JPS6257010A - Position controller - Google Patents

Abstract

PURPOSE:To obtain a small-sized, lightweight, and inexpensive position controller by constituting the controller including a control circuit which varies the output of an oscillator according to a position signal and selects one of a couple of ultrasonic vibrators to control the level and direction of an ultrasonic traveling wave. CONSTITUTION:A position detecting circuit 7 inputs the output of the 2nd oscillator 4 and the output of a detector 6 and measures the delay time between both signals to detect the position of a slider 3, outputting the position signal 7. The signal 71 is inputted to a control circuit 8 to perform processing such as the generation of a speed signal when necessary, and the signal is compared with a target position or target speed specified with a control input signal 80 supplied from external control equipment. The output level of the 1st oscillator 82 determining the output levels of the 1st ultrasonic vibrators 2 and 2' is set on the bases of the comparison level and the circuit is switched to determine which of the vibrators 2 and 2; is used as an oscillator and which of them is used as a vibration absorber. Consequently, the magnitude and direction of driving ultrasonic vibrations generated on the rail 1 are determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position control device that uses a motor and a position detector to control the speed and position of a movable member.

[Prior art and its problems]

In a typeface serial printer, printing is performed by moving and positioning a carriage carrying a type head to a predetermined position. The movement and positioning of the carriage is controlled by the driving force transmitted from the rotary DC motor to the carriage via a wire pulley system and position information obtained from a rotational position detector mounted on the shaft of the rotary DC motor. It is carried out using That is, the rotation speed and stop position of the rotation angle of the motor are directly controlled, and this rotation angle? A wire pulley system is used to transmit the movement of the carriage. Therefore, the characteristics of the wire pulley system directly affect the speed and position of the carriage actually obtained. For example, vibrations due to the stretching of the wire and variations in the stopping position due to friction between the wire and the pulley occur. This limits the positioning speed and positioning accuracy of the printer, making it impossible to improve the printing speed and print quality of the printer.

In order to ensure carriage positional accuracy, it is conceivable to perform control using a linear position detector that directly detects the carriage position, but in this case, the carriage is driven via the same wire pulley system as in the past. The wire
Oscillation of the control system is unavoidable due to the transmission delay caused by the pulley system, so it is necessary to use a motor that directly drives the carriage, such as a linear DC motor.

However, linear DC motors require a magnetic circuit to be formed over the entire movable range of the carriage, which inevitably increases the size and weight of the motor, making it difficult to apply it to printers where compactness and weight reduction are essential conditions. Can not.

In addition, conventional optical and inductive position detectors that can detect the position of the carriage over its entire range of motion are expensive and difficult to install, and cannot be used by incorporating them into printers. .

In addition, some industrial robots that operate in a Cartesian coordinate system use linear DC motors and optical linear position detectors to control the positioning of movable parts. It is strongly desired to realize a small, lightweight IJ near motor and a position detector that is inexpensive and easy to install.

[Purpose of the invention]

An object of the present invention is to provide a position control device that is small, lightweight, inexpensive, and has a simple configuration, by realizing an ultrasonic motor and an ultrasonic position detector using the same ultrasonic transmission rail, without the above-mentioned drawbacks. Our goal is to provide the following.

[Structure of the invention]

The position control device & of the present invention includes a rail, a pair of oscillators that contact the rail and are connected to the ultrasonic traveling wave according to a pair of outputs that are in contact with the vicinity of the first oscillator, and the rail. a second ultrasonic vibrator that contacts near one end and transmits ultrasonic vibrations for position detection to the rail according to the output of the second oscillator; a detector that receives the vibration wave; and a position detection circuit that detects a signal delay time from the output signal of the second oscillator to the corresponding output signal of the detector and outputs a position signal corresponding to the position of the slider. The output of the first oscillator is changed according to the position signal, and which one of the pair of first ultrasonic transducers? The device includes a control circuit that controls the magnitude and direction of the ultrasonic traveling wave by selecting a device that generates ultrasonic waves.

It consists of a circuit.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the position control device according to the present invention. One ultrasonic vibrator 2 of the ultrasonic vibrators 2 and 2' is in contact with appropriate positions near both ends of the rail l. Excite the rail l
A driving ultrasonic vibration is generated in the other ultrasonic vibrator 2'.
When the driving ultrasonic vibration is absorbed and photographed, the driving ultrasonic vibration becomes a traveling wave traveling in the direction from the ultrasonic transducer 2 to 2', and is brought into contact with the rail 1 with an appropriate pressure. The slider 3 is driven along the rail 1 in a direction opposite to the traveling direction of the traveling wave. This is because each point on the surface of the rail l moves in a circular orbit due to the traveling wave, and only the vicinity of the top of the traveling wave comes into contact with the slider 3, which is well known as an ultrasonic motor. A theoretical explanation will be omitted.

On the other hand, according to the output of the second oscillator 4, position detection ultrasonic vibrations are transmitted from the second ultrasonic vibrator 5 that is in contact with the vicinity of one end of the rail 1 to the rail 1, and this vibration is transmitted onto the slider 3. The mounted detector 6 receives the wave, the position detection circuit 7 inputs the output of the second oscillator 4 and the output of the detector 6, and measures the delay time between these two signals. 3
The position of is detected and output as a position signal 71.

In addition, by setting the ultrasonic vibration for position detection to a sufficiently high frequency, the rail l
A practical traveling wave can be obtained by processing and scattering the ends of the wave.

The position signal 71 is input to the control circuit 8, where it undergoes processing such as generating a speed signal as necessary, and is then processed to produce a target position specified by a control input signal 80 given from an external control device (not shown). setting of the output level of the first oscillator 82, which is compared with the target speed and determines the output level of the first ultrasonic transducers 2, 2' based on this result; .2' is used as an oscillator and which is used as a vibration absorber. As a result, the strength and direction of the driving ultrasonic vibration generated on the rail l described above are determined.

With the configuration described above, a servo system is formed in which the slider 3 is moved by an ultrasonic motor, and the 30th position of the slider is detected by an ultrasonic cage detector and fed back, thereby forming a position control device. This position control device! c is because the driving force is generated at the contact part between the slider 3 and the rail l,
The slider 3 is directly driven, and there is no need for a wire pulley system or a large and heavy magnetic circuit. Further, position detection does not require a particularly complicated configuration since the position of the slider 3 can be directly measured and the same rail tt is used as the drive system. As a result, by directly driving and directly detecting the position of the slider 3, it is possible to perform high-precision, high-band position control, and to obtain a position control device that is small, lightweight, inexpensive, and has a simple configuration.

FIG. 2 is a block diagram of the position detection circuit 7.

A burst signal 41 intermittently output from the second oscillator 4 in FIG. 1 and a burst signal 6 detected by the detector 6
1 are input to the position detection circuit 7, the respective burst detection circuits 72, 73 generate timing signals corresponding to each other, for example, by detecting the start of the Hurst pulse, and these t counter clear signals 721. It is output as a latch signal 731. This counter clear signal 721H, riQ
The counter 75 which is counted up by the burst clock 741 generated by the burst signal 74 is cleared, and a counter 751 is generated which starts integration every time the burst signal 41 is generated, and is inputted to the latch 76. The latch signal 731 latches the output cuff 51 inputted to the latch 76 and outputs it as a position signal 71.

Therefore, the position signal 71 output from the position detection circuit 7 is
In FIG. 1, the second oscillator 4 has a value corresponding to the delay time from when the burst signal is generated to when the burst signal is detected from the detector 6. Since it is proportional to the distance from to slider 3,
This is a signal indicating the slider position 30m.

The position signal 71 has a repetition period for the slider position determined by the generation period of the burst signal 41 of the second oscillator 4 and a resolution determined by the clock 741. This is the position signal obtained. Therefore, by setting the burst signal generation period of the second oscillator 4 to be longer than the time required for the ultrasonic wave to propagate the entire length of the rail l, the position on the rail l and the position signal 71 are matched one-to-one. It can be configured accordingly.

Furthermore, in this embodiment, since the burst signal 41 outputted from the second oscillator 4 is input and the timing of generation of the burst signal 4I is detected, the burst signal detection circuit 72 is required. Of course, it is also possible to input the timing signal for generating the burst signal 41 used inside the second oscillator 4 to the position detection circuit 7 and use it directly as the clear signal 721 of the counter 75.

FIG. 3 is a block diagram of the control circuit 8.

When moving and positioning the slider 3 to the target position, the speed side mode controls the speed t of the slider 3 until the slider 3 enters a predetermined range near the target position, and the position of the slider 3 after entering the position. Control is performed by switching between the position control mode for full control and the mode. The mode signal generator 81 generates a mode signal 81 by comparing the position signal 71 with the control input signal 80 indicating the target position given from an external control device.
1.

In the speed control mode, the control input signal 8o is input to the reference speed generator 83, the position signal 71 is input to the reference speed generator 83 and the speed signal generator 84, and the reference speed generator 83 calculates the residual distance to the target position. A reference speed signal 831 indicating the reference speed that the slider 3 should take, which is appropriately determined according to the
At the same time, the speed signal generator 84 generates a speed signal 841 indicating the speed 11f' of the slider 3, and the subtracter 85 extracts the speed signal 841 from this reference speed signal 831.
is subtracted from , and a speed deviation signal 851 is output. This speed deviation signal 851 is input to the selector 86 which is switched by the eighth mode signal mentioned above, and is input to the selector 86 which is switched by the mode signal 81
In response to the fact that indicates the speed control mode, it is output as a control deviation signal 861. The control deviation signal 861 consists of a signal 862 indicating an absolute value and a signal 863 indicating a sign. Of these, the signal 862 indicating the absolute value is input to the first oscillator 82 to determine its output level, and furthermore, the signal 862 indicating the absolute value is input to the first oscillator 82 to determine its output level. The output of the oscillator 82 and a signal 863 indicating the sign are input to a drive circuit 87, and two outputs 871° 872 (each of which is an ultrasonic transducer 2.2' A drive signal corresponding to the output of the first oscillator 82 is output to one of the input circuits (input to the drive circuit 87), and the other is connected to a vibration absorption circuit inside the drive circuit 87. As a result, the signal 863 indicating the sign determines which of the first ultrasonic transducers 2 and 2' in FIG. is determined by the signal 862 indicating the absolute value, and the rail 1
The intensity and direction of the driving ultrasonic vibrations generated above are determined.

On the other hand, in the position control mode, the control input signal 80 indicating the target position and the position signal 71 are input to a position error signal generator 88, which outputs a signal indicating the residual distance to the target position.
Further, the phase is compensated by a compensator 89 and a position error signal 891e is output.

This position deviation signal 891 is input to the aforementioned selector 86, and is output as a control deviation signal 861 in response to the fact that the mode signal 811 indicates the position control mode.

This control deviation signal 861 is the output 871.872 of the control circuit 8 in the same way as previously explained in the speed control mode.
ft is determined, and the strength and direction of the driving ultrasonic vibration generated on the rail l are determined.

Due to the operation of the control circuit 8 described above, the slider 3 on the rail l is controlled by the control human power signal 8 given from an external control device.
0, the speed is controlled to follow a predetermined reference speed until near the target position, and then stopped at the target position when near the target position.

Note that in the control circuit 8 described here, the slider 3
to position it at a certain target position? As mentioned above, the main focus of the control circuit is that the slider 3 can be easily moved by adding a speed selection signal as the control type gear signal 80 and using this speed selection signal to select the reference speed that the slider 3 should take. It is also possible to realize a control circuit whose main purpose is to control speed.

〔Effect of the invention〕

As explained above, according to the present invention, an ultrasonic motor and an ultrasonic position detector are realized by using the same rail for ultrasonic transmission, and the structure is simple, compact, lightweight, and inexpensive. A position control device that can perform accurate and high-bandwidth control can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram of the position detection circuit 7 shown in FIG. 1, and FIG. 3 is a block diagram of the control circuit 8 shown in FIG. 1. ! ...Rail, 2.2' Old...First ultrasonic transducer, 3...Slider, 4...Second oscillator, 5... ...Second ultrasonic transducer, 6...
...Detector, 7...Position detection circuit, 8...
...Control circuit, 82...First oscillator. Agent Patent Attorney Otohara Uchihara Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] a rail, a first oscillator, and a pair of first ultrasonic vibrators connected near each end of the rail to generate an ultrasonic traveling wave in the rail according to the output of the first oscillator. , a slider that contacts the rail and is driven by the ultrasonic traveling wave; a second oscillator; and a slider that is connected near one end of the rail and generates position detection ultrasonic waves on the rail in accordance with the output of the second oscillator. a second ultrasonic transducer that transmits vibrations, a detector mounted on the slider that receives the ultrasonic vibrations for position detection, and a corresponding one of the detectors based on the output signal of the second oscillator. a position detection circuit that detects a signal delay time to an output signal and outputs a position signal corresponding to the position of the slider; and a position detection circuit that changes the output of the first oscillator in accordance with the position signal; A position control device comprising: a control circuit that controls the magnitude and direction of the ultrasonic traveling wave by selecting one of the ultrasonic transducers to generate ultrasonic waves.