JPH0333905A - Position controller - Google Patents

Abstract

PURPOSE:To attain positioning with high precision by estimating the position of a target from the relative position of the target with a movable body and the position of the movable body and performing feedforward control for the target which repeats almost equal position fluctuation at a constant cycle. CONSTITUTION:In the tracking control of a XCR, the position of a magnetic tape on a rotary cylinder can be varied based on the position fluctuation of a post P4 turned integrally with a motor 6-1 and an arm 6-2. A first detector 7 outputs the relative position error signal (b) of a magnetic head 5 with a signal track. Also, a second detector 8 outputs the position signal (c) of the post P4. A position estimator 9 adds the signals (b) and (c) with a prescribed gain, and estimates and calculates the track deviation of the signal track. A signal (d) that is an estimated result is inputted to a position controller 11, and the post P4 can be controlled by supplying a power corresponding to the signals (d) and (c) to the motor 6-1 with the controller 11. In such a way, the position of the magnetic tape i.e. the position of the signal track can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a position control device that positions a movable object by following a target whose position changes at regular intervals.

Conventional technology Conventionally, for control purposes such as positioning a movable object by following a target with positional fluctuations, it has been common to detect the relative position error between the target and the movable object to configure a feedbank control system. there were.

Problems to be Solved by the Invention However, in the conventional configuration, in order to reduce the relative position error between the target and the movable object, it is necessary to increase the loop gain of the feed bank control system and improve the frequency characteristics. However, due to resonance of the driving mechanical system, increasing the loop gain causes oscillation, making it difficult to ensure stability and making it difficult to achieve highly accurate positioning.

An object of the present invention is to provide a position control device that can perform highly accurate positioning of a target whose position changes at a constant cycle without increasing the frequency characteristics of the control loop of a drive mechanical system that includes a movable object. .

Means for Solving the Problem In an apparatus for positioning a movable object by following a target that repeats substantially equal positional fluctuations at a constant cycle, a first position detection device detects a relative position error between the target and the movable object. a second position detector for detecting the position of the movable object, and the outputs of the first position detector and the second position detector are added with a predetermined gain to determine the position of the target. The present invention includes a position estimator that estimates the position of the object, and a position controller that drives and positions the movable object according to the output of the position estimator.

Further, in order to gain time for estimation calculation in the position estimator, the output of the position estimator is provided with a delay device that delays the output of the position estimator by a time approximately equal to the basic cycle of the positional fluctuation of the target, and the output of the delay device is The position controller is operated accordingly to position the movable object.

Further, in order to be able to follow the movement even if the positional fluctuation period of the target changes, it is provided with a fluctuation period detection means for detecting the basic period of the positional fluctuation of the target.

Further, in the operation of the delay device, the delay device is configured to delay by a time obtained by subtracting the phase delay time at the fundamental frequency of the positional fluctuation of the target of the position controller from the basic cycle time of the positional fluctuation of the target, and the position controller The present invention includes a phase lag time detector for detecting a phase lag time at the fundamental frequency of the positional fluctuation of the target.

In addition, in order to absorb the gain variation of each of the above-mentioned components, the first position detector and the The addition gain when adding up the respective outputs of the second position detectors is made variable.

Effect of the Invention With the above-described configuration, the present invention estimates and calculates the normally unobservable target position from the relative position of the target and the movable object and the position of the movable object, and feeds it with a delay of approximately - period of the period of the target position fluctuation. Forward and control the movable object by the position controller. Generally, the fundamental frequency component of the target position fluctuation is large and the harmonic component is small, so the response frequency required of the position controller is at most 3 times the fundamental frequency of the target position fluctuation, considering only the amplitude characteristics. About twice as much is fine.
Furthermore, since the estimated position of the target is fed forward in consideration of the phase delay time of the position controller that directly controls the position of the movable object, the relative position error due to the phase delay time of the position controller can be reduced.

That is, it is possible to perform highly accurate positioning of a target whose position changes at regular intervals without increasing the frequency characteristics of the control loop of the drive la mechanical system including the movable object.

Embodiment Hereinafter, a position control device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram when the position control device of the present invention is applied to a tracking control device for a VTR. In FIG. 1, the magnetic tape l is located at the posts Pi, P2. P3.
P4. A signal track 20 (not shown here) is recorded on the 0M1 tape l, which is transported at a constant speed by the capstan shaft 2 and pinch roller 3 while being regulated by P5, and the magnetic tape rotates together with the rotating cylinder 4. Helical scanning is performed by Herad 5. Here, magnetic herad 5
The scanning process will be explained using FIG. 2.

Figure 2 shows the signal track on the magnetic tape l and the magnetic head 5.
FIG. 2 is a conceptual diagram showing a scanning trajectory of FIG. The magnetic head 5 helically scans a signal track 20 recorded on the magnetic tape l along a scanning locus 21. signal trunk 20
When scanning the signal track 20, ideally it is desirable to scan on the dotted line shown in the figure, but if the device that recorded the signal track 20 and the device that reproduces it are different, due to the difference in the running system, the magnetic The signal track 20 has a track deviation when viewed from the scanning locus 21 of the head 5.

If the signal track 20 deviates from the scanning locus 21 of the magnetic head 5 in this manner, the recorded signal may not be correctly reproduced, or the S/N of the reproduced signal may become extremely low. Figure 3 shows the change in track deviation over time.

Figure 3 is a waveform diagram showing the time change of track deviation.
In the figure, the magnetic head 5 is scanning the signal track 20 in sections AI and A2, and the magnetic head 5 is away from the magnetic tape 1 in sections B1 and B2. As is clear, the track deviation repeatedly changes every rotation period of the rotary cylinder 4.

Therefore, if the magnetic tape 1 is driven and the position of the signal trunk 20 is moved by the amount of track deviation seen from the magnetic head 5, the positions of the magnetic head 5 and the signal trunk 20 can always be aligned, and good playback can be achieved. You will get a signal.

Now, in FIG. 1, the motor 6-1, the arm 6-2, and the boss P4 are configured to rotate together, and the position of the magnetic tape 1 on the rotating cylinder 4 is changed by changing the position of the boss P4. (that is, the position of the signal trunk 20).

The first position detector 7 detects a relative positional error between the magnetic node 5 and the signal track 20 from the reproduced signal f obtained from the magnetic node 5, and outputs a signal S as a result. Also,
The second position detector 8 detects the position of the post 4 and outputs a signal C as a result. Specifically, the first position detector 7 is realized, for example, by detecting the ratio of crosstalk from signal tracks adjacent to the left and right sides of the signal trunk being reproduced. Specifically, the second position detector 8 can be realized by a Hall element or the like, for example, by attaching a maghont to the arm 6-2.

The position of the boss P4 is the position of the boss P3. P4. Corresponding to the regulation value of the tape length of the magnetic tape l in P5, and furthermore, the signal track 20 on the magnetic tape 1 in the rotating cylinder 4.
corresponds to the position of That is, signal C is signal trunk 2
It will represent the 0 position. The position estimator 9 that receives the signal C adds the signal C and the signal C with a predetermined gain.

That is, by adding the signal C representing the position of the signal track 20, the relative t between the signal trunk 20 and the magnetic head 5, and the signal S representing the positional error with an appropriate gain, the track deviation of the signal trunk 20 can be corrected. An estimate will be calculated.

The signal d of the estimation result of the position estimator 9 is directly inputted to the position controller 11, and the position controller 11 posts the signal d.
The position of the post 4 is controlled by supplying electric power to the motor 6-1 according to the difference between the position detection signal C and the position detection signal C of ) to match the position of the signal trunk 20 with respect to the position of the magnetic head 5. However, due to the calculation time delay in the estimation calculation in the position estimator 9 described above, a time delay may occur in the operation of the motor 6-1, and a case may occur in which sufficient trunking control cannot be performed.

Therefore, the signal d representing the estimation result of the track deviation of the position detector 9 is delayed by a time approximately equal to the repetition period of the track deviation by the delay device 10 (signal e), and is input to the position controller 11. The position controller 11 controls the power supplied to the motor 6-1 according to the difference between the human power signal e and the position detection signal C of the boss P4, and controls the position of the boss 1-P4. That is, the position of the magnetic tape l (the position of the signal track 20) is shifted by an amount corresponding to the track deviation of the signal track 20 obtained by the position estimator 9, and the position of the signal track 20 is matched with the position of the magnetic head 5. let In the case of the tracking control device as in this embodiment, the target trunk deviation changes with respect to the position of the boss 1-P4, that is, the signal track 20, in an extremely regular manner.
There is no problem even if the signal d is delayed by the fluctuation period time unit.

In other words, it is sufficient to complete the estimation calculation in the position estimator 9 within the fluctuation period of the track deviation (the rotation period of the rotary cylinder 4), and even if the position estimator 9 is realized by software in a microprocessor, for example, Consideration of calculation time is greatly improved.

Now, when special playback (slow playback, fast forward playback, etc.) is performed, the rotational speed of the capstan shaft 2 is lowered or increased compared to normal times, and at the same time, the rotational speed of the rotary cylinder 4 is also varied accordingly. In other words, the fluctuation cycle of the track deviation changes. Regardless of the case where the change in the fluctuation period is uniquely known as in this example, if other embodiments are considered, the change in the fluctuation period may not necessarily be known in advance. Therefore, it is desirable to add a fluctuation period detection means 13 for detecting the fluctuation period of the target from the signal of the estimation result of the position estimator 9. The specific structure of the fluctuation cycle detection means 13 can be easily realized by, for example, passing the signal through a high-pass filter, shaping the waveform, and measuring the cycle using a counter or the like. Then, the delay time of the delay device 10 is set based on the detection result signal g of the fluctuation period detection means 13.

As mentioned earlier, since the track deviation occurs repeatedly in the rotation period of the rotary cylinder 4, the posted position 4 is varied by delaying by a time approximately equal to this period by the delay device IO. Boss 1 composed of
- It is more preferable if the phase delay time of the position control system of F4 is considered. Therefore, the phase delay time detector 12 compares the signal e, which is the human power of the position controller 11, and the position signal C of the post P4, whose position is controlled according to the signal e, with a predetermined value using a comparator, and shapes the signal into a rectangular wave. Compare the phases and detect the phase difference time. The signal r resulting from this phase delay time detector 12 has a delay i? It is input to ilO, and in the delay device IO, the period represented by the signal r is subtracted from the - period time (represented by the output signal g of the fluctuation period detection means 13) of the rotation period of the rotary cylinder 4 (repetition period of trunk deviation). The result is set as the delay time. Usually, the frequency component of the track deviation is dominated by the frequency component of the rotation period of the rotary cylinder 4, and the harmonic component is small. That is, the response frequency of the position control system by the position controller 11 may be at most three times the component corresponding to the fundamental frequency of the repetition period of the track deviation, and the phase adjustment may also be performed at this fundamental frequency component. Therefore, the phase lag time detector 1
At the signal input section 2, the signal e and the signal C are filtered by a low-pass filter that passes frequencies below the fundamental frequency of the repetition period of the track deviation.

By installing this low-pass filter, it is possible to prevent chattering in the phase comparison operation due to noise components and harmonic components.

Now, the position control device shown in FIG. 1 can be expressed as a block diagram as shown in FIG. 4. FIG. 4 is a block diagram showing transmission from track deviation to track position. block 4
0 represents the transmission of the first position detector, block 40-2
The value “K 1 ” represents the detection gain. Block 41 represents the transmission of position estimator 9, and the value of block 41-1 “Fl
” and the value “F2” of the pro-noc 41-2 represent the addition gain, the pro-noc 42 represents the transmission of the delay device IO,
L'' is the rotation period of the rotary cylinder 4 (repetition period of track deviation), and α'' is the value of the signal r obtained by the phase lag time detector 12 (the phase lag time of the position control system by the position controller 11). It is. Pro node 43 represents the transmission of the position controller 11, and A(s) is the characteristic of a stabilizing compensator (not shown) of the position controller 11. Block 44 represents transmission of motor 6-1, arm 6-2, and boss P4,
'J'' is the motor 6-1 seen from the rotating shaft of the motor 6-1,
This is the value of the moment of inertia of the arm 6-2 and the post 4. Block 45 is connected to signal track 2 from the position of boss P4.
Block 46 represents the transmission of the second position transducer (transmission gain is 2). Note that S'' represents a Laplace operator, where the values of the additive gain Fl and F2 of the position estimator 9 are selected as F1 = (1/Kl) ・K2 ・ (1/to 3) 2-1. So, if we transform the block diagram in Figure 4, we get
It will look like the block diagram shown in FIG. In FIG. 5, a block 53 again surrounded by a broken line represents a position control system for the posted 4 by the position controller 11. This block 53
Below the response frequency of the block 53, the transfer gain of the block 53 is approximately (1/2). Furthermore, the block 42 compensates for the phase delay time (-α) of the position control system caused by the position controller 11. That is, a certain number of laps! 1.1l
The response of the track position to the track deviation repeated at (=L) becomes "1" in the response frequency range of the position controller 11, and as a result, the signal trunk position coincides with the scanning locus of the magnetic head 5.

FIG. 6 is a signal waveform diagram of essential parts of the position control device shown in FIG. 1. In FIG. 6, the waveform ds is the waveform of the output signal d of the position estimator 9. The solid line portion represents the trunk deviation, and the broken line portion is output as a track deviation pseudo signal for setting the initial position of the post P4 in the next signal reproduction section. The waveform es is the waveform of the output signal e of the delay device 10,
The waveform ds is delayed by the time indicated by the arrow 61.

Further, the time indicated by 62 almost corresponds to the phase delay time of the position control system by the position controller 11, and the time indicated by the phase delay time detector 1
It is set based on the detection result of step 2.

The waveform cs is a detection waveform (waveform of the output signal C of the second position detector 8) of the position of the post P4 in response to the signal e (waveform es). As is clear from the figure, it can be seen that the position of the signal track corresponds well to the track deviation.

Now, the detection gain of the first position detector 7 is 3. The detection gain of the second position detector 8 is 2, and the transmission gain from the position of the post P4 to the position of the signal track 20 is 3, depending on the degree of contact between the magnetic tape 1 and the magnetic head 5, the degree of azimuth deviation, and the circuit configuration. Variations may occur due to manufacturing variations in element characteristics, mechanical placement accuracy of posts, etc.

Therefore, the addition gain of the signal C in the position estimator 9 is determined by the first position controller 7, which represents the tracking control error (difference in relative position between the magnetic head 5 and the signal trunk 20).
variable adjustment based on the output signal of That is, the addition gain F1. Introducing a variable parameter ``F2'' again, F l = (1/K11) ・K22・ (1, /
2-1. However, Kll, K22, and K33 are the detection gain values determined at the time of device design, and Kl.
l is the design value of the detection gain of the first position detector 7, K22 is the design value of the detection gain of the second position detector 8, and K33 is the design value of the transfer gain from the position of the post P4 to the position of the signal trunk 20. 2 to each gain Kl of the actual device. 3 is K1 due to manufacturing variations as mentioned above.
1K22. The value is slightly different from 33. Now, suppose Kl=
q 1-Kl l (ql is a real number) K2=Q
2・K22 (q2 is a real number) K3=43・K33
Assuming that the following relationship holds true (Q 3 is a real number), if the value of `` can be set to (q2・q3/ql), it will be possible to absorb the variation.

FIG. 7(a), Φ) is a flowchart when the positioning device 9 having an addition gain adjustment function is realized by software on a microprocessor. Figure 7 (a), (b)
), AX, BX, CX, DX, EX.

D X, F First, process 7I
In this step, the initial value "1" is set in the register AX.

The value indicated by the register AX corresponds to the value of the above-mentioned variable parameter ``.In process 72, interrupts of a preset microprocessor timer are managed, and when a timer interrupt occurs, the process moves to process 73.A timer interrupt occurs. If not, the standby state continues.The timer interrupt period corresponds to the sampling period of the control system.In process 73, the value of signal C is A/D converted and stored in register BX, and the value of signal C is converted to A/D. It is converted and stored in the register CX. In process 74, the constant β, the value of the register AX (the value of the variable parameter r), and the value of the register BX (the value of the output signal S of the first position detector 7; trunking error) The result obtained by multiplying by the value of register CX (second position detector 7
The value of the output signal C (signal trunk position) is added and the result is stored in the register DX. Here, β-(1/K
11)・K22・(1/33). That is, as described above, it is a value determined at the time of device design. In process 75, the value of the register DX is D/A converted and outputted as a signal d()Ranok deviation).

Next, in process 76, the value of register BX is squared, added to the value of register frequency X, and stored in register EX. That is, the sum of squares of the signal S is calculated. Processing 77
In this step, it is determined whether one period of the repetition period of track deviation fluctuation has elapsed, and if - period has elapsed, the process moves to day 7. - If the periodic time has not elapsed, the process returns to process 72 for managing timer interrupts while retaining the contents of register EX. In process 78, the signal b(1-
Register FX that holds the value of the sum of squares of ranking error)
The value is compared with the register EX that holds the value of the sum of squares of the signal S in the repetition cycle time of the current trunk deviation fluctuation, and if EX<FX, then in process 79, °゛1°゛ is stored in the register GX. However, if EX<FX is not the case, process 80
"-1" is stored in register GX. Then, in process 81, the contents of the register EX are transferred to the register FX for the processing of the next trunk deviation variation period, and then °゛O°゛ is stored in the register EX, and the contents are cleared. In process 82, register A, which is the value of the variable parameter
The product of the value of register GX and the constant ΔF is added to the contents of X, and the result is stored anew in register AX. Then, the process returns to process 71 for managing timer interrupts. Here, the constant Δ" represents the amount of correction of the minute modification of the variable parameter".

That is, the sum of squares of the tracking error is compared for each period of fluctuation of the track deviation, and the value of the variable parameter is slightly modified in the direction of decreasing the sum of the squares of the tracking error. Eventually, the sum of squares of the signal S representing the tracking control error will converge to the minimum, and the value of F at this time will converge to (q2・q3/ql), and each gain variation will be absorbed. become.

Effects of the Invention As described above, the position control device of the present invention enables sufficiently accurate positioning without increasing the control frequency characteristics of the drive mechanical system. In the explanation of the position control device of the present invention, the case where it is applied to trunking control of a helical scanning magnetic tape recording device has been explained, but various other applications are possible without changing the gist of the present invention. It is. For example, it is ideal for trunking control in a disc-type information reproducing device.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram when the position control device of the present invention is applied to a trunking control device of a VTR, Fig. 2 is a conceptual diagram showing a signal trunk on a magnetic tape and a scanning locus of a magnetic head, and Fig. 3 is a conceptual diagram showing a scanning locus of a signal trunk on a magnetic tape and a magnetic head. Waveform diagram showing time change of track deviation, 4th
The figure is a block diagram of the position control device shown in Fig. 1, Fig. 5 is a block diagram obtained by equally deforming the block diagram of Fig. 4, and Fig. 6 is a block diagram of the position control device shown in Fig. 1.
This figure is a signal waveform diagram of the main parts of the position control device shown in FIG. 1, and FIG. 7 is a flowchart when the position estimator is realized by software on a microprocessor. 7...First position detector, 8...Second
position detector, 9... position estimator, 10...
...Delay ff1Ltl...Position controller, 12
. . . Phase delay time detector, 13 . . . Fluctuation period detection means.

Claims (7)

[Claims] (1) In a device that positions a movable object by tracking a target that repeats approximately equal positional fluctuations at a constant cycle, a first device that detects a relative position error between the target and the movable object.
a position detector, a second position detector that detects the position of the movable object, and the outputs of the first position detector and the second position detector are added with a predetermined gain to calculate the position of the movable object. A position control device comprising: a position estimator that estimates the position of a target; and a position controller that drives and positions the movable object according to an output of the position estimator. (2) In a device that positions a movable object by tracking a target that repeats approximately equal positional fluctuations at a constant cycle, a first device that detects a relative position error between the target and the movable object;
a position detector, a second position detector that detects the position of the movable object, and the outputs of the first position detector and the second position detector are added with a predetermined gain to calculate the position of the movable object. a position estimator for estimating the position of a target; a delay device for delaying the output of the position estimator by a time approximately equal to a fundamental cycle of the positional fluctuation of the target; and driving the movable object in accordance with the output of the delay device. 1. A position control device comprising: a position controller that performs positioning. (3) In a device that positions a movable object by tracking a target that repeats approximately equal positional fluctuations at a constant cycle, a first device that detects a relative position error between the target and the movable object;
a position detector, a second position detector that detects the position of the movable object, and the outputs of the first position detector and the second position detector are added with a predetermined gain to calculate the position of the movable object. a position estimator for estimating the position of the target; a fluctuation period detection means for detecting a basic period of position fluctuation of the target based on the output of the position estimator; and a fluctuation period detection means for detecting the output of the position estimator. Position control comprising: a delay device that delays the detected positional fluctuation of the target by a basic period time; and a position controller that drives and positions the movable object according to the output of the delay device. Device. (4) In a device that positions a movable object by tracking a target that repeats approximately equal positional fluctuations at a constant cycle, a first device that detects a relative position error between the target and the movable object.
a position detector, a second position detector that detects the position of the movable object, and the outputs of the first position detector and the second position detector are added with a predetermined gain to calculate the position of the movable object. a position estimator for estimating the position of a target; a fluctuation period detection means for detecting a fundamental period of positional fluctuation of the target based on an output of the position estimator; and a position controller for driving and positioning the movable object. , a phase lag time detection means for detecting a phase lag time of the response of the position controller at the fundamental frequency of the position fluctuation of the target, and an output of the position estimator to detect the position of the target detected by the fluctuation period detection means. a delay device that delays by a time obtained by subtracting a phase lag time at the fundamental frequency of the position fluctuation of the target of the position controller detected by the phase lag detecting means from the basic cycle time of the fluctuation; A position control device characterized in that the movable object is driven and positioned by the position controller according to an output. (5) The phase delay time detector includes a first comparator that compares the output of the position estimator with a predetermined value, and a second comparator that compares the output of the second position detector with the predetermined value. 5. The position control device according to claim 4, wherein the position control device is configured to detect a phase difference time between the output of the first comparator and the output of the second comparator. (6) The first comparator includes a first low-pass filter that passes frequency components of the output of the position estimator that are lower than the fundamental frequency of the target position fluctuation, and the first low-pass filter The second comparator is configured to compare the output with the predetermined value, and the second comparator converts the output of the first position detector into a second low-pass device that passes frequency components below the fundamental frequency of the target position fluctuation. 6. The position control device according to claim 5, further comprising a filter and configured to compare the output of the second low-pass filter with the predetermined value. (7) A position estimator outputs each of the first position detector and the second position detector based on a relative position error signal between the target and the movable object obtained by the first position detector. Claims (1), (2), (3), (4), (
The position control device according to either 5) or (6).