JP2576644B2 - filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a filter that is inserted into a speed feedback control loop of a motor control device and suppresses resonance characteristics generated in the speed feedback control loop due to mechanical resonance of the motor. Things.

<Conventional Technology> A direct drive motor (hereinafter referred to as a DD motor) is directly coupled to a load without a reduction gear, and thus is susceptible to mechanical resonance of the load. For example, D
In a SCARA robot driven by a motor, the speed feedback control loop of the motor may have a resonance characteristic due to a mechanical resonance having a high Q value generated in a high frequency region of, for example, 200 to 1000 Hz due to the structure of the robot arm. .

In order to suppress such resonance characteristics, there is a filter that is inserted into a speed feedback control loop and that makes the gain of the loop a resonance characteristics suppressed.

<Problem to be Solved by the Invention> Conventionally, a filter capable of effectively removing mechanical resonance having a high Q value has not yet been realized in such a filter.

The present invention has been made in view of such a point,
It is an object of the present invention to realize a filter whose characteristics are set in accordance with the resonance frequency of mechanical resonance and which can effectively remove resonance having a high Q value.

<Means for Solving the Problems> The present invention is directed to a filter which is inserted into a speed feedback control loop of a motor control device and suppresses a resonance characteristic generated in the speed feedback control loop due to mechanical resonance of the motor. It has a switched capacitor integrator and a coefficient unit that multiplies the output of this integrator by 1 / Q (Q is a constant) and feeds it back to the input stage. The transfer function is given by Notch filters connected by the number of stages, ω ₁ : ω ₁ / 2π = (mechanical resonance frequency of the motor) Angular velocity set s: Laplace operator First-order lag filter connected in series with the notch filter and having a transfer function given by the following equation When, A filter characterized by having ω ₃ ≠ ω ₄ , ω ₃ ≪ω ₁ , ω ₄フ ィ ル タ ω ₁ .

<Operation> In the present invention, the resonance characteristics generated in the speed feedback control loop due to the mechanical resonance are suppressed by using the characteristics of the first-order lag filter and the notch filter connected in series.

Hereinafter, the present invention will be described with reference to the drawings.

 FIG. 1 is a configuration diagram of one embodiment of the present invention.

This filter is a filter inserted into a speed feedback control loop having two gain resonance points.

In the figure, reference numeral 10 denotes the input Vi in the frequency band of 20 to 200 Hz, for example.
This is a first-order lag filter that attenuates by about 0 dB. The transmission of this filter is given by:

{1+ (s / ω ₄ )} / {1+ (s / ω ₃ )} s: Laplace operator Here, ω ₃ and ω ₄ are angular velocities, and ω ₃ ≠ ω ₄ .

Notch filters 20 and 30 are connected in two stages in series.

In the notch filter 20, 21 is a subtractor, 22 and 23 are switched capacitor integrators, and 24 is a coefficient unit.

The output of the first-order lag filter 10 and the output of the coefficient unit 24 are inverted and given to the attenuator 21.

The switched capacitor integrator 22 integrates a difference signal between the output of the subtractor 21 and the output of the integrator 23.

The switched capacitor integrator 23 integrates the output signal of the integrator 22.

The transfer function of these integrators 22 and 23 is given by ω ₁ / s. ω ₁ is an angular velocity, which is set by the clock CLK 1 from the clock generator 40 so that ω ₁ / 2π is the first resonance frequency of the gain of the feedback control loop.

Coefficient multipliers 24 subtractor is multiplied by the coefficient 1 / Q ₁ at the output of the integrator 22
Negative feedback to 21. Q ₁ is set to suppress value the value of Q of the first resonance point.

The notch filter 30 has the same configuration as that of the notch filter 20, and includes a subtractor 31, a switched capacitor integrator.
32 and 33, and a coefficient unit 34.

Subtractor 31, one of the inputs is placed in the output of the subtractor 21, the output becomes the output V ₀ which filter.

The angular velocity ω ₂ giving the gain of the switched capacitor integrators 32 and 33 is set by the clock CLK 2 from the clock generator 40 so that ω ₂ / 2π becomes the second resonance frequency of the gain of the velocity feedback control loop.

The value of Q ₂ giving the coefficient of the coefficient unit 34 is set to suppress value the value of Q of the second resonance point.

The transfer function of the entire filter shown in FIG. 1 is given by the following equation.

FIG. 2 is a Bode diagram of the transfer characteristic of the first-order lag filter 10.

FIG. 3 is a Bode diagram of a transfer characteristic of a portion where notch filters 20 and 30 are connected in series.

In such a filter, due to the mechanical resonance of the motor,
When a resonance point as shown by a broken line in FIG. 4 occurs in the gain of the speed feedback control loop, if the filter of FIG.
The resonance characteristics are suppressed by the notch characteristics of the notch filters 20 and 30, and the gain of the speed feedback control loop becomes as shown by the solid line in the figure.

FIG. 5 is a diagram showing a place where a filter according to the present invention is inserted.

This figure is a block diagram showing the gain of each element constituting the speed feedback control loop of the DD motor.

In the figure, Vin and VF _{/ V} are the speed command signal of the DD motor and the speed feedback signal detected by the F / V converter, and K _DC is the signal that amplifies the difference signal between the command signal and the speed feedback signal and excites the motor coil excitation signal. _KT is the torque constant, _JS is the inertia of the motor, M (s) is the gain of the portion having the mechanical resonance characteristic, and _{KF / V} is the gain of the F / V converter.

The filter is inserted between the motor unit and a circuit unit that supplies an exciting current to the motor coil.

In the embodiment, the case where two notch filters are provided has been described. However, the number of stages of the notch filter may be any other number according to the number of resonance points.

<Effects> According to the present invention, the following effects can be obtained.

Since the notch filter uses a switched capacitor integrator, the notch frequency can be set by changing the clock frequency applied to the integrator. That is,
The notch frequency can be externally set in accordance with the resonance frequency by a host controller or the like based on the measured transfer characteristics, so that adjustment is easy.

The coefficient value of the coefficient unit of the notch filter can be set according to the resonance Q value. As a result, the effect of high Q value mechanical resonance can be effectively eliminated.

Since the first-order lag filter has a small phase lag, the phase lag caused by inserting this filter is small.

[Brief description of the drawings]

1 is a block diagram of an embodiment of the present invention, FIGS. 2 and 3 are Bode diagrams of transfer characteristics of a first-order lag filter and a notch filter of FIG. 1, and FIG. 4 is a diagram of a speed feedback control loop. FIG. 5 is a diagram showing a gain, and FIG. 5 is a diagram showing a place where a motor according to the present invention is inserted. 10 ... first-order lag filter, 20,30 ... notch filter, 2
2,23,32,33 …… Switched capacitor integrator, 24,34…
... coefficient unit, 40 ... clock generator.

Claims (1)

(57) [Claims] A filter inserted into a speed feedback control loop of a control device of a motor to suppress resonance characteristics generated in the speed feedback control loop due to mechanical resonance of the motor, comprising: a switched capacitor integrator having a variable gain from outside; The output of the integrator is multiplied by 1 / Q (Q is a constant) and has a coefficient unit that feeds back to the input stage. The transfer function is given by the following equation.
A notch filter connected by the number of stages corresponding to the number of resonance points, ω ₁ : ω ₁ / 2π = (mechanical resonance frequency of the motor) Angular velocity set s: Laplace operator First-order lag filter connected in series with the notch filter and having a transfer function given by the following equation When, A filter comprising: ω ₃ ≠ ω ₄ , ω ₃ ≪ω ₁ , ω ₄ ≪ω ₁ .