JPS6279508A - Lead angle compensating system in position control - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the time delay by making the difference between the fetched position data and the present position data into the lead angle compensating quantity in the position control. CONSTITUTION:When the time corresponding to the time data set as the lead angle compensating parameter is DELTAt, the fetching means fetches position data X before DELTAt only from the present time point from the memory means. A difference DELTAX between the fetched position data and the present position data is used as the lead angle compensating quantity. For example, to the present position data, DELTAX is added, and the apparently present position data are proceeded only for the lead angle compensating quantity DELTAX. Thus, the lead angle compensated apparent present position data forcast the position of the object after DELTAt time from the present time point, and by adding the difference DELTAX of the position before the DELTAt time to the present position data, the position after the DELTAt time can be forcast. Thus, the lead angle compensation corresponding to various delay conditions of th machine system instantaneously can be executed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a lead angle compensation system in position control [Prior Art] When controlling various machines, a cam switch, a limit switch, etc. attached to the machine is used. When detecting the machine position and performing various controls based on this position detection output, there is a time delay due to various factors between the position detection output timing and the time when the control based on it is applied to the machine. do. Due to such a time delay, the position at which a switch or the like is activated becomes apparent, which becomes a cause of hindering accurate control. Therefore, in order to eliminate such inconveniences, it has been conventional practice to perform compensation by apparently shifting the operating position of a limit switch, position detection data, positioning target set value, etc. by an amount commensurate with the time delay or operation delay. This is generally called lead angle compensation.

The simplest example of lead angle compensation is to mount a limit switch or the like at a position that is shifted from the desired position by the lead angle compensation amount.

However, the amount of time delay as mentioned above is not uniform and varies depending on the speed of the machine, so the amount of advance angle compensation will also differ depending on the speed, and the switch mounting position will need to be adjusted each time. The problem arises that it must be changed.

Therefore, instead of actually using limit switches, etc., a position detector that can continuously detect the position of the machine is installed, and by comparing the position detection data and the target position setting value, the target position detection output is What is being done is to get the results. In that case, conventional advance angle compensation is performed by detecting the speed of the machine, determining the amount of advance angle compensation according to the speed, and correcting the position detection data or target position data according to this amount of advance angle compensation. It is being said. This is illustrated in FIG. 5, where the advance amount calculation circuit 1 advances the machine according to the speed V of the machine determined by the speed detector 2 and the advance angle compensation parameter a set according to the operating conditions of the machine. The dose θ4 is determined, and this is added to the position data X detected by the position detector 3, and the current position data of the machine is advanced to obtain the dose θ4.
The advance angle is compensated by apparently advancing the In this case, the arithmetic circuit 1 has a configuration in which the advance amount θA is obtained by actually executing the calculation of the predetermined function fH in real time, or a memory in which the advance amount θA corresponding to each speed is stored in advance. Either configuration may be used in which reading is performed according to the speed υ.

[Problem that the invention seeks to solve]

The conventional method described above requires a speed detector, which increases the cost.The problem is that the calculation time is short when calculating the function f(-) to determine the advanced dose in real time. Therefore, there is a problem that this causes a time delay, and another problem that when the speed is determined by calculating the position detection data, a time delay occurs by the calculation time.

The present invention aims to provide an advance angle compensation system that solves the various problems mentioned above.

[Means for solving problems]

The lead angle compensation method according to the present invention includes: a position detection means for detecting the position of an object; a storage means for storing the detected position data; a setting means for setting desired time data as a lead angle compensation parameter; and a retrieving means for retrieving position data from the storage means for a time corresponding to the set time data, and the difference between the retrieved position data and the current position data is used as an advance angle compensation amount in position control. This is a characteristic feature.

In the lead angle compensation method of the second invention, the retrieval means retrieves the set time data from the time storage means, and substantially multiplies the difference between the retrieved position data and the current position data. The present invention is characterized in that it further comprises means for determining the difference multiplied by N, and uses the difference multiplied by N as an advance angle compensation amount in position control.

[Action and effect of invention]

An example of the trajectory of the position data detected by the position detection means over time is shown in FIG. 1, and this is stored in the storage means. Assuming that the time corresponding to the time data set as the advance angle compensation parameter is △t, the retrieving means extracts the position data X(
−Δt) from the storage means. The difference ΔX between the extracted position data and the current position data is used as the advance angle compensation amount. For example, by adding ΔX to the current position data, the apparent current position data is advanced by the advance angle compensation amount ΔX. The apparent current position data that has been compensated for by the lead angle in this manner is a prediction of the position of the object after Δ time from the current point.

In other words, by adding the difference ΔX between the position of Δ before the time to the current position data, it is possible to predict the position of Δ after the time.

Therefore, according to the present invention, there is no need for a speed detection means, and there is no need to calculate the function f(y) for determining the advanced dose, so there is the problem of high cost. It is possible to solve the problems of time delays caused by calculations. Further, since the advance angle compensation parameters can be set in detail on a time-by-time basis, advance angle compensation can be performed that immediately corresponds to various delay conditions of the mechanical system.

If the time △t set as the lead angle compensation parameter becomes excessive, △ is changed to the difference △X between the previous position and the current position.
may not accurately correspond to the current speed. That is, there is a greater possibility that the speed will fluctuate during the time Δt. Therefore, it is preferable that the position data retrieved from the storage means be as close to the current time as possible. Therefore,
In case the set time Δt is relatively large, the second
In the invention, the lead angle compensation parameter is set as a lead angle compensation parameter and taken out from the storage means. Then, by effectively multiplying the difference △X between the retrieved position data and the current position data by N times, the difference N・△X corresponding to the set time △t is obtained, and this is calculated as the lead angle compensation amount. shall be. This situation is shown in FIG.

According to the second invention, even if the time Δt set as the lead angle compensation parameter is relatively large, data that reflects the current speed as much as possible can be used as the lead angle compensation amount, and a lead angle with high accuracy can be obtained. Compensation can be made. Further, since the storage means for storing position data does not need to store even very old position data, storage capacity can be saved.

〔Example〕

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

In FIG. 3, a position detector 10 detects the position of the object to be controlled and outputs digital position data DX. If the object is a rotating body such as a motor, a rotary position detector is used. In the case of a linear moving body such as a cylinder, a linear position detector is used. The storage circuit 11 sequentially stores the detected position data Dx in accordance with the write clock CK, and is composed of, for example, a shift register or a RAM (random access memory). The lead angle setter 12 sets desired time data as a lead angle compensation parameter. The time set here will be referred to as advance angle setting time Δt. The logic circuit 16 outputs a probability of the ratio N according to a predetermined standard according to the magnitude of the advance angle setting time Δt, and also outputs data indicating N.

Note that such a logic circuit 16 can be included in the advance angle setter 12.

The take-out circuit 14 receives a signal from the logic circuit 16 (△t)
is taken out from the memory circuit. For example, if the storage circuit 11 is a shift register, the extraction circuit 14 is composed of a selection circuit that selects the output of an arbitrary stage of the storage circuit 11, and
When the storage circuit 11 is a RAM, it is comprised of a readout circuit that specifies an arbitrary address and reads out the stored data.

The subtracter 15 converts the previous position data Dx (-△t) extracted by the extraction circuit 14 into the current position data Dx.
The difference ΔX=DX−Dx(−Δt) is obtained by subtracting from . The difference ΔX thus obtained corresponds to the amount of movement of the object, and the faster the moving speed, the larger the amount of movement, that is, the difference ΔX. The multiplier 16 uses the data N given from the logic circuit 16 as a multiple and performs the following operation: 'The above difference ΔX is multiplied by N. N times the difference data N・△X or △X (N=1
) is added to the current position data Dx in the adder 17, and data indicating the predicted position after t to the advance angle setting time ■) . In this way, advance color compensation of position data is performed.

The target position setter 18 is used to set data indicating a target position for stop control or other appropriate operation control. The comparator 19 compares the set target position data Sx with the advance color compensated position data DX (+Δt), and when the two match, it outputs a control signal for stop control or other appropriate operation control. Output. This control signal is known as a normal position control or is controlled by a minotosinch. Note that in this specification, position control includes not only stop control but also the case where appropriate operation control is performed at any specific position.

For example, if there is a time delay of t in the target positioning control system, if advance color compensation is not performed, the control will be executed △ time after the actual position DX reaches the target position SX, In this case, the current position has passed the target position. However, if advance color compensation is performed as in the embodiment described above, before the current position reaches the target position, the apparent current position index Dx (+△t) that has undergone advance color compensation and the target position When the data Sx matches and the control is executed △1 hour thereafter, the true current value Dx
should reach the target position Sx exactly.

Therefore, accurate position control is performed.

In addition, a subtractor 15 for directly calculating the difference ΔX,
The multiplier 16 that directly multiplies this difference ΔX by 8 is not essential, and the difference ΔX may be substantially obtained, or the difference ΔX substantially multiplied by 8 may be obtained. For example, the position data Dx (+ to t) with advanced color compensation becomes DX (+△t)=I)x+N(T\-f\(-to 1))
= (N+i)T)x-N-1)x(-tot), so when N=1, the difference △ Dx(-1-△t) can be obtained by omitting the calculation for
) can be multiplied by 8 first, and the difference ΔX can be obtained by subtracting the products. Of course, such a detour complicates the arithmetic circuit (especially the multiplier), so
Although this is not preferable, it is substantially equivalent to finding the difference ΔX and multiplying it by 8, so it is within the scope of the present invention.

Further, the advancing color compensation is not limited to advancing the position data Dx as shown in FIG.
This can also be achieved by accelerating x. The omitted parts in FIG. 4 are the same as in FIG. 3, and only the changed parts are shown.

The subtracter 20 converts the target position data SX provided from the setter 18 to the difference data N.ΔX provided from the multiplier 16.
Or, by subtracting ΔX, the target position is apparently halved. The target position data Sx'- which has been color compensated in this way
8X-N.ΔX is input to the comparator 19 and compared with data Dx indicating the true current position, and when the two match, a control signal is generated. That is, the apparent target position Sx
' is set to a position N・△X or △X before the true target position Sx, and the true current position ■) is set to a position N・△X or △X before x reaches the true target position Sx. When the comparator 19 matches the position and the control is executed after a time period of Δ, the true current position Dx should exactly reach the true target position Sx.

Further, the advanced color compensation may be based on position data I)x and a target position method.

Next, an example of the relationship between the value of N and the advance angle setting time Δt to which it is applied will be shown.

Assuming that the number of storage positions (number of addresses or stages) in the memory circuit 11 is 199 and the period of the write clock CK is 0°1 ms, the memory circuit 11 stores position data of 1991 samples up to 19.9 ms ago. 0.1ms
Can be memorized in units. Therefore, when N=1 (in this case, the logic circuit 16 and multiplier 16 in FIG. 3 are unnecessary), the settable lead angle setting time Δt is 0°1.
ms to 19.9mS, and can be set in 0.1ms increments.

Lead angle setting time △t = 1 in the range of 2Qms to 39.8ms
It is sufficient to retrieve the position data 9.9 ms ago from the memory circuit 11. In this case, Δt can be set in steps of 0.2 ms.

Lead angle setting time Δt = 1 in the range of 4Qms to 99.5ms
．． It is sufficient to retrieve the position data 9.9 mS ago from the memory circuit 11. In this case, Δt can be set in steps of 0.5 ms.

Advance angle setting time Δt - range of 100m5 to 199m5 ~19. It is sufficient to retrieve the position data Qms ago from the storage circuit 11. In this case, Δt can be set in 1 ms increments.

The above examples are listed in the table below.

The first table position detector 10 may have any configuration as long as it can continuously detect the position of the object and digitally generate the position take. For example, an absolute encoder, an incremental encoder and a counter that counts its output pulses, a resolver and means for obtaining digital position detection data based on its output signal, etc. can be used. In particular, JP-A-57-7'0406 and JP-A-58-106 related to the applicant's application.
No. 691, Japanese Unexamined Patent Publication No. 59-79114, Utility Model Application No. 58-1
It is preferable to use an induction type (variable magnetic resistance type) rotational position detection device or linear position detection device that employs a phase shift method as shown in No. 3671, No. 8.

In such a phase shift type position detection device,
A digital count value indicating the phase shift of the secondary output AC signal is sampled every O phase of the reference AC signal that excites the primary coil, and this is output as position detection data T). It is preferable to use this sampling clock (that is, a clock pulse synchronized with the reference AC signal) as the acquisition clock CK of the storage circuit 11.

Note that although the circuit in the embodiment shown in FIG. 3 is configured by hard-wired logic, the circuit is not limited to this, and similar functions can be implemented by a software program using a microcomputer, and such implementation is also possible. be within the scope of the present invention.

[Brief explanation of drawings]

1 and 2 are graphs for explaining the invention in detail, FIG. 3 is a block diagram showing an embodiment of the invention, and FIG. 4 is a block diagram showing a modified example of FIG. FIG. 5 is a block diagram showing an example of the prior art. 10... Position detector, 11... Memory circuit, 12...
・Advance angle setter, 14... Takeout circuit, 15.20・
...Subtractor, 16... Multiplier, 17... Adder, 1
8...Target position setter, 19...Comparator.

Claims (1)

[Claims] 1. A position detection means for detecting the position of the object, a storage means for storing the detected position data, and a setting means for setting desired time data as an advance angle compensation parameter; and a retrieving means for retrieving position data from the storage means a time before the time data corresponding to the time data, and the difference between the retrieved position data and the current position data is used as an advance angle compensation amount in position control. Lead angle compensation method. 2. A position detection means for detecting the position of the object, a storage means for storing the detected position data, a setting means for setting desired time data as an advance angle compensation parameter, and a setting means corresponding to the set time data. comprising a retrieving means for retrieving position data from the storage means from a time corresponding to 1/N of time before, and means for substantially multiplying the difference between the retrieved position data and the current position data by N times; A lead angle compensation method characterized in that the difference obtained is used as a lead angle compensation amount in position control.