JPH063443Y2 - Open loop controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an open loop control device that can be effectively used for stop control of a drive device with a brake such as a motor with a brake or an air cylinder with a brake.

In a motor with a brake or a cylinder with a brake, a position signal of a rotary shaft or a cylinder stroke is obtained by a position detector, and when a predetermined position is reached, the brake is operated and stopped. At that time, since the moment of inertia acts even slightly, a deviation occurs between the position where the brake is operated and the actual stop position, and this deviation becomes larger as the moving speed of the controlled object immediately before the brake is operated becomes larger. It is known to be great. Therefore, conventionally, when manually setting the stop position set value,
In consideration of the moving speed of the machine, the set value is empirically set to a value deviating from a desired stop position (a value indicating a position in front). Therefore, there is a problem that the setting operation is troublesome and a stop error is likely to occur. Further, there is also a drawback that appropriate control cannot be performed when the actual speed is different from the planned speed. Also,
Since the setting operation has to be performed each time the control is performed, there is a drawback that the reproducibility is poor.

The present invention has been made in view of the above points, and can respond to changes in the speed of the machine to be controlled at any time, is highly reproducible in control, is versatile, and provides accurate control. It is intended to provide an open loop control device capable of performing the above.

The open loop control device according to the present invention is a phase shift type position sensor that produces an output AC signal by phase-shifting a reference AC signal in accordance with the current position of a control target, and an output AC signal of this position sensor and a reference AC signal. Position detection means having a conversion circuit for measuring the phase difference and outputting the phase difference information as a digital position signal indicating the current position of the controlled object, and sequentially storing the position signal output from the position detection means, A speed detection unit that calculates a change in the position signal with time based on this storage and detects the speed of the control target based on the calculation result, and a memory that stores a function of position correction information with respect to the speed in advance, By reading the function from the memory according to the speed information detected by the speed detecting means, the position correction information according to the speed follows the function. The position correction information generating means that is generated according to the desired characteristics, the correction means that corrects the value of the position signal detected by the position detecting means according to the position correction information generated by the position correction information generating means, and the correction means. The control means compares the corrected position signal with a target value and performs open loop control of the controlled object according to the comparison result.

According to this invention, the position correction information is generated with the characteristic according to the function stored in the memory according to the detected actual speed. Then, the position correction information is corrected so that the position signal is apparently changed, and the open loop control of the controlled object is performed based on the comparison between the corrected position signal and the target value. Therefore, it is not necessary to modify the target value according to the speed, and the setting operation of the target value becomes extremely simple. Further, since the position signal is automatically corrected according to the detected speed, the manual operation relying on experience is eliminated, and the control accuracy can be improved. Moreover, since the position correction information corresponding to the speed at that time is generated according to the function stored in the memory, it is possible to respond to the change in the speed of the machine to be controlled at any time, and the reproducibility of the control becomes rich. . Also,
Since the inertia characteristics of various machines can be dealt with at any time by changing / selecting the function stored in the memory, the versatility is enhanced.

In this invention, a single sensor is commonly used for the position detector and the speed detector, which can simplify the structure and reduce the cost. That is, the speed detector obtains speed information by calculating the position signal detected by the position detector, and does not require a sensor (tachometer generator or the like) dedicated to speed detection. As the position detector, it is preferable to use a phase shift type position detector because it has an advantage that position information can be digitally obtained with high resolution.
Among them, the one using a variable reluctance type sensor is preferable because it is a non-contact type, has a simple structure, and is excellent in environment resistance.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, the position detector 10 is for detecting the current position of the controlled machine, and is composed of, for example, a phase shift type position detector including a sensor unit 11 and a conversion unit 12.
A reference AC signal is given from the conversion unit 12 to the sensor unit 11, and the sensor unit 11 produces an output signal obtained by phase-shifting the reference AC signal in accordance with a detection target position (hereinafter, referred to as a rotation angle, for example). . The exchange unit 12 measures the phase difference between the output AC signal of the sensor unit 11 and the reference AC signal, and outputs this measured value as data D _x representing the current position of the rotation angle.

When the reference AC signal is sinωt, when the detection target is stationary at an arbitrary angular position θ, the output signal of the sensor unit 11 is sin (ωt−θ), and the phase difference θ does not change with time. On the other hand, when the detection target is moving at an arbitrary speed, the sensor output signal can be represented by sin (ωt−θ (t)), and the phase difference θ (t) changes with time. The phase difference measurement in the conversion unit 12 is performed at every predetermined sampling timing (for example, every one cycle of the sensor output signal), and when the detection target is moving, the value of the position signal D _x changes at each sampling timing. To do. That is, the position signal D _x indicates the instantaneous current position of the detection target.

In this embodiment, the speed detector 13 detects the speed using the output signal D _x of the position detector 10. A plurality of stages of shift registers 14 and subtractors 15 capable of holding all bits of the data of the position signal D _x are provided in one stage. The signal S indicating the sampling timing of the phase difference measurement in the conversion unit 12 is given to the shift clock input of the shift register 14, the position signal D _x is taken in the first stage in accordance with this shift clock, and the taken position signal is Shift to the next stage in sequence. The position signal D _x1 held in the first stage of the shift register 14 and the position signal D _xn held in the final stage of the shift register 14 are subtracted from each other.
The difference between the two is calculated. As a result, the subtractor 15 outputs a signal "D _xn -D _x1 ", that is, a signal corresponding to the change amount of the position signal during the predetermined n sampling time period.

The speed information output from the speed detector 13 is input to the position correction data memory 16 as an address. The position correction data memory 16 stores the function of the position correction data having the speed as a variable in advance. For example, the function stored in the memory 16 is set so that the value of the position correction data increases in direct proportion to the speed. Here, the slope of the functional characteristic of the speed-to-position correction data value is determined by using the moment of inertia of the controlled machine as a parameter. That is, even at the same speed, the braking distance varies depending on the magnitude of the moment of inertia peculiar to the machine. Therefore,
The function of the velocity-to-position correction information according to the moment of inertia peculiar to the machine to be used may be stored in advance in the memory 16. In order to easily deal with the case where the machine used changes, a plurality of functions corresponding to various moments of inertia are preliminarily stored in the memory 16, and one function is calculated according to the moment of inertia of the machine used. Should be selected.

The position correction data d is read from the memory 16 according to the speed information at each time. The adder 17 adds the current position signal D _x output from the position detector 10 and the position correction data d read from the memory 16. As a result, the apparent position signal D _x + d, which is ahead of the current position by the correction amount corresponding to the speed, is output from the adder 17. The comparator 18 includes the stop position setting data and the adder 17
Output D _x + d is input, and when the two match, a stop command signal is output. The machine to be controlled is braked based on this stop command signal. There is a braking distance depending on the speed of the machine at that time from when the brake is applied to when the machine is actually stopped. However, according to this invention, the brake operation is performed earlier than the set stop position by the position correction data d corresponding to the speed at that time. Therefore, if the position correction data d stored in the memory 16 is set to a value corresponding to the braking distance according to the speed, the machine can be accurately stopped at the position indicated by the stop position setting data. .

As the position detector 10, a variable reluctance type detector, a resolver, an optical encoder, or the like can be used, but it is variable because it is a non-contact type, has a simple structure, and has excellent environmental resistance. It is preferable to use a magnetoresistive type. Third example of variable magnetic resistance type position detector 10
Shown in the figure.

In FIG. 3, the sensor unit 11 shown in a plan view includes a stator 19 in which a plurality of poles A, B, C, and D are provided at predetermined intervals in the circumferential direction (90 degrees as an example), and each pole A. And a rotor (movable iron core) 20 inserted in a stator space surrounded by D. The rotor 20 has a shape that changes the reluctance of each pole A to D according to the rotation angle, and is, for example, an eccentric cylindrical shape. Stator 1
The primary coils 1A to 1D and the secondary coils 2A to 2D are wound around the poles A to D of 9, respectively. The two poles A and C facing each other in the radial direction are coiled so as to operate differentially, and a differential reluctance change occurs. The same applies to the other pair of poles B and D. The primary coils 1A and 1C of one pole pair A and C are sine signals sinω
Excited at t, the primary poles 1B, 1 of the other pole pair B, D
D is excited by the cosine signal. As a result, the reference signal sinωt is obtained as the combined output Y of the secondary coils 2A to 2D.
It is possible to obtain a signal Y = sin (ωt−θ) in which (or cosωt) is phase-shifted by an angle corresponding to the rotation angle θ of the rotor 20. As mentioned above, the rotor 2
When 0 is rotating at a certain speed, θ is represented by θ (t).

In the conversion unit 12, a predetermined high speed clock pulse CP
Is counted by the counter 21, and the sine signal si is generated by the sine / cosine generation circuit 22 based on the output of the counter 21.
The nωt and the cosine signal cosωt are respectively generated and applied to the primary coils 1A, 1C, 1B and 1D, respectively, as described above. Output signal Y = sin (ωt− of the secondary coils 2A to 2D
θ) is given to the zero-cross detection circuit 24, and this signal Y
The pulse is output in synchronization with the timing of the electrical phase angle of zero. The output pulse of this circuit 24 is used as a latch pulse of the latch circuit 23. The latch circuit 23 latches the count output of the counter 21 in response to the rising edge of the pulse supplied from the circuit 24 '. The period in which the count value of the counter 21 makes one cycle can be synchronized with one cycle of the sine signal sinωt. Then, in the latch circuit 23, the reference AC signal sinωt and the sensor unit output signal Y = sin (ω
The count value corresponding to the phase difference θ with respect to (t−θ) will be latched, and this will be output as the position data D _x . The latch pulse of the latch circuit 23 can be used as the sampling timing signal S.

The sensor unit 11 is not limited to the rotary type, but may be used in Japanese Utility Model Application No. 56-22.
A linear type as shown in No. 075 may be used. Further, the speed detector 13 is not limited to the above-mentioned one, and any kind may be used. For example, as shown in Japanese Patent Application No. 56-750, a method for obtaining speed information by calculating the frequency or period of the secondary coil output signal of a phase shift type sensor, or Japanese Patent Application No. 57-59729.
It is also possible to use a method in which the signal of each bit of the digital position signal is regarded as an incremental pulse and the speed or period is calculated to calculate the speed information, as shown in FIG.

As described above, according to the present invention, since the position signal is corrected according to the speed, it is not necessary to modify the position setting data according to the speed, and the setting operation becomes extremely easy. Further, since the correction is automatic according to the speed, control accuracy is improved. Further, since the position signal is corrected, only one correction device is required even when there are a plurality of setting data, and the device is simplified as compared with the case where the setting data is automatically corrected. Further, in the present invention, the function of the position correction information with respect to the speed is stored in the memory in advance, and the position correction information is generated according to the speed with the characteristic according to the function stored in the memory. By setting the contents of the function to be set arbitrarily, the characteristics of the speed vs. position correction function can be set in any way,
It has an excellent effect of being extremely versatile.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a plan view of a sensor section and a conversion section showing an example of the phase shift type position detector of FIG. 1 for a variable magnetic resistance type rotary position detector. 2 is an electrical block diagram of FIG. 10 ... Phase shift type position detector, 11 ... Sensor part, 12
... Conversion unit, 13 ... Speed detector, 14 ... Shift register,
15 ... Subtractor, 16 ... Position correction data memory, 17 ... Adder, 18 ... Comparator, 19 ... Stator, 20 ... Rotor,
1A-1D ... primary coil, 2A-2D ... secondary coil.

Claims (2)

[Scope of utility model registration request] 1. A phase shift type position sensor that produces an output AC signal by phase-shifting a reference AC signal according to a current position of a control target, and a phase difference between the output AC signal of the position sensor and the reference AC signal. , Position detecting means having a conversion circuit for outputting this phase difference information as a digital position signal indicating the current position of the controlled object, and position signals output from the position detecting means are sequentially stored, and time is stored based on this storage. The speed detecting means includes a speed detecting means for calculating a change in the position signal with the passage of time and detecting the speed of the controlled object based on the result of the operation, and a memory for storing a function of position correction information with respect to the speed in advance. By reading the function from the memory according to the detected speed information, position correction information according to the speed is generated at an arbitrary characteristic according to the function. Positive information generating means, a correcting means for correcting the value of the position signal detected by the position detecting means according to the position correction information generated by the position correction information generating means, a position signal corrected by the correcting means, and a target. An open loop control device comprising: a control means for comparing the value with a value and performing open loop control of the controlled object according to the comparison result. 2. The utility model registration claim, wherein the memory stores a plurality of functions of position correction information with respect to speed, and an arbitrary function can be selected and read according to the speed information. The open loop control device according to item 1.