Article transport apparatus

Abstract

The present application provides an article conveying apparatus. A control section generates a reference speed command in accordance with a time change pattern of the running speed which changes in steps like a running acceleration in a case where the running speed of a conveying vehicle is changed, and generates a moving average command obtained by taking a moving average of the reference speed command in a set period, and controls a running action of a running section based on the moving average command to make the running speed of the conveying vehicle a target speed at a target position which is on a downstream side of a running path from a current position of the conveying vehicle.

Description

Technical Field

[0001] The present invention relates to a goods conveying device, which includes a conveyor vehicle that travels along a travel path and conveys goods, and a control unit that controls the travel motion of the conveyor vehicle's travel mechanism. Background Technology

[0002] An example of such an article conveying device is disclosed in Japanese Patent Application Publication No. 2010-282569 (Patent Document 1). Hereinafter, the reference numerals in parentheses in the background description are reference numerals of Patent Document 1. The article conveying device of Patent Document 1 includes a conveyor (3) that travels along a track (2) and a travel control unit (59) that controls the travel motion of the conveyor (3). The travel control unit (59) includes components generated in Patent Document 1... Figure 5 The speed pattern generator (62) represents such a speed pattern, and the driving control unit (59) controls the driving action of the transport vehicle (3) according to the speed pattern. Summary of the Invention

[0003] Incidentally, when the speed of the conveyor vehicle changes, the change in the vehicle's acceleration may cause vibration due to the force exerted in the direction of travel by the conveyor vehicle and the transported items. For example, in Patent Document 1... Figure 5 At the deceleration starting point shown, the acceleration of the conveyor vehicle can change drastically, potentially causing significant vibrations in both the conveyor vehicle and the items being conveyed. However, Patent Document 1 does not mention any consideration of such vibrations.

[0004] Therefore, it is desirable to achieve the following technology: to reduce the vibration that may occur in the conveyor vehicle and the items being conveyed when the speed of the conveyor vehicle is varied.

[0005] The article conveying device disclosed herein includes: a conveying vehicle that travels along a travel path to convey articles; and a control unit that controls the travel operation of the travel unit of the conveying vehicle; the control unit generates a reference speed command according to a time variation pattern of the travel speed such that the travel acceleration changes in a step-like manner when the travel speed of the conveying vehicle changes, and generates a moving average command obtained by moving average of the reference speed command during a set period, and controls the travel operation of the travel unit based on the moving average command so that the travel speed of the conveying vehicle becomes a target speed at a target position downstream of the travel path from the current position of the conveying vehicle.

[0006] In this structure, when the conveyor's speed is varied toward a target speed, the driving action of the vehicle is controlled based on a moving average command obtained by moving average of a reference speed command. Therefore, the change in the conveyor's speed allows for a smoother change in acceleration compared to the case where the driving action is controlled using the reference speed command as is. Consequently, when the conveyor's speed is varied, vibrations that may occur in the conveyor and the items being transported can be reduced.

[0007] Furthermore, to smooth out changes in the vehicle's speed and acceleration, a time-varying pattern of speed variation could be derived by calculating the jerk (rate of change of acceleration). However, this approach might struggle to handle changes in the target speed. In contrast, this design allows for smoothing of speed variations and acceleration changes simultaneously using a time-varying pattern of step-like acceleration changes, making it easier to handle changes in the target speed.

[0008] Further features and advantages of the goods conveying equipment will become clear from the following description of the embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 It is a 3D view of the transport vehicle.

[0010] Figure 2 It is a control block diagram.

[0011] Figure 3 This is a diagram illustrating an example of a reference speed command.

[0012] Figure 4 This is a diagram illustrating an example of a moving average instruction.

[0013] Figure 5 It is a graph showing the difference in the stopping distance between the baseline speed command and the moving average command.

[0014] Figure 6 It is a graph that shows the distance required to stop when the time specified in the time-varying speed pattern is earlier than expected.

[0015] Figure 7 This is another example of a baseline speed command and a moving average command. Detailed Implementation

[0016] The implementation method of the article conveying equipment is described with reference to the accompanying drawings. For example... Figure 1As shown, the goods conveying device 100 includes a conveyor 1 that conveys goods 2 along a travel path 40. Here, the length direction (the direction in which the travel path 40 extends) of the travel path 40 is defined as the path length direction X, and the width direction of the travel path 40 is defined as the path width direction Y. The path width direction Y is a direction orthogonal to both the path length direction X and the vertical direction Z. Let the side in front of the travel direction of the conveyor 1 in the path length direction X be the downstream side X1, and let the side behind the travel direction of the conveyor 1 in the path length direction X be the upstream side X2.

[0017] In this embodiment, the article conveying device 100 includes a travel track 41 arranged along the travel path 40 (here, a pair of travel tracks 41 spaced apart in the path width direction Y), and the conveyor 1 travels along the travel track 41. Figure 1 In the example shown, the transport vehicle 1 is a roof-mounted transport vehicle that travels along a travel path 40 formed along the roof, with the travel track 41, for example, suspended from the roof. Alternatively, the transport vehicle 1 can be a transport vehicle other than a roof-mounted transport vehicle. As a transport vehicle other than a roof-mounted transport vehicle, a transport vehicle that travels along a travel path formed along the floor can be exemplified. In this case, the travel path can be formed by a travel track or can be virtually defined. Furthermore, the type of item 2 is not limited to this; item 2 can be, for example, a FOUP (Front Opening Unified Pod) that houses semiconductor wafers.

[0018] like Figure 1 As shown, the transport vehicle 1 includes a traveling unit 10. The traveling unit 10 travels along a traveling track 41 (here, a pair of traveling tracks 41). The traveling unit 10 includes wheels 11 that roll on the traveling surface of the traveling track 41 and a drive unit M (e.g., an electric motor such as a servo motor) that rotates the wheels 11. Driven by the rotation of the wheels 11 by the drive unit M, the traveling unit 10 travels along the traveling track 41. Details omitted, the traveling unit 10 includes guide wheels that roll on the guide surface of the traveling track 41, and the traveling unit 10 travels along the traveling track 41 while the guide wheels are in contact with and guided by the guide surface of the traveling track 41. Figure 1 In the example shown, the transport vehicle 1 has a pair of traveling units 10 arranged in the path length direction X.

[0019] like Figure 1 As shown, the transport vehicle 1 includes a main body 20 connected to the traveling unit 10. Figure 1 In the example shown, the main body 20 is supported by the travel unit 10 in a state where it is positioned below the travel unit 10 in the vertical direction Z. Details omitted, the main body 20 has a support portion for supporting the article 2, and the article 2 is transported by the transport vehicle 1 while being supported by the main body 20.

[0020] like Figure 2 As shown, the goods conveying device 100 includes a control unit 30. The control unit 30 includes a processing unit such as a CPU and peripheral circuits such as a memory. Through the cooperation of these hardware components and the program executed on the processing unit, the various functions of the control unit 30 are realized. The control unit 30 can be installed on the conveyor 1 or installed independently of the conveyor 1. Furthermore, if the control unit 30 has multiple hardware components that can communicate with each other, some of the hardware can be installed on the conveyor 1, while the remaining hardware can be installed independently of the conveyor 1. The technical features of the control unit 30 disclosed in this specification can also be applied to the control method of the conveyor 1 of the goods conveying device 100, and the control method of the conveyor 1 is also disclosed in this specification.

[0021] The control unit 30 controls the driving action of the driving unit 10. Specifically, the control unit 30 controls the driving action of the driving unit 10 by controlling the drive of the drive unit M. Hereinafter, the control of the driving unit 10 (control of driving action) performed by the control unit 30 of this embodiment will be described, but as described above, in Figure 1 In the example shown, the transport vehicle 1 has two traveling units 10 arranged in the path length direction X. In this case, it can be configured to control both traveling units 10 equally, or it can be configured to control the first traveling unit 10 as described below, and control the second traveling unit 10 to follow the travel of the first traveling unit. In the latter case, the control unit 30 controls, for example, the driving torque of the wheels 11 generated by the drive unit M of the second traveling unit, so that the second traveling unit follows the travel of the first traveling unit. The control unit 30 can also control (torque-free control) to make the driving torque of the wheels 11 generated by the drive unit M of the second traveling unit zero, so that the second traveling unit follows the travel of the first traveling unit.

[0022] For example, when stopping the transport vehicle 1 at a stop position corresponding to the transport source or destination of the item 2, or when controlling the distance between the transport vehicle 1 and other transport vehicles 1 located downstream X1 of the travel path 40, or when decelerating the transport vehicle 1 as it enters a straight section that appears straight in view (viewed along the vertical Z direction) and then a curved section that appears curved in view, the control unit 30 changes the travel speed of the transport vehicle 1 so that the travel speed of the transport vehicle 1 becomes a target speed located downstream X1 of the travel path 40, beyond the current position of the transport vehicle 1. When changing the travel speed of the transport vehicle 1 in this way, the control unit 30 generates a reference speed command according to a traveling speed time change pattern that changes in a step-like manner with the travel acceleration. The control unit 30 generates a reference speed command for each set time (each calculation cycle). Furthermore, the traveling speed time change pattern is set so that the travel speed of the transport vehicle 1 becomes a target speed located downstream X1 of the travel path 40, beyond the current position of the transport vehicle 1. like Figure 2 As shown, in this embodiment, the control unit 30 includes a reference speed command generation unit 31 for generating reference speed commands.

[0023] Furthermore, the control unit 30 generates a moving average command obtained by moving the average of a reference speed command within a set period (moving average time), and controls the driving operation of the driving unit 10 based on this moving average command. The moving average command (the speed command after moving average processing) is generated based on the time series data of the reference speed command within the set period. In this embodiment, the moving average is set to an unweighted simple moving average, but it is not limited to this; it can also be set to a weighted moving average, etc. Figure 2 As shown, in this embodiment, the control unit 30 includes a moving average instruction generation unit 32 that generates moving average instructions. The moving average instruction generation unit 32 generates moving average instructions based on the reference speed instructions input from the reference speed instruction generation unit 31. Furthermore, the reference speed instruction generation unit 31 and the moving average instruction generation unit 32 are at least logically distinct, but do not necessarily need to be physically distinct.

[0024] The drive unit M includes a motor unit that rotates the wheels 11, and an amplifier unit that drives the motor unit through feedback control to follow the drive command input from the control unit 30. The drive unit M rotates the wheels 11 so that the travel speed of the transport vehicle 1 corresponds to the travel speed of the drive command input from the control unit 30. In this embodiment, the control unit 30 or the drive unit M generates a position command based on a moving average command, and the amplifier unit of the drive unit M drives the motor unit of the drive unit M through position control based on the position command. The position command is generated, for example, by integrating the moving average command. Alternatively, the amplifier unit of the drive unit M may be configured to drive the motor unit of the drive unit M through speed control based on the moving average command.

[0025] exist Figure 3 This is an example of a time-varying speed pattern where the acceleration changes in a step-like manner (in other words, an example of a reference speed command). This time-varying speed pattern is used to make the speed of transport vehicle 1 reach a target speed (speed change end speed Ve) at a target position X1 downstream of the current position on the travel path 40. Here, the target position is the position of transport vehicle 1 on the travel path 40 at time t2. This time-varying speed pattern is used to make the speed of transport vehicle 1, traveling at a certain speed (speed change start speed Vs), change at a certain rate from the speed change start speed Vs to (here, decreasing) to the speed change end speed Ve during the period from time t1 to time t2. As shown in... Figure 3 In the context of travel speed, acceleration is expressed as the rate of change of travel speed (relative to time). Figure 3 In the time-varying speed pattern shown, the acceleration changes in a stepwise manner at times t1 and t2.

[0026] exist Figure 4 In the diagram, the time-varying pattern of the driving speed, which will become the source for generating the reference speed command, is... Figure 3 In the pattern shown, the moving average command (the speed command after moving average processing) and the rate of change of the moving average command (the rate of change relative to time) are represented together by a solid line. Additionally, in... Figure 4 In the middle, Figure 3 The two graphs shown are represented by dashed lines. For example, from... Figure 4 As is clear, in the moving average-based instruction (in Figure 4 When the speed command (represented by a solid line) is used to control the movement of the traveling unit 10, the speed of the transport vehicle 1 can be varied so that the reference speed command (in the case of...) can be used as before. Figure 4Compared to the case where the speed command (represented by a dashed line) controls the driving action of the driving unit 10, the change in driving acceleration becomes smoother.

[0027] In addition, Figure 4 In the example shown, the reference speed command (represented by the dashed line) reaches the speed change termination speed Ve at time t2, while the moving average command (represented by the solid line) reaches the speed change termination speed Ve at time t3, which is later than time t2. Therefore, when the driving operation of the vehicle 10 is controlled based on the moving average command, compared to the case where the driving operation of the vehicle 10 is controlled using the reference speed command as is, the time when the driving speed of the transport vehicle 1 reaches the speed change termination speed Ve is delayed, and this delay time (the time difference between time t2 and time t3) is equal to the set period (moving average time).

[0028] Due to the aforementioned delay time, such as Figure 5 As shown, when the driving action of the vehicle 10 is controlled based on a moving average command, compared to the case where the driving action of the vehicle 10 is controlled using a reference speed command as is, the distance traveled by the transport vehicle 1 until its speed reaches the speed change termination speed Ve is longer. Let the set period (moving average time) be T, and the increase in travel distance be represented by (Vs - Ve) × T / 2. Furthermore, in Figure 5 In the scenario where the velocity change ends and the velocity Ve is zero (i.e., the target velocity is zero), in... Figure 5 In the middle, Figure 4 The graph showing the moving average instruction and the graph showing the travel distance of the transport vehicle 1 when the driving action of the driving unit 10 is controlled based on the moving average instruction are represented by solid lines, and the graph showing the travel distance of the transport vehicle 1 is represented by solid lines. Figure 3 The graph showing the reference speed command and the graph showing the travel distance of the transport vehicle 1 when the travel unit 10 is controlled using the reference speed command as is are represented by dashed lines. Additionally, the graph showing the travel distance of the transport vehicle 1 represents the travel distance along the travel path 40 from the reference position at each time point (in other words, the position in the path length direction X). Figure 5 As shown, the distance required to stop (the distance traveled until the transport vehicle 1 stops) when the travel action of the travel unit 10 is controlled by the reference speed command as is becomes the first distance D1. In contrast, the distance required to stop when the travel action of the travel unit 10 is controlled by the moving average command becomes the second distance D2, which is longer than the first distance D1.

[0029] When the speed Ve ends at zero, let the set period (moving average time) be T, and represent the difference between the first distance D1 and the second distance D2 as Vs×T / 2. Therefore, as long as the deceleration from the speed change start speed Vs begins at a position X2 upstream of the distance represented by Vs×T / 2 compared to the case where the driving action of the vehicle 10 is controlled using the reference speed command as is, in other words, as long as the deceleration from the speed change start speed Vs begins at a time represented by T / 2 earlier than the case where the driving action of the vehicle 10 is controlled using the reference speed command as is, the stopping distance required when the driving action of the vehicle 10 is controlled based on the moving average command is equal to the stopping distance required when the driving action of the vehicle 10 is controlled using the reference speed command as is.

[0030] exist Figure 6 In this process, the time specified in the time variation pattern of the driving speed used in the generation of the reference speed command will be compared with... Figure 5 The graphs showing the moving average command compared to half of the previously set period (moving average time), and the graphs showing the travel distance of the transport vehicle 1 when the driving action of the driving unit 10 is controlled based on the moving average command, are represented by solid lines. Figure 5 In the example shown, the deceleration of velocity Vs begins at time t1, starting from the change in velocity. In contrast, at... Figure 6 In the example shown, as described above, advancing the time specified in the time-varying speed pattern results in the deceleration of the speed Vs starting at time t0, which is half the time preceding time t1. Therefore, in Figure 6 In the case where the driving action of the driving unit 10 is controlled based on the moving average command, the stopping distance required is the same as before. Figure 5 The distance required to stop when the reference speed command controls the driving action of the driving unit 10 is also called the first distance D1. Furthermore, in Figure 6 In the process, at time t4, which is half the set period after time t2, the moving average command reaches the speed change termination speed Ve. This is not limited to the case where the target speed is zero (i.e., the case where the transport vehicle 1 stops at the target position). Even when the transport vehicle 1's speed is reduced to a target speed greater than zero, by advancing the time specified in the time change pattern of the travel speed used in generating the reference speed command by a time corresponding to the set period (e.g., half the set period), the travel distance of the transport vehicle 1 until its speed reaches the target speed can be made close to the travel distance when the travel unit 10's movement is controlled using the reference speed command as is (e.g., the same or similar degree).

[0031] For the reasons described above, it is preferable to have a structure in which, for example, the control unit 30 advances the time specified in the time variation pattern of the driving speed as the setting period lengthens. In this case, it is possible to adjust the advance time of the time specified in the time variation pattern of the driving speed, based on the case where the time specified in the time variation pattern of the driving speed is not advanced, for example, compared with... Figure 6 The example shown is also set to half the duration of the set period.

[0032] Additionally, the graph showing the change in speed over time is as follows: Figure 3 The pattern shown is illustrated, but of course, all patterns can be used to represent the time-varying speed. Figure 7 The graph representing the time change of driving speed is shown in the figure. Figure 3 One of the different examples.

[0033] exist Figure 7 In the diagram, the time-varying pattern of driving speed is represented by dashed lines, and the moving average command generated based on this pattern is represented by solid lines. Figure 7 In, it means with Figure 3 This differs from the case where the transport vehicle 1 decelerates in two stages, from the initial speed Vs to the final speed Ve. Specifically, Figure 7 The time-varying pattern of the travel speed is as follows: from time t10 to time t11, the travel speed decreases from the initial speed Vs to the intermediate speed Vt; from time t11 to time t12, the travel speed is maintained at the intermediate speed Vt; from time t12 to time t13, the travel speed decreases from the intermediate speed Vt to the final speed Ve; from time t13 to time t14, the travel speed is maintained at the final speed Ve; and at time t14, the travel speed decreases stepwise to zero. Time t12 is, for example, defined as the moment when the transport vehicle 1 detects a detected object (e.g., a strip-shaped component representing the stop area) located upstream of the target stop position X2, and time t14 is defined as the moment when the transport vehicle 1 detects a detected object (e.g., a light reflector) located at the target stop position. Even though the time-varying pattern of the travel speed is... Figure 7 In the case of the pattern shown, by controlling the driving action of the driving unit 10 based on the moving average command, it is also possible to make the change in the driving speed of the transport vehicle 1 smooth the change in driving acceleration.

[0034] Incidentally, the optimal setting period (moving average time) may vary depending on the position of the transport vehicle 1 on the travel path 40 and the travel state of the transport vehicle 1. For example, when the transport vehicle 1 travels along a curved section of the travel path 40 that forms a curve when viewed from above, it is preferable to shorten the setting period (including setting the setting period to zero, i.e., using the reference speed command as is). However, if only the setting period is changed, the moving average command becomes discontinuous before and after the change, which may cause vibration in the transport vehicle 1 and the item 2 being transported by the transport vehicle 1. Therefore, in order to maintain the continuity of the moving average command before and after the change of the setting period, it is preferable to make the following structure: when the setting period is changed, the control unit 30 changes the setting period (including changing the setting period to zero) while the transport vehicle 1 is traveling at a constant speed of more than the length of the setting period before the change. Alternatively, the control unit 30 may be configured not to change the length of the setting period during the travel of the transport vehicle 1.

[0035] The embodiments disclosed in this specification are merely illustrative in all respects, and various changes can be made as appropriate without departing from the spirit of this disclosure.

[0036] [Summary of the above embodiments]

[0037] The following is a summary of the article conveying equipment described above.

[0038] A goods conveying device includes: a conveying vehicle that travels along a travel path to convey goods; and a control unit that controls the travel operation of the travel unit of the conveying vehicle; the control unit generates a reference speed command according to a time variation pattern of the travel speed such that the travel acceleration changes in a step-like manner when the travel speed of the conveying vehicle changes, and generates a moving average command obtained by moving average of the reference speed command during a set period, and controls the travel operation of the travel unit based on the moving average command so that the travel speed of the conveying vehicle becomes a target speed at a target position downstream of the travel path from the current position of the conveying vehicle.

[0039] In this structure, when the conveyor's speed is varied toward a target speed, the driving action of the vehicle is controlled based on a moving average command obtained by moving average of a reference speed command. Therefore, the change in the conveyor's speed allows for a smoother change in acceleration compared to the case where the driving action is controlled using the reference speed command as is. Consequently, when the conveyor's speed is varied, vibrations that may occur in the conveyor and the items being transported can be reduced.

[0040] Furthermore, to smooth out changes in the vehicle's speed and acceleration, a time-varying pattern of speed variation could be derived by calculating the rate of change of acceleration (the rate of change of acceleration). However, this approach might struggle to handle changes in the target speed. In contrast, this design allows for smoothing of speed variation and acceleration changes simultaneously using a time-varying pattern of step-like acceleration changes, making it easier to handle changes in the target speed.

[0041] Here, it is preferable that the control unit advances the time specified in the aforementioned time change pattern as the aforementioned setting period becomes longer.

[0042] When controlling the movement of the vehicle based on a moving average command, compared to controlling the movement using a reference speed command as is, the distance the vehicle travels (the distance required for deceleration) until its speed reaches the target speed is longer when the vehicle decelerates. This distance increases with the length of the set period. When the target speed is zero (i.e., when the vehicle stops at the target position), this distance required for deceleration becomes the distance traveled until the vehicle stops (the distance required to stop). According to this structure, this can be taken into account, and the time specified in the time variation pattern is advanced as the set period lengthens. Therefore, regardless of the length of the set period, the vehicle can be decelerated to the target speed (e.g., stopped) at or near the target position.

[0043] Furthermore, it is preferable that when the length of the aforementioned setting period is changed by the control unit, the length of the aforementioned setting period is changed while the aforementioned transport vehicle is traveling at a constant speed of more than the length of the aforementioned setting period before the change.

[0044] For example, when the conveyor travels along a curved section of the path that appears curved when viewed from above, it is preferable to shorten the length of the set period (including setting the length of the set period to zero, i.e., using the reference speed command as is). According to this structure, even when the optimal length of the set period varies depending on the position of the conveyor on the path and its travel state, the length of the set period can be changed while maintaining the continuity of the moving average command before and after the change. This suppresses vibrations in the conveyor and the items being transported when the length of the set period changes.

[0045] The article conveying device disclosed herein is sufficient to achieve at least one of the aforementioned effects.

[0046] Explanation of reference numerals in the attached figures

[0047] 1: Conveyor vehicle

[0048] 2: Items

[0049] 10: Driving Department

[0050] 30: Control Department

[0051] 40: Driving route

[0052] 100: Goods conveying equipment

[0053] X1: Downstream side.

Claims

1. A material conveying device, comprising: Conveyor vehicles travel along a designated path to transport goods; and The control unit controls the driving movements of the driving unit of the aforementioned transport vehicle; Its features are, When the aforementioned control unit changes the speed of the aforementioned transport vehicle, it generates a reference speed command based on a time-varying pattern of speed change with a step-like variation in acceleration. It also generates a moving average command obtained by averaging the reference speed command over a set period. Based on this moving average command, it controls the movement of the aforementioned transport unit to achieve a target speed for the transport vehicle at a target position downstream of its current position along the aforementioned travel path. As the aforementioned setting period lengthens, the control unit advances the start time of the aforementioned speed change according to the aforementioned time change pattern.

2. The article conveying device as described in claim 1, characterized in that, The aforementioned control unit changes the length of the aforementioned set period based on the shape of the aforementioned travel path traveled by the aforementioned transport vehicle.

3. The article conveying device as described in claim 1 or 2, characterized in that, When the aforementioned transport vehicle is traveling in a curved section of the aforementioned travel path, the control unit shortens the length of the aforementioned set period compared to when it is traveling in a straight section of the aforementioned travel path.

4. The article conveying device as described in claim 1 or 2, characterized in that, When the control unit changes the length of the aforementioned set period, the aforementioned transport vehicle travels at a constant speed of more than the length of the aforementioned set period before the change.

5. The article conveying device as described in claim 3, characterized in that, When the control unit changes the length of the aforementioned set period, the aforementioned transport vehicle travels at a constant speed of more than the length of the aforementioned set period before the change.

Images