JPS59183317A - Method and device for regenerating position of reference - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention provides an incremental measurement system in which a measuring graduation with at least one reference mark is fixed on one of the objects to be measured and a scanning device is fixed on the other of said objects. The present invention relates to a method for regenerating reference positions of relatively mutually movable objects whose relative positions are measured using a distance measuring device.

A machine - or measuring system - that is movable relative to one another - moves components from a starting position to a reference mark and detects and stores the value advanced so far, or sets the reference mark to have a value of "zero". Methods are known for detecting a reference position, which is defined relative to a reference position. Such a method is possible with an incremental length- or angle-measuring device, as described in German patent specification 196 4 381. However, this method requires unimpeded relative movement of the object to be measured.

This is because the components of the measuring device are tightly connected to the object to be measured and must be moved together with it to the reference mark.

From German Publication No. 1678887, the reference position can be detected with a mechanical slider tightly clamped to a mechanical vent.
Mechanical measurement systems are known.

As a first step, the slider is driven to a position which must later be defined to zero as a reference position. after that,
The slider is tightened and fixed to the machine vent. Subsequently, the scanning plate is moved relative to the scale until a reference mark is detected. When the reference mark is reached, the electronic counter of the measuring device is set to zero. The mechanical parts can then be loosened and the slider moved to the desired position. The position of the reference mark thus represents the reference position of another work step.

The known method of detecting a reference position defined as a starting position - which takes place before the actual working process - is useful both when a working process has already been carried out and, for example, during an ongoing working process. is no longer possible with the above-mentioned incremental measuring device. Interruption of the ongoing work process can occur, for example, in the case of automatic handlers, commonly referred to as industrial robots, by interrupting the electrical current. At that moment, the robot is a moss that remains stationary at that momentary position. However, the measured value detected according to the above method, relative to its original reference position,
Because the measurement is also interrupted due to an accident, it is lost.

However, in order to continue the interrupted work process,
The reference position must be known.

However, the movement of the robot back from its instantaneous position to its original starting position is e.g.
Generally not possible.

Therefore, the inventive gun eliminates the drawbacks of known methods and devices to detect a reference position from an unknown instantaneous position after interruption of measurement and movement without moving the object to be measured. The purpose of the present invention is to plan a method for regenerating a reference position and a device for implementing this method.

This problem is solved by the method steps defined in patent claim 1, with the method steps defined in patent claims 2 to 4.
The method according to paragraph 1 can be carried out in a particularly well suited manner with the device according to paragraph 1.

Further advantageous developments of the device for carrying out the method according to claim 1 are provided in the embodiment section.

The advantages achieved with the invention are, inter alia, that with the proposed method a reference position can be regenerated in a simple and rapid manner from an unknown instantaneous position after an interruption of measurement and movement, and the object to be measured can be moved. There is no need for it. Therefore, such an object to be measured in the form of a tool can be the one that engaged with the workpiece when the measurement process is interrupted due to a fault, so after detecting the reference position excluding the fault, the The machining process can be immediately resumed. Removing the tool from the point of engagement with the workpiece and restarting this engagement point anew and accurately is time consuming, cumbersome, and
It is possible that the power supply will be lost. Furthermore, this method makes it possible, for example in the case of robots, to carry out a controlled inspection of the respective reference position during each individual task, thereby making it possible to control the operation of such robots. Safety is significantly increased.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

The angle measuring device shown in FIG.
This housing is fixed to a housing A of an industrial robot (not shown). A shaft 2 rotatably supported in the housing 1 projects into the housing 1 and carries a disc 3 with an incremental graduation 4 in the form of a grid. The incremental graduation 4 is scanned photoelectrically. For this purpose, a second disc 5 is provided, which disc 5 is rotatably mounted on the shaft 2.

In the normal operating state, the second disk 5 is stationary, so that the illumination device 6 fixed to it, together with the capacitor 7, the scanning plate 8 and the photoelectric element 9, is also stationary, and the graduation disk 3 When rotates, the movement causes the grating scale 4 and the scanning plate 8
By modulating the light flux passing through the photoelectric element 9,
The measured value is captured by an electronic counter Z and counted as a measured value.

In effect, the second disk 5 is completely stationary together with the housing 1, so that in this way - the rotational movement of the shaft 2 carrying the scale disk 3 can be detected precisely.

In an industrial robot, the housing 1 is rigidly fixed to the housing A of the industrial robot, and the shaft 2 is rigidly connected to a handling component, for example a gripping device B. The rotations carried out by the gripping device B are captured by a measuring device and fed back to the evaluation device Z for measurement and control purposes.

In order to obtain a reference base in such incremental measuring devices, reference marks are provided along the graduation trunk (for example, as described in the initially mentioned DE 16 738
87 or as also described in German Patent Specification 2952106). Before starting a machining cycle, and thus before starting a new measurement, the gripping device B is rotated until one of the reference marks is reached. This position is “
Z is defined as "zero" or is set in the digitizer Z as a previously determined or programmatically determined value. During subsequent work movements of the robot, this initially selected value is Reference base. Adjustments to the reference base can be made as described on page 14 of DE 1673887.

Now, if a failure occurs during the machining cycle due to an interruption in the current, the working process must be interrupted and thus, of course, the measurement as well.

If the current is interrupted, the measured value that was determined when the fault occurred disappears, and thus also the reference base of the starting position. However, in the event of a failure, the tool of gripper B is generally just engaged, so that gripper B is rotated until the original reference mark is captured by the scanning device, such as at the beginning of the work cycle. I can't do it.

However, the method according to the invention allows the reference position to be determined again in this case as well.

To carry out this method, the measuring device comprises a drive motor 1
0. The drive motor 10 has a pinion 11 that meshes with the external teeth 12 of the disc 5 (
Figure 2). In the event of a fault, the drive motor 10 is controlled to rotate the disc 5 via the transmission 11/12 and finally the scanning device consisting of the illumination device 6, the capacitor 7, the scanning plate 8 and the photoelectric element 9 is referenced. Align with the mark. With the reference mark the counter is again set to "zero" or to some other selected value, the drive motor 10 is switched off and the disk 5 is returned to its position at the time of the failure.

The increments of the grid graduation 4 are then counted and the distance of the instantaneous position from the reference position is known again.

During this process, the Nakaguchi bot remains stationary. No Ujing 1,
The shaft 2 and the scale disk 3 do not move.

Following this method for regenerating the reference position, the work cycle can be continued.

In a particularly advantageous manner, the method according to the invention can be carried out in the apparatus according to FIGS. 3 to 5.

A shaft 32 is supported in the housing 31, which shaft carries a disk 33 with an incremental grid graduation 34 (see also figure $5). Shaft 3 inside the housing
2 carries another disk 35, on which the scanning plate 3 is attached.
8 is installed. The disc 35 is rotatably supported on the shaft 32, and has a structure including a switching arm 351 and two prongs 352 on the upper side opposite to the scale disc 83. two-pronged three
An eccentric wheel 311 is engaged between the arms of 52 and is seated on the shaft of the drive motor 310. A drive motor 310 is fixed to the holder 30 in the housing 31. An illumination device 36, a capacitor 37 and a photoelectric element 39 are likewise fixedly arranged on the housing 31 for scanning the grating graduation 34 and the reference marks R1 to Rn.

In the rest state, the disc 35 is adjusted to its position by the stopper 353. This position is occupied by the disc 35 in the normal operating state. Normal function occurs as described with respect to FIGS. 1 and 2.

However, in the event of a failure, a method for regenerating the reference position can be implemented very quickly.

An illumination device 36 and a capacitor 37 illuminate a light of a predetermined size. The array of reference marks R1-R11 and the photoelectric element 39 are tuned to the size of this illumination field. As is clear from FIG. 5, a row of reference marks R1 to Rn is provided along the grid scale 34, and these reference marks are arranged in concentric trunks. The individual reference marks R3 to Rn include coat marks C4 to Cn.
are provided and therefore numbered, so to speak. The code mark c1 defines the distance of the associated reference mark R1 from the determined zero point of the grid graduation 34. The distribution of the reference marks I%1 to Rn is such that the reference mark R1 is exactly 100 grid division lines away from the zero point of the scale, and the reference mark R2 is exactly 200 grid division lines away from the zero point of the scale. It is sized like this. When the lattice constant is 40 pm, this means that the reference marks Ri are arranged every 4 mm.

The size of the illumination field is selected such that at each position of the scale plate 33 one of the reference marks R1 to Rn and the associated code mark 01 to Cn are located inside this illumination field.

Therefore, in the event of a failure, in order to reliably scan one of the reference marks R1 to Rn and the code mark present in each case on the reference mark, the second of the rotatable discs 35 with the scanning plate 88 can only be turned up to a maximum. All you have to do is rotate it a distance of 4mm. Then, at the reference mark R1, the counter Z is set to the value determined by the code mark C1 of the scanned reference mark Ri. From this value, the grid lines of the graduation 34 are counted during a counter-rotational movement of the disc 35, until the disc 35 reaches its starting position again, which is fixed by the stator bar 353. The instantaneous position is now detected again with respect to the reference position and is expressed as a measurement value obtained from the reference mark position (as determined by the code mark) and as this superimposed count value of the grid lines of the graduation 34, This count value was detected when the scanning plate 38 moved in reverse together with the disk 35.

The vibration-sensitive lighting device 36 does not need to be moved during this process and therefore has a relatively long life. Adjustment problems do not arise because the position of the illumination device 36 cannot be changed.

The disk 35 is oscillated by a drive motor 310, on the shaft of which an eccentric wheel 311 is seated. An eccentric wheel 311 is present between the arms of the fork 352, and these arms are attached to the disc 3.
A structure is formed on the upper side of 5. When the motor rotates, the disk 35 moves by 4 m due to the cooperation of the eccentric wheel 311 and the forks 352.
It is rotated by a distance of m and returned to its starting position of the stopper 353. A spring 354 assists in the return swing and ensures accurate abutment against the stop 353. At the moment of reversal to the starting position, a switch 355 is actuated by a switching arm 351 in the upper structure of the disc 35, which switches the drive motor 310 off.

, the drive motor 310 has a small time constant such that rotation of the eccentric wheel 311 and thus a complete oscillation of the disk 35 is carried out within a tenth of a second.

With the measuring device described above, the method of the invention can be carried out quickly as follows. This means that not only can the reference position be reliably regenerated in the event of a failure, but also that the robot can be programmed immediately between individual tasks with its further calibration process, which lasts only a tenth of a second. It is possible to change the controlled 'Pr - such a fungicidal process', thereby significantly increasing the safety of operation of such a system.

It is within the scope of the invention to carry out this particularly advantageous method also in the case of other measuring devices, for example length measuring devices.

It is likewise within the skill of the person skilled in the art to choose other drives instead of the drive motor for adjusting the scanning device.

The angle measuring device shown in Fig. 6 in longitudinal section is No. 3 Uzing G.
The housing is fixed to the object to be measured O, for example, to the housing of an industrial robot (not shown). Inside the housing G, a second shaft W1 is rotatably supported by a bearing L and carries a scale disk T having an incremental scale and a reference mark that absolutely belongs to the incremental scale. The incremental graduations and reference marks of the graduation disk T are scanned photoelectrically by a scanning unit AE fixed to the housing G, scanning unit AEil-i, illumination unit BE.
with a capacitor CD, a scanning plate AP and a photoelectric element P on a plate PL fixed to the housing G.

The rotation of the graduation disk T is captured by the photoelectric element P in a known manner by modulation of the light beam passing through the graduation disk T and the graduation of the scanning plate AP, the periodic scanning signal of which is transmitted to the scanning unit. A counter is led to detect the measured value of the relative position of the scale plate T with respect to the city.

A first shaft W1 with a scale disc T is connected to a second shaft W2 in a driving joint, and this second shaft W2 is likewise supported inside the housing G by a bearing L2. ,
and protrudes from the housing G in order to be rotatably fastened to another object 02 to be measured, for example to a gripping device of an industrial robot.

a connecting boss F1 fixed to the shaft W1;
It consists of a connection boss F2 fixed to the shaft W2 and an annular plate R8. At the outer periphery of the two connecting bosses Fl, F2, three stops Sl, S are respectively offset from each other by 120°.
2 protrudes in the radial direction. Both connection bosses FLF2
An annular plate R8 is arranged between the annular plate R8 and the annular plate R8.
8 has on its outer periphery three poles BZ that are offset from each other by 120 degrees, and these poles BZ protrude on both sides of the annular plate R8, and are connected during rotation of the axes Wl and W2. Boss F1. F2 stopper 81. In contact with S2.

The annular plate R3 has no bearing of its own and, due to the symmetrical arrangement of the bolts BZ, the axis W1. Rotation of W2 □ is automatically centered and axis Av1. W2 bearing L1. It exerts no lateral force on L2.

□ on the entraining joint is the axis W of the rotatable object 02
The port BZ of the annular plate R3 and the stopper S1 of the connecting boss F1 r F2 are in contact with each other in the predetermined rotational direction of the two.
+ 82 entrains the shaft W1 with the graduation disc T. If the predetermined direction of rotation of the shaft W2 is reversed, the shaft W□ is no longer entrained. Because the annular plate R8 Pol) B
This is because Z and the stomper 82 of the connection boss F2 no longer come into contact with each other. The rotation direction of this reversed shaft W2 is also connected to the bolt BZ of the annular plate R8 and the stomper 82 of the connecting boss F.
In order to ensure contact between them, the shaft end of the shaft W1 on the opposite side of the driving joint is connected to the drive motor M fixed to the nozzle G and the sliding clutch via 2, and the drive motor M drives the shaft W in a direction opposite to the predetermined direction of rotation of the shaft W2.

Therefore, in both rotational directions of the object to be measured 020, both axes W
1 and W2 are tightly connected to each other, the relative positions of both objects to be measured 01, 02 can be accurately detected by the angle measuring device.

In order to obtain a reference position determined for measuring the relative position of both objects 01, 02, when the drive motor M is activated before the start of a new collapse, the measured object 02 is rotated while in the trench scanning the reference mark. With this reference mark, the count 2 is set to the value "zero" and the sweet is set to the other count determined by the previously established shuffle program.

If a fault occurs due to a current interruption during the machining process, and therefore during the measurement, the working process will therefore be interrupted by the rotatable object 02.
measurement will also be interrupted. Current force; when interrupted, the measured value and therefore also the reference position that existed when the fault occurred disappears. 1. When a failure occurs, the object 02 in the form of a gripping device of an industrial robot is generally just engaged, so the object 02 is Furthermore, the scanning unit AE cannot be rotated until scanning the original reference mark.

To reproduce the reference position, according to the invention, the polarity of the drive motor M is reversed when the axis W2 is stationary.

The drive motor M rotates the shaft W with the scale plate T in the opposite direction of rotation via the slip joint 2, and finally scans the original reference mark again, so that
The counter power S is again set to its original value. Subsequently, the polarity of the drive motor M is reversed to the original direction of rotation, and the shaft W1 with the scale plate T is returned to the position where the stomper 81 of the connecting boss F1 comes into contact with the pole BZ of the annular plate R8. Since it is rotated, the axis W1 and scale plate T75E take the instantaneous position at the time of failure again. In this way, while the axis W1 and the scale plate T return from the original reference mark to the instantaneous position at the time of occurrence of the fault, the increment of the scale of the scale plate T is set in the counter, so that the measured value disappears. Once again, the interrupted working and measuring processes can be continued.

The driving joint 1 has a bolt BZ and a stop S1, S2 mutually offset by 120° in each case, so that the relative movement of the axis W1 with respect to the axis W2 when reproducing the reference position is within an angle of <2400 Since it is only possible to use the scale disk T
In order to regenerate the lost reference position, two reference marks are required, and these reference marks are, for example, as described in German patent specification 2952106.
Requires coding in the form of code marks to distinguish them from each other.

In order to be able to fully reproduce the lost reference position with a single reference mark on the graduation disk T (which then no longer requires coding), the entrainment joint according to FIG.
propose. By twisting this entraining joint, it is possible to rotate the shaft W1 relative to the shaft W2 through an angle of 360°. In order to stop the shaft W2, three stops S'2 mutually offset by 120° are installed. Connecting boss F with
≦ is the same as the connection boss F2 in FIG. 6 (FIG. 7b).

The connection boss F1 for connecting the shaft W1 is 7b, 7
According to figure c, it has three concentric steps U1', U, Q, U'3 displaced in the radial and axial directions.

A stopper S'□ projects from each step U/U/U/ in the radial direction. Three steps U,', U'2. U'
The three stompers S' of No. 3 are offset from each other by 120°. In the annular plate R8', three bolts BZ'2 projecting in the axial direction, mutually offset by 120° from the peripheral side facing the connection boss F6, these bolts BZ
'2 is in contact with the stopper S'2 of connection boss F≦ (Fig. 7b). On the side facing the connection boss Fte, the annular plate RS' has three concentric steps U7. U'4. tJg wo, each step LJ
'1. U'2+ U'6 Holt BZ'1 protrudes in the axial direction. Stepped portion U/: , U/l, , U4
The three bolts BZ'1 of 1 are offset from each other by 1200, and the stoppers S/, respectively, of the connecting boss Ff are
come into contact with.

In a manner that is clearly illustrated, it is also possible to arrange the stop S6 of the connecting hub F4 and the associated pole BZ'2 of the annular plate R8' in concentric steps displaced in the radial and axial directions.

It is also possible to design 1 in the joint as a simple driver.

The slip joint 2 can be designed as a flow brake, as a hydraulic joint or as a magnetic drive element.

It is also possible to connect the scale disk T directly to the drive unit 1-M.

[Brief explanation of the drawing]

1 is a cross-sectional view of an angle measuring device for carrying out the method according to the invention, FIG. 2 is a cross-sectional plan view of the device of FIG. 1, and FIG.
The figure is a sectional view of a modified example of the angle measuring device, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. Fig. 6 is a longitudinal sectional view of the angle measuring device, Fig. 7a, 7b
, 7c shows a longitudinal section and two end views of the entraining joint. A, B, O,,02...Object to be measured 4.34. T
...Measurement scale 8.38...Scanning device R1...
Reference mark Z...Evaluation device agent Hikaru Esaki Good agent Hikaru Esaki Fumi 1j stone? 2 2M1ノJTIt4 1Lh〆3

Claims (15)

[Claims] (1) Using an incremental distance measuring device in which a measuring graduation with at least one reference mark is fixed on one of the objects to be measured and a scanning device is fixed on the other of said objects. In a method for reproducing the reference positions of relatively mutually movable objects whose positions are to be measured, said objects (A, B, Of, 02) have an arbitrary, unknown, unchanging instantaneous position of each other. After stopping the measurement and movement at , the measuring scale (4, 34, T) or the scanning device (8,
38) from the belonging object (A, B, 02) and from the reference mark (Ri) and adjust it to match the reference mark (Ri), followed by the released configuration. Return the element (measuring graduation 4.84.T or scanning device 8.38) to the defined starting position and fix it there again, evaluating the adjustment path from the coincident reference mark (R1) to the instantaneous position. A method characterized in that a small amount of information is recorded on a device (Z). (2) using an incremental distance measuring device in which a measuring graduation with at least one reference mark is fixed on one of the objects to be measured and a scanning device is fixed on the other of said objects; A device for carrying out a method for reproducing a reference position of a relatively mutually movable object whose position is to be measured, characterized in that: a) the scanning device (8) is connected to the object to be measured (A-! or B);
and is adjustable from its defined starting position to the drive device (10, 11, 12) at least at the nearest reference mark (Ri) i and back; b) a counterpart; (3) has, in addition to the incremental measuring graduation (4), at least one reference mark (Ri) whose position with respect to the zero point of the scale is absolutely determined; C) defined from the reference mark (Ri); When the scanning device (8) is returned to its starting position, the counted graduation increments are transferred to the evaluation device (Z) together with the value of the position of the reference mark (Ri).
device, characterized in that it is supplied to a scale and represents an instantaneous measured value relative to the zero point of the scale. (3) Incremental distance measuring device in which a measuring graduation with at least one reference mark is fixed to one of the objects to be measured and a force-scanning device is fixed to the other of said objects. An apparatus having an optoelectronic measuring device for carrying out a method for reproducing a reference position of relatively mutually movable objects whose relative position is measured using: a) a carrier of a scanning plate (38); (35) is separated from one of the objects to be measured (A or B) and from a defined starting position the drive device (310, 311° 352)
b) the carrier (33) has an incremental measuring graduation (34);
) in addition to success/failure reference marks (R-Rn), the reference marks are provided with code marks (Cz-Cn) whose position with respect to the zero point of the scale is absolutely determined, and the code mark ( C1-Cn), C) the illumination device (36, 37) and the photoelectric element (39) are fixedly arranged, and one of the photoelectric elements (39) for the reference mark (R1-Rn) , extending over the length of at least two adjacent reference marks (Ri and Ri+1); d) counted when the scanning plate (38) returns from one of the reference marks (Ri) to a defined starting position; Device characterized in that the graduation increment is fed to the evaluation device (Z) together with the value of the position of the corresponding reference mark (R1) and represents an instantaneous measured value relative to the zero point of the graduation. (4) Using an incremental distance measuring device in which a measuring graduation with at least one reference mark is fixed on one of the objects to be measured and a scanning device is fixed on the other of said objects. A device for implementing a method for regenerating a reference position of relatively mutually movable objects whose relative positions are measured by: It is connected to this object (02) via a driving joint (K1) that acts only in the direction and acts in the opposite direction of movement, but is reversible in the direction of movement and acts on the drive unit (M). b) scanning unit) (AE) is another object to be measured (01)
A device characterized by being tightly connected. (5) Coded reference marks [1 to R
4. Device according to claim 3, characterized in that n) is distributed on the scale (34). (6) The movement of the separated components (5, 6, 7, 8, 9) is caused by the motor (10) and the gear transmission (11, 12).
). (7) The device according to claim 6, wherein the gear (J2) is formed on the outer periphery of the disc (5). 8. Device according to claim 3, in which the oscillation of the separated components (85, 38) takes place with the aid of a motor (810) and an eccentric transmission (311, 352). (9) The forward and backward movement of the scanning plate (38)
This is accomplished by the rotation of a motor-driven eccentric wheel (all) engaged between the arms of 352'). Claim No. 8
Apparatus described in section. (10) Defined starting position with mechanical stop (5
3,353). (11) The device according to claim 9 or 10, which is provided with a switching arm (351) and a switch (355), thereby stopping the motor (310) at the moment of stopping. (12) The measuring device is a rotation generator, the scale disk (33) is rigidly arranged on the axis (32) of the generator, and the disk (35) carrying the scanning plate (38) is rotatable. 4. The device according to claim 3, wherein the device is arranged in a. (13) The entraining joint (K1) is connected to the shaft (Wθ) connection boss (F2) connected to the object to be measured (02) and the shaft (Wl) connected to the measurement scale (T). boss(
It has a connection boss (Fl,
F2) has three stops (Sl, S2) on its outer circumference, each offset from one another by 120 and running in the radial direction.
These stoppers have connecting bosses (F, ,
12 around the annular plate (R8) placed between F2)
Three poles running in the axial direction, offset from each other by 0°) (B
5. A device according to claim 4, in contact with Z). (14) Contact! Boss (p f ) stopper (S;)
and/or the stomper (S4) of the connection boss (F7)
are respectively arranged in radially and/or axially offset concentric trunks (Uf, U2', U3,
and the annular plates (BZ1') and/or poles (BZα) respectively have radially and/or axially offset concentric trunks (Ufi, U
;+US)
The device according to item 3. (15) The device according to claim 4, wherein the measuring scale (T) is connected to the drive unit l-(M) via a slip joint (K2).