshold ΔX, the transfer control unit <NUM> determines that the lifting height swaying amount X2 is stably smaller than or equal to the predetermined determination threshold ΔX, and starts the transfer operation of the transfer apparatus <NUM>. In this case, if the lifting height swaying amount X2 is smaller than or equal to the predetermined determination threshold ΔX for at least a quarter of the above-described natural period, it is determined that the lifting height swaying amount X2 is stably smaller than or equal to the predetermined determination threshold ΔX. In the example shown in <FIG>, at the time T2, the lifting height swaying amount X2 is determined as being stably smaller than or equal to the predetermined determination threshold ΔX.

In this way, the transfer control unit <NUM> regards the lifting height swaying amount X2 as the swaying amount of the transfer apparatus <NUM> supported by the lift <NUM>, and determines whether or not to start the transfer operation of the transfer apparatus <NUM>. The above-described determination threshold ΔX is preferably set to a value as large as possible within a range in which no failure will occur in the transfer operation of the transfer apparatus <NUM>. Also, the determination threshold ΔX is preferably set taking into consideration the connection relationship or positional relationship between the lift <NUM> and the transfer apparatus <NUM> (taking into consideration that, for example, sway may be amplified at the connection part that connects the lift <NUM> and the transfer apparatus <NUM>).

As described above, in the present embodiment, the sway detection unit <NUM> detects a difference between the reference position A and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1. The following will describe the method for deriving the reference position A that is performed in the control system <NUM> of the present embodiment.

As described above, in the present embodiment, the travel carriage <NUM> is controlled so as to be stopped at the reference stop positions S (see <FIG>) that are preset at a plurality of locations in the route longitudinal direction L. In the present embodiment, the control system <NUM> includes the storage unit <NUM> (see <FIG>) in which information regarding a mast reference position A0 measured when the travel carriage <NUM> is stopped at each of a plurality of reference stop positions S is stored, the mast reference position A0 being a position of the masts <NUM> at the detection height H1 in a state in which the travel carriage <NUM> is stopped at the reference stop position S, and the masts <NUM> are standing still (are in the static state). Each piece of information regarding the mast reference position A0 is stored in the storage unit <NUM> in association with a reference stop position S (specifically, the reference stop position S at which the mast reference position A0 was measured). <FIG> shows the masts <NUM> and the mast reference position A0 in the static state at three reference stop positions S, namely, a first stop position S1, a second stop position S2, and a third stop position S3.

As shown in <FIG>, the positional relationship between the reference stop position S and the mast reference position A0 in the route longitudinal direction L is common between a plurality of reference stop positions S, in terms of design. However, actually, the positional relationship may vary between the reference stop positions S due to a level difference (difference in height) of the travel rail <NUM>, or the like. In this regard, in the present embodiment, since the travel carriage <NUM> is stopped at each of the plurality of reference stop positions S and the mast reference position A0 is measured as described above, the mast reference position A0 can be appropriately set for each of the plurality of reference stop positions S even if the above-described positional relationship varies between the reference stop positions S.

As shown in <FIG>, the sway detection unit <NUM> includes the stop position acquiring unit <NUM> that acquires stop position information that indicates at which of the plurality of reference stop positions S the travel carriage <NUM> is stopped. The stop position acquiring unit <NUM> acquires the stop position information, for example, from the operation control unit <NUM> (specifically, the travel control unit <NUM>). If the reference stop position S is set at a position common between a plurality of storage spaces <NUM> belonging to the same column, the stop position information is information that indicates, for example, at which column of the storage rack <NUM> the travel carriage <NUM> is stopped. The sway detection unit <NUM> acquires, from the storage unit <NUM>, the mast reference position A0 associated with the reference stop position S indicated by the stop position information, and detects a difference between the mast reference position A0 and a detection result of the position detection sensor <NUM>, as a reference swaying amount X1. That is to say, in this case, the mast reference position A0 serves as the above-described reference stop position A (see <FIG>).

Meanwhile, if the travel carriage <NUM> is controlled to stop at the reference stop position S, an actual stop position R, which is a stop position at which the travel carriage <NUM> is actually stopped, may be shifted from the reference stop position S. <FIG> shows a situation in which the travel carriage <NUM> controlled so as to stop at the second stop position S2 is stopped at a position shifted from the second stop position S2 by a stop position error ΔL. Note that, in <FIG>, the stop position error ΔL is exaggerated for ease of understanding. It is also possible to take into consideration this stop position error ΔL to correct the reference stop position S, which serves as a reference for use in detecting the reference swaying amount X1, as will be described below.

In the case where the reference stop position S is to be corrected, the stop position acquiring unit <NUM> includes the stop-position detection sensor <NUM> that detects the actual stop position R, as shown in <FIG>. A sensor that is used when the travel control unit <NUM> controls the travel operation of the travel carriage <NUM> may also be used as the stop-position detection sensor <NUM>, or another sensor may be used as the stop-position detection sensor <NUM>.

As shown in <FIG>, in the present embodiment, the stop-position detection sensor <NUM> is an optical distance detection sensor. The stop-position detection sensor <NUM> projects detection light D toward a second reflective plate <NUM>, and receives light reflected from the second reflective plate <NUM>, thereby detecting the distance between the stop-position detection sensor <NUM> and the second reflective plate <NUM>. Based on the distance between the stop-position detection sensor <NUM> and the second reflective plate <NUM> in a state in which the travel carriage <NUM> is stopped, the actual stop position R is derived.

Either the stop-position detection sensor <NUM> or the second reflective plate <NUM> (in the example shown in <FIG>, the second reflective plate <NUM>) is fixed to a portion whose position in the route longitudinal direction L does not change, such as the floor part <NUM>. The remaining one of the stop-position detection sensor <NUM> and the second reflective plate <NUM> (in the example shown in <FIG>, the stop-position detection sensor <NUM>) is fixed to the travel carriage <NUM>. Note that the stop-position detection sensor <NUM> may be a sensor (e.g., a rotary encoder) other than an optical distance detection sensor.

The sway detection unit <NUM> obtains a corrected mast reference position A1 based on a detection result of the actual stop position R obtained by the stop-position detection sensor <NUM>. Specifically, by correcting the mast reference position A0 based on a difference between the actual stop position R and the reference stop position S that corresponds to the actual stop position R, the sway detection unit <NUM> obtains the corrected mast reference position A1. In the example shown in <FIG>, the difference between the actual stop position R and the reference stop position S (here, the second stop position S2) that corresponds to the actual stop position R is the stop position error ΔL, and the corrected mast reference position A1 is the position obtained by shifting the mast reference position A0 by the stop position error ΔL in the same direction as the direction of the shift of the actual stop position R from the reference stop position S. Also, the sway detection unit <NUM> detects a difference between the corrected mast reference position A1 and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1. That is to say, in this case, the corrected mast reference position A1 serves as the above-described reference stop position A (see <FIG>).

The following will describe a procedure of processing for determining the start of the transfer operation of the transfer apparatus <NUM> that is executed in the control system <NUM> according to the present embodiment, with reference to <FIG>. The technical features of the control system <NUM> disclosed in the present specification are applicable to the method for controlling the stacker crane <NUM>, and the method for controlling the stacker crane <NUM> is also disclosed in the present specification. The control method includes processing (steps) shown in <FIG> and <FIG>.

As shown in <FIG>, when, for positioning the transfer apparatus <NUM> at a position that corresponds to the transfer destination <NUM>, the travel operation of the travel carriage <NUM> and the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM> are complete, and these operations are stopped (Yes in step #<NUM>), the sway detection unit <NUM> (specifically, the position detection sensor <NUM>) detects the positions of the masts <NUM> at the detection height H1 in the route longitudinal direction L (step #<NUM>). The detection of the positions of the masts <NUM> in step #<NUM> is repeated until a peak of swaying of the masts <NUM> is detected (No in step #<NUM>). When a peak of the swaying of the masts <NUM> is detected (Yes in step #<NUM>), the sway detection unit <NUM> calculates the reference swaying amount X1 (specifically, the amplitude of the swaying of the masts <NUM> at the detection height H1) (step #<NUM>). In the present embodiment, the sway detection unit <NUM> derives a difference between the reference position A (mast reference position A0 or corrected mast reference position A1) and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1.

Then, the transfer control unit <NUM> calculates the lifting height swaying amount X2 (the amplitude of swaying of the masts <NUM> at the lifting height H2) (step #<NUM>). The transfer control unit <NUM> converts the reference swaying amount X1 calculated in step #<NUM> into the lifting height swaying amount X2, thereby deriving the lifting height swaying amount X2. The processing from steps #<NUM> to #<NUM> is repeatedly executed until the lifting height swaying amount X2 calculated in step #<NUM> is smaller than or equal to the determination threshold ΔX (No in step #<NUM>). When the lifting height swaying amount X2 calculated in step #<NUM> is smaller than or equal to the determination threshold ΔX (Yes in step #<NUM>), the transfer control unit <NUM> starts the transfer operation of the transfer apparatus <NUM> (step #<NUM>).

The following will describe a second embodiment of the stacker crane control system with reference to a drawing (<FIG>). The present embodiment differs from the first embodiment in the method for detecting the reference swaying amount X1 that is executed by the sway detection unit <NUM>. The following description is given focusing on the difference from the first embodiment. Features that are not stated clearly are the same as those of the first embodiment, and the same reference numerals are given thereto and detailed descriptions thereof are omitted.

In the first embodiment, the sway detection unit <NUM> detects a difference between the reference position A and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1. In contrast, in the present embodiment, the sway detection unit <NUM> detects a detection result of the position detection sensor <NUM> as a reference swaying amount X1, and detects the amplitude of swaying of the masts <NUM> at the detection height H1 without using the reference position A. Therefore, in the present embodiment, there is no need for the sway detection unit <NUM> to include the stop position acquiring unit <NUM> nor store information regarding the mast reference position A0 in the storage unit <NUM>.

In the present embodiment, the sway detection unit <NUM> acquires the amplitude of a dynamic change in the positions of the masts <NUM> (i.e., the amplitude of swaying of the masts <NUM>) at the detection height H1 indicated by the detection result of the position detection sensor <NUM>, and detects the amplitude as the reference swaying amount X1. Specifically, the sway detection unit <NUM> repeatedly acquires a detection result of the position detection sensor <NUM>. The sway detection unit <NUM> subjects time-series data of the detection results of the position detection sensor <NUM> to differential processing or the like to detect a peak of the swaying of the masts <NUM>, and acquires the detection result of the position detection sensor <NUM> at this peak, as a crest value. Also, after having detected the peak of the swaying of the masts <NUM>, the sway detection unit <NUM> detects the value of half of a difference (i.e., peak-to-peak value) between the currently acquired crest value and the previously acquired crest value, as the amplitude of the dynamic change in the positions of the masts <NUM> at the detection height H1 (i.e., as the reference swaying amount X1). In the example shown in <FIG>, at the time T2 for example, the value of half of a difference between the detection result of the position detection sensor <NUM> at the time T2 and the detection result of the position detection sensor <NUM> at the time T1 is detected as the reference swaying amount X1.

The following will describe a procedure of processing for determining the start of the transfer operation of the transfer apparatus <NUM> that is executed in the control system <NUM> according to the present embodiment, with reference to <FIG>.

As shown in <FIG>, when, for positioning the transfer apparatus <NUM> at a position that corresponds to the transfer destination <NUM>, the travel operation of the travel carriage <NUM> and the operation performed by the lifting apparatus <NUM> to raise and lower the lift <NUM> are complete, and these operations are stopped (Yes in step #<NUM>), the sway detection unit <NUM> (specifically, the position detection sensor <NUM>) detects the positions of the masts <NUM> at the detection height H1 in the route longitudinal direction L (step #<NUM>). The detection of the positions of the masts <NUM> in step #<NUM> is repeated until a peak of swaying of the masts <NUM> is detected (No in step #<NUM>). When a peak of the swaying of the masts <NUM> is detected (Yes in step #<NUM>), the sway detection unit <NUM> acquires the detection result of the position detection sensor <NUM> at this peak as a crest value, and stores this crest value as the previous value (step #<NUM>).

Then, the sway detection unit <NUM> (specifically, the position detection sensor <NUM>) detects the positions of the masts <NUM> at the detection height H1 in the route longitudinal direction L (step #<NUM>). The detection of the positions of the masts <NUM> in step #<NUM> is repeated until a peak of the swaying of the masts <NUM> is detected (No in step #<NUM>). When a peak of the swaying of the masts <NUM> is detected (Yes in step #<NUM>), the sway detection unit <NUM> calculates the reference swaying amount X1 (specifically, the amplitude of the dynamic change in the positions of the masts <NUM> at the detection height H1) (step #<NUM>). In the present embodiment, the sway detection unit <NUM> acquires a detection result of the position detection sensor <NUM> at the currently detected peak as a crest value, and derives the value of half of a difference between the currently acquired crest value and the previously acquired crest value (crest value stored as the previous value), as the reference swaying amount X1.

Then, the transfer control unit <NUM> calculates the lifting height swaying amount X2 (the amplitude of swaying of the masts <NUM> at the lifting height H2) (step #<NUM>). The transfer control unit <NUM> converts the reference swaying amount X1 calculated in step #<NUM> into the lifting height swaying amount X2, thereby deriving the lifting height swaying amount X2. If the lifting height swaying amount X2 calculated in step #<NUM> is not smaller than or equal to the determination threshold ΔX (No in step #<NUM>), the previous value is updated to the crest value currently acquired by the sway detection unit <NUM> (step #<NUM>), and the procedure returns to step #<NUM>. The processing from steps #<NUM> to #<NUM>, and #<NUM> is repeatedly executed until the lifting height swaying amount X2 calculated in step #<NUM> is smaller than or equal to the determination threshold ΔX (No in step #<NUM>). When the lifting height swaying amount X2 calculated in step #<NUM> is smaller than or equal to the determination threshold ΔX (Yes in step #<NUM>), the transfer control unit <NUM> starts the transfer operation of the transfer apparatus <NUM> (step #<NUM>).

The following will describe other embodiments of the stacker crane control system.

The first embodiment has described a configuration in which information regarding the mast reference position A0 measured when the travel carriage <NUM> is stopped at each of the plurality of reference stop positions S is stored in the storage unit <NUM>, as an example. However, the present disclosure is not limited to such a configuration. Based on the information regarding the mast reference position A0 measured when the travel carriage <NUM> is stopped at one reference stop position S, the mast reference position A0 may be set for a plurality of reference stop positions S, as long as no failure will occur in the transfer operation of the transfer apparatus <NUM> even if the positional relationship between the reference stop position S and the mast reference position A0 in the route longitudinal direction L is regarded as constant.

The first embodiment has described a configuration in which, assuming that the mast reference position A0 or the corrected mast reference position A1 is the reference position A (position of the mast <NUM> in the static state), the sway detection unit <NUM> detects a difference between the reference position A and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1, as an example. However, the present disclosure is not limited to such a configuration. A configuration is also possible in which the sway detection unit <NUM> detects a difference between the reference position A set according to the actual stop position R and a detection result of the position detection sensor <NUM>, as the reference swaying amount X1, as long as no failure will occur in the transfer operation of the transfer apparatus <NUM> even if the positional relationship between the actual stop position R and the reference position A is regarded as constant.

The above-described embodiments have described a configuration in which the transfer apparatus <NUM> is configured to advance and retract the holding unit <NUM> in the route width direction W, and as a result of the advancement and retraction of the holding unit <NUM> (specifically, as well as raising and lowering of the lift <NUM>), the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>, as an example. However, the present disclosure is not limited to such a configuration. A configuration is also possible in which, for example, the transfer apparatus <NUM> advances and retracts a pair of forward/rearward moving members (for example, a pair of clamp units, or a pair of arms equipped with a hook) in the route width direction W, the pairs of forward/rearward moving members being arranged on both sides of the article <NUM> in the route longitudinal direction L, and as a result of the transfer operation of the transfer apparatus <NUM> (specifically, operation of advancing and retracting the pair of forward/rearward moving members), the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>. In this case, a configuration is also possible in which a conveyor (such as a belt conveyor) for conveying the article <NUM> in the route width direction W is provided on the holding unit <NUM> or the above-described forward/rearward moving members, and as a result of the conveying operation of the conveyor as well as the operation of advancing and retracting the pair of forward/rearward moving members, the article <NUM> is transferred between the holding unit <NUM> and the transfer destination <NUM>.

The above-described embodiments have described a configuration in which two masts <NUM> are supported on the travel carriage <NUM> while being lined up in the route longitudinal direction L, as an example. However, the present disclosure is not limited to such a configuration. A configuration is also possible in which, for example, only one mast <NUM> is supported on the travel carriage <NUM>, and the lift <NUM> and the one mast <NUM> are lined up in the route longitudinal direction L.

Claim 1:
A stacker crane control system (<NUM>) for controlling a stacker crane (<NUM>),
the stacker crane (<NUM>) including:
a travel carriage (<NUM>) configured to travel along a travel route (<NUM>);
a mast (<NUM>) supported on the travel carriage (<NUM>) in an orientation along a vertical direction (V);
a lift (<NUM>) configured to move up and down within a predetermined lifting range (E) along the mast (<NUM>);
a lifting apparatus (<NUM>) configured to raise and lower the lift (<NUM>); and a transfer apparatus (<NUM>) supported by the lift (<NUM>) and including a holding unit (<NUM>) configured to hold an article (<NUM>),
the stacker crane (<NUM>) being configured to perform a transfer operation of transferring the article (<NUM>) between the holding unit (<NUM>) and a transfer destination (<NUM>), the stacker crane control system (<NUM>) comprising:
a sway detection unit (<NUM>) configured to detect a reference swaying amount (X1) that is a swaying amount (X) of the mast (<NUM>) at a detection height (H1), the detection height (H1) being set greater than or equal to the height of a lowermost part (26a) of the transfer apparatus (<NUM>) when the lift (<NUM>) is located at an upper limit of the lifting range (E);
a lifting height acquiring unit (<NUM>) configured to acquire lifting height information that indicates a lifting height (H2), which is the height of the lift (<NUM>), at a plurality of points in time; and
a transfer control unit (<NUM>) configured to control the transfer apparatus (<NUM>),
characterised in that,
the transfer control unit (<NUM>) converts the reference swaying amount (X1) detected by the sway detection unit (<NUM>) into a lifting height swaying amount (X2) that is a swaying amount of the mast (<NUM>) at the lifting height (H2) indicated by the lifting height information, and starts the transfer operation of the transfer apparatus (<NUM>) if the lifting height swaying amount (X2) is stably smaller than or equal to a predetermined determination threshold (ΔX).