JPH048642B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning control device for a pneumatic or other fluid pressure cylinder, and particularly to one that can stop the cylinder at any position in its stroke.

[Conventional technology]

In the past, pneumatic cylinders and other fluid pressure cylinders operated only in full stroke motions, but recently cylinders with brakes have been used to stop the cylinders at arbitrary mid-stroke positions. An example of such prior art is shown in FIGS. 1 and 2. A brake 2 is provided in the cylinder 1, and a brake solenoid valve 3
By switching the brake cylinder 4, the brake cylinder 4 is actuated, thereby applying a brake to the piston rod 5. 6 is a directional control valve for switching the rod drive direction of cylinder cylinder 1;
7 is an air source, and 8 and 9 are throttle valves for controlling drive speed. The detection unit 10 for detecting the stroke position of the cylinder includes a roller 10a that constantly contacts the rod 5 and rotates following the linear motion of the rod 5, and generates incremental pulses in response to the rotation of the roller 10a. and an incremental encoder 10b (FIG. 2).
When the cylinder rod 5 is at the home position, the home set switch 11 resets the counter 12, and thereafter the counter 12 counts the incremental pulses given from the encoder 10b. The count value of the counter 12 indicates the cylinder rod position, and a comparison circuit 14 compares the set positions of various operations set by the setting device 13 with this count value. The comparison operation of the comparison circuit 14 and the operation of the drive circuit 16 are controlled by the sequence circuit 15. The output of the comparison circuit 14 is applied to a drive circuit 16, and a drive signal for switching the directional control valve 6 and the brake valve 3 is applied to the valves 3 and 6 according to the comparison result. for example,
A desired stroke intermediate position is set using the setting device 13, and when the current position of the rod 5 measured using the detection unit 10 matches this set position, the brake valve 3 is switched to operate the brake 2, and at the same time the directional control valve is switched. 7 to the neutral position and stop the rod 5.

By the way, even if you apply the brakes, the Rod 5 will not stop immediately and will overrun. Conventional systems do not take many measures against this overrun, and at most they simply assume that the amount of overrun is constant and apply the brakes at a certain distance before the desired stopping position. However, in reality, the amount of overrun varies depending on the moving speed of the rod 5, and also varies depending on the acceleration during the transition period at the start of movement (rise). FIG. 3 shows an example of the corresponding changes in speed, acceleration, and overrun amount, with the horizontal axis representing the amount of movement of the rod 5 over time from the start of movement. As described above, even if the intention is to move at a constant speed, the speed, acceleration, and overrun amount fluctuate unstablely during the transition period of startup. For example, this unstable period is the beginning of
The range is about 30mm.

Therefore, since the conventional brake control system did not take into account the amount of overrun depending on the speed, there was a limit to the stopping accuracy. In addition, during the transition period of the start-up, the speed, acceleration, and overrun amount were unstable and unpredictable, making it difficult to perform appropriate brake control. Conventionally, it was not possible to stop the rod 5 at this portion. This is not only due to the instability of the overrun amount;
Conventional startup methods also played a role. In other words, in the past, the brake was released and the directional control valve 6 was switched at the same time at startup, so the sudden release of the brake while the driving force was applied to the rod 5 prevented the initial pop-out phenomenon of the rod 5. It was intense. This makes it difficult to perform fine stop control during the start-up period.

Further, the conventional rod position detection section 10
Displacement was transmitted through friction between 0a and rod 5, so if a slip occurred,
Position detection became inaccurate, which also affected stopping accuracy.

JP-A-56-86202 discloses an improvement to the conventional pneumatic cylinder positioning control device as described above. In order to improve positioning accuracy, calculations are performed based on the error between the set stop position and the actual stop position using experimental formulas and data for air cylinder behavior stored in advance by a microcomputer. Then, the next braking position is determined. In addition, the cylinder linear position sensor used at that time is the second one.
This is a system that counts incremental pulses as shown in the figure.

[Problem to be solved by the invention]

The above-mentioned Japanese Patent Laid-Open No. 56-86202 corrects the braking position by reflecting the error between the set stop position and the actual stop position in the next positioning, so it can be said to be a kind of learning method. The drawback was that it was complicated. In other words, calculations must be performed using experimental air cylinder behavior equations and data stored in advance by a microcomputer, and using the error between the set stop position and the actual stop position as a parameter. Therefore, it is necessary to prepare a fairly accurate experimental formula for the behavior of the air cylinder in advance, which is difficult. The experimental formula for this behavior is
It must be created according to various work environments, work conditions, load conditions, etc., and if it is inaccurate, it will immediately affect the accuracy of control, so it is required to be accurate.

Further, since the position of the cylinder is detected by an incremental pulse count method, there is a problem in the accuracy of position detection, and for example, in the event of a power interruption such as a power outage, the cylinder must be returned to its original position.

This invention was made in view of the above points,
The system improves positioning accuracy by providing a learning function that takes into account the previous positioning error and makes appropriate corrections in subsequent positioning control. It is an object of the present invention to provide a fluid pressure cylinder positioning control device that can be easily positioned without any preparation.

Furthermore, the present invention provides a positioning control device for a fluid pressure cylinder that is equipped with such a learning function and that accurately detects the position of the cylinder and improves positioning accuracy. be.

[Means to solve the problem]

A positioning control device for a fluid pressure cylinder according to the present invention includes a position detection means for detecting a linear position of a piston rod in a fluid pressure cylinder, a setting means for setting a positioning target value, and a position detection means for detecting a linear position of a piston rod in a fluid pressure cylinder. control means for supplying a stop command to the cylinder in accordance with the relationship between the set position data and the target value, and positioning the piston rod of the cylinder at a position corresponding to the target value; In accordance with the storage means for storing and outputting the stop command, and the offset data, one or more of the factors that determine the timing of supplying the stop command are modified in the control means, thereby adjusting the supply timing of the stop command. means for detecting an error in the actual piston rod stop position relative to the target value when the stop positioning of the piston rod is completed in accordance with the stop command; and calculating means for adding/subtracting and accumulating the offset data and updating the value of the offset data stored in the storage means.

Further, a positioning control device for a fluid pressure cylinder according to the present invention includes a fluid pressure cylinder, a piston that is linearly movable within the cylinder, a rod connected to the piston, and a plurality of primary coils and secondary coils. a coil portion fixed to the cylinder and movable relative to the rod; and a coil portion provided on the rod for changing the magnetic resistance in the magnetic circuit of the coil portion depending on the position of the rod. a magnetoresistive variable member, a circuit that individually excites each of the primary coils using a plurality of phase-shifted reference AC signals, and a sum of the outputs of the secondary coils corresponding to each of the primary coils, an output circuit for generating an output signal that is phase-shifted from the reference AC signal according to the relative linear position of the rod; and detecting a phase difference between a predetermined one of the reference AC signals and the output signal from the output circuit. a circuit for outputting the detected phase difference data as piston rod position data; a setting means for setting a positioning target value; control means for supplying a command to position the piston rod of the cylinder at a position corresponding to the target value, and an actual piston rod stop position relative to the target value when the stop positioning of the piston rod is completed according to the stop command; and learning means for detecting an error in the detection error and controlling the subsequent timing of supplying the stop command to the control means in accordance with the detected error.

[Effect]

First, the first invention has a learning function that detects an error in the actual piston rod stop position with respect to the target position when piston rod stop positioning is completed, and corrects subsequent positioning control according to this detected error, that is, based on past experience. In performing the review function that makes the most of the learning function, the aim is to make it possible to easily perform calculations for the learning function without preparing special behavioral experimental formulas.

That is, in the control means that supplies a stop command to the cylinder according to the relationship between the position data and the target value and positions the piston rod of the cylinder at a position corresponding to the target value, the correction means is applied, Modifying one or more of the factors that determine the timing of supplying the stop command according to the offset data, thereby controlling the supply timing of the stop command, is different from the conventional method described above. The same is true. However, in the present invention,
It has features regarding the creation of offset data. That is, the present invention is characterized in that the error between the stop target value and the actual stop position is added to and subtracted from the offset data, and the value of the offset data stored in the storage means is updated. Through this addition and subtraction, the previously used offset data is constantly corrected in accordance with the error at that time, and the optimum correction value is always provided for the working conditions, environment, etc. at that time.

Since the calculation is simply the addition and subtraction of errors, it is extremely simple, and there is no need to prepare special experimental behavioral formulas. Furthermore, the accuracy is much better than when the stopping error in the previous positioning is simply used as offset data.

In the second invention, the cylinder piston rod position can be detected in a non-contact manner, resulting in high accuracy. In addition, an output signal is generated by phase-shifting the electrical reference AC signal according to the relative linear position of the rod, the phase difference between the two is detected, and the detected phase difference data is used as piston rod position data, so absolute position detection is possible. Therefore, there is no need to return to the origin even in the event of a power outage. Furthermore, since it is a phase method, there are fewer errors due to environmental fluctuations such as temperature, and it is possible to detect a position with much higher accuracy than a voltage level method in which the voltage level corresponds to the detected position.

〔Example〕

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

In FIG. 4, numerals 1 to 4 and 6 to 9 are the same as those shown in FIG. 1. The detection unit 20 for detecting the relative linear position of the piston rod 21 with respect to the cylinder 1 is capable of detecting the position of the piston rod 21 in a non-contact manner.
It consists of a variable magnetic resistance type cylinder position detector as shown in Japanese Patent No. 117826. This detection section 20
The four primary coils A1 to D1 arranged in a predetermined arrangement shifted in the axial direction and the corresponding secondary coils A2 to D2 are mounted in a casing 22.
The coil part is fixed at the end of the cylinder 1 with the rod 21 slidably penetrating the coil space so that the cylindrical space of the coil is concentric with the rod 21. has been done. The rod 21 is a cylindrical shaft 21a with a piston 21e inside the cylinder 1 attached to one end.
A plurality of annular magnetic rings 21b and an annular non-magnetic spacer 21c of a predetermined width are alternately fitted around the mandrel 21a in the axial direction, and a cylindrical non-magnetic spacer is fitted around the outermost periphery of these rings. It includes a sleeve 21d consisting of a body. Non-magnetic spacer 21c
is a solid non-magnetic substance or air. As an example, the length (width) of each magnetic ring 21b is "P/2"
(P is an arbitrary number), and the same applies to the spacer 21c, and the interval of one pitch in the alternate arrangement is "P". In this example, the coils are 4
It is arranged to operate in two phases. For convenience, these phases are distinguished using symbols A, B, C, and D. The reluctance generated in each phase A to D is shifted by 90 degrees depending on the position of the magnetic ring 21b of the rod 21. For example, if the A phase is a cosine phase, the B phase is a sine phase, and the C phase is a negative cosine phase. The phase and D phase are designed to be negative sign phases. In the embodiment of FIG. 4, each phase A~
Primary coils A1 to D1 and secondary coils A2 to D2 are provided for each coil D. The length of each coil is approximately equal to the length of the magnetic ring 21b, and is "P/2".
It is. In the example of Fig. 1, the A-phase coils A1, A
2 and C-phase coils C1, C2 are provided adjacent to each other, and B-phase coils B1, B2 and D-phase coils D1, D2 are also provided adjacently. Also,
The interval between the A-phase and B-phase or C-phase and D-phase coils is "P (n±1/4" (n is any natural number). With this configuration, the distance between the rod 21 (more specifically, the magnetic ring) is The reluctance of the magnetic circuit in each phase A to D changes according to the linear displacement, and the phase of the reluctance change shifts by 90 degrees for each phase (therefore, the phase A and C are shifted by 180 degrees, and the phase B and For example, the primary coils A1 and C1 of the A phase and C phase are connected to a sine signal.
They are excited in opposite phases by sinωt, and the outputs of the secondary coils A2 and C2 are added in phase. B phase and D
As for the phase, the primary coils B1 and D1 are excited in opposite phase with the cosine signal cosωt, and the secondary coils B2 and D2 are excited in the same way as described above.
Add the outputs of in-phase. The outputs of the secondary coils are finally summed to obtain the output signal Y. However, the present invention is not limited to this, and the primary coils A1 and C1 of the A phase and C phase are excited in the same phase by the sine signal sinωt, the secondary coils A2 and C2 are connected in opposite phases, and the The secondary coils B1 and D1 may be excited in the same phase by the cosine signal cosωt, the secondary coils B2 and D2 may be connected in opposite phases, and finally the secondary coil outputs may be added.

The output signal Y of the detection unit 20 is obtained by phase-shifting the reference AC signal (sinωt or cosωt) by a phase angle φ corresponding to the linear position of the magnetic ring 21b in the rod 21, as shown in the following equation. The reason for this is that the reluctance of each phase A to D is shifted by 90 degrees, and the electrical phases of the excitation signals of one pair (A, C) and the other pair (B, D) are shifted by 90 degrees. It's for a reason.

Y=Ksin(ωt+φ) K is a constant determined depending on various conditions. By measuring the phase shift φ corresponding to the reference signal sinωt of the output signal Y expressed by the above equation, the position of the rod 21 can be detected.

When the amount of phase shift φ is 2π in full width, the amount of displacement of the rod 21 corresponds to one pitch length P of the magnetic ring 21b. That is, according to the electrical phase shift amount φ in the signal Y, an absolute linear position can be detected within the range of the distance P. If you want to find the absolute linear position beyond the distance P, use any appropriate means (this detection accuracy may be rough, with distance P being one unit) to find the absolute linear position of each magnetic ring 21b in the rod 21. It is sufficient to obtain the address and use a combination of the absolute address of each ring 21b and the detected linear position value based on the above-mentioned phase shift φ.

In FIG. 5, the output signal Y of the detection section 20 is given to the conversion circuit 23, and the above-mentioned electrical phase shift amount φ is measured. This measured value is data indicating the current position (cylinder stroke position) of the rod 21.
Output as _DX . A speed detection circuit 24 and an acceleration detection circuit 25 are provided to detect the moving speed and acceleration of the rod 21. In this embodiment, a dedicated sensor for detecting speed and acceleration is not provided, and the rod position detection data _DX is used to detect the speed, and the detected speed data _DV is used to detect the acceleration. It's getting old. For this purpose, position data _DX is input to the speed detection circuit 24, and speed data _DV output from the speed detection circuit 24 is input to the acceleration detection circuit 25.

When the rod 21 is stationary at an arbitrary position, the position data _DX maintains the value indicating the position and does not change. When the rod 21 is moving at a certain speed, the value of the position data _DX changes over time in accordance with changes in the rod position. Therefore, the velocity data _DV is determined by calculating the change in the position data _DX per predetermined unit time (or period) in the velocity detection circuit 24. Furthermore, the acceleration data D can be obtained by calculating the amount of change in the velocity data D _V per predetermined unit time (or period) in the acceleration detection circuit 25.

The overrun ROM (or RAM) 26 is
Overrun amounts corresponding to various speed values are stored in advance. Similarly, the overrun ROM (or RAM) 27 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 rod 21, and this overrun amount is measured (learned) in advance corresponding to various speeds and accelerations. this
It is stored in the ROM (or RAM) 26 and 27. As an example, as shown in FIG. 3, when there is acceleration (that is, during the rising period), the overrun amount is determined almost in dependence on the acceleration (speed is also taken into consideration as appropriate). Furthermore, when entering the constant speed period, the overrun amount is determined approximately according to the speed at that time. Therefore, in predicting the amount of overrun, it is important not only to determine the speed and acceleration, but also to determine the position at which the vehicle is to be stopped, that is, the set amount of movement.

Overrun amount data OVR1 and OVR2 read from the ROMs 26 and 27, respectively, in accordance with the current speed data _DV and acceleration data D≦ are given to an overrun amount calculation circuit 28. The overrun amount calculation circuit 28 uses the predicted overrun amount data OR1 according to the current speed, the predicted overrun amount data OR2 according to the current acceleration, and the movement setting value (target value) S _X set by the setting device 29 as parameters. The data OVR that predicts the actual amount of overlap is obtained by calculation, selection, mixing, etc. As an example, the arithmetic circuit 28 selects the overrun amount data OVR2 corresponding to the acceleration when the movement set value _S Select OVR1 as OVR. As another example, data OVR2 corresponding to acceleration
and data OVR1 corresponding to the speed are mixed at a predetermined ratio according to the movement setting value _S
Output as OVR. In this case, it is preferable to provide a memory for reading out the ratio data for VOR1 and OVR2, respectively, according to the movement setting value SX. As yet another example, the larger of data OVR1 corresponding to velocity and data OVR2 corresponding to acceleration is
It may be selected as OVR. As another example, it may include a memory for reading out the predicted overrun amount corresponding to the movement setting value S _X , and the data read from this memory may be appropriately increased or decreased according to OVR1 and OVR2 and output as OVR. As still _another example, in each of the above examples, time data (or position data _D Movement setting value
S _X may be an absolute value from the origin or a displacement amount from an arbitrary movement start point.

The compensation calculation circuit 30 increases or decreases the value of the position data _D
D Change to _X0 . The comparison circuit 31 compares the overrun-compensated position data D _X0 with the movement setting value S _X set by the setting device 29, that is, the stop setting position. This comparison timing, comparison conditions, etc. are controlled by the sequence circuit 32 according to the overall sequence operation of the cylinder 1. Comparison circuit 31
The output is given to the drive circuit 33, and the direction control valve 6 and the brake valve 3 are switched depending on the comparison result.

For example, if _the movement setting value S _X is 5 mm, and when the current position data _D The compensated position data D _X0 at that time becomes 5 mm, a matching output is generated from the comparator circuit 31, and the brake 2 is applied to stop the rod 21. An overrun of approximately 2 mm occurs from this brake timing, and the rod 21 stops at the desired position of 5 mm.
Since brake control is performed in consideration of speed, acceleration, and travel set value, it is possible to set the travel set value _S , it is possible to stop it correctly at that position.

By the way, the sequence circuit 32 is connected to the rod 21.
In order to minimize the initial amount of protrusion when the brake valve starts moving, the switching timings of the directional control valve 6 and the brake valve 3 are controlled to be shifted somewhat. That is, the end of the brake valve 3 is switched to release the brake 2, and then the directional control valve 6 is switched to the on position for forward or backward movement, and the rod 21 is turned on.
start moving. If you do this, Rod 2
At the moment when the rod 1 starts moving, the reaction by the brake 2 does not work, and the rod 21 starts moving relatively smoothly, making it possible to reduce the initial popping out. If the initial protrusion amount is reduced, the range in which stop control is possible during the rising period increases, and even a smaller set value S _X can be set.

Note that the compensation calculation circuit 30 may increase or decrease the movement set value (target value) S _X (for example, decrease it by the amount of predicted overrun). Furthermore, the same overrun compensation effect can be obtained by compensating both the current position data D _X and the target value S _X by appropriate amounts.

By the way, due to variations in cylinder load conditions, aging, and other factors, the relationship between speed or acceleration and the actual overrun amount may differ from that stored in the overrun ROM (or RAM) 26, 27. Sometimes. If the stored contents of the overrun ROMs 26 and 27 begin to 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,
The predicted overrun amount OVR (or OVR1,
OVR2, D _X0 ) may be corrected, and the corrected predicted overrun amount may be used to perform a compensation calculation for the position data D _X0 . Such learning and correction of the predicted overrun amount can be realized, for example, by changing a part of the embodiment shown in FIG. 5 as shown in FIG. 6.

In FIG. 6, when the piston rod 21 of the cylinder 1 completely stops after stop control (brake control), the error calculation circuit 34 calculates the actual stop position (represented by _D This is to compare the current stop city setting value _S The stop detection circuit 35 detects that the rod 21, which had been moving until then, has completely stopped, and provides a calculation command to the error calculation circuit 34. This detection can be performed based on the fact that the speed data D _V has become zero, or on the lapse of a certain amount of time since the brake was applied. The error calculation circuit 34 calculates the difference between the current position data D _X and the set value S _X based on the calculation instruction, and provides the result to the deviation calculation circuit 38 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 38 via the buffer register 39, and the value of this deviation data is input to the circuit 34.
Increase or decrease depending on the value of error data from. This arithmetic circuit 38 is a circuit 35 similar to the arithmetic circuit 34.
It is enabled for calculation according to the calculation instruction from . The deviation data output from the deviation calculation circuit 38 is stored in RAM.
(Read/Writable Memory) Provided to 36 data inputs. A set value (target value) _S
The same arithmetic instruction as that given to 38 is given. Therefore, the deviation data related to the error of the actual stop position with respect to the set position determined by the circuit 34 when the cylinder stop positioning is completed is stored in the RAM 36.
is written to the address corresponding to its setting position in . If the positioning is accurate, the error data output from the arithmetic circuit 34 is zero, and the deviation data given from the arithmetic circuit 38 to the RAM 36 is the same as that given from the buffer 39. If there is an error in positioning, the output error data of the circuit 34 has a positive or negative value depending on the error, and the value of the old deviation data from the buffer 39 changes (increases or decreases) depending on the error data value. ) to be done.

The buffer register 39 temporarily stores the deviation data read from the RAM 36, and this storage is held at least until the calculation of the error and deviation in the calculation circuits 34 and 38 is completed.

The RAM 36 is kept in read mode while positioning control is being performed, and an appropriate circuit such as the sequence circuit 3 is read during positioning control.
A read command signal is given from 2. Therefore,
Deviation data is read from the address corresponding to the target position S _X set in the positioning control at that time. The deviation data read in this way is the target setting position _S
This is determined and stored as described above in accordance with the latest positioning results made in the past regarding the target setting position having the same value as the value of . Therefore, it is the best deviation data that reflects the current load conditions or operating conditions of the cylinder 1 as much as possible. The deviation data read out from the RAM 36 in this way would be the same as this deviation data if additional compensation (further advancing or delaying the position data _D This indicates that there is a high possibility that an error of 0.5 or close to it will occur between the set position S _X and the actual stop position.

Overrun amount calculation circuit 28 and compensation calculation circuit 30
A correction calculation circuit 37 is provided between the
While performing positioning control, the RAM 36
Correct the value of the predicted overrun amount OVR from the circuit 28 according to the latest deviation data given from
Compensation calculation circuit 30 for the corrected predicted overrun amount
given to. This correction operation is performed, for example, in circuit 2
RAM3 for the predicted overrun amount OVR from 8
This is done by adding or subtracting the latest deviation data from 6. As mentioned above, RAM36
The deviation data stored in the overrun ROM (or RAM) 26, 2 corresponding to speed and acceleration
This corresponds to the latest known changes in the cylinder load and other conditions when the table No. 7 was created. Therefore, by the above-described modification, it is possible to obtain a predicted overrun amount that offsets such fluctuations in cylinder conditions. By using the predicted overrun amount corrected in this way to compensate for the phase advance or phase delay of the position data _D can.

On the other hand, the deviation data given from the RAM 36 to the buffer register 39 is not used when the above-mentioned correction and compensation calculations are being performed, that is, during positioning control, but after that, when the stop positioning is completed, the deviation data is As described above, it is used by the deviation calculation circuit 38 in order to change it according to the positioning error at the time.

Note that the correction arithmetic circuit 37 is indicated by a broken line block 37.
Even if it is inserted at the locations indicated by a, 37b, 37c, and 37d, the same effect as described in detail can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, by providing the review function, errors in past positioning are recognized and corrective change control is performed in subsequent positioning control to eliminate the errors. Optimum control can be performed that reflects the usage conditions, usage status, load status, etc. for each use, and positioning accuracy can be improved. Moreover, in this case, the error between the stop target value and the actual stop position is accumulated by adding and subtracting offset data, and the value of the offset data is constantly updated. It is extremely simple as there is no need to prepare anything in advance.
Furthermore, the accuracy is much better than when the stopping error in the previous positioning is simply used as offset data.

Furthermore, according to the present invention, the cylinder piston rod position can be detected absolutely in a non-contact manner and using a phase method, so when used in conjunction with the review function, even higher accuracy and accuracy can be achieved. Highly reliable positioning can be performed.

[Brief explanation of drawings]

Fig. 1 is a side sectional view and fluid pressure circuit diagram of a conventional pneumatic cylinder with a brake, Fig. 2 is an electrical block diagram showing a conventional example of a control system for determining the position of the pneumatic cylinder with a brake shown in Fig. The figure is a graph showing an example of the characteristics of speed, acceleration, and overrun amount according to the amount of movement (movement setting value) in a pneumatic cylinder, and FIG. The fluid pressure circuit diagram, FIG. 5 is an electrical block diagram showing an example of the positioning control system in the same embodiment, and FIG. FIG. 2 is an electrical block diagram shown in FIG. 1... Cylinder, 2... Brake, 3... Brake valve, 4... Brake cylinder, 5, 21...
... Piston rod, 6 ... Direction control valve, 7 ... Air source, 8, 9 ... Throttle valve, 20 ... Position detection section,
21a... Rod shaft, 21b... Magnetic ring, 21c... Non-magnetic spacer, 21d... Non-magnetic sleeve, 21e... Piston, 24... Speed detection circuit, 25... Acceleration detection circuit, 26, 27
... Overrun ROM, 28 ... Overrun amount calculation circuit, 29 ... Setting device, 30 ... Compensation calculation circuit, 31 ... Comparison circuit, 32 ... Sequence circuit, 33 ... Drive circuit, 34 ... Error calculation circuit , 36...deviation data RAM, 37... correction calculation circuit.

Claims (1)

[Claims] 1. Position detection means for detecting the linear position of the piston rod in the fluid pressure cylinder; Setting means for setting a positioning target value; Position data obtained by the position detection means and the target. control means for supplying a stop command to the cylinder in accordance with the relationship with the target value and positioning the piston rod of the cylinder to a position corresponding to the target value; and a memory for storing and outputting offset data. and modifying, in response to the offset data, one or more of the factors determining the timing of supplying the stop command in the control means, thereby:
correcting means for controlling the supply timing of the stop command; means for detecting an error in the actual piston rod stop position relative to the target value when the stop positioning of the piston rod is completed in accordance with the stop command; a calculation means for adding and subtracting the error to the offset data and updating the value of the offset data stored in the storage means. 2. The positioning control device for a fluid pressure cylinder according to claim 1, wherein the correction means corrects at least one of the position data and the target value. 3. A fluid pressure cylinder, a piston that is linearly movable within the cylinder, a rod connected to the piston, and a plurality of primary coils and secondary coils, fixed to the cylinder and relative to the rod. a coil portion that is movable according to the rod; a magnetoresistive variable member provided on the rod for changing the magnetic resistance in the magnetic circuit of the coil portion depending on the position of the rod; and a plurality of phase-shifted standards. A circuit that individually excites each of the primary coils with an alternating current signal and an output of a secondary coil corresponding to each of the primary coils are summed to produce the reference alternating current signal according to the relative linear position of the rod. an output circuit that generates an output signal that is phase-shifted; and a circuit that detects a phase difference between a predetermined one of the reference AC signals and the output signal from the output circuit, and outputs the detected phase difference data as piston rod position data. and a setting means for setting a positioning target value; supplying a stop command to the cylinder according to the relationship between the piston rod position data and the target value, and adjusting the position of the piston rod of the cylinder to the target value. control means for positioning the piston rod at a position corresponding to the target value; and detecting an error in the actual piston rod stop position relative to the target value when the stop positioning of the piston rod is completed in accordance with the stop command, and determining the subsequent position according to the detected error. A positioning control device for a fluid pressure cylinder, comprising: learning means for controlling supply timing of the stop command in the control means. 4. The learning means includes means for detecting an error in the actual piston rod stop position with respect to the target value when the positioning is completed, and storing offset data based on the detected error and using this offset data in the next positioning control. one or more of the factors that determine the timing of supplying the stop command in the control means according to the storage means read at the time and the offset data, thereby controlling the supply timing of the stop command. 4. A positioning control device for a fluid pressure cylinder according to claim 3, comprising a correction means as described above. 5. The fluid pressure cylinder positioning control device according to claim 4, wherein the correction means corrects at least one of the position data and the target value.