JPH0297990A - Servo control system for planetarium - Google Patents

Abstract

PURPOSE:To obtain a servo system to be economically advantageous by detecting the rotation angle of a projector with an incremental encoder and a counter in a servo control to specify the positions of stars and determining an origin with a digital processing circuit. CONSTITUTION:At the time of the power-on of a servo control system 12 or a reset command, the value of a counter 16 is set to a lamp function generator 19. Next, when the servo is made operatable, the function generator 19 makes the counter value set beforehand into a start point, and a projector 5 starts a movement according to the lamp function. When a Z phase signal is inputted in a condition in which an origin proximity detecting sensor 15 is on, the output of the function generator 19 is zero-reset and fixed by the output of an AND 17. Further, by the output of a wave head differentiating circuit 18, the counter 16 is reset only one moment, and the origin as the servo system is determined. Thereafter, the counter 16 executes a counting with an A phase and a B phase, and as a result, the absolute value of the rotation angle of the projector 5 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo control system used to determine the position of stars in a planetarium.

[Conventional technology]

FIG. 3 is a diagram showing a conventional servo control system in a planetarium.

(11 to (1n) are conventional servo control systems each having the same configuration, (21 is a conventional servo mechanism section).

(3) is the motor, (4) is the tachometer generator, (
6) is a structure equipped with an optical system for projecting stars.

That is, the projector (6) is an absolute encoder. Absolute encoder (6) and projector (5)
are connected with a rotation ratio of 1:1, and the projector (5) returns to its original position after one rotation, that is, 360 degrees. Therefore.

The number of bits of the absolute encoder (6) determines the resolution of the servo control system. For example, if the number of bits of the absolute encoder (6) is 16, the minimum resolution is 0.33' in 360 degrees, 216 degrees, and 0.00549 degrees.

(71 is a servo amplifier, (8) is a digital/analog converter that converts digital quantities into analog quantities, and (9) is for managing the entire planetarium and outputting servo command angles calculated based on performance requests to individual servo control systems. aI is an input/output signal processor that interfaces signals with the computer (9), (a) is a servo command angle calculated based on the performance request sent via the input/output signal processor aGt-, (ro) ) is the rotation angle of the projector output from the absolute encoder (6), aυ is the servo command angle (a) calculated based on the performance request and the rotation angle of the projector (bj 'e), and the difference numerator k is The output error generator (e) is a servo-on signal to put the servo amplifier into operation. When the servo-on signal (c) is turned on, the motor (3) starts to be energized and starts operating as a servo loose. do.

Now, the conventional servo control system fl+ with the configuration described above uses an absolute encoder to detect the rotation angle of the projector (5).

After the system power is turned on, it becomes possible to control the servo command angle (A) calculated based on the performance request at any time.

In addition, the rotation angle of the projector (51, that is, the output of the absolute encoder (6), that is, the rotation angle of the projector (Ron sends it to the computer (9) via the input/output signal processing processor αG for use as system management information of the planetarium) be done.

[Problem to be solved by the invention]

The conventional servo control system for planetariums is configured as described above and has the following first-order problems.

First, absolute encoders are expensive.

Second, the absolute encoder has a large external shape, which impairs the design space factor of the servo mechanism. The M3 absolute encoder requires output signal lines equal to the number of bits, and unless the number of output signals is reduced, the wiring materials for signal transmission, the number of slip rings in the servo mechanism, and the wiring effort will be increased. It is uneconomical. This invention attempts to solve the above three problems.

[Problem't-Means for solving it]

The servo control system according to this invention uses an incremental encoder as a sensor that detects the rotation angle of the projector, and converts the output of the incremental encoder into an absolute value using a counter, so that it has the same effect as an absolute encoder.

On the other hand, unlike the absolute encoder, the incremental encoder does not output information about the current rotation angle of the projector when the power is turned on. Therefore, a processing circuit is required to determine the origin of the projector when the power is turned on or when a reset command is issued. This processing circuit can be easily assembled with a digital processing circuit. This digital processing circuit basically consists of a ramp function generator for rotating the projector with a ramp function, a origin proximity detection sensor for detecting the origin vicinity during the rotation of the projector, and an incremental The A required to determine the origin by momentarily resetting the counter to zero and the AND circuit that ANDs the two phases of the encoder.
It consists of a circuit that differentiates the wave front of the ND circuit output. Furthermore, in this digital processing circuit, it is important to match the values of the ramp function generator and the counter before rotating the projector using the ramp function in order to perform the origin determination operation. This is to prevent the projector from suddenly moving at a high speed by matching the values of the ramp function generator and the counter. There are two methods to match the values of this ramp function generator and the counter. One is to set the counter value to the ramp function generator when the power is turned on or a reset command is given, and the other is when the power is turned on. Or the ramp function generator and clunk at the reset command.
This method resets the controller to zero in both directions at the same time. A servo control system that has a circuit configuration that sets a counter value in a ramp function generator and performs an origin determining operation corresponds to claim (1), and has a circuit configuration that resets the counter value and the ramp function generator to zero at the same time. The scope of the claim (
Corresponds to 2).

That is, the servo control system according to the present invention uses an incremental encoder and a counter to detect the rotation angle of the projector, introduces a digital processing circuit to determine the origin, and uses an absolute encoder to detect the rotation angle of the projector. This is intended to replace the servo control system that was previously used.

[Effect]

According to the present invention, by using an incremental encoder and adding a counter for counting its output and a digital processing circuit for determining the origin, a servo control system equivalent to that using an absolute encoder can be formed.

The counter and the digital processing circuit for determining the origin can be realized using extremely small-scale digital circuits. Therefore, regarding the first problem raised as a problem to be solved by the invention, even if the incremental encoder of this invention, the newly added counter, and the digital processing circuit for determining the origin are combined, it is several steps more cost-effective than the absolute encoder. becomes. The problem of the second space factor can also be improved by changing to an incremental encoder such as absolute xy=-/ih. Regarding the third problem, if you use an incremental encoder for an absolute encoder that requires the number of output signal points equal to the number of bits,
The number of lines for phase, B phase, and Z phase signals and the output of the sensor for detecting the vicinity of the origin is sufficient, and the number of lines can be significantly reduced, which is economically advantageous.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the servo control system according to the present invention, which includes a motor (3), a tachometer generator (4), a projector (5), a servo amplifier (7), and a digital/analog converter (8). ), Calculator (9)l Error generator αV, 9 servo command angle u calculated based on the production request
) and the servo-on signal (c) are the same as those shown in FIG. 3, which shows a conventional servo control system. α2~(12n)
are the servo control system according to the present invention having the same configuration, aS is the servo mechanism unit according to the present invention, α knob is an incremental encoder that outputs A-phase, B-phase, and Z-phase signals, and α9 is a sensor for detecting the vicinity of the origin) are the A-phase and B-phase signals output from the incremental encoder α4, (E) is the 2-loss cancellation signal output from the incremental encoder No. 0, and αe is the A-phase and B-phase signals). The output of the detection sensor near the origin and the Z-phase signal (f[-AND circuit,
aS is a wavefront differentiation circuit that differentiates the wavefront of the output of the AND circuit αη, a9 is a ramp function generator that outputs a ramp function, c
lU is a selector that selects the servo command angle (a) calculated based on the output of the ramp function generator and the production request, and the profit is the interface with the computer (9) and each of the servo control system α2 according to the present invention. Input/output signal processing processor that controls and interfaces circuits Part 2
．． (f) is the value of the counter αG, that is, the counter output, (g) is the switching signal of the selector ω, and (1) is the ramp function output custard signal that instructs the ramp function generator α9 to generate a ramp function output.

Now, when the power of the servo control system α2 according to the present invention is turned on, or when a reset command is given from the computer (9), the input/output cuff 0 sensor No. 2 f2
D reads the value of the counter value and immediately sets it to the ramp function generator α9. Next, the switching signal (T) is turned on and the selector even is set to output the output signal of the ramp function generator a9 to the error generator αD. Next, turn on the servo-on signal (c) to make the servo loop ready for operation. In this state, the counter value (to) has already been set to the ramp function generator α9, and since both values match, the output of the error generator aD is zero, and the motor (3)
is not driven, so the projector will not suddenly start moving.

Next, a ramp function output custard signal (41) is generated.The ramp function generator α9 generates a ramp function output with the previously set counter value as the starting point.

A differential output between the output of the output side pressure ramp function generator α9 of the error generator all and the counter value (to) is generated, and the motor (
3) is driven and the projector starts moving. A phase.

According to the B-phase signal), the counter ae performs counting and the output value (to) is provided to the error generator aυ. As a result, the projector (5) moves with a ramp function.

When the Z-phase signal (E) is input while the origin proximity detection sensor is on, the output of the AND circuit +171 is set to zero and the output of the sylumb function generator a9 is fixed.

Furthermore, the output of the wavefront differentiating circuit Nishiki momentarily resets the capacitor αG to zero. After resetting this counter IiG to zero, it is assumed that the origin has been determined for this servo control system, and from now on, the counter IiG is A.
phase and B phase signals), and outputs the absolute value of the rotation angle of the projector (5) as a result. After determining the origin,
The projector (5) overshoots due to inertia, but since the output of the ramp function generator (19) has already been set to zero, it converges to this position, that is, the origin. Z phase signal is incremental encoder rotation 1
One pulse is output per rotation. For example, set the A phase or B phase signal output of the incremental encoder to 65.538.
If you want to make one revolution of the pulse/projector, set the gear ratio between the projector and the incremental encoder to N, and set the A phase or B phase.
If the phase output is n pulses/incremental encoder rotation, it is necessary to satisfy Nφn=65.536,
If N=512 then n=128, if N=256 then n=
It becomes 258. That is, the Z-phase signal is output n times per one rotation of the projector. Therefore, the origin cannot be determined only by outputting the Z-phase signal, and this is the reason why a sensor for detecting the vicinity of the origin is required.

The output of the AND circuit αn is sent to the computer (via the input/output signal processor 2Qυ) to notify that the origin has been determined.
9). Thereafter, the switching signal (g) is turned off at a timing that anticipates the convergence time of servo 1, and the servo command angle (a) calculated based on the performance request is sent to the error generator a1.
1 and enters servo operation under normal operating conditions as a planetarium.

FIG. 2 is a diagram showing another servo control system according to the present invention.

4-(22n) Vi Other servo control systems according to the present invention each having the same configuration, (to) When the power of the other servo control system according to the present invention @ is turned on or a reset command is issued from the computer (9) A reset signal generator generates a signal that resets the ramp function generator a9 and the counter α9 when received. In FIG. 1, the same reference numerals as in FIGS. 1 and 3 indicate the same or equivalent components or signals in FIGS. 1 and 3.

The reset signal generator is activated when the power of the other servo control system (2) according to the present invention is turned on, or when the input/output signal processing processor 3@ from the computer (9) is turned on.
When a reset command is received in the mode, the rung function generator (19) and the counter l[i generate a heliset signal, and the counter 11G and the ramp function generator α3 are reset to zero at the same time.Next, the switching signal (g) Turn on and set selector @ so that the output of ramp function generator a9 is connected to error generator t111.

Next, turn on the servo-on signal (c) to make the servo loop ready for operation. In this state, the counter value (to) and the output of the ramp function generator σ9 are both set to zero and match, so the output of the error generator αB is zero and is small. Since the motor f31 Fi cannot be driven mid-drive, the projector It never starts to move. Next, in response to the Lang function output custard signal (1), the ramp function generator α9 generates a Lang function output starting from the zero value. Thereafter, other servo control systems (to) according to the present invention perform the same operations as servo control system 0 according to the present invention.

〔Effect of the invention〕

As described above, according to the present invention, an incremental encoder is used as a sensor for detecting the rotation angle of the projector, and at this time, a sensor for detecting the vicinity of the origin and a complete digital processing circuit for determining the origin must be added. However, even if a sensor for detecting the vicinity of the origin and a digital processing circuit for determining the origin are added.

The use of an absolute encoder is also significantly advantageous in terms of price, and it is also possible to replace a small incremental encoder with a large absolute encoder due to the mechanical design.

It is also advantageous as a space factor for 11RLh.

Furthermore, by replacing the absolute encoder with an incremental encoder, the number of force signal points can be reduced, and a great economical effect can be obtained in terms of the number of slip rings prepared in the wiring material 1 mechanism section and the labor involved in wiring.

[Brief explanation of drawings]

Fig. 1 is a diagram of an embodiment of a servo control system according to the present invention in a planetarium, Fig. 2 is a diagram of an embodiment of another servo control system according to the invention, and Fig. 3 is a diagram illustrating a conventional servo control system. It is. In the figure, (1) to 1n) is a conventional servo control system, (2) is a conventional servo control mechanism, and (3) is a motor. (4) is a tachometer generator, (5) is a projector, (
6) is an absolute encoder, and C7) is a servo amplifier. (81 is a digital/analog converter, (9) is a computer, αG is an input/output signal processing processor, α11 is an error generator, Q2 to (12n) fl is a servo control system according to this invention, α3 is a servo mechanism section according to this invention , α4
1 is an incremental encoder, (151 [K point vicinity detection sensor, 011 is a counter, αη is an AND
The circuit, Nishiki is a wave front differentiation circuit, (19 is a curve/branch function generator, cai is a selector, Qυ is an input/output signal processing processor part 2, (c) to (22n) are other servo control systems according to the present invention, ■ is a reset signal generator, c
! 41 is an input/output signal processing processor No. 3. (a) is the servo command angle calculated based on the performance request, (b) is the rotation angle of the projector, (c) is the servo on signal, and (b) is the A phase, B
phase signal. (e) is the Z-phase signal, (f) is the counter value, and (g) is the switching signal. (1) is a ramp function output custard signal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a planetarium servo control system that rotationally controls a projector that projects stars to determine the star projection position, A-phase, B-phase,
An incremental encoder that outputs a Z-phase signal, a counter that performs forward/reverse counting using the A-phase and B-phase signals of this incremental encoder, and a predetermined point including a point that outputs the Z-phase signal in the rotation angle direction of the projector. a detection sensor near the origin that outputs a signal with a width of a ramp function generator that outputs, a selector that selects the servo command angle, and an error generator that outputs the difference between the servo command angle and the output of the counter;
The servo amplifier is equipped with a servo amplifier that amplifies the output of the error generator and drives the motor connected to the projector through gears, and the error generator, servo amplifier, motor, incremental encoder, and counter form a servo loop, and the servo control system When the power is turned on or a reset command is given from the outside, set the counter value to the ramp function generator, connect the output of the ramp function generator to the error generator using the selector to set the servo command angle, and set the output of the ramp function generator to the error generator. The function generator generates a ramp function output starting from the counter value that has just been set, and the servo loop is operated using this ramp function output as the servo command angle. The Z-phase signal is ANDed with an AND circuit, the output of the AND circuit resets the ramp function generator to zero, the ramp function generator is held at zero value for a while, and the counter is momentarily reset to zero with the output of the wavefront differentiator. In particular, the origin of the projector is determined, and from then on the counter is always enabled for counting, so that the projector converges on the origin, and from then on, the rotation angle calculated by a separate computer based on the planetarium production request is set as the servo command angle. A servo control system for a planetarium, characterized in that a projector is positioned by switching with a selector. (2) In a planetarium servo control system that rotationally controls a projector that projects stars in order to determine the star projection position, A-phase, B-phase,
An incremental encoder that outputs a Z-phase signal, a counter that performs forward/reverse counting using the A-phase and B-phase signals of this incremental encoder, and a predetermined point including a point that outputs the Z-phase signal in the rotational direction of the projector. An origin detection proximity sensor that outputs a signal with a width, an AND circuit that ANDs the output of the origin proximity detection sensor and the above Z-phase output signal, a wavefront differentiation circuit that differentiates the wavefront of the output of the AND circuit, and outputs a ramp function. a lamp generator to select the servo command angle, a selector to select the servo command angle, an error generator to output the difference between the servo command angle and the output of the above counter, and a motor that amplifies the output of the error generator and is connected to the projector in gear. The error generator, servo amplifier, motor, and incremental encoder form a servo loop, and the power supply for the servo system is When turned on or when a reset command is given from the outside, the reset signal generator generates a reset signal, and this signal simultaneously resets the values of the ramp function generator and counter to zero, and changes the output of the ramp function generator. In order to set the servo command angle, connect it to the error generator using the selector, generate a ramp function output starting from the zero point that has just been reset from the ramp function generator, and operate the servo loop using this ramp function output as the servo command angle. , the output of the origin proximity detection sensor obtained during the operation process and the Z phase signal are ANDed by an AND circuit, and the same A
The ramp function generator is reset to zero by the ND circuit output, and the ramp function generator is held at zero value for a while, while the origin of the projector is determined by momentarily resetting the counter to zero by the output of the wavefront differentiator circuit, and the counter is then reset to zero. By making it possible to count at all times, the projector is brought to the origin, and from then on, the rotation angle calculated by a separate computer based on the planetarium production request is switched with the selector to be the servo command angle, and the projector is positioned. A planetarium servo control system featuring the following features: