JPH0527846A - Inertial load correcting device - Google Patents

Abstract

PURPOSE:To provide an inertial load correcting device which maintains the conventional relation of an optimum control system against the fluctuation of the inertial load. CONSTITUTION:A control system consists of a position detector 25 which detects the position of the inertial load 21, a position control means 23 which controls the position of the load 21, and a feedback means 24 which detects the position and the velocity of the load 21 with the output of the detector 25 and gives these position and velocity to the means 23 after multiplying them by a fixed coefficient. Then a mass change input means 32 is added to input the mass change of the load 21 together with a coefficient correcting means 31 which multiplies the fixed coefficient by a coefficient accordant with the mass change. In such a constitution, the load 21 can be controlled at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for correcting inertial load. For example, the present invention relates to a rotation control of a cylindrical drum that stores a large number of recording media in a library apparatus, and a device that corrects a load caused by a change in the number of recording media mounted on the cylindrical drum.

[0002]

2. Description of the Related Art Conventionally, when an object is moved, particularly when it is suddenly stopped at a predetermined position, the position and speed of the object are detected to control the drive source of the object.

8 and 9 show the overall configuration of a conventional mass storage device. In the figure, reference numeral 2 is a cylindrical storage rack (hereinafter referred to as a drum) for storing an optical disk cartridge 1 (hereinafter referred to as a cartridge), which is provided with a rotation mechanism. Reference numeral 5 denotes a cartridge transport mechanism (hereinafter referred to as an accessor), which drives the mechanical hand 6 in the vertical direction (Y direction) and rotates in a direction for accessing a read / write station 3 and a cartridge access station 4 described later. It is driven in the (θ direction). Reference numeral 3 is a read / write station for reading / writing the cartridge 1, which is arranged below the drum, and 4 is an entry station for loading a new cartridge 1 from the outside and an exit station for discharging the unnecessary cartridge 1 to the outside. And a cartridge access station (hereinafter referred to as CAS), which is provided on the drum side. The operation of the embodiment of the conventional mass storage device shown in FIGS. 8 and 9 will be described. The drum 2 is driven by the drum drive circuit according to a command from the main control unit, and is rotated to a desired position where the cartridge 1 is stored. At the same time, the accessor 5 is also driven by the accessor drive circuit and moves in the θ direction, and further the hand 6 Drive in the Y (up and down) direction to position the hand 6 at the desired position of the cartridge 1 on the drum storage shelf 2, drive the hand 6 at that position to take out and hold the cartridge 1, and then read / write station. The accessor 5 moves to convey the cartridge 1, and the hand 6 is driven to set the cartridge 1 in the read / write station.

After the read / write operation is completed, the cartridge 1 is similarly taken out from the read / write station with the hand 6, gripped, and similarly conveyed and stored in the original drum storage rack 2. The same applies when the cartridge 1 is transported from the entry station to the drum storage shelf 2 and from the drum storage shelf 2 to the exit station.

FIG. 5 shows a block diagram of a conventional device. In the figure, 11 is an inertial load to be rotationally moved, 12 is a motor for rotationally driving the inertial load 11, 13 is a drive circuit for driving the motor 12, 14 is a higher-level control unit 18, tacho counter 15 and observer control unit 16. A servo control unit that calculates an input, determines an operation amount, gives the operation amount to the drive circuit 13 and drives the motor 12, and a tacho that counts tacho pulses according to the rotation amount of the motor 12 and outputs a rotation position. Counter, 16
Is an observer control unit 16 or 17 that calculates the change in the rotational position of the output of the tacho counter 15 and outputs the rotational speed.
A sensor that detects a reference position mark provided on 11 to notify that the inertial load 11 is at the reference position, and 18 is a host controller that controls the entire apparatus.

The host controller 18 commands the servo controller 14 to rotate the inertial load 11. Servo control unit 14 is the upper control unit
An appropriate operation amount is obtained from the rotational position instruction from 18, the rotational position of the inertial load 11 output from the tacho counter 15 and the rotational speed output from the observer control unit 16, and the value is supplied to the drive circuit 13. . The drive circuit 13 supplies a current corresponding to the manipulated variable, which is an input, to the motor 12, and the motor 12 causes the inertia load 11
Is driven to rotate and move to a predetermined position. The rotational position of the inertial load 11 is indicated by the tacho counter 15, but every time the reference position mark of the inertial load 11 passes the sensor 17, the host controller
Corrected by 18.

A control system for performing such control can be expressed as a transfer function by the control theory.
FIG. 6 shows a basic form of a transfer function in a conventional control system, which is a diagram in which the control system of FIG. 5 is simplified and expressed as a control system based on a control theory, which is called a block diagram.

In FIG. 6, the input is represented by a function E ₁ (s), the function at each point is E ₂ (s), E ₃ (s) _, E ₄ (s) _, and the output is E ₅ (s). The relationship is expressed by the following function: physically, E ₂ (s) is distance, E ₃ (s) is acceleration, E ₄ (s) is velocity, and output E ₅ (s ) Represents the distance, 1 / S in the figure means the integral function of the Laplace transform, K1, K2 and K3 are coefficients, and the values multiplied by the coefficients are transmitted. The acceleration is fed back by the coefficient K3 from the velocity, and the position is fed back to the input. The input is transmitted to the acceleration by the coefficient K2, and the integrated amount of the input is transmitted to the acceleration by the coefficient K1. In the figure, E ₂ (s) = E ₁ (s) + E ₅ (s) E ₃ (s) = (K2 + K1 / s) E ₂ (s) + K3 · E ₄ (s) E ₄ (s) = 1 There is a relationship of / s ・ E ₃ (s) E ₅ (s) ＝ 1 / s ・ E ₄ (s). E ₅ (s) / E ₁ (s) obtained from this relationship is the transfer function.

Further, FIG. 7 is a block diagram display of the transfer function including the actual inertial load and the force coefficient of FIG. 6, and a coefficient when the amount of current becomes a rotational force by the motor (a proportional coefficient of the current and the force). Kt, the mass of the inertial load is M, the coefficient of the current amount by the integrated amount of the rotational position is Ks, the coefficient of the current amount by the rotational position is Kx, and the coefficient of the current amount by the rotational speed is Kv. It is a diagram display. The velocity is fed back to the acceleration with a coefficient Kv, and the position is fed back to the input. The input is transferred to the amount of current by a coefficient K2, and the integrated amount of the input is a coefficient.
It is transmitted to the amount of current with K1. Transfer from current amount to acceleration
It is shown in Kt / M.

According to this figure, each gain (K
The relationship with (1, K2, K3) is K1 = Kt / M × Ks K2 = Kt / M × Kx K3 = Kt / M × Kv from the comparison with Fig. 6.

By analyzing such a transfer function, it is possible to set the coefficient relationship for the earliest and stable control. Such a relationship is called an optimum control system. Where K
It is assumed that 1, K2, K3 are optimally set.

[0012]

However, when controlling the storage itself for storing the cartridges and the like, every time the cartridge is put in and out, when the cartridge is not loaded, and when the storage is full of cartridges. If the control system with the same setting is used when the mass of the inertial load changes, such as in the case of the state, optimal control cannot be performed, and there is a problem that the movement time to a predetermined position takes more than necessary and the access speed decreases. .

For example, in a control system optimized with the mass of the inertial load as M, when the mass M of the inertial load changes to N, new optimum coefficients K1 ', K2', K3 'are K1' = Kt / N × Ks K2 ′ = Kt / N × Kx K3 ′ = Kt / N × Kv. Therefore, each gain changes at the following rate of change.

K1 / K1 '= Kt / M × Ks / (Kt / N × Ks) = N / M K2 / K2' = Kt / M × Kx / (Kt / N × Kx) = N / M K3 / K3 '= Kt / M × Kv / (Kt / N × Kv) = N / M Therefore, the optimum coefficient changes according to the change in inertial load, so if the coefficient of the control system is fixed no matter what inertial load The optimum control system cannot always be provided.

In view of the above points, the present invention has an object to provide a device for maintaining the relationship of the conventional optimum control system with respect to the fluctuation of the inertial load.

[0016]

The above-mentioned problems can be solved by an inertial load correcting device configured as described below.

FIG. 1 shows the principle of the present invention. (1) Position detector 25 for detecting the position of the inertial load 21, position control means 23 for controlling the position of the inertial load 21, and position and speed of the inertial load 21 from the output of the position detector 25 Then, in the control system constituted by the feedback means 24 for multiplying the position and velocity by a constant coefficient and giving the position control means 23, a mass change input means 32 for inputting a change in the mass of the inertial load 21 and By providing a coefficient correction means 31 for multiplying the constant coefficient by a coefficient according to the change in the mass, the conventional optimum control system is maintained with respect to the fluctuation of the inertial load. (2) In the above item 1, when the mass of the inertial load changes by a fixed amount unit, the coefficient correction amount corresponding to the change amount is shown in the correspondence table 33.
Therefore, the correspondence table 33 is used to correct the coefficient.

[0018]

[Operation] (1) The mass change input means 32 inputs a change in the mass of the inertial load 21. In addition, the coefficient correction means 31 multiplies the constant coefficient of the feedback means 24 which is given to the position control means 23 by multiplying the position and speed of the inertial load 21 by a constant coefficient by the coefficient correction means 31. As described above, the relationship of the conventional optimum control system is maintained with respect to the fluctuation of the inertial load. (2) In the above item 1, when the mass of the inertial load changes by a fixed amount unit, the coefficient correction amount corresponding to the change amount is shown in the correspondence table 33.
And the coefficient is corrected using the correspondence table 33.

[0019]

2 is a block diagram of an embodiment of the present invention, which is a block diagram of a mass storage device. In the figure, 42 is a mass change input unit that receives a notification of a mass change of the inertial load 11 from the upper control unit 18, 41 is a notification of a mass change of the inertial load 11 from a mass change input unit 42, and is used by the servo control unit 14. This is a coefficient correction unit that corrects the coefficient to be changed. In addition, the same reference numerals as those in FIG. 5 are the same.

The correction operation in FIG. 2 will be described. The upper control unit 18 manages the number of cartridges stored in the storage, and notifies the mass change input unit 42 when the mass of the inertial load 11 changes due to the increase or decrease in the number. The mass change input unit 42 receives a notification of the number of cartridges currently mounted on the drum from the host controller 18 before operating the drum. The mass change input unit 42 notifies the coefficient correction unit 41 of the notification, and the coefficient correction unit 41 corrects the coefficient used in the servo control unit 14 according to the number of N2 values in 10 steps with respect to the total number of mountable drums. Is calculated to control as a conversion coefficient.
As a result, the drum can always maintain the control system close to the set optimum value.

FIG. 3 is a block diagram of a transfer function showing the principle of the present invention. Here, N2 and N3 are coefficients for correcting the coefficients K1, K2, and K3, Io is the output current of the drive circuit with respect to the unit input, Me is the inertial load at the time of design, and P is the rotational speed converted to the corrected position. The coefficient, Q is a coefficient for converting the rotation speed into the correction speed. From the speed, the current amount is fed back by Q × N3 × K3, and from the position, the input is fed back by P × N2. Also, considering that the relationship with FIG. 6 is set to be equal, N2 = (K2 × Me) / (K2 × P × I ₀ × Kt) = Me / (P × I ₀ × Kt) N3 = (K3 X Me) / (K3 x Q x I ₀ x Kt) = Me / (Q x I ₀ x Kt) Looking at the position loop, K2 = P x N2 x K2 x I ₀ x Kt / M Substituting N2 gives K2 = P × Me / (P × I ₀ × Kt) × K2 × I ₀ × Kt / M K2 = Me / M × K2 Design inertial load (Me) and actual inertial load (M ), The relationship shown in FIG. 6 can be maintained.

The same applies to the velocity loop. Therefore, if the actual inertial load (M) fluctuates, the design inertial load (M
It is possible to keep the control system always at the optimum value set at the beginning by changing the so-called N2 and N3 values as needed by adjusting to e).

FIG. 4 is a block diagram of a transfer function in the embodiment of the present invention shown in FIG. In FIG. 2, the output of the tacho counter 15 is processed as the rotational speed by the observer control unit 16 to obtain the rotational speed. Therefore, an accurate transfer function is expressed as shown in FIG. That is, in FIG. 3, the feedback from the velocity is Q × N3 × K3, but here, the feedback is corrected from the position to P × N2 × (observer conversion coefficient) × K3.

When the inertial load changes over a wide range from time to time, the control system close to the optimum value set at the beginning can always be maintained by changing N2 and N3 stepwise to some extent. For this reason, when the mass of the inertial load changes in a fixed amount unit, a coefficient correction amount corresponding to the change amount is provided as a correspondence table, and the coefficient is corrected using the correspondence table, so that rapid control can be performed.

[0025]

As is apparent from the above description, according to the present invention, there is a remarkable industrial effect that the optimum control system initially set can always be maintained.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a block diagram of a transfer function showing the principle of the present invention.

FIG. 4 is a block diagram of a transfer function according to an embodiment of the present invention.

FIG. 5 is a block diagram of a conventional device

FIG. 6: Basic form of transfer function in conventional control system

FIG. 7: Display of block diagram of transfer function in conventional device

FIG. 8 is an overall configuration diagram of a conventional mass storage device (part 1)

FIG. 9 is an overall configuration diagram of a conventional mass storage device (part 2)

[Explanation of symbols]

1 Cartridge 2 Drum 3 Read / Write Station 4 Cartridge Access Station 5 Accessor 6 Hand 11 Inertial Load 12 Motor 13 Drive Circuit 14 Servo Control Section 15 Tacho Counter 16 Observer Control Section 17 Sensor 18 Upper Control Section 21 Inertial Load 23 Position Control Means 24 Returning means 25 Position detector 31 Coefficient correction means 32 Mass change input means 33 Correspondence table 41 Coefficient correction section 42 Mass change input section

Claims (2)

[Claims] 1. A position detector (25) for detecting the position of an inertial load (21), position control means (23) for controlling the position of the inertial load (21), and the position detector (25). From the output, the inertial load (2
The inertial load (21) in the device constituted by the feedback means (24) for detecting the position and speed of (1), multiplying the position and speed by a constant coefficient and giving the position control means (23). Mass change input means (32) for inputting a change in the mass of, and coefficient correction means (31) for multiplying the constant coefficient by a coefficient according to the change in the mass. Equipment to do. 2. When the mass of the inertial load changes in a fixed amount unit, a coefficient correction amount corresponding to the change amount is provided as a correspondence table (33), and the coefficient is corrected using the correspondence table (33). An apparatus for performing inertial load correction according to claim 1.