KR20080009632A - Moving body and controlling method thereof - Google Patents

Abstract

A moving body and a control method thereof are provided to feedback a drive mechanism of the moving body according to the position of the moving body and the vibration of the moving body. A lift member(4) is guided to a mast(6) to be lifted. A linear scale is installed in the mast according to the direction of height of the mast. A linear sensor(10) installed in the lift member reads the height of the lift member. The lift member is suspended by a suspension support material(12) such as a belt, a wire, or a rope to which a gear is attached. The lift member is lifted by a lift motor together with a counter weight. A stacker crane conveys a weight such as a cassette of a liquid crystal substrate between a shelf and a station.

Description

MOVING BODY AND CONTROLLING METHOD THEREOF}

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows typically the goods of a platform, a slide fork, and a shelf in an Example.

2 is a view showing a model from a command position to the lift motor to the slide fork in the embodiment.

3 is a block diagram of a feedback controller in an embodiment.

4 shows the characteristics of the embodiment when unloading the article, A) shows the input speed command, B) shows the deviation from the basic command of the height position of the platform, and C) shows the acceleration of the article.

5 shows the characteristics of the embodiment when lifting the article, A) is the input speed command, B) the deviation from the basic command of the height position of the platform, C) the acceleration at the tip of the slide fork, D) Represents the acceleration of the article.

(Explanation of symbols for the main parts of the drawing)

2: stacker crane 4: platform

6: mast 8: linear scale

10: linear sensor 12: suspension support

16: feedback controller 20: lifting motor

22: slide fork 24: article support

26: acceleration sensor 28: lathe

29: prop 30: shelf support

32: article 34: target height storage

38: difference 40, 42: adder

46: integral means 44, 48 to 52: multiplication means

The present invention relates to vibration damping of a mobile body.

In conveying trolleys, such as a stacker crane, an unmanned conveying truck, and a tracked trolley | bogie, goods are conveyed by the combination of the retractable arm, such as a slide fork and a scalar arm, and a platform or a lifter. Moreover, in a ceiling traveling car, a chuck of a platform raises and lowers an article, and it moves, and conveys. In either of these cases, there is a demand to suppress vibrations of articles during transfer. If the vibration can be suppressed, the force applied to the article at the time of conveyance can be reduced, the time to wait until the vibration is accommodated can be shortened, the height precision at the time of conveyance can be improved, and the rigidity of the conveying device can be improved. This may be small, and there are advantages such as being able to transport a heavier and more fragile article. However, Patent Document 1 (Japanese Patent 3526014) raises the platform at a high speed before the slide fork contacts the article in the transport by the stacker crane, and at a low speed from the time of the contact start time, thereby preventing the impact of the article and the slide fork. It is proposed to make small.

[Patent Document 1] Japanese Patent 3526014

The basic problem of this invention is to make it possible to perform the movement required in a short time, while suppressing vibration.

A further object of the present invention is to make it possible to transport an article in a short time while suppressing vibration of the article.

A further object of the present invention is to suppress the vibration during the transfer of the article to the stacker crane, to allow the article to be transported in a short time, and to reduce the dead space of the shelf of the transfer partner.

A further object of the present invention is to provide a configuration of the control system for the above.

The movable body of the present invention is characterized by the position detecting means for detecting the position of the movable body, the vibration detecting means for detecting the vibration of the movable body, and at least the motion of the vibration object, depending on the detection result of the respective means. The control part for feedback control of a drive mechanism is provided.

Preferably, the movable body is provided with a conveying apparatus for the article, and the respective detection means detects the position and vibration of the conveying apparatus and feeds back the operation of the conveying apparatus in the control unit.

Particularly preferably, the control unit comprises: basic command generating means for generating a basic command of an open loop to the drive mechanism, reference signal generating means for converting the basic command into a reference signal of the position and acceleration of the moving object;

Calculation means for calculating an error of the position and acceleration of the movable body obtained by the respective detection means, an error of the position and vibration acceleration of the movable body obtained by the reference signal generating means, and updating means for updating the estimated value of the state of the movable body based on the calculated error. and,

An addition means for adding a correction value based on the estimated value of the state of the moving object to the basic command to make a control input to the drive mechanism is provided.

The present invention provides a stacker crane equipped with an arm that can move back and forth on a platform that is elevated along a mast by a lift motor.

In addition to installing the height sensor of the platform, an acceleration sensor is installed at the arm tip to detect vibration of the arm tip,

And a control unit for feedback-controlling the elevating motor by the signal of the height sensor and the acceleration sensor when the elevating platform is raised and lowered in the state where the arm is advanced.

Preferably, the control unit comprises: basic command generating means for generating a basic command of the open loop to the lifting motor, reference signal generating means for converting the basic command into a reference signal of the height of the platform and the acceleration of the arm;

The platform is calculated based on the height of the platform obtained by the height sensor and the vibration acceleration of the arm obtained by the acceleration sensor, the calculation means of the error of the height of the platform obtained by the reference signal generating means and the acceleration of the arm, and the calculated error. Updating means for updating an estimated value of the state of cancer,

Addition means for adding the correction value based on the estimated value of the platform and the arm to the said basic instruction | command and used as a control input to a lift motor is provided.

Further, in the present invention, the position and vibration of the moving body are detected, and the driving mechanism of the moving body is feedback-controlled to control the position and the vibration of the moving body, at least according to the detection result of the position and the vibration, at least for the movement to be the vibration suppression target. .

Moreover, this invention is the lifting control method of the stacker crane equipped with the arm which can move forward and backward to the lifting platform which raises and lowers along a mast by a lifting motor,

The height of the platform is detected by a height sensor, and an acceleration sensor is installed at the arm tip to detect vibration of the arm tip,

It is characterized in that the lifting motor is feedback-controlled by the signal of the height sensor and the acceleration sensor when the lifting table is lifted with the arm advanced.

Best Mode for Carrying Out the Invention The following shows an optimal embodiment.

(Example)

1-5, the Example and the characteristic of control of the platform 4 in the stacker crane 2 are shown. In each drawing, the lifting platform 4 is guided and lifted by the mast 6, and the linear sensor 10 provided with the linear scale 8 along the height direction in the mast 6, and installed in the lifting platform 4 The height position x0 of the platform 4 is read. In addition, the platform 4 is suspended by a suspension support member 12 such as a belt, a wire, a rope, or the like with a gear, and is lifted by the lift motor 20 in FIG. 3 together with a counterweight (not shown).

22 is a slide fork, and other arms, such as a scalar arm which can advance and retreat in a horizontal plane, may be an article support part which consists of a top plate of the slide fork 22, and 26 is an acceleration sensor provided in the article support part 24. . The shelf 28 is provided facing the traveling path of the stacker crane 2, 29 is the support post, and the article 32 is mounted on the shelf support 30.

Here, the stacker crane 2 shall convey the heavy goods, such as the cassette of a liquid crystal substrate, as the article 32 between the shelf 28 and the station which is not shown in figure. The liquid crystal substrate is liable to be damaged, and if the rigidity of the slide fork 22 or the platform 4 is increased, the stacker crane 2 becomes large, which is not preferable. Moreover, since the shelf 28 etc. are installed in a clean room, it is necessary to make the dead space for exchange small, and to shorten the cycle time of exchange in the point of productivity of a liquid crystal display.

Lifting the article 32 will be described as an example of the lifting operation at the time of conveyance. The platform 4 stops at a position sufficiently lower than the bottom of the article 32 to advance the slide fork 22. Subsequently, when the slide fork 22 approaches the bottom surface of the article 32 at the first speed, the rising speed is switched to the second speed at the slow speed, and the article 32 is transferred from the shelf support 30. When the article 32 ascends to the position conveyed by the article support part 24 reliably, it will increase and raise at the 3rd speed | rate close to a 1st speed, and will stop a raise, and will return the slide fork 22 after that. In addition, since the bottom distance of the article 32 and the remaining distance of the slide fork 22 are not measured, the exact time at which the article is transferred from the slide fork 22 to the shelf support 30 is unpredictable. The stroke for lifting the article is related to the bending and amplitude of the slide fork 22, and the stroke can be shortened as long as the amplitude can be reduced. When the shelf support 30 is provided in multiple numbers above and below the shelf 28, and the amplitude of the slide fork 22 is ± h, in order to avoid the interference with the shelf support which supported the article in the arrangement | positioning of the shelf support 30, In order to avoid the interference of at least h, and to avoid interference with the shelf support on the upper side of the article, a margin of h is required, and a total dead space of 2h is required. The first step of elevating the platform 4 at a slightly higher speed, and then elevating at a lower speed, exchanging the article 32 with the shelf support 30, and then elevating the platform 4 at a slightly higher speed. The same applies to unloading goods.

2 shows a platform and a control model of the article on the slide fork or slide fork. The platform is modeled as a base of mass m3 in which the posture is held horizontally, and a rigid body [mass (m)] which is inclined at an inclination angle θ and bonded with a pin. In addition, the rigid body and the base are connected by a spring k3 and a frictional resistance C3. The slide fork and the article supported by it are represented by the quality point m1, and are connected with the rigid body by the spring k1 and the frictional resistance C1. In addition, the mass of the material point m1 changes abruptly by lifting the article. The platform is connected to the counter weight (quality point m2) through the suspension support material, and the counter weight is also connected to the lift motor with the suspension support material. The spring constant of the suspension support material between the counterweight and the platform is k2 and the frictional resistance is C2. The spring constant between the counterweight and the lifting motor is k4 and the frictional resistance is C4. The height of the base of the platform is set to x0, the height of the slide fork tip is x1, the height of the counterweight is x2, and the height from the counterweight to the command position to the lifting motor is x3 at relative coordinates based on x0. .

The state X of the system of FIG. 2 can be expressed by four variables representing heights, x0 to x3, their time derivatives, the inclination angle θ of the platform and their time derivatives. And state (X) shows the state of the system which consists of a platform and a slide fork in a stacker crane. In addition, variables F1 to F4 are determined as variables related to the ^H∞ filter for robust control, and the state (X) is represented by 14 variables in total. U is the control input to the lift motor.

3 shows a control system in the embodiment. The target height storage unit 34 stores a pattern of basic commands to the lift motor 20, which is a pattern of lift speed for lifting or lowering the article while suppressing the vibration of the slide fork 22. However, since the exact time of sending and receiving the goods between the shelf support is unclear, in the model of FIG. 2, even if the mass of the material point m1 is only the slide fork or the slide fork + article, the natural vibration is suppressed. The basic directive is determined. The reference signal generator 36 converts the basic command into a two-dimensional reference signal ref consisting of the height position of the platform and the acceleration of the slide fork according to the elevation of the platform. In addition, this acceleration does not include as much as the vibration of a slide fork.

The divider 38 outputs an error vector e consisting of the difference between the signals of the sensors 10 and 26 and the reference signal ref, which translates the shift from the basic command into the height position of the platform and the vibration of the slide fork tip. It is shown as. The multiplication means 44 multiplies the error vector by the matrix B, and the multiplication means 48 multiplies the estimated value of the state X by the matrix A, adds them to the adder 40 to integrate the means 46. ) Is updated to update the state (X). The multiplication means 44 corrects the estimated value of the state X based on the error vector, and the multiplication means 48 corrects X based on the estimated value of the state X itself. For example, the state Xn + 1 at time n + 1 is represented by Xn + 1 = Xn + AXn + Ben from the state Xn at time n, where the subscripts indicate time. If the time unit between each time is Δ, for example, considering the second term,

Xn + 1 = (1 + A · Δ + A 2/2 · Δ 2) Xn + (B · Δ + B 2/2 · Δ 2) en

Becomes

The multiplication means 50 multiplies the matrix C by the state X which is a 14-dimensional vector, for example, and produces the output CX. The output CX is a control input based on the state X, and corrects the basic command FF according to the shift of the height position and the vibration acceleration from the basic command. The multiplication means 52 multiplies the error vector by the matrix D, and adds the output De to the control input. The adder 42 adds CX and De to the basic command FF to make the control input u. It is not necessary to form the term De. The control input u has robustness in the sense of ^H∞ control, and its influence is equal to or less than a predetermined value even for the assumed worst disturbance. Moreover, although the degree of freedom at the time of elevating a platform is 5, the feedback control by the sensors 10 and 26 is performed about the vibration of the front end of a slide fork, and the height position of a platform. Therefore, the control of the embodiment is robust control of two degrees of freedom.

[Table 1] Items of 2 degrees of freedom robust control

Item Out of value Contents Physical model degrees of freedom 5 x0, x1, x2, x3, θ H ^∞ filter order 4 Number of sensors 2 Height position of platform, tip acceleration of slide fork Control input (u) One Command to lift motor Error vector (e)  2D Height position of 2D platform, tip acceleration of slide fork and error of basic command State quantity (X)  14 dimensions For each of the four degrees of freedom of the 5x2 + filter order of degrees of freedom, the value and the time derivative are taken as the state quantities. Output (y) 2D Height position of platform, tip acceleration of slide fork Matrix (A) 14 rows 14 columns Represents the contribution from the state (X) to that time change. Matrix (B) 14 rows and 2 columns The state X is corrected by the error vector e. Matrix (C) 1 row 14 columns Determine the contribution from state (X) to control input (u) Matrix (D)  1 row 2 columns The contribution from the error vector e to the control input u can be determined and omitted FF Basic command

[Table 2] Detailed model of two degree of freedom robust control

dX / dt = AX + Be

u = FF + CX + De

4 shows operational waveforms of the embodiment in the case of unloading the article. A) represents an input speed command for the lifting motor, and the non-control adds only the basic command and does not perform the feedback control. For example, the two degree of freedom robust control is fed back by the linear sensor 10 and the acceleration sensor 26. Shows the result of adding control. B) shows the deviation from the target height position of the platform, and C) shows the acceleration in the workpiece of the object to be conveyed. In addition, the lowering itself of the article from the slide fork to the shelf support is performed in the vicinity of the first second of time. As is clear from Fig. 4C), the degree of vibration applied to the work is the same as in the embodiment only by the basic instruction, but in the embodiment, the deviation of the height of the platform is almost zero after the third time. For this reason, the platform can be quickly lowered to the target height, the slide fork can be retracted, and the transportation time can be shortened. The basic command is designed to sufficiently suppress the vibration of the work, and the vibration of the work does not increase even if the feedback control is added so that the height of the platform quickly converges to the target position.

Fig. 5 shows the characteristics when lifting the article, A) shows the input speed command by the basic command FF and the speed command by the two degree of freedom robust control, and B) from the target height position of the platform. , C) represents the acceleration of the slide fork tip, and D) represents the acceleration applied to the workpiece. The lifting of the article is performed in the vicinity of the first second of time, and correspondingly, the input speed command is also changed from the basic command FF in the vicinity of the first second of time. In the acceleration of the workpiece, there is a peak of acceleration only in the case of the basic command FF two seconds before the time, but in the embodiment, this peak is lost. With respect to the height of the platform, in the embodiment, the deviation is almost zero after the fifth time, but the deviation is not solved only by the basic command FF.

In the embodiment, as described above, the deviation of the height position of the platform can be eliminated in a short time. In addition, the acceleration applied to the tip of the work or slide fork according to the lifting or lowering of the article is about the same as the basic instruction. As a result of this, it is possible to transfer in a short time without exerting a great impact on the end of the work or the slide fork, and since the positioning accuracy of the platform is high, the dead space on the shelf side can be reduced.

Although the lifting platform of the stacker crane was demonstrated in the Example, it can implement also in the conveying apparatus which mounted the scalar arm and the slide fork to the lifting platform which raises and lowers by the suspension support material along a fixed guide. In addition, the embodiment can be similarly applied to the control of the lifter in the transfer apparatus in which the slide fork or the scalar arm is mounted on the lifter to perform the transfer. Moreover, an Example can be similarly applied also to the damping of the travel control of conveyance trolleys, such as a stacker crane. Further, the embodiment can be similarly applied to the elevating control of the lift table which is suspended from the ceiling car body by the suspension support material and supports the article by the chuck. In this case, the vibration of the tip of the slide fork may be replaced with the horizontal vibration of the platform, and the elevation of the platform in the stacker crane may be replaced with the elevation of the platform as the ceiling traveling car. Although ^H∞ control was used as an example of robust control, the present invention is not limited to this, and may be H ² control or μ control.

A sensor for detecting the distance to the article or the presence or absence of a load from the article may be provided at the tip of the slide fork so that the state can be estimated more accurately. The height of the platform is not limited to the linear scale, but may be obtained by an absolute distance sensor such as an encoder that reads the number of revolutions of the roller for lifting guides of the platform and a laser rangefinder.

In the present invention, since the drive mechanism of the movable body is feedback-controlled based on the position of the movable body and the detection result of the vibration, the necessary movement can be performed in a short time while suppressing the vibration.

In particular, when the present invention is applied to the conveying operation of the conveying apparatus, the conveying can be performed in a short time while suppressing the vibration applied to the article during the conveying.

And if this invention is applied to the lifting control at the time of conveyance with respect to the lifting platform of a stacker crane, the height of a target of the height of a platform or the height of an arm tip may be suppressed, suppressing the vibration of an arm tip and at least not increasing the vibration of an arm tip. By reducing the deviation from, it can transfer in a short time. In addition, since the height of the tip of the platform and the arm can be controlled accurately, the dead space on the side of the transfer partner such as the lathe can be reduced.

Further, if the estimated value of the state of the moving body is updated based on the position and the vibration obtained by the detection means and the error of the position and the vibration calculated from the basic command of the open loop, the state of the moving body is in accordance with the deviation of the actual state with respect to the basic command. You can modify the estimate of. When the correction value based on this estimated value is corrected to the basic command by the addition means, the feedback control according to the deviation from the basic command can be performed, and the movable body can be moved to follow the basic command.

Claims (7)

Position control means for detecting the position of the movable body, vibration detecting means for detecting the vibration of the movable body, and feedback control of the driving mechanism of the movable body in accordance with the detection result of each of the means at least with respect to the movement to be suppressed vibration. Moving body characterized in that the control unit for the installation. The movable body according to claim 1, wherein the movable body has a conveying apparatus for the article, and the respective detecting means detects the position and vibration of the conveying apparatus and feeds back to the operation of the conveying apparatus in the control unit. The apparatus of claim 1, wherein the control unit comprises: basic command generating means for generating a basic command of an open loop to a drive mechanism, and reference signal generating means for converting the basic command into a reference signal of a position and acceleration of a moving object; Update means for calculating the error of the position and vibration acceleration of the movable body obtained by the said detection means, the error of the position and acceleration of the movable body calculated by the said reference signal generation means, and the estimated value of the state of a movable body based on the calculated error. Way; And And a adding means for adding a correction value based on an estimated value of the state of the moving object to the basic command to form a control input to the drive mechanism. In a stacker crane equipped with an arm that can move back and forth on a platform lifted along a mast by a lift motor: In addition to installing a height sensor of the platform, an acceleration sensor is installed at the arm tip to detect vibration of the arm tip, A stacker crane, comprising: a control unit configured to feedback-control the lifting motor by a signal of the height sensor and an acceleration sensor when the lifting table is lifted with the arm advanced. 5. The control apparatus according to claim 4, wherein the control unit comprises: basic command generation means for generating a basic command of an open loop to the elevating motor, and reference signal generation for converting the basic command into a reference signal of the height of the platform and the acceleration of the arm; Way; A platform for calculating the error between the height of the platform obtained by the height sensor and the vibration acceleration of the arm obtained by the acceleration sensor, the error of the height of the platform obtained by the reference signal generating means and the acceleration of the arm; Updating means for updating an estimated value of the state of cancer; And And a adding means for adding a correction value based on an estimated value of the platform and the arm to the basic command to form a control input to the lifting motor. A method of controlling a moving body, the position and vibration of the moving body being detected, and the drive mechanism of the moving body being feedback-controlled according to the detection result of the position and the vibration, at least, for the movement to be the vibration suppression object. In the elevating control method of a stacker crane equipped with an arm that can move back and forth on a platform lifted along the mast by an elevating motor: The height of the platform is detected by a height sensor, and an acceleration sensor is installed at the arm tip to detect vibration of the arm tip, A lift control method for a stacker crane, characterized in that the lift motor is feedback-controlled by a signal of the height sensor and an acceleration sensor when the lift table is lifted with the arm advanced.

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