JPH0262721B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a multi-axis control device that uses pneumatic or other fluid pressure cylinders as shaft drive devices, and in particular to a multi-axis control device that uses pneumatic or other fluid pressure cylinders as shaft drive devices, and particularly to This invention relates to devices that are controlled simultaneously.

BACKGROUND ART AND PROBLEMS TO BE SOLVED BY THE INVENTION When pneumatic cylinders are used as drive devices for the X-axis and Y-axis, a common air source is usually used. Therefore, the tool path from the starting position to the target position (the moving path of the object to be controlled along the Take a combination of paths parallel to the axis. This is because the loads applied to the X-axis cylinder and the Y-axis cylinder are somewhat different, so compressed air flows into the cylinder with a lower load first, and the cylinder with a higher load flows later. That is, one of the X-axis or Y-axis cylinders is first positioned to the target coordinates, and then the other is positioned to the target coordinates. Such a detour of the tool path is undesirable when there is a restriction on the movement space of the object to be controlled, as it may cause the object to exceed this restriction and collide with other objects.

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 multi-axis control device that can set a tool path to a target position without major detours.

Means for Solving the Problems A multi-axis control device according to the present invention has a means for detecting the current position of each axis, and a positioning target position given corresponding to each axis, which is divided into multiple parts for each axis. means for setting a plurality of sequential sub-target positions;
means for sequentially positioning the fluid pressure cylinder of each axis for each of the sequential sub-target positions based on the current position of each axis and the sequential sub-target positions, and finally the given position It is characterized in that it is positioned at a target position.

Operation The positioning target position for each axis is divided into a plurality of parts, and a plurality of sequential sub-target positions are set. The hydraulic cylinders of each axis are sequentially positioned at each of these sequential sub-target positions. As a result, each axis is positioned little by little for each sub-target position, and therefore, the axis with the smaller load is not unilaterally moved to the final target position first. Tool paths can be set appropriately.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows a block diagram of an example of a positioning control device that performs simultaneous positioning control of two X and Y axes. In this example, positioning calculation circuit 2
0 is used in time division on the X and Y axes. Piston rod position detectors 12 and 13 are provided in connection with the X-axis drive fluid pressure (for example pneumatic) cylinder 10 and the Y-axis cylinder 11, and detect the current position of the piston rod of each cylinder 10 and 11. be done. Each position detector 12, 13
The output signals are given to the position data conversion circuits 14 and 15, respectively, and the position data indicating the current position on the X axis is
Position data D _Y indicating the current position on the D _X and Y axes is obtained, for example, in digital quantities. These position data D _X and D _Y are applied to a switching circuit 16, one of which is selected according to a switching signal applied from a sequence circuit 17, and applied to a positioning calculation circuit 20.

The positioning calculation circuit 20 receives X-axis or Y-axis position data D _X or
D _Y is compared with the corresponding _X -axis or Y _- axis sub-target position data S It is applied to the Y-axis drive circuit 22. The drive circuits 21 and 22 are driven by a signal given from the sequence circuit 17.
The axis corresponding to the axis (one of X or Y) currently used by the positioning calculation circuit 20 is selectively enabled. For example, when the comparison result between the X-axis position data D _X and the sub-target position data _S The movement of cylinder 10 is controlled. Furthermore, when the comparison result of the Y-axis data D _Y and S _Y is output from the positioning calculation circuit 20, the Y-axis drive circuit 22 is selectively enabled, and the movement of the Y-axis cylinder 11 is controlled based on this output. be done.

The X-axis and Y-axis positioning target positions are set by the X-axis setting section 23 and the Y-axis setting section 24, respectively, and data indicating the X and Y coordinate values T _X and T _Y of the target positions are provided. The setting units 23 and 24 may be either manual setting means or automatic setting means by reading from a storage device, recording device, etc.

The target value dividing circuit 18 divides the target position coordinate values T _X and T _Y of each axis given from the setting units 23 and 24 into a plurality of sections at small intervals, and corresponds to each divided small interval section. to set the sub-target positions sequentially. FIG _{. 3 shows an example of the sequential sub-target positions S X1 ,} S _X2 . _. . S _X6 on the _X axis and the sequential sub target positions S _Y1 , S _Y2 , . Subscripts 1 to 6 of the sub-target position displays S _X1 to S _X6 and S _Y1 to S _Y6 indicate the order, and items in the same order form a set to specify the X to Y coordinates of each sub-target position. In the example shown in Figure 3, the positioning target positions T _X and T _Y are each divided into six parts, and the final sub-target position coordinates are
S _X6 and S _Y6 correspond to the desired positioning target positions T _X and T _Y.

The sequence circuit 17 sequentially extracts the X-Y coordinate set (S _X1 , S _Y1 ) of the sub-target position from the target value division circuit 18 ,
(S _X2 , S _Y2 )...(S _X6 , S _Y6 ) are read out in order,
The read data is controlled to be provided to the positioning calculation circuit 20 as sub-target position data S _X and S _Y. Since the positioning calculation circuit 20 is time-divisionally used for the X-axis and Y-axis, in order to make this possible, the sub-target position data sets S _X and S _Y for the X-axis and Y-axis are simultaneously used. is controlled so that one side (for example, the X axis) is read out first and the other side later, without being read out. X/Y selection (or switching) is made in the switching circuit 16 and the drive circuits 21 and 22 in response to the time-sharing readout of the X-axis and Y-axis data S _X and S _Y.
A signal is given. The step of reading out the sub-target positions S _X and S _Y is advanced by the sequence circuit 17 every time positioning to the intended sub-target position is achieved. For example, first, the first X-axis sub-target position S _X1 is read out, and at this time, _the X-axis position data D S _X1
is positioned. The completion of this positioning control is determined by the comparison output of the comparison circuit 25 in the positioning calculation circuit 20. Therefore, comparison circuit 2
5 is input to the sequence circuit 17, and the sequence circuit 17 advances the sequence step (in a narrow sense, the sub-target position read step) based on the comparison result. After the positioning control of S _X1 , the first _Y -axis sub-target position _S Cylinder 11 is positioned at S _Y1 . The readout step then switches to the second sub-target position and the X-axis sub-target position
S After positioning control to _X2 , sub target position of Y axis
Positioning control to S _Y2 is performed. From then on, similarly,
The sub-target positions are sequentially stepped and finally the desired positioning target positions T _X and T _Y are positioned. The moving path of the object, that is, the tool path, achieved by such sequential positioning for each sub-target position is shown in FIG. Here, the large detour of the tool pulse as shown in FIG. 1 is not seen.

An example of the sequential sub-target position setting process in the target value dividing circuit 18 is shown in FIG. "Start" is, for example, data given from the setting sections 23 and 24.
Starts when the values of T _X and T _Y are changed. In block 26, the X-axis and Y-axis positioning target position values are compared and the smaller one (the one with the smaller amount of movement) is selected. In block 27, the target value selected in block 26 (referred to as _Tx for convenience) is divided by a predetermined minimum step amount k to determine the number of divisions N. In block 28, the positioning target value for the remaining axes (for convenience, it will be referred to as T _Y ) is divided by the division number N obtained in block 27 to obtain the unit step amount j per one movement step for this axis. In block 29, a sub target position table is sequentially created using the unit movement step amounts k and j of the X and Y axes. That is, the sub-target positions of each axis are sequentially set for each of the above-mentioned unit movement step amounts k, j (k<j). The contents of this table are as shown in Fig. 4, and the sequential sub-target positions on the X axis are in the order 1, 2, 3...N, S _X1 =k, S _X2 =2k, S _X3 =3k... , and the final position is S _XN =Nk+n, taking into account the remainder in the division of block 27. The same applies to the Y axis, and the final position is set to S _YN =Nj+m, taking into account the remainder m of the division of block 28. When the table creation is completed, a signal is given to the sequence circuit 17, and its sequence operation is started.

An example of the sequential sub-target position reading sequence in the sequence circuit 17 is shown in FIG. "Start" starts, for example, when the creation of the above-mentioned sub-target position table is completed. In block 30, the sub-target position rank address ADRS is set to "1". This address ADRS is for reading out the sub-target position table shown in block 29 of FIG. 4, and its value corresponds to the order column of the table. In block 31, the X-axis sub target position of the rank corresponding to the value of the rank address ADRS is read from the above-mentioned table (block 29 in FIG. 4) in the target value division circuit 18. The read data is given to the comparison circuit 25 of the positioning calculation circuit 20 as the X-axis target value data S _X. For example, when ADRS=1, S _X1 , that is, k is read out as S _X. At the same time, a signal for selecting the X axis is transmitted from the sequence circuit 17 to the switching circuit 1.
6, applied to the X-axis drive circuit 21. During this period, the positioning calculation circuit 20 operates for the X-axis, and positioning control to the X-axis sub-target position is performed. In block 32, based on the comparison result of the comparison circuit 25, it is determined whether the positioning control to the intended sub-target position _SX has been completed.

Blocks 33 and 34 are similar to blocks 31 and 3 described above.
The same process as in 2 is performed on the Y axis. Block 3
In step 5, it is checked whether the rank address ADRS has reached the final rank N. If NO, proceed to block 36, advance the rank address ADRS by one, and then repeat the loop of blocks 31 to 35. When this loop is repeated for the sub-target position division number N, block 35 becomes YES and the desired positioning target position is reached.
Positioning to T _X and T _Y is completed.

In addition, in the above description, to simplify the explanation, the movement start coordinates are used as the origin (that is, the target position _{T
( T _} However, this invention is of course practicable. In that case, each sub-target position may be set by performing coordinate conversion or other appropriate relativization calculations according to the design concept of the positioning control system.

Furthermore, the target value dividing circuit 18 is not limited to one that creates a table by calculations as shown in FIG. 4, but may also use an appropriate interpolation function.

By the way, according to the implementation of the present invention, positioning is performed at relatively small intervals corresponding to each sub-target position, but in order to do so, the piston rod must be reliably stopped once at an arbitrary cylinder stroke intermediate position. For this purpose, it is desirable to use cylinders with brakes as the cylinders 10 and 11. However, there is inevitably a deviation due to overrun between the position at which the brake is applied and the position at which the piston rod actually stops, and in order to perform accurate positioning control, it is necessary to perform the brake operation in consideration of this amount of overrun. According to the applicant's research, it has been confirmed that the amount of overrun is affected not only by the moving speed of the piston rod but also by the acceleration. ), making it difficult to position the cylinder at minute distances. Therefore, in this embodiment, the positioning calculation circuit 20 appropriately predicts the amount of overrun according to the speed and acceleration, and the values of the position data D _X , D _Y or the target value data S _X , S _Y are The two are compared after compensating for increases and decreases.

An example of such a positioning calculation circuit 20 will be explained with reference to FIG. 2. A speed detection circuit 37 and an acceleration detection circuit 38 are provided to detect the moving speed and acceleration of the piston rod.
Position data D _X or D _Y given from the switching circuit 16 ( _hereinafter explained assuming that D
The velocity data _DV is input to the acceleration detection circuit 37 and is calculated by calculating the change in the position data _DX per predetermined unit time. The acceleration detection circuit 38 calculates the amount of change in this velocity data D _V per predetermined unit time to obtain acceleration data.
Find D _X. Overrun ROM (or RAM) 3
9 and 40 respectively store in advance overrun amounts corresponding to various velocity values and acceleration values, and the overrun amounts corresponding to the detected velocity data _DV and acceleration data _DX are read out, respectively.

The oran amount calculation circuit 41 includes ROMs 39 and 40.
Overrun amount data OVR1, OVR2 corresponding to the speed and acceleration read from the sub-target position data S _X given from the target value dividing circuit 18
or S _Y (hereinafter S _X is given)
Data for predicting the actual amount of overrun using
Ask for OVR. In the arithmetic circuit 41, for example,
OVR1, depending on the size of target position data _S
Select one of OVR2 as OVR. For example, _S
If is within a predetermined minimum value, select overrun amount data OVR2 corresponding to acceleration as OVR, otherwise select data OVR1 corresponding to speed.
Select as OVR. As another example, data
A mixture of OVR1 and OVR2 at a predetermined ratio depending on the value of the target position S _X is output as OVR. In this case, it is preferable to provide a memory for reading out the ratio data for OVR1 and OVR2, respectively, according to the target value S _X. As yet another example, data OVR1 corresponding to velocity and data corresponding to acceleration
The larger OVR2 may be selected as the OVR. As yet another example, the target value _S
It includes a memory that reads out the predicted overrun amount in response to the OVR.
1 and OVR2 may be changed as appropriate and output as OVR. Furthermore, as another example, in each of the above examples, time data or position data D _X from the start of movement to the current time may be used instead of the target position S _X. Furthermore, in each of the above examples, the target value S _X may be an absolute value from the origin, or may be a displacement from an arbitrary movement start point.

The compensation calculation circuit 42 increases or decreases the value of the position data D _X according to the over-run amount prediction data OVR, and changes it to a value D _X0 that compensates for the predicted over-run amount. The comparison circuit 25 compares the overrun-compensated position data D _X0 with the sub-target position S _X , that is, the set stop position. The output of the comparison circuit 25 is given to the drive circuits 21, 22 and the sequence circuit 17 as described above. For example, D _X0 with respect to the X axis
When = _S is output from. The same applies to the Y axis.

For example, if the target value S _X is 5 mm, the current position data _D
Speed, acceleration and target value when reaches 3mm
Overrun amount prediction data determined by _S
Assuming that the OVR is plus 2 mm, the compensated position data _D
The brakes are applied. An overrun of approximately 2mm occurs from this brake timing, resulting in a desired 5mm overrun.
The X-axis cylinder 10 is positioned at the position. Since the brake control is performed by appropriately predicting the amount of overrun in consideration of the speed, acceleration, and target value, accurate positioning can be achieved even at a sub-target position consisting of a small amount of movement.

Note that the compensation calculation circuit 42 may increase or decrease the target value S _X (for example, decrease it by the predicted overrun amount). Furthermore, current location data
Even if both D _X and target value S _X are increased or decreased by appropriate amounts, the same overrun compensation effect can be obtained.

Effects of the Invention As described above, according to the present invention, the movement path (tool path) of an object can be appropriately set in multi-axis simultaneous positioning control using a fluid pressure cylinder as a drive device. It has a great effect.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional tool path in two-axis simultaneous positioning control using a pneumatic cylinder, Fig. 2 is a block diagram showing an example of a two-axis positioning control device used to implement the present invention, and Fig. A diagram showing an example of a tool path realized by the invention,
FIG. 4 is a flowchart showing an example of the sequential sub target position setting process executed by the target value division circuit of FIG. 3, and FIG. 3 is a flowchart illustrating an example of a target position reading sequence. 10...X-axis cylinder, 11...Y-axis cylinder, 12, 13... Piston rod position detector,
23, 24...Positioning target position setter, 18...
...Target value division circuit, 17...Sequence circuit, 20
...Positioning calculation circuit.

Claims (1)

[Claims] 1. A multi-axis control device that positions an object along multiple axes by driving each of the multiple drive axes using an individual fluid pressure cylinder, which detects the current position of each axis. means for dividing a positioning target position given corresponding to each axis into a plurality of sequential sub-target positions for each axis; and dividing the current position of each axis and the sequential sub-target positions. and means for sequentially positioning the fluid pressure cylinder of each axis at each of the sequential sub-target positions based on the target position, and finally positioning the hydraulic cylinder at the given positioning target position. A multi-axis control device using a characteristic fluid pressure cylinder. 2. A multi-axis control device using a fluid pressure cylinder according to claim 1, wherein each of the fluid pressure cylinders is a pneumatic cylinder. 3. A multi-axis control device using a fluid pressure cylinder according to claim 2, wherein the pneumatic cylinder is a cylinder with a brake. 4. The sequential setting of the sub-target positions consists of selecting the minimum target value by comparing the positioning target position values of each axis, and dividing the selected minimum target value into a plurality of predetermined minimum step amounts. and a second division that divides the target values of the remaining axes, respectively, by the number of divisions of this first division, and the sequential order with respect to the axis corresponding to the minimum target value according to the first division. A multi-axis system using a fluid pressure cylinder according to claim 1, wherein the sub-target positions for the remaining axes are respectively set according to the second division. Control device.