JPH0981124A - Pedal driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the speed of a pedal with high accuracy without delay of detection from a low speed to a high speed. SOLUTION: A speed calculating part 14a prepares a speed signal Vc based on a position signal Fs outputted from an up-down counter and a driving current I* outputted from a driver. The speed signal Vc is exact without delay of detection in a low-speed region while the error increases in a high-speed region. On the other hand, a speed signal V* is a speed signal calculated based on the pulse interval of a pulse string outputted in accordance with the displacement of a pedal and has the delay of detection in the low-speed region. A cross- over network 14b mixes both speeds according to a cross-over characteristic so as to mainly use the speed signal Vc in the low-speed region and mainly use the speed signal V* in the high speed region and outputs a speed signal V*.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pedal drive device suitable for use in, for example, an automatic piano for automatically playing music.

[0002]

2. Description of the Related Art In recent years, various automatic performance pianos have been put into practical use in which a keystroke action or a pedal action is generated in accordance with prerecorded performance information (or performance information supplied from the outside) to automatically perform a performance.

In this type of automatic playing piano, feedback control, feedforward control, or a combination of both is appropriately used when driving and controlling the pedal. In this case, a position sensor and a position sensor for detecting the pedal position and speed, respectively. A speed sensor is used.

A linear encoder is generally used as the position sensor. The pulse output from this linear encoder is generally counted up and down, and the count value is detected as the pedal position. Further, a moving magnet type sensor that can output a signal corresponding to the pedal speed is often used as the speed sensor.

By the way, the moving magnet type sensor has a problem that it is expensive and vulnerable to noise. On the other hand, since the linear encoder is inexpensive, a method of detecting the speed using this can be considered. That is, if the interval between the output pulses of the linear encoder is measured, it can be used as speed information, and thus it may be used also as a speed sensor.

[0006]

However, when the linear encoder is used, the speed can be favorably detected when the speed is high, but the detection delay becomes significant when the speed is low. This is because speed detection is performed based on the pulse output interval, so long as the next pulse is not output,
This is because the speed at that time cannot be obtained. In addition, since speed detection using a linear encoder is an average speed during the output of two pulses, if the moving speed of the pedal is slow and the pulse interval is long, the detection result does not become an instantaneous speed,
The problem that control becomes unstable arises.

The present invention has been made in view of the above-mentioned circumstances, and a pedal capable of detecting an instantaneous speed by using an inexpensive pulse encoder or the like and not causing delay in detection even when the speed is low. An object is to provide a speed detection device.

[0008]

In order to solve the above problems, in the invention described in claim 1, a drive device for driving a pedal at a speed corresponding to a drive signal, and the drive signal for the drive device. In a pedal drive device having a controller for supplying and controlling the movement of the pedal, a position information output means for outputting position information corresponding to the position of the pedal, and a first speed based on a change in the position information. First speed information calculation means for calculating information, second speed information calculation means for calculating second speed information based on the position information and the drive signal, and the first speed information calculation means for calculating the second speed information according to the amount of change in speed of the pedal. Crossover means for changing the mixing ratio of the first speed information and the second speed information to generate the third speed information, and using the third speed information, a speed feedback loop. And said that you configure.

Further, in the invention according to claim 2,
The crossover unit increases the ratio of the second speed information in a region where the pedal speed change amount is small, and increases the ratio of the first speed information in a region where the pedal speed change amount is large. It is characterized by increasing.

According to the third aspect of the invention, the crossover means uses only the second speed information in a region where the change amount of the speed of the pedal is small, and In a region where the amount of change is large, only the first speed information is used to generate the third speed information.

(Operation) In the inventions according to claims 1 to 3, the ratio of the more accurate and detection-free one of the first and second speed information is increased (including 100%), and the first and second speed information is increased. Three
Since the speed information can be generated, the pedal speed can be detected with high accuracy. Since the speed feedback loop is constructed using the third speed information, accurate pedal control can be performed over the entire region.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

A: Modeling in Embodiments Embodiments of the present invention will be described below with reference to the drawings. First, in this embodiment, since the pedal drive system is modeled and handled, this modeling will be described.

FIG. 2 is a side view showing the outline of the drive system of the pedal. In the figure, 31a is a pedal, and a plunger 30ap of a solenoid 30a is connected via a rod 32a.
It is connected to the. Further, 35a is a solenoid 30a
It is a position sensor that detects the position of p. In such a configuration, when the solenoid 30a is excited, the plunger 30ap and the rod 32a rise according to the current value thereof. Then, when the plunger 30ap rises,
The lever 40 rotates around the fulcrum 41 and pushes up the rod 42. When the rod 42 is pushed up, the lever 43
Rotates around the fulcrum 44 and pushes up the damper wire 45. When the damper wire 45 is pushed up, the damper head 46 rises and is separated from the string 47. On the other hand, when the solenoid 30a is in the non-excited state, the damper head 46 descends due to the opposite operation to the above.
It comes into contact with the strings 47.

The above is the outline of the pedal drive system.
[Fig. 4] is a conceptual diagram when the pedal drive system is mechanically modeled. The x-axis shown in FIG. 3 is the driving direction of the rod 32a when the solenoid is excited (the same as the moving direction when the pedal is depressed). Further, f (t) is a time function of thrust, and is the force of the solenoid 30a that drives the pedal 31a. M _S and M _D are the static weight and inertial mass of the entire pedal system, respectively, and μ is the viscous resistance. Where k is the spring constant of the pedal system and x (t)
Is a time function of the displacement of the rod 32a, the equation of motion for the force applied to the pedal is

[0015]

[Equation 1] Then, this is Laplace transformed and the following equation is obtained.

[0016]

[Equation 2] Here, as initial values, x (0 ⁺ ) = 0 and x '(0 ⁺ ) = 0
If you put it

[0017]

(Equation 3) Becomes Then, when the equation 3 is expressed in a block diagram, it becomes as shown in FIG. It is understood that the above is the model of the pedal drive system in this embodiment and has the transfer function shown in FIG.

B: Structure of Embodiment Next, FIG. 1 is a block diagram showing the structure of an embodiment of the present invention. In this figure, 2 is a subtracter for subtracting a feedback position signal Fs (described later) from the position target signal X _R. Reference numeral 4 denotes a multiplier that multiplies the output of the subtractor 2 by the position gain Kp. A subtracter 5 subtracts a feedback speed signal Fv (described later) from the output of the multiplier 4 and outputs it. An adder 6 offsets the force Ms · g corresponding to the stationary mass of the pedal drive system to the output of the adder 5. Reference numeral 7 denotes a multiplier, which multiplies the output of the adder 6 by a scale factor 1 / K _F to generate a drive current control signal I _R. A driver 8 drives the solenoid 30a according to the drive current control signal I _R.

Next, the drive current I ^* output from the driver 8 is supplied to the solenoid 30a as shown in FIG. 1, and the thrust F (t) generated thereby is transmitted to the pedal drive mechanism (physical model 11). To be done. The physical model 11 shown in the figure is a pedal drive mechanism modeled in this embodiment, and its transfer function is as shown in FIG.

The pedal drive mechanism, as shown in FIG.
As described above, the position sensor 35a for detecting the position of the pedal is incorporated. In this case, the position sensor 35
a is composed of a linear encoder, and outputs a number of pulses corresponding to the displacement of the pedal. Instead of the linear encoder, a rotary encoder whose shaft rotates according to the movement of the pedal may be used, or another sensor may be used. The point is that the configuration is such that a signal corresponding to the pedal position can be taken out.

The pulse train output from the position sensor 35a is used as the position signal X ^* (s) in the speed detector 12
And to the up / down counter 15. The position signal X ^* (s) of the pulse train output from the position sensor 35a is up / down counted in the up / down counter 15 and converted into a feedback position signal Fs (multi-bit digital signal) indicating the pedal position, and the subtracter Returned to 2. This constitutes a position feedback loop. Since the input / output relationship of the up / down counter 15 has no dead time,
The transfer function in control is "1". However, in order to consider this, it is necessary that the resolution of the position sensor 35a is so small that it can be ignored, and that the sampling frequency of each part of the circuit is sufficiently small.

Configuration of Speed Detection Unit 12 Next, the speed detection unit 12 and the speed estimation unit 14, which are important elements of this embodiment, will be described. First, the speed detection unit 12 will be described. First, the speed detector 12
Position signal X ^* is a circuit for generating a velocity signal V ^* on the basis of the (s), by measuring the pulse interval of the in-position signal X ^* (s), obtains the pedal velocity signal V ^* from the measurement period.

The curve Va shown in FIG. 5 (a) shows the displacement of the pedal, and the curve (b) in FIG. 5 (b) shows the position sensor 35a.
It shows the pulse output from. Now consider velocity measurement between times T ₁ and T ₂ . The velocity measured based on these time intervals (T ₂ −T ₁ ) is an average velocity between T ₁ and T ₂ , when it is considered to be uniform acceleration motion,
If this is represented by [V] and the velocities at times T ₁ and T ₂ are V ₁ and V ₂ , respectively, then [V] = (V ₁ + V ₂ ) / 2. Here, for one measurement section, a velocity straight line passing through two points (T ₁ , V ₁ ) and (T ₂ , V ₂ ) is v = ((V ₂ −V ₁ ) / (T ₂ −T ₁ ). ) ・ (T−T ₁ ) +
It becomes V ₁ . Here, if V ₂ −V ₁ = ΔV (= in this case means congruence) and T ₂ −T ₁ = τ ₁ , then v = (ΔV / τ ₁ ) · (t−T ₁ ) + V ₁ . On this straight line, the time T at which the speed reaches [V]
Is obtained as follows.

[V] = (ΔV / τ ₁ ) · (T−T ₁ ) + V ₁ (V ₂ + V ₁ ) / 2 = (ΔV / τ ₁ ) · (T−T ₁ ) + V ₁ T = here τ _1/2 + T _1, consider a time T corresponding to the average velocity [V], actually the delay in the time at which the value is output. First, the average speed [V] is output after the calculation, but since the calculation time can be ignored, the time T2
Can be output at. Note that FIG.
The polygonal line v ^* shown in (a) indicates the output of the speed calculation.

The delay time between time T and time T ₂ is τ = T ₂ −T = T ₂ −τ ₁ / 2-T ₁ = τ _1/2 .

[0026] Here, if the hold time and tau _2, the speed sensor is regarded as being composed of a dead time system and the zero-order hold systems with tau ₂ becomes the hold time with tau _1/2 becomes delayed , So the overall transfer function Go (s)
Is represented by the following equation.

[0027]

(Equation 4) Here, FIG. 6 is a functional block diagram of the speed detection unit 12, and in the drawing, 12a shows a function of calculating an average speed during the pulse output interval. 12b shows dead time characteristics when the speed is detected from the interval of the output pulse of the position sensor 35a. Further, 12c shows a hold characteristic when the velocity is calculated from the pulse interval.

Structure of Speed Estimator 14 Next, reference numeral 14 shown in FIG. 1 is a speed estimator, which includes the position signal Fs output from the up / down counter 15 and the driver 8
Based on the value of the drive current I ^* output by the
And a speed signal V ^* supplied from the speed detection unit 12 to generate a speed signal V ^. Here, FIG. 7 is a block diagram showing a schematic configuration of the speed estimation unit 14,
Reference numeral 4a is a speed calculation unit that creates a speed signal Vc, and 14b is a crossover network that creates a speed signal V ^ from the speed signals Vc and V ^* .

Here, the calculation principle in the speed calculation unit 14a will be described. First, the solenoid drive current I ^*
The principle of obtaining the speed signal Vc will be described. Considering the physical model of the pedal as a general second-order lag system, its transfer function is as shown in equation 5.

[0030]

(Equation 5) By the way, the value to be obtained is Vc, and if this is written in Laplace, it becomes Vc (s), so multiply both sides of Eq. 5 by S, and SX (s) = Vc (s) Focusing attention, the expression 5 is sequentially transformed into the following expressions 6 and 7.

[0031]

(Equation 6)

[0032]

(Equation 7) Then, considering the static weight of the pedal mechanism, the drive current I ^*
When F (s) is calculated using (s), it becomes as shown in Formula 8.

[0033]

(Equation 8) Then, substituting Equation 8 into Equation 7 and rearranging it yields Equation 9.

[0034]

[Equation 9] The functional block diagram of the operation shown in Equation 9 is the block diagram shown in FIG. That is, the functional block diagram shown in FIG. 8 shows the calculation principle of the speed calculation unit 14a.

Next, when the functional block diagram is sequentially modified, it becomes as shown in FIG. 9 (A) → (B) → (C) → (D). Then, in FIG. 9D, focusing on the innermost loop, the transfer function of this loop can be expressed as (1 / M _D ) / (S + μ / M _D ). That is, this loop is (μ /
It is nothing but a low-pass filter with a cut-off angular frequency of M _D ).

Considering the pedal drive mechanism system, it is considered that μ << M _D, and if the L component in the crossover network 14b, which will be described later, is set so that μ << L, then μ is ignored. It is considered that there is almost no effect of Therefore, the functional block diagram shown in FIG. 9D can be rewritten as shown in FIG. Further, since the actual position measurement value Fs is obtained from the up / down counter 15 (see FIG. 1), and this value, unlike the speed, is considered to include almost no time delay, it can be considered that Xc = Fs. . Therefore, if Fs · k is added to the addition / subtraction point as a subtraction signal and (1 / S ² ) · S is summarized as 1 / S, the functional block diagram shown in FIG.
It can be rewritten as shown in FIG. That is, the speed calculator 14a calculates the pedal speed based on the drive current I ^* and the actually measured position signal Fs of the pedal.

Next, the crossover network 14b
Will be described. This crossover network 1
4b is an actually measured speed signal V ^* output by the speed detector 12 ^.
In order to compensate for the time delay of, the calculated speed signal Vc of the speed calculation unit 14a, which is the speed based on the drive current I ^* , is adopted on the high frequency side of the frequency component of the pedal speed. More specifically, the crossover characteristics shown in FIG. 12 are provided, the signal Vc that is the calculation speed is given priority in the high range, and the speed signal V ^* that is the measured speed is obtained in the low range ^.
Is prioritized. That is, when there are many harmonic components included in the pedal speed (when the pedal has a large speed change per unit time), such as at the time of rising, the delay of the speed signal V ^* , which is the measured speed, becomes a problem. , The ratio of the calculation speed signal Vc is increased to improve the accuracy, and conversely,
When the harmonic components included in the pedal speed are small (when the speed change per unit time of the pedal is small and stable), the error of the calculated speed signal Vc becomes a problem, so the ratio of the measured speed signal V ^* To increase the accuracy.

The crossover network 14b has a structure in which a low-pass filter and a high-pass filter are combined in order to realize the characteristics shown in FIG. FIG. 13A shows an example of the basic configuration. As shown in this figure, the calculated speed signal Vc passes through the high-pass filter, and the measured speed signal V _* passes through the low-pass filter.
And both signals are added after passing through the filter,
The speed signal V ^ is obtained. In this case, when the change in the pedal speed is large, the measured speed signal Vc is also included in the calculated speed signal Vc.
^{Although *} also contains a lot of harmonic components, the former passes through the high-pass filter and the latter passes through the low-pass filter, and as a result, the ratio of the calculated speed signal Vc to the speed signal V ^. Will increase. On the other hand, when the change in pedal speed is small, the measured speed signal V _* is also included in the calculated speed Vc _.
Does not contain much harmonic components, the velocity signal V ^
Therefore, the ratio of the measured speed signal V _* becomes large. By the way, the configuration shown in FIG. 13 (a) is changed to (b) → (c) → (d) →
When it is transformed in the order of (e), the configuration of (f) in the figure is finally obtained. Note that in FIG. 13, S indicates jω, and L indicates L in FIG.

Therefore, the overall structure of the speed estimating unit 14 is as shown in FIG. 14, and if this structure is further simplified, the structure shown in FIG. 15 is obtained. That is, FIG.
3 is a functional block diagram showing an overall configuration of a speed estimation unit 14. FIG.

Next, reference numeral 13 shown in FIG. 1 denotes a multiplier, which multiplies the speed signal V ^ by the speed gain Kv and feeds it back to the subtractor 5 as the above-mentioned feedback speed signal Fv to form a speed feedback loop. To do.

Here, the function of the velocity feedback loop will be described. Now, as shown in FIG. 16A, when the position target signal X _R is given at a certain timing, the feedback position signal Fs obtained from the sensor 35a gradually approaches the position target signal X _R. As a result, the position target signal X _R
The position error signal ER obtained from the feedback position signal Fs and the feedback position signal Fs changes as shown in FIG. On the other hand, the subtractor 5 subtracts the feedback speed signal Fv from the value corresponding to the position error signal ER, so that the output signal shown in FIG. Here, focusing on the velocity feedback loop, the feedback velocity signal Fv serves to suppress the driving force of the solenoid due to the position error signal ER.
That is, when the solenoid is driven only based on the position error signal ER, the solenoid suddenly reacts and the system becomes unstable. However, when velocity feedback is used, the reaction of the solenoid is suppressed and the system is guided toward a stable direction. here,
In the block diagram shown in FIG. 1, if only velocity feedback is extracted, the block diagram shown in FIG. 17 is obtained. Now, assuming that the input is V _R (s) and the output is X (s), the transfer function is as shown in the following equation.

(Equation 10) Then, by comparing Equation 10 and the transfer function of the physical model 11, it can be seen that the coefficient corresponding to μ changes to (μ + Kv) and the other terms do not change. This other parameter (M _D, k) without changing at all, by changing only Kv, which means that can increase or decrease only the viscosity coefficient. That is, apparently the viscous resistance of the pedal is (μ + Kv),
The value can be arbitrarily changed by Kv.

C: Effect of Embodiment In the present embodiment, pedal drive control is performed by two feedback loops of position feedback and speed feedback, and feedforward is not used, so that the structure of the control system is not complicated. can get. Further, by having position feedback, highly accurate control is possible.

D: Modified Example In the above-described embodiment, the speed signal Vc and the speed signal V ^* are mixed according to a predetermined crossover characteristic, but instead, the speed change per unit time is not less than a predetermined value. The speed signals Vc and V ^* may be switched depending on whether or not.

In the embodiment, the increment type encoder is used as the position sensor, but an absolute type encoder may be used instead. In this case, the speed may be calculated from the interval at which the output value of the encoder changes.

[0045]

As described above, according to the present invention, the pedal speed can be detected with high accuracy, and an inexpensive pulse encoder can be used as the pedal position sensor.

[Brief description of drawings]

FIG. 1 is a control block diagram showing a configuration of an embodiment according to the present invention.

FIG. 2 is a schematic configuration diagram of a pedal drive system to be controlled in the same embodiment.

FIG. 3 is a conceptual diagram showing modeling of a pedal drive system in the same embodiment.

FIG. 4 is a block diagram showing a transfer function of a model of a pedal drive system in the same embodiment.

FIG. 5 is a waveform chart showing a waveform example of a main part in the same embodiment.

FIG. 6 is a functional block diagram of a speed detection unit 12 in the same embodiment.

FIG. 7 is a block diagram showing a configuration of a speed estimation unit 14 in the same embodiment.

8 is a functional block diagram for explaining a calculation principle of a speed calculation unit 14a shown in FIG.

9 is a diagram showing a modification of the functional block diagram shown in FIG.

FIG. 10 is a diagram showing a modification of the functional block diagram shown in FIG. 9.

11 is a diagram showing a modification of the functional block diagram shown in FIG.

FIG. 12 is a characteristic diagram showing characteristics of the crossover network 14b.

FIG. 13 is a diagram showing a modification of the functional block diagram of the crossover network 14b.

FIG. 14 is a functional block diagram of a speed estimation unit 14.

FIG. 15 is a diagram showing a modification of the functional block diagram shown in FIG.

FIG. 16 is a timing chart for explaining the function of the velocity feedback loop in the same embodiment.

FIG. 17 is a block diagram in which velocity feedback is extracted in the same embodiment.

[Explanation of symbols]

5 ... Subtractor (speed feedback loop), 8 ... Driver (driving means), 11 ... Pedal physical model, 12 ... Speed detecting section (first speed information calculating means), 14a ... Speed calculating section Second speed information calculating means ), 14b ... Crossover network (crossover means), 30a ... Solenoid (driving device).

Claims (3)

[Claims] 1. A pedal drive device comprising: a drive device that drives a pedal at a speed corresponding to a drive signal; and a controller that supplies the drive signal to the drive device to control the movement of the pedal. Position information output means for outputting position information corresponding to the position, first speed information calculation means for calculating first speed information based on a change in the position information, and based on the position information and the drive signal. Second speed information calculating means for calculating second speed information, and a mixing ratio of the first speed information and the second speed information depending on a change amount of the speed of the pedal,
Crossover means for generating speed information of
A pedal driving device comprising a speed feedback loop using the third speed information. 2. The crossover means increases the ratio of the second speed information in a region where the change amount of the pedal speed is small, and the first crossover portion in a region where the change amount of the pedal speed is large. 2. The pedal drive device according to claim 1, wherein the ratio of the speed information is increased. 3. The crossover means uses only the second speed information in a region where the pedal speed change amount is small, and uses the first speed information in a region where the pedal speed change amount is large. The third speed information is generated by using only the speed information.
The described pedal drive device.