JPS62173993A - Motor positioning control unit - Google Patents

Abstract

PURPOSE:To determine the accurate positioning simply and inexpensively by controlling the unit with an open loop in compliance with speed command signals in decceleration, and in stopping by controlling it in the position where the predictable amount of overrun is taken into consideration. CONSTITUTION:The rotating position of the axis of rotation of an AC motor 1 is detected by a rotating position sensor 3. A speed command means 15 gives out a speed command signal of the motor 1 as a function of the position of the axis of rotation detected by the rotating position sensor 3. An overrun amount predicting means 7 determines the predictable overrun amount in accordance with the speed or the acceleration of the motor 1. The positioning data from the rotating position sensor 3 in accordance with this predictable overrun amount are compensated by a compensation arithmetic circuit 11. The output of this compensation arithmetic circuit 11 and that of a stop-position setting circuit 12 are compared by a comparison means 14, from the output of which the stop-timing of the motor 1 is determined.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to speed and position control devices for motors such as AC motors, DC motors, and pulse motors, and in particular, to control the positioning of motors with high precision using an open loop method. Concerning what can be done.

[Conventional technology]

In order to position the motor without shock, it is preferable to perform appropriate deceleration control. Furthermore, in order to start the motor softly, it is preferable to perform appropriate acceleration control. Therefore, it has been conventional practice to control the speed of the motor according to an appropriate acceleration/deceleration pattern.

[Problem that the invention seeks to solve]

However, conventional motor speed control has been a closed-loop servo control, which is suitable for precision positioning, but has the following drawbacks. That is, since the motor is controlled by a drive signal consisting of a minute current or voltage, it is not possible to increase the loop gain, and there is always the problem of oscillation or hunting during positioning.

Also, servo control devices are expensive.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a motor positioning control device that allows accurate motor positioning by a simple and inexpensive open-loop method. Specifically, we provide a positioning control device that allows accurate positioning (stopping) to be performed easily and inexpensively using an open-loop method by performing control that takes into account the overrun amount according to motor speed and acceleration. This is what I am trying to do.

[Means for solving problems]

The positioning control device according to the present invention includes: a position detection means for detecting the rotational position of a rotating shaft of a motor; a speed command means for generating a speed command signal for the motor as a function of the detected position; and a speed command signal for the motor as a function of the detected position. overrun amount prediction means that determines a predicted overrun amount according to at least one of data of acceleration; and at least one of a set positioning target value and a value of position data obtained by the position detection means to determine the predicted overrun amount according to the determined prediction. The position data and the target value are compared using a compensation means that is changed according to the amount of overrun, and the changed value is used for the compensation means, and the motor is stopped according to the result of this comparison. The present invention is characterized by comprising a comparison means for determining a timing and setting the value of the speed command signal to a value that makes the speed of the motor zero in accordance with the stop timing.

[Effect]

When performing positioning control, deceleration control is performed in an open loop according to a speed command signal, and stop control is performed at a position that takes into account the predicted overrun amount, and as a result, it is accurately stopped at a desired target position. If only the predicted overrun amount compensation control is used, there may be a large shock at the time of stopping, which may cause poor accuracy.On the other hand, if only the open-loose deceleration control is used, there is a problem in accuracy. This allows accurate positioning without shock.
Moreover, since it is an open loop, it is simple and low cost, and the loop gain can be increased to quickly perform positioning.

〔Example〕

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

In FIG. 1, reference numeral 1 indicates an AC motor, such as a cage-type induction motor. 2 is a brake, motor 1
It is attached to the rotating shaft 1a of.

Reference numeral 3 denotes a rotational position sensor for detecting the rotational position (angle) of the rotational shaft 1a of the motor 1, and in this embodiment, a variable magnetic resistance sensor of a phase shift type as shown in Japanese Patent Application No. 55-147425 is used. A mold rotation position detector is used.

That is, the rotational position sensor 3 shows a magnetic resistance change according to the rotational position of the motor rotation shaft 1a, and according to this magnetic resistance, the phase changes from the reference AC signal sinωt by an electrical phase angle θ corresponding to the current rotational position of the shaft 1a. shifted output signal Y
=sin (ω is - θ) is output. The position conversion circuit 4 receives the output signal Y of the sensor 3, measures the electrical phase shift amount θ, and outputs the measurement result as the current rotational position data Dθ of the motor 1. Speed detection circuits 5 and 6 are provided to detect the rotation speed and acceleration of the motor rotation shaft 1a. In this embodiment, dedicated sensors for speed and acceleration detection are provided, and rotational position detection data Dθ
The speed is detected using the Dv, and the acceleration is detected using the detected speed data Dv. For this purpose, the position data Dθ is input to the speed detection circuit 5, and the speed data Dv output from the speed detection circuit 5 is input to the acceleration detection circuit 6.

When the motor 1 is stationary at an arbitrary rotational position, the position data Dθ maintains the value indicating the position and does not change. When motor 1 is rotating at a speed of
The value of θ changes over time as the rotational position changes. Therefore, the speed data Dv is determined by calculating the change in the position data Dθ per predetermined unit time (or period) in the speed detection circuit 5. In addition, the acceleration detection circuit 6 obtains speed data D per predetermined unit time (or period).
Acceleration data DX is obtained by calculating the change in v.

The overrun amount prediction means 7 detects the detected speed data Dv.
and acceleration data Dx to determine the predicted overrun amount. For example, overrun ROM (or RAM)
8.9 and an overrun amount calculation circuit 10. The overrun ROM 8 stores in advance overrun amounts corresponding to various speed values. Similarly, Overrun RO
M9 stores in advance overrun amounts corresponding to various acceleration values. Here, the overrun amount is the distance from the start position of the brake 2 to the actual stop position of the motor 1, and this overrun amount is measured and learned in advance in response to various speeds and accelerations. ), and store this in ROM (or RAM) 8°9. ROM8 according to the current speed data Dv and acceleration data Dx.
．． Overrun amount data 0VR1 and 0VR2 are read from 9, respectively, and provided to an overrun amount calculation circuit 10. The overrun amount calculation circuit 10 calculates, selects, and calculates data OVR that predicts the actual overrun amount using predicted overrun amount data OR1 according to the current speed and predicted overrun amount data OR2 according to the current acceleration as parameters.
It is determined by calculation operations including mixing. - For example, when there is acceleration, the arithmetic circuit 10 determines the amount of overrun approximately depending on the acceleration (with appropriate consideration of speed), and during a constant speed period, determines the amount of overrun approximately according to the speed at that time. do. As another example, data 0 corresponding to acceleration
A mixture of VR2 and data OVR1 corresponding to the speed at a predetermined ratio depending on the degree of acceleration may be output as OVR. As yet another example, the larger of data 0VRj corresponding to velocity and data 0VR2 corresponding to acceleration may be selected as QVR.

The compensation calculation circuit 11 increases or decreases the value of the rotational position data Dθ in accordance with the overrun amount prediction data OVH to obtain a value Dθ that compensates for the predicted overrun. Change to

The stop position setter 12 is used to set a stop position, that is, a positioning target value, and outputs target value data Sθ indicating a rotational position at which the rotation is to be stopped.

The control unit 13 provides a brake activation signal to the brake driver 60, and also generates a speed command signal for controlling the movement of the motor 1 and an acceleration setting signal as necessary, and a comparison means 14 for position comparison. and speed command means 15. The comparison means 14 compares the overrun-compensated position data Dθ0 and the target value data Sθ set by the setting device 12. The speed command means 15 is
Based on the outputs of the speed setting device 16, position setting device 17, comparison means 14, etc., a speed command signal including a first speed command signal according to the set speed and a second speed command signal according to a predetermined deceleration pattern is generated. Occur.

In relation to the comparison means 14, when the stop timing is determined as a result of the comparison by the comparison means 14, the speed command signal is set to zero. The generated speed command signal is applied to the inverter 18 of the motor 1, thereby controlling the motor 1.

Stop position setter 12, speed setter 16, position setter 17
is given sequence information from the sequence circuit 19,
Changes in the stop target position, other operating positions, set speeds, output timings of these data, etc. are controlled according to the sequence information.

A detailed example of the speed command means 15 is shown in FIG. 2, which includes a speed setting means 20 that generates a first speed command signal vl according to a set speed, and a second speed that follows a predetermined deceleration pattern. The deceleration pattern generating means 21 generates the command signal v2 as a function of the position data Dθ.

- For example, the speed command means 15 generates a speed command signal in a pattern as shown in FIG. 3, and by controlling the speed and position of the motor 1 in an open loop according to such a speed pattern, the software This enables start and shock-less positioning control.

To explain the speed pattern shown in FIG. 3, the speed increases according to a predetermined acceleration curve from the start to the maximum speed, and once the maximum speed is reached, it is maintained. From the deceleration start position to the low speed start position, the speed decreases according to a predetermined deceleration curve from the highest speed to the lowest speed. A predetermined minimum speed is maintained from the low speed start position to the stop position. The maximum speed and minimum speed can be set to arbitrary values using the speed setting device 16, and the maximum speed setting data can be set to H5.
, minimum speed setting data is indicated by L3. Note that the minimum speed here does not mean zero. The deceleration start position and low speed start position can also be set to arbitrary values by the position setting device 17. The stop position corresponds to the target value Sθ mentioned above. The deceleration start position setting data is indicated by Sl, and the low speed start position setting data is indicated by 82. - As an example, Sl is set at the angle from the desired deceleration start position to the stop position Sθ,
l is set as the distance from the desired low speed start position to the stop position Sθ. Further, the characteristics of the acceleration curve and deceleration curve are not limited to linear, but can be set to arbitrary curves.

In the example of FIG. 2, the acceleration curve is generated as a function of time, and its characteristics are switched by controlling the time constant. On the other hand, the deceleration curve is generated as a function of the position of the motor 1. Of course, the acceleration curve can also be modified to be generated as a function of position. Alternatively, the maximum speed H5 may be set from the start without setting an acceleration curve.

The speed setting means 20 generates a speed command signal during acceleration and a subsequent maximum speed speed command signal as first speed command signals in accordance with the characteristics shown in FIG. Time constant setting data T to control the time constant of the acceleration curve.

is given.

The frequency divider 31 uses this data T. A predetermined clock pulse cp is frequency-divided by a frequency division ratio controlled by .

The frequency-divided clock pulse is applied to the count input of counter 32. The counter 32 is reset at the start of movement, and thereafter counts up every time a pulse is applied to the count input. The count output of the counter 62 is given to a rising pattern memory 33, and speed setting data consisting of a predetermined rising pattern is read out from the memory 33 as the count value increases. This speed setting data is input as the first speed command signal Vl to the digital/analog converter 35 via the gate 34, where it is converted to an analog speed command signal and sent to the inverter 18 (Fig. 1).
supplied to

The coincidence detection circuit 36 compares the speed setting data read from the memory 33 with the maximum speed setting data Hs, and when a coincidence is detected, provides a signal to inhibit the counting operation of the counter 62. Therefore, the speed setting data read from the memory 33 gradually increases according to a predetermined rise characteristic, but when it reaches the set maximum speed, it maintains the same value as the maximum speed setting data H3. Since the increase rate of the counter 32 is determined by the frequency of the output pulse of the frequency divider 61, the slope of the rising characteristic, that is, the time constant, is controlled by the time constant setting data Tc.

A control signal T1 for the gate 34 is provided from a comparator 37). The comparator 37 inputs the difference Sθ-Dθ between the stop position setting data Sθ and the current position data Dθ to the A input, and inputs the deceleration start position setting data S1 to the B input. 1 has not yet reached the deceleration start position, the signal I+1'' is output as the control signal T1. Therefore, the gate 34 is enabled from the start to the deceleration start position in FIG. Speed setting data with a rising characteristic shown as an acceleration curve and subsequent continuous maximum speed setting data pass through gate 34.

The deceleration pattern and minimum speed generating section 38 generates a speed command signal during deceleration and also generates a speed command signal for the minimum speed according to the characteristics shown in FIG. The calculation and comparison circuit 39 inputs the current position data Dθ, the stop position setting data Sθ, the deceleration start position setting data Sl, the low speed start position setting data S2, the maximum speed setting data H5, and the minimum speed setting data Ls. Based on the predetermined calculations and comparisons, an address signal AD (Dθ) for reading the falling pattern memory 40 is generated as a function of the current position data Dθ. Also, S1≧Sθ−Dθ≧
A comparison condition S2 is determined, and when this is satisfied, that is, when the current position is between the deceleration start position and the low speed start position, a control signal T2 is generated to open the gate 41.

Address signal AD (Dθ) is applied to the address input of memory 40 via this gate 41. Also, Sθ−D
A comparison condition θ<S2 is determined, and when this is satisfied, that is, when the current position exceeds the low speed start position, a control signal T3 is generated to open the gate 42. Gate 42 has minimum speed setting data L.

has been entered.

The falling pattern memory 40 stores a predetermined falling pattern, the highest and lowest values of which are variably set by the highest speed setting data H5 and the lowest speed setting data Ls, respectively. Address signal AD (Dθ) is basically S+
The equation (Sθ-Dθ) therefore changes according to changes in Dθ, and when Sθ-Dθ=Sl, the maximum speed setting data H5 is read out with AD(Dθ)=0. And Sθ−Dθ”
The function of the address signal AD (Dθ) is determined according to the total number of addresses in the memory 40 (the number of addresses from Hs to L5) so that the lowest speed setting data Ls can be read at S2. Therefore, the speed setting data that sequentially decreases according to a predetermined falling pattern from the highest speed setting data H5 to the lowest speed setting data Ls from the deceleration start position to the low speed start position is the address signal AD corresponding to the position data Do. (Dθ) is read from the memory 40.

The speed setting data read from the memory 40 is sent to the D/A converter 3 via the gate 46 as the second speed command signal v2.
given to 5.

When the current position exceeds the low speed start position, the gate 41 closes,
Reading of the falling pattern from the memory 40 is completed, but the gate 42 is now opened and the lowest speed setting data L8 is continuously applied to the gate 43, and the data Ls is sent to the D/A converter 35. Given.

The control input of the gate 43 is connected to the control signal TI and the comparison means 14.
An output (a signal indicating the stop timing) is provided via an OR circuit 44 and an inverter 45. Before the current position reaches the deceleration start position, Sθ-Dθ>Sl is satisfied, so the control signal Tl is 1'', the gate 34 is open, and the gate 43 is closed. 1
The speed command signal V is selected. However, after the current position reaches the deceleration start position, Sθ-Dθ≦81, so the control signal T1 becomes 0'', the gate 34 is closed, and both human powers of the OR circuit 44 are ``O''. The output of the inverter 45 becomes 1'', which causes the gate 43
will be held. Therefore, the speed setting data of the deceleration curve read from the memo IJ 40 and the continuous minimum speed setting data Ls that follows, that is, the second speed command signal V2.
passes through gate 43 and is applied to D/A converter 65. .

The comparing means 14 compares the overrun-compensated position data Dθ0 and the stop position setting data Sθ, and when it is determined that it should be stopped (Dθo=Sθ holds true), the output signal is set to “l” and the flip-flop is activated. Pu 46
cent. This set output Q is inverted by an inverter 45 via an OR circuit 44, and the gate 43 is closed. Therefore, the second speed command signal is set to zero at the stop timing. Flip-flop 46 is reset at start.

Note that in place of the position data Dθ and stop position setting data Sθ used in FIG. 2, overrun-compensated position data Dθ is used. Or modified setting data Sθ described later
' may also be used.

Although the rising pattern memory 33 is used in the above description, the output of the counter 32 may be used as it is as the speed setting data for the rising characteristic without using the memory 63. Alternatively, the speed setting data of the rise characteristic may be generated using an analog time constant circuit without using the memory 66.

The deceleration start position S and the low speed start position S2 are the speed data D
It may be configured to be automatically and variably set according to v and acceleration data Dx.

Here, an example of overrun compensation operation will be explained.
For example, if the movement setting value Sθ is 50 degrees, the current position data Dθ
If the overrun amount prediction data OVR determined by the speed and acceleration is plus 15 degrees when reaches 35 degrees, the compensated position data Dθ0 at that time becomes 50 degrees, and the output of the comparing means 14 outputs a signal "1'' occurs, and the speed command signal is made zero to stop the motor 1. An overrun of approximately 15 degrees occurred from this stop timing,
Motor 1 stops at the desired rotational position of 50 degrees.

Note that the compensation calculation circuit 12 may increase or decrease the movement set value (target value) Sθ (for example, decrease it by the predicted overrun amount). Furthermore, the same overrun compensation effect can be obtained by compensating both the current position data Dθ and the target value Sθ by appropriate amounts.

By the way, due to fluctuations in the load conditions of the motor 1, changes over time, and other factors, the relationship between the speed or acceleration and the actual overrun amount may change depending on the overrun ROM (or RA
M) It may differ from what was stored in 8.9. If the stored contents of the overrun ROM 8.9 itself contain errors as described above, it becomes difficult to perform accurate stop positioning using only the above-mentioned configuration. In order to solve this problem, the error between the actual stop position determined according to the present invention and the set position (target position) at that time is memorized each time, and when the next positioning control is performed, the error is updated to the latest error. Using the target value Sθ (or predicted overrun amount OVR or 0VR1, 0VR2, Dθ0)
It is a good idea to modify the data and perform comparison operations using the modified data. Such learning can be realized, for example, by modifying a portion of the embodiment of FIG. 1 as shown in FIG.

In FIG. 4, the error calculation circuit 51 calculates the actual stop position (Dθ represents this) when the motor 1 completely stops after stop control (brake control).
This is to compare the stop position set value Sθ at that time and find the error between the two with positive and negative signs. The stop detection circuit 52 detects that the rotating shaft 1a that has been moving until then has completely stopped, and provides a calculation command to the error calculation circuit 51. This detection can be performed based on the fact that the speed data Dv has become zero, or on the lapse of a certain period of time since the brake was applied. The error calculation circuit 51 calculates the difference between the current position data Dθ and the set value Sθ based on the calculation command, and provides the result to the deviation calculation circuit 53 as error data. The deviation data (with positive and negative signs) used in the stop positioning control just performed is given to the other input of the deviation calculation circuit 53 via the buffer register 54, and the value of this deviation data is applied to the error data from the circuit 51. Increase or decrease depending on the value of. This arithmetic circuit 53, like the arithmetic circuit 51, is made operable in accordance with an arithmetic instruction from the circuit 52. The deviation data output from the deviation calculation circuit 56 is applied to a data input of a RAM (readable/writable memory) 55. The set value (target value) Sθ is input to the address of RAM55.
is given, and the same arithmetic command given to the circuits 51 and 53 from the stop detection circuit 52 is given as the write command input. Therefore, when the stop positioning is completed, the circuit 5
Deviation data related to the error between the actual stop position and the set position determined in step 1 is written to the address corresponding to the set position in the RAM 55. If the positioning is accurate, the error data output from the arithmetic circuit 51 is zero, and the error data from the arithmetic circuit 53 to the RAM 55 is
The deviation data provided to is the same as that provided from buffer 54. If there is an error in positioning, the output error data of the circuit 51 has a positive or negative value depending on the error, and the value of the old deviation data from the buffer 54 changes (increases or decreases) depending on the error data value. ) to be done.

The buffer register 54 temporarily stores the deviation data read from the RAM 55, and this storage is held at least until the calculation of the error and deviation in the calculation circuits 51 and 53 is completed.

The RAM 55 is kept in a read mode while positioning control is being performed, and a read command signal is applied from an appropriate circuit, such as the sequence circuit 19, during positioning control. Therefore, the deviation data is read from the address corresponding to the target position Sθ set in the positioning control at that time. The deviation data read in this way is the target setting position Sθ whose address was input this time.
This is determined and stored as described above in accordance with the latest positioning results made in the past with respect to the target setting position having the same value as the position. Therefore, it is the best deviation data that reflects the current load conditions or operating conditions of the motor 1 as much as possible. The deviation data read out from the RAM 55 in this way would be the same amount as this deviation data if additional compensation (further advancing or delaying the position data Dθ) according to this deviation data was not performed in the current positioning control. This indicates that there is a high possibility that an error close to the error will occur between the set position Sθ and the actual stop position.

A correction calculation circuit 56 is provided on the output side of the stop position setter 12, and the RA is
The circuit stop position target value Sθ is corrected in accordance with the latest deviation data provided from M55, and the corrected stop position target value Sθ' is provided to the comparing means 14. This correction operation is
For example, this is done by adding or subtracting the latest deviation data from the RAM 55 to the stop position target value So from the setter 12. As mentioned above, the deviation data stored in the RAM 55 is an error known through the latest positioning control, and if this error is not corrected in the current control, there is a risk that a similar error will occur again. It is something. Therefore, the target value Sθ is changed according to this deviation data, and the changed target value Sθ′ and position data Dθ are obtained. By making a comparison with the above, it is possible to perform accurate positioning control that cancels out expected errors.

Note that the correction calculation circuit 56 is inserted into the locations indicated by broken line blocks 56a to 56e to calculate the predicted overrun amount OVR or the rotational position data Dθ, Dθ. Even if the above is modified, the same effect as described above can be achieved.

Note that the present invention is applicable not only to an induction motor but also to a case where a synchronous motor such as a pole change motor is used.

Further, in the above embodiments, the present invention has been described as being constituted by a hard-wired circuit, but it goes without saying that a microcomputer can also be used.

〔Effect of the invention〕

As described above, according to the present invention, accurate positioning can be performed without shock using the open loop method.
It is simple and low-cost, and since the loop gain can be increased, oscillation does not occur and positioning operations can be performed quickly, providing various excellent effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the positioning control device according to the present invention, FIG. 2 is a block diagram showing an example of the configuration of main parts in the control unit of FIG. 1, and FIG. 3 is the configuration of FIG. 2. A graph showing an example of a speed setting pattern realized by
FIG. 4 is a block diagram showing an example of a review means that can be added to FIG. 1. 1...AC motor, 1a...motor rotating shaft, 2...
Brake, 6... Rotational position sensor, 4... Position conversion circuit, 5... Speed detection circuit, 6... Acceleration detection circuit, 7
... Overrun amount prediction means, 11. Compensation calculation circuit, 12
Stop position setter, 13. Control unit, 14. Comparison means, 15. Speed command means, 16. Speed setting device, 1
7...Position setting device, 18...Inverter, 19.Sequence circuit, 20..Speed setting means, 21..Deceleration pattern generation means

Claims (1)

[Scope of Claims] Position detection means for detecting the rotational position of a rotating shaft of a motor; speed command means for generating a speed command signal for the motor as a function of the detected position; and at least one of the speed or acceleration of the motor. overrun amount prediction means for determining a predicted overrun amount according to one of the data; and at least one of the set positioning target value and the position data value obtained by the position detection means to the determined predicted overrun amount. Compare the position data with the target value using a compensating means that is changed accordingly, and using the modified compensation means, and determine the stop timing of the motor according to the comparison result. and a comparison means for setting the value of the speed command signal to a value that makes the speed of the motor zero in accordance with the stop timing.