Mobile device

Abstract

This mobile device comprises: guide parts that extend in a prescribed direction; a mobile body that moves in the prescribed direction along the guide parts; drive parts that drive the mobile body in the prescribed direction; and a control unit that controls the driving of the mobile body by the drive parts. The control unit executes specific control for suppressing vibration of the mobile body in the prescribed direction during the movement when the movement distance from the start to the stopping of movement by the mobile body is within a predetermined distance range, but does not execute the specific control when the movement distance deviates from the predetermined distance range.

Description

Mobile device

[0001] The present disclosure relates to a mobile device.

[0002] As a type of mobile device, for example, a stacker crane can be cited. In the stacker crane described in Patent Document 1, a lifting table is lifted and lowered by a lifting motor. In the lifting control of the lifting table, dynamic vibration control (anti-phase control) is performed in which vibration with the opposite phase is applied to the lifting motor so as to cancel out the vibration in the height direction of the lifting table.

[0003] Japanese Patent Application Laid-Open No. 2007-276962

[0004] By the way, in the actual operation of a mobile device such as a stacker crane, the movement mode of the moving body such as the lifting table is not constant and can change depending on the time and situation. For example, when there are a large number of transfer commands, the moving distance of the moving body can be different for each transfer command. In the conventional vibration control described above, vibration control is always executed in a specific vibration control area in the lifting pattern of the lifting table. Since constant control is always executed without considering the movement mode of the moving body, calculations by the control unit are also performed even when vibration does not pose a problem, which is not necessarily efficient.

[0005] The present disclosure describes a mobile device that can efficiently suppress vibration in a predetermined direction of a moving body.

[0006] [1] One aspect of the present disclosure is a mobile device including a guide portion extending in a specified direction, a moving body moving in the specified direction along the guide portion, a driving portion driving the moving body in the specified direction, and a control portion controlling the driving of the moving body by the driving portion, wherein the control portion executes specific control for suppressing vibration in the specified direction of the moving body during the movement when the moving distance of the moving body from the start to the stop of the movement is within a predetermined distance range, but does not execute the specific control when the moving distance deviates from the predetermined distance range.

[0007] According to the mobile device of [1], by executing specific control for suppressing specific vibration only when the moving distance of the moving body is within a predetermined distance range, vibration in the specified direction of the moving body can be efficiently suppressed.

[0008] [2] In the mobile device described in [1] above, the specified direction is the vertical direction, and the mobile body may be a lifting platform that moves vertically along the guide. With this configuration, vertical vibration of the lifting platform can be efficiently suppressed by executing specific control only when the movement distance of the lifting platform is within a predetermined distance range.

[0009] [3] In the mobile device described in [1] or [2] above, the control unit does not need to perform specific control when the travel distance is within a long-distance range that is longer than the first threshold. When the mobile device travels over a long distance, vibrations may converge during the journey. By not performing specific control (prohibiting specific control) when the travel distance is within a long-distance range, and by performing normal control that does not consider vibration suppression, vibrations of the mobile device in a specified direction can be suppressed more efficiently. Specifically, the time required for travel can be reduced.

[0010] [4] In the mobile device described in [3] above, the control unit executes specific control when the travel distance is within a medium-range range where it is less than or equal to the first threshold and greater than or equal to the second threshold which is smaller than the first threshold, but does not have to execute specific control when the travel distance is within a short-range range where it is less than the second threshold. When the mobile body travels only a short distance, deceleration begins before the mobile body reaches its maximum speed (maximum speed for medium-range or long-range travel), so the above-mentioned specific control may not be effective. By not executing specific control (prohibiting specific control) when the travel distance is within a short-range range and executing normal control that does not consider vibration suppression, vibration of the mobile body in a specified direction can be suppressed more efficiently.

[0011] [5] In any one of the mobile device described in [1] to [4] above, a braking device for the mobile device may be provided, and the specific control may, when the mobile device starts moving, first control the movement of the mobile device based on a first velocity command indicating that the mobile device should move at a first acceleration, and then control the movement of the mobile device based on a second velocity command indicating that the mobile device should move at a second acceleration greater than the first acceleration. The braking device can be released while the speed is low, and a delay in releasing the braking device can be prevented.

[0012] [6] In any one of the moving body devices described in [1] to [5] above, the control unit may, after the absolute value of the speed of the moving body reaches a predetermined value during acceleration control of the moving body, execute vibration suppression control different from the specific control in order to suppress vibration of the moving body in a specified direction during the movement, regardless of the distance traveled. By applying the specific control when the movement of the moving body begins, vibration is suitably suppressed. After the speed exceeds a predetermined value, vibration suppression according to the speed of the moving body (or several states included in a series of movements) is achieved by applying a different vibration suppression control than the specific control.

[0013] According to this disclosure, vibrations of a moving body in a specified direction can be efficiently suppressed.

[0014] Figure 1 is a front view of a mobile device according to one embodiment of the present disclosure. Figure 2 is a block diagram of the control unit and drive unit of the mobile device of Figure 1. Figure 3 is a flowchart showing an example of movement control. Figure 4 is a diagram illustrating an example of the range to which specific control is applied. Figure 5 is a diagram showing an example of specific control in the mobile device of the present disclosure. Figure 6 is a diagram showing an example of specific control in a conventional mobile device. Figures 7(a) and 7(b) are diagrams illustrating other examples of the range to which specific control is applied, respectively. Figure 8 is a diagram showing the range of stopping positions after movement of the mobile device in a modified example to which vibration suppression control is applied. Figure 9 is a diagram showing one pattern example of vibration suppression control in Figure 8. Figure 10 is a diagram showing an enlarged view of the speed from the start of deceleration to the time of stopping in a modified example to which vibration suppression control is applied. Figure 11 is a table showing the time difference of the first and second acceleration changes according to the stopping position after movement. Figure 12(a) shows an example of speed control at the start of deceleration, Figure 12(b) schematically shows two examples of vibration waveforms generated by the first and second acceleration changes, and Figure 12(c) schematically shows an example of a composite waveform of the two vibration waveform examples in Figure 12(b).

[0015] Embodiments of this disclosure will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0016] First, with reference to Figure 1, a stacker crane 1 as an example of a mobile device will be described. In some figures, mutually orthogonal X, Y, and Z axes may be shown together for convenience of explanation. In this embodiment, the X direction corresponds to the travel direction (horizontal direction) of the stacker crane 1, the Y direction corresponds to the transfer direction (horizontal direction) of the stacker crane 1 by the transfer device 23, and the Z direction corresponds to the lifting direction of the lifting platform 20 of the stacker crane 1. In the following description, the lifting platform 20 will be used as an example of the "mobile body" described in the claims, the lifting direction of the lifting platform 20 will be used as an example of the "specified direction," and vibration suppression of the lifting platform 20 in that direction will be described. Also, the terms "front and back" are used with reference to the X direction, and the terms "left and right" are used with reference to the Y direction.

[0017] If we consider the stacker crane 1 as an example of a moving body, the direction of travel of the stacker crane 1 corresponds to the "specified direction." Even in this case, vibrations of the moving body can be suppressed by performing speed control according to a predetermined speed pattern (a speed control pattern according to time or position) based on the concept described below.

[0018] The stacker crane 1 is applied, for example, to an automated warehouse. The stacker crane 1 transfers goods (articles) W to shelves (not shown) of a rack in the automated warehouse. The rack extends in both the X and Z directions. The stacker crane 1 is movable in the X direction along a lower rail 100 laid on the floor and extending in the X direction, and an upper rail 101 supported by a fixed object at a high place such as the ceiling and extending in the X direction. The stacker crane 1 has two masts (guide parts) 3 that extend in the Z direction between the lower rail 100 and the upper rail 101. A base 2 connects the lower ends of the two masts 3. The base 2 is fitted or engaged with the lower rail 100 via a plurality of drive wheels 8, etc. On the other hand, a support beam 4 connects the upper ends 3a of the two masts 3 via a plurality of brackets 10. The support beam 4 is fitted or engaged with the upper rail 101 via a plurality of upper wheels 9, etc. The stacker crane 1 is equipped with two travel motors 5 fixed to the front and rear of the base 2. Each travel motor 5 drives the stacker crane 1 in the travel direction by rotating a drive wheel 8. The upper wheel 9 is, for example, a driven wheel, but an upper travel motor may also be provided on the upper bracket 10, and the upper wheel 9 may be rotated by the upper travel motor.

[0019] The stacker crane 1 includes a lifting platform 20 provided between two masts 3 spaced apart in the X direction. The lifting platform 20 has a horizontal frame 21 that is rectangular in plan view, and a pair of vertical frames 22 integrated with the front and rear ends of the horizontal frame 21. A transfer device 23 for transferring loads W is mounted on the horizontal frame 21. Each vertical frame 22 is fitted with a plurality of first guide rollers 27 arranged vertically and a plurality of second guide rollers 26 arranged horizontally. Each first guide roller 27 sandwiches a guide portion 3b that protrudes from the left and right sides of each mast 3 and extends in the Z direction. Each second guide roller 26 abuts against the guide portion 3b of each mast 3. The lifting platform 20 may be provided with other guide rollers or other members that abut against the masts 3, etc.

[0020] Each bracket 10 is fitted with a plurality of pulleys 11 that are rotatable around an axis extending, for example, in the Y direction. Each pulley 11 is located near the upper end of the mast 3. Two lifting motors 6 and a drum (not shown) are fixed to the front and rear of the base 2 described above. The base ends of at least one timing belt 15 is provided at the front and rear, and the ends of the timing belts 15 are fixed to the drum, and the tips of the timing belts 15 are fixed to the vertical frame 22 of the lifting platform 20. Each timing belt 15 is wrapped around the drum and also around the pulleys 11, suspending and supporting the lifting platform 20. The lifting platform 20 is able to maintain a position substantially parallel to the XY plane (horizontal position) by the various rollers described above.

[0021] The lifting platform 20 is movable in the Z direction along two masts 3. The lifting platform 20 transports goods by moving up and down while supporting the load W. Each lifting motor (drive unit) 6 drives the lifting platform 20 up and down by rotating the drum. For example, the lifting motor 6 can rotate in both forward and reverse directions, allowing the lifting platform 20 to be raised freely and lowered freely. The lifting platform 20 is provided with a brake 16 as a braking device. When the brake 16 is applied, it restrains the lifting platform 20 (making it immobile). When the brake 16 is released, the lifting platform 20 is movable. Note that other known mechanisms other than those described above may be used for the mechanism related to supporting and guiding (guiding in the Z direction) of the lifting platform 20, and the mechanism related to driving the lifting platform 20 up and down.

[0022] Next, the configuration related to the speed control of the lifting platform 20 will be described with reference to Figures 2 and subsequent figures. As shown in Figure 2, the stacker crane 1 is equipped with a control unit 30. The control unit 30 is a computer or electronic control unit that includes, for example, a processor such as a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The control unit 30 is housed, for example, inside a suitable enclosure attached to the base 2. The control unit 30 controls the driving of the stacker crane 1 by the travel motor 5, the driving of the lifting platform 20 by the lifting motor 6, and the braking (brake ON) and release (brake OFF) of the brake 16. The control unit 30 has an information acquisition unit 31, a judgment unit 32, a motor control unit 33, a brake control unit 34, and a storage unit 36. The information acquisition unit 31 acquires information related to transport commands from, for example, a higher-level controller (not shown). The transport command includes information relating to the location (From position) of the shelf or transfer port or station where the load W to be transported by the stacker crane 1 is stored, and information relating to the location (To position) of the destination shelf or transfer port or station to which the load W will be transported.

[0023] The determination unit 32 determines whether the travel distance of the lifting platform 20 is within a predetermined distance range in the specific control described later. Based on the information related to the transport command acquired by the information acquisition unit 31, the determination unit 32 calculates the travel distance of the lifting platform 20 from the start of movement until it stops. In this specification, the "travel distance" of the lifting platform 20 (moving body) is the travel distance in the Z direction (i.e., the specified direction). Based on this determination, the determination unit 32 determines whether or not it is necessary for the motor control unit 33 to perform specific control. As a result of the determination unit 32's determination, the speed suppression control (specific control) by the control unit 30 will only be performed in certain limited situations, that is, in the movement of the lifting platform 20 in response to certain limited transport commands. The storage unit 36 ​​stores several thresholds for this determination. The storage unit 36 ​​also stores several patterns related to the movement control (speed control) of the lifting platform 20. A pattern is a speed control pattern related to the transport operation of a moving body to which a certain transport command has been assigned. In patterns corresponding to specific control, the first and second accelerations are applied when the lifting platform 20 starts moving. The second acceleration is greater than the first acceleration. If specific control is not performed, the motor control unit 33 performs normal control. In patterns corresponding to normal control, only the second acceleration (one type of acceleration) is applied when the lifting platform 20 starts moving. Note that the determination unit 32 is not limited to calculating the travel distance, and the transport command may include information related to the travel distance.

[0024] Next, referring to Figures 3 and subsequent figures, patterns corresponding to specific control will be explained, and a series of control flows (processing flows) in specific control will be described. Figure 5 is a diagram showing an example of specific control in the mobile device of this disclosure. As shown in Figure 5, in specific control, when the lifting platform 20 starts moving, first a gentle acceleration control is performed (the first acceleration described above is applied), followed by a steep acceleration control (the second acceleration described above is applied).

[0025] As shown in Figure 5, the pattern generally includes an initial stopping section, an acceleration section, a maximum speed maintenance section, a deceleration section, and a final stopping section in that order. In the example shown in Figure 5, the initial stopping section is until time t1a, the acceleration section is from time t1a to t2, the maximum speed maintenance section is from time t2 to t3, the deceleration section is from time t3 to t4, and the final stopping section is from time t4 onwards. Thus, all transport operations fit into this roughly trapezoidal pattern. Note that since Figure 5 shows an example where the lifting platform 20 is descending, the direction in which the vertical axis (velocity) decreases corresponds to the direction of movement of the lifting platform 20. That is, "Va" in "-Va" shown on the vertical axis is a positive value and is the absolute value of the velocity. Therefore, the velocity during descent is a negative value. The above maximum speed means that the absolute value of the velocity is at its maximum. Note that the same applies to Figures 9, 10, and 12, which will be referred to later.

[0026] In the specific control, when switching from the stopping section to the acceleration section (hereinafter referred to as the start of movement), the lifting motor 6 (movement of the lifting platform 20) is controlled with two stages of acceleration as described above. That is, in the specific control, when the movement of the lifting platform 20 begins, the movement of the lifting platform 20 is first controlled based on a first speed command indicating that the lifting platform 20 should be moved with a first acceleration, and then the movement of the lifting platform 20 is controlled based on a second speed command indicating that the lifting platform 20 should be moved with a second acceleration greater than the first acceleration.

[0027] In this embodiment, the motor control unit 33 executes specific control to suppress vertical vibration of the lifting platform 20 during transport only when the travel distance of the lifting platform 20 during transport is within a predetermined distance range. If the travel distance deviates from the predetermined distance range, the motor control unit 33 does not execute the specific control and executes normal control. In other words, the motor control unit 33 prohibits the execution of specific control if the travel distance deviates from the predetermined distance range. Figure 4 is a diagram illustrating an example of the range to which specific control applies. As shown in Figure 4, a first threshold Lb and a second threshold La are used as thresholds stored in the memory unit 36. The second threshold La is smaller than the first threshold Lb.

[0028] In stacker crane 1, the maximum movable distance Lmax is determined according to the length of the mast 3 (or the height of the shelves in the automated warehouse). The first threshold Lb and the second threshold La are each smaller than the maximum movable distance Lmax. For example, the first threshold Lb and the second threshold La are each less than or equal to half the maximum movable distance Lmax. "Half" means "(1 / 2) times".

[0029] The determination unit 32 determines not to perform specific control if the travel distance is within the long-distance range RL, which is longer than the first threshold Lb. The determination unit 32 also determines not to perform specific control if the travel distance is within the short-distance range RS, which is less than the second threshold La. The determination unit 32 determines to perform specific control only if the travel distance is within the medium-distance range RM, which is less than or equal to the first threshold Lb and greater than or equal to the second threshold La. In other words, the specific control in this embodiment is subject to the distance between the second threshold La and the first threshold Lb, including the values ​​at both ends of the range between the second threshold La and the first threshold Lb.

[0030] Next, with reference to Figure 3, a series of control flows (processing flows) in specific control will be explained. Figure 3 is a flowchart showing an example of movement control. As shown in Figure 3, first, the information acquisition unit 31 acquires information such as transport commands from a higher-level controller (not shown) (step S01). Next, the determination unit 32 determines whether the transport related to the transport command is within the scope of the specific control execution target (step S02). The criteria for this determination process are as described above. If the determination unit 32 determines that the transport related to the transport command is within the scope of the specific control execution target (step S02; YES), the motor control unit 33 executes the specific control (step S03). If the determination unit 32 determines that the transport related to the transport command deviates from the scope of the specific control execution target (step S02; NO), the motor control unit 33 prohibits the execution of the specific control and executes normal control (step S04).

[0031] When specific control is executed, the brake control unit 34 of the control unit 30 releases the brake 16 of the lifting platform 20 in conjunction with the acceleration control of the lifting motor 6 by the motor control unit 33. Refer to Figure 5 again. As shown in Figure 5, the command speed (the signal related to the speed control of the motor control unit 33) rises at time t1a. However, at this point, the brake control unit 34 is still maintaining the brake 16 in a braking state. Therefore, even after time t1a, the speed (drum speed) of the lifting platform 20 remains at 0. The brake control unit 34 releases the brake 16 at time tx. This starts the acceleration of the lifting platform 20. The command speed from time t1a to t1b is the speed based on the first acceleration. At time t1b, the lifting platform 20 has already started to accelerate, and after time t1b, the command speed increases to the second acceleration. Subsequently, at time t2, the speed of the elevator platform 20 reaches its maximum speed, and this maximum speed is maintained until time t3. After time t3, the elevator platform 20 decelerates. The magnitude of the acceleration between time t1b and t2 (the second acceleration described above) is approximately the same as the magnitude of the acceleration between time t3 and t4. The elevator platform 20 stops at time t4 and arrives at its destination.

[0032] According to the stacker crane 1 of this embodiment, vertical vibrations of the lifting platform 20 can be efficiently suppressed by executing specific control to suppress specific vibrations only when the travel distance of the lifting platform 20 is within a predetermined distance range. For example, if the specific control of this embodiment is not implemented, a command speed with a large acceleration from time t1 is used, as shown in Figure 6. When the brake 16 is released with a delay, a large vibration occurs in the lifting platform 20. This vibration persists throughout the entire movement process, and even if a transfer operation by the transfer device 23 is attempted at time t4, it is necessary to wait until this large sway subsides. According to the specific control of this embodiment, as shown in Figure 5, the magnitude of the sway is within (or approaching) an allowable value at time t4. As a result, the transfer of the load W can be carried out quickly.

[0033] Furthermore, when the lifting platform 20 moves over a long distance, vibrations may subside during the movement. By not executing specific control (prohibiting specific control) when the movement distance is within the long-distance range RL, and instead executing normal control that does not consider vibration suppression, vertical vibrations of the lifting platform 20 can be suppressed more efficiently. Specifically, the time required for movement can be reduced compared to the case where specific control is executed.

[0034] Furthermore, if the elevator platform 20 moves only a short distance, deceleration begins before the elevator platform 20 reaches its maximum speed (maximum speed for medium or long distance travel), so the above-mentioned specific control may not be effective. For example, it is thought that there are significant vibration factors other than the delayed release timing of the brake 16. By not executing the specific control (prohibiting the specific control) when the travel distance is within the short distance range RS, and by executing normal control that does not consider vibration suppression, vibrations of the elevator platform 20 in the specified direction can be suppressed more efficiently.

[0035] When the elevator platform 20 starts moving, the movement of the elevator platform 20 is controlled based on a first speed command indicating that the elevator platform 20 should first move with a first acceleration, and then the movement of the elevator platform 20 is controlled based on a second speed command indicating that the elevator platform 20 should move with a second acceleration greater than the first acceleration. This allows the brake 16 to be released while the speed is low, preventing a delay in the release of the brake 16.

[0036] Although embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments. The judgment made by the judgment unit 32 (content of the judgment process) may be changed. For example, as shown in Figure 7(a), the judgment unit 32 may decide not to perform specific control when the travel distance is within the long-distance range RL which is longer than the first threshold Lc, and decide to perform specific control only when the travel distance is within the short-distance range RS which is less than or equal to the first threshold Lc. In this case as well, vertical vibration of the lifting platform 20 can be suppressed more efficiently. The time required for movement can be shortened compared to the case where specific control is assumed to be performed.

[0037] Alternatively, as shown in Figure 7(b), the determination unit 32 may decide to execute specific control only when the travel distance is within the long-distance range RL, which is greater than or equal to another threshold Ld, and decide not to execute specific control when the travel distance is within the short-distance range RS, which is less than the first threshold Lc. If residual shaking is undesirable during long-distance transport, such an opposite control (control that reverses the decision based on travel distance) is also effective.

[0038] As shown in Figures 8 to 12, control may be performed using a combination of specific control based on the travel distance of the lifting platform 20 and vibration suppression control different from the specific control. In that case, the determination unit 32 shown in Figure 2 also functions as a pattern determination unit. The determination unit 32 selects one of several patterns related to the moving body (details will be described later) that are stored in the storage unit 36 ​​in advance. The motor control unit 33 controls the lifting motor 6 (or the travel motor 5 if the moving body is the stacker crane 1) according to the pattern selected by the determination unit 32.

[0039] In the example pattern shown in Figure 9, the above-mentioned specific control is executed at the start of movement. After the absolute value of the speed of the elevator platform 20 reaches a predetermined value during the acceleration control of the elevator platform 20, the motor control unit 33 executes vibration suppression control different from the specific control in order to suppress vibration of the elevator platform 20 in a specified direction during movement, regardless of the distance traveled. The speed control, i.e., vibration suppression control, from time t2a onward will be explained.

[0040] The memory unit 36 ​​stores multiple patterns. The pattern selection in this modified example is provided based on two perspectives. From the first perspective, multiple patterns are predetermined, each corresponding to the stopping position of the lifting platform 20 after movement. As shown in Figure 8, three ranges (regions) are defined as the stopping position after movement, starting from the one closest to the pulley 11 (the higher one, i.e., the one with the shortest hanging length from the pulley 11): the upper range RC, the middle range RB, and the lower range RA. The upper range RC, the middle range RB, and the lower range RA are set, for example, between the upper limit position PH and the lower limit position PL.

[0041] The "position of the lifting platform 20" can be determined based on any specific point on the lifting platform 20 in the Z direction. For example, the "position of the lifting platform 20" may be the height position of the mounting surface on the transfer device 23. Alternatively, the "position of the lifting platform 20" may be the height position of the bottom surface of the horizontal frame 21 on the transfer device 23. Regardless of which point is set as the reference, the control unit 30 can determine the current position of the lifting platform 20 through calculation. As shown in Figure 1, at least two laser distance meters 28 are mounted on the side of the base 2, spaced apart in the X direction, and at least two reflectors 29 are mounted on the bottom surface of the horizontal frame 21 at positions corresponding to the X-direction positions of each laser distance meter 28.

[0042] In the multiple patterns prepared to correspond to the stopping position after the lifting platform 20 has moved, as shown in Figure 9, the timing of the acceleration change in the acceleration change control, specifically the time difference, is different when switching from the acceleration section to the maximum speed maintenance section (hereinafter referred to as "when constant speed is reached"), when switching from the maximum speed maintenance section to the deceleration section (hereinafter referred to as "when deceleration begins"), and when switching from the deceleration section to the final stopping section (hereinafter referred to as "when stopping").

[0043] The pattern is predetermined to perform a first acceleration change when the acceleration of the lifting platform 20 starts to change from a state where the acceleration is constant, such as at times t2a, t3a, and t4a. Subsequently, at times t2b, t3b, and t4b, a second acceleration change is predetermined to perform in order to generate a second vibration in a direction that cancels out the first vibration in a predetermined direction that occurred in the moving body due to the first acceleration change. The time difference mentioned above is the difference between the time when the second acceleration change occurs and the time when the first acceleration change occurs.

[0044] In this modification example, as an example, in one pattern, the same time is applied at the start of acceleration, at the arrival of constant speed, at the start of deceleration, and at the stop. In the following description, the case where the "position of the lifting table 20" is the height position of the mounting surface in the transfer device 23 will be described. Now, assume that the From position is included in the upper range RC and the To position is included in the lower range RA. In that case, the determination unit 32 selects the frequency corresponding to the lower range RA from a predetermined table shown in FIG. 11 based on the information related to the transfer command acquired by the information acquisition unit 31.

[0045] Here, in the selection of the frequency, a second aspect is also required (incorporated). In the second aspect, as patterns, a first pattern corresponding to the case where the load W is placed on the lifting table 20 (with load) and a second pattern corresponding to the case where the load W is not placed on the lifting table 20 (without load) are respectively predetermined. Now, assume that the load W is not placed on the lifting table 20. The determination unit 32 selects the pattern of "13 Hz" corresponding to the lower range RA and without load.

[0046] The difference between the times t3a and t3b shown in FIG. 12(a) is half of the reciprocal of 13 Hz. As shown in FIG. 12(b), the motor control unit 33 controls the lifting motor 6 to cause a first acceleration change at the time t3a first, with a time difference that is half of the reciprocal of 13 Hz (a time difference based on the reciprocal), and then controls the lifting motor 6 to cause a second acceleration change at the time t3b. By such two-stage acceleration change control with a predetermined time difference, as shown in FIG. 12(c), the second vibration acts in the direction of canceling the first vibration. As a result, the amplitude gradually attenuates. Note that until the time t3a, the speed is constant (-Va) and thus the acceleration is zero. After the time t3b, the speed increases with a constant acceleration.

[0047] As shown in FIG. 11, the lower the stop position of the lift table 20 after movement (as seen from the ground), the smaller the frequency is set. That is, the longer the stop position of the lift table 20 after movement, the longer the time difference is set. Also, the frequency is set smaller when there is a load compared to when there is no load. That is, the time difference is set longer when there is a load than when there is no load. Note that it is not limited to the three ranges (regions) of the upper range RC, the middle range RB, and the lower range RA. The vertical length for dividing each range and the number of ranges may be adjusted as appropriate.

[0048] As described above, the determination unit 32 selects one of a plurality of patterns according to the stop position of the lift table 20, and the motor control unit 33 controls the driving of the lift table 20 by the lift motor 6 based on the pattern. There is a correlation between the stop position of the lift table 20 and the natural frequency. By configuring as described above, it is possible to efficiently suppress vibrations in a specified direction with simple control of only selecting a pattern.

[0049] Further, when a load W is placed on the lift table 20, the determination unit 32 selects the first pattern (the pattern with a load shown in FIG. 11), and the motor control unit 33 controls the driving of the lift table 20 by the lift motor 6 based on the first pattern. When no load W is placed on the lift table 20, the determination unit 32 selects the second pattern (the pattern without a load shown in FIG. 11), and the motor control unit 33 controls the driving of the lift table 20 by the lift motor 6 based on the second pattern. According to this configuration, appropriate vibration suppression control can be executed according to the presence or absence of the load W on the lift table 20, that is, according to the total weight of the moving body including the load W. Note that as internal processing of the control unit 30, the presence or absence of the load W is grasped, but the weight is unknown. Even so, speed control and vibration suppression control are possible without problems.

[0050] Even with the control modifications described above, applying specific control based on the travel distance of the lifting platform 20 at the start of movement of the moving body produces the same effects and benefits as in the above embodiment, and vibrations are suitably suppressed. After the speed exceeds a predetermined value, vibration suppression according to the speed of the lifting platform 20 (or several states included in the series of movements) is achieved by applying another vibration suppression control based, for example, on the stopping position of the lifting platform 20 after movement. That is, at the time of reaching a constant speed (time t2a), the start of deceleration (time t3a), and the time of stopping (time t4a), a first vibration in the vertical direction occurs due to a first change in acceleration, followed by a second vibration due to a second change in acceleration, which somewhat cancels out the first vibration. The control unit 30 only needs to drive the lifting platform 20 based on a predetermined pattern, and vertical vibrations can be suppressed with simple control.

[0051] Other vibration suppression control methods may include using a notch filter (a control method that prevents the excitation of natural frequencies from the outset) or other known control methods.

[0052] The speed control described herein may be applied not only to the stacker crane 1 described above, but also to the speed control of each moving body in an overhead transport vehicle or AGV. When an overhead transport vehicle is considered as an example of a moving body, the direction of travel of the overhead transport vehicle corresponds to the "specified direction". When a lateral transfer device is considered as an example of a moving body, the transfer direction by the lateral transfer device corresponds to the "specified direction". When an AGV is considered as an example of a moving body, the direction of travel of the AGV corresponds to the "specified direction". In any case, vibration of the moving body can be efficiently suppressed based on the above-described concept.

[0053] 1...Stacker crane (moving device), 3...Mast (guide unit), 16...Brake (braking device), 20...Lifting platform (moving unit), 6...Lifting motor (drive unit), 30...Control unit, La...Second threshold, Lb...First threshold, Lc...First threshold, Ld...Another threshold, RL...Long-range range, RM...Medium-range range, RS...Short-range range.

Claims

1. A mobile body device comprising: a guide portion extending in a specified direction; a mobile body that moves along the guide portion in the specified direction; a drive unit that drives the mobile body in the specified direction; and a control unit that controls the drive of the mobile body by the drive unit, wherein the control unit performs specific control to suppress vibration of the mobile body in the specified direction during movement if the distance traveled from the start of movement to the stop of movement is within a predetermined distance range, but does not perform the specific control if the distance traveled deviates from the predetermined distance range.

2. The specified direction is the vertical direction, and the moving body is a lifting platform that moves vertically along the guide portion, as described in claim 1.

3. The mobile device according to claim 1 or 2, wherein the control unit does not perform the specific control when the travel distance is within a long-distance range that is longer than the first threshold.

4. The mobile device according to claim 3, wherein the control unit executes the specific control when the travel distance is less than or equal to the first threshold and greater than or equal to a second threshold smaller than the first threshold within a medium-distance range, but does not execute the specific control when the travel distance is less than the second threshold within a short-distance range.

5. The mobile body device according to claim 1 or 2, further comprising a braking device for the mobile body, wherein the specific control controls the movement of the mobile body based on a first velocity command to move the mobile body at a first acceleration when the mobile body starts moving, and then controls the movement of the mobile body based on a second velocity command to move the mobile body at a second acceleration greater than the first acceleration.

6. The mobile body device according to claim 1 or 2, wherein, after the absolute value of the speed of the mobile body reaches a predetermined value during the acceleration control of the mobile body, the control unit executes a vibration suppression control different from the specific control in order to suppress vibration of the mobile body in a specified direction during the movement, regardless of the distance traveled.

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