JPS60202302A - Coordinate measuring apparatus - Google Patents

Abstract

PURPOSE:To make it possible to judge which side of a body a probe is contacted automatically, by providing a means, which memorizes the locus of the probe immediately before the probe is contacted with the body and the data at the remotest point among the locus data. CONSTITUTION:Up to the time immediately before the contact of a probe 3 and a body 1, coordinate data Xi is continuously outputted from an AND gate 12 at every 10ms. A fluctuation detector 21 computes the difference between the data Xi and Xi+1. When the difference is greater than a specified value, a high-level gate signal is generated and applied to an AND gate 22. Therefore, the data are received during the period the probe 3 is moved. Even though the capacity of a FIFO memory 13 is small, the coordinate data from the remote place can be stored. When the probe 3 is contacted with the surface of the body, the data Xi indicating the locus of the probe 3 up to the time immediately before is stored in the FIFO memory 13. Coordinate data X0 of the surface of the body is stored in a buffer memory 14. The radius (r) of the probe 3 is corrected by an operation and display part 15. Thus the accurate data are displayed.

Description

[Detailed description of the invention] The present invention relates to improvements in coordinate measuring devices.

2. Description of the Related Art Conventionally, coordinate measuring devices are known that measure the shape of an object by bringing a spherical contact at the tip of a probe into contact with the surface of the object to be measured and measuring the coordinates of this contact point. However, the center coordinates of this contact are separated from the actual object surface by a distance corresponding to the radius r of the contact. For this reason, it is necessary to determine the true object surface coordinates by correcting them by adding or subtracting the radius r to the center coordinates of the first concubine. To do this, the operator first confirms the relative positional relationship between the contact and the object surface, then decides whether to add or subtract the contact radius r, and then sends this value to the calculation section of the four-torque measuring device. It was necessary to input various correction information. Therefore, the operation is complicated and operation errors are likely to occur.

The present invention was made to improve these drawbacks.
The present invention provides a coordinate measuring device that can automatically correct the contact radius r as described above.

The present invention will be described in detail below with reference to Examples.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an object to be measured, 2 is a probe, and 3 is a contact.

The machine/coder 6 has an X-axis scale 6a, and when the base 2a of the probe 2 moves on the scale 6a, it generates a pulse having a shape corresponding to the direction of movement for each unit movement amount. The noculus is an up-down counter (hereinafter referred to as U
D counter) 8, and is added or subtracted depending on the direction of movement to become position data of the base 2a of the probe 2 on the X axis, which is added to AND gates 9 and 12. The output of the pulse oscillator 10 is applied to the gate terminal of the AND gate 12 and the clock terminal of the fiber-optic memory 13 via the AND gate 11 . Also, a contact detection switch 4 and a manual switch 5 built into the contactor 3
The input sides 4a and 5a of are grounded and the output sides 4b and 5b
is connected to the gate terminal of Antogame) 11, and
It is connected to the one-shot multi 7 and the calculation display section 15. The output of the one-shot multi 7 is applied to the gate terminal of the AND gate 9. The outputs of AND gates 9 and 12 are buffer memory 14 and fiber memory 1, respectively.
3, each memory output is added to the subtraction section 16 of the arithmetic display section 15, and its output is added to the correction sign detection section 17. The correction code detection section 17 and buffer memory 14
The output is applied to the correction calculation unit 18, and the output is applied to the display unit 19 to display the calculation result.

The operation of the above configuration will be explained.

Now, when the spherical contact 3 of the probe 2 is moved toward the object to be measured 1, the encoder 6 generates a pulse, and when the probe 2 moves downward, the UD counter 8 becomes a down state, and when it moves upward, the UD counter 8 becomes an up state. Since the pulses are integrated for each unit movement amount, the output of the UD counter 8 becomes the coordinate data of the contact 3 on the X-axis measured by the base 2a of the probe 2. Here, since the switches 4 and 5 are normally open, the output sides 4b and 5b are at a high level, and therefore the analogue 11 is open. Also, the AND gate 9 is normally open. Therefore and gate 12
A pulse output from a pulse oscillator IO is applied to the gate terminal of the circuit every 10m5eC. As a result, the fiber memory 13 inputs coordinate data every lQmsec, so
If the fiber-optic memory 13 has an n-stage configuration, the fiber-optic memory 13 will always store coordinate data for the immediately preceding period of about 10 nmsec 0.

Next, as soon as the contactor 3 contacts the surface of the object 1 at time to as indicated by 3', the detection switch 4 is closed and its output side 4b is grounded, and the AND gate 9 is opened for a short time determined by the multiplier 7. In this way, the fiber memory 13 stores coordinate data X1,
X2...Xn are recorded, and the buffer memory 14 responds within 17 Asec after contact and records the coordinate data Xo. In this way, the response of the fiber memory 13 may be slow, but the buffer memory 14 must be fast.

The coordinate data obtained in the above manner is displayed on the calculation display section 15.
is added to determine the true coordinate values of the object surface. That is, the subtraction unit 16 calculates the trajectory B of the contactor 3 and the data X'i
(i=1, 2 m**n) is sequentially subtracted from the measured coordinate data XO of the object plane. The sign detection unit 17 obtains the subtraction result X for the n pieces of data X1. -Xl, the one that gives the largest absolute value is selected, and the coordinate data Xi at this time is regarded as the first coordinate data Xn. If the sign of Xo-Xn obtained in this way is positive, a positive correction sign is added to the correction calculation section 18, and if it is negative, a negative correction sign is added to the correction calculation section 18. If the correction sign is negative, this indicates that the contact 3 approaches the object from above and contacts the top surface of the object, so the correction calculation unit 18 subtracts the radius r of the contact from the coordinate data Xo, and the thus obtained Xo
'(-Xor') is displayed on the display unit 19 as coordinate data of the true object surface. If Xo−Xn is positive, it is determined that the object has touched the bottom surface, and the correction calculation unit 18
Now, Xo' (=X
o1r ) is displayed on the display section 19 as true data.

Next, a case where the switch 4 is not built into the contactor 3 will be described with reference to FIG. 2. FIG. 2 shows the trajectory of the contactor 3 just before it comes into contact with the surface of the object 1 and stabilizes. Initially, at time tn, the contact 3 is above the object and its initial coordinate data is Xn, and as time passes, it gradually approaches the object, and at time ta, the coordinate data becomes XO, and the contact 3 is on the object surface. Stop on contact. However, the probe 2 may be bent due to excessive force being applied to the probe 2 due to the operator's inexperience, etc.
Since the base 2a moves further downward, the coordinate data of the contact 3 apparently continues to fall further and reaches the lowest position at time tb, and the coordinate data at this time becomes xb. After that, the base 2a returns upward by correcting the excessive force applied to the probe 2, etc., so the coordinate data of the contact 3 also apparently returns to become coordinate data X1 at time t1, and at time to, the operator returns to this position. Since the coordinate data Xo is determined to be the correct object surface and the switch 5 is closed, the coordinate data Xo is recorded in the buffer memory 14 as described above.

Also, in the fiber memory 13, there is a glove 2 as shown in Fig. 2.
Coordinate data obtained by measuring the trajectory of 1Qmsec every 1Qmsec is stored. These coordinate data are processed in exactly the same manner as in the case described above to calculate true coordinate data.

Note that if the difference between Xo and xb is greater than the difference between coordinates Xo and Xn, the correction sign will be determined to be positive, and the correction will not be performed correctly. In order to avoid such malfunctions, it is sufficient to record the trajectory in the fiber memory 13 from a state where the contact 3 is as far away from the surface of the object 1 as possible. For this purpose, there are methods such as increasing the capacity n of the fiber memory 13 or lengthening the period of the pulse oscillator 10.

In the embodiment shown in Figure 1 above, when measuring using the manual switch 5, the time from when the contact 3 contacts the object to when the switch 5 is closed is too long and exceeds 1゜n m5ec. In this case, the data before the contact 3 contacts the object 1 is not recorded in the fifo memory 13, which is inconvenient because the correction cannot be performed correctly. FIG. 3 shows another embodiment of the present invention which has been made to improve these drawbacks.

In the figure, the output of the AND circuit 12 is only applied to the fifo memory 13 in the embodiment of FIG. 1, but in this embodiment, it is also applied to the data fluctuation detector 21,
Its output is applied to the gate terminal of AND gate 22. The output of AND gate 11 is applied to the gate terminal of AND gate 12 and to the input terminal of AND gate 22. The output of the AND gate 22 is applied to the clock terminal of the fiber memory 13. The other parts are the same as the embodiment shown in FIG.
The same reference numerals as in the drawings are used to omit detailed explanation.

The operation of the above configuration will be explained below.

As in the case of FIG. 1, the coordinate data Xi of the contact 3 is outputted from the AND gate 12 every 10 m5ec until just before the contact 3 contacts the object. Data fluctuation detector 2
1 calculates the difference between this coordinate data Xi and X1+1,
If the difference is smaller than the predetermined value, a zero-level gate signal is generated, and if it is larger, a high-level gate signal is generated and added to the AND gate 22.
The pulse every m5ec is applied to the clock terminal of the fiber-optic memory 1J13 only while the difference between the above two data is large.

Therefore, the fiber memory 13 performs a recording operation and takes in data only while the change in the successively arriving coordinate data Xi is large. As a result, data is captured only while the contactor 3 is moving, and useless data such as while the contactor 3 is stopped is not captured.
Although its capacity is small, it can store coordinate data from a long distance. Next, when the contact 3 comes into contact with the object surface, the coordinate data Xi indicating the trajectory 8' of the contact 3 up to that point is recorded in the fiber memory 13, as in the case of FIG. 1, and the buffer memory 14 is the coordinate data of the object surface
Since o is recorded, the radius r of the contactor 3 is corrected by the calculation display unit 15, and accurate coordinate data is displayed.

The case of -dimensional measurement has been described above, but the same applies to two-dimensional measurement. In this case, trajectory data of the contactor is obtained for the Y-axis as well as the data for the Y-axis described above. For example, when calculating the coordinates of a circle, there are three points a,
# Touch b and C, coordinates of the contact at these contact points (Xa.

From Ya), (xb, yb) and (Xc, Yc), the center coordinates of the circle (Xo, Yo
), and calculate the radius Ro using the formula below.

Regarding the radius Ro obtained in this way, if the contact is inscribed in a circle, the contact radius r must be added, and if it is circumscribed, it is necessary to subtract it. For this purpose, as described above, the trajectory 9 (Xi, Y
i) for one point a out of the three points above. Next, each point on this trajectory 8 (Xi.

Yi) and the center coordinates (Xo, Yo)
is calculated by the following formula.

The maximum value of each of these distances (usually the first data 11,
m) from the radius Ro, and determine whether the sign of the value R8-R is positive or negative. If the sign is positive, it can be determined that the contact is inscribed in the circle from the inside of the circle, so the true radius Ro' can be calculated as Ro'' = Ro+ r.Also, if the sign is negative, it is determined that the contact is inscribed in the circle from the inside of the circle. Since it is known that the child is circumscribed to the circle from the outside of the circle, the true radius Ro' can be calculated as R□' = R□ - r.

The same applies to three-dimensional measurements. For example, in the case of plane measurement, in order to determine the plane equation of a given plane, as is well known, the coordinates (X
a, Ya, Za) (Xb, Yb, Zb)
Substitute and (Xc, Yc, Zc) into the following formula, and add l, rn, and d to each coefficient.

kXa+lYa+mZa+d-O k Xb+ l Yb+ m Zb+ d = 0kX
o+IY(+mZo+d=O F)] 1 "Site review - 1 The plane to be drawn can be determined in this way, but even in this case, an error of the radius r of the contact will occur in the coefficient d. To correct this error, Similarly to the above, for one point a among the three points above, the previous trajectory 8 data (Xai, Yai, ZaI)
, i = 1.2++*en (7) Calculate hi = kXai + IYai + m Zai + d for each data, and 1
The sign g of hi when hil takes the maximum value (g: +1
or -1), the true value d' of the coefficient d can be determined as d' = d + gr.

As described above, according to the present invention, it is possible to automatically determine which side of the object the contact has touched from the trajectory immediately before the contact touches the object, and the coordinates are easy to operate. A measuring device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the invention, FIG. 2 is a diagram explaining its operation, and FIG. 3 is a block diagram showing another embodiment of the invention. In the figure, ■ is an object, 3 is a contact, 13 is a fiber memory, and 15 is a calculation and display unit. Patent applicant Unidata System Co., Ltd. ↓ Figure 2

Claims (1)

[Claims] A contact, means for obtaining coordinate data of the contact in contact with an object to be measured, and adding or subtracting the dimensions of the contact to the coordinate data depending on the direction in which the contact approaches the object. means for calculating true coordinate data of the contact point by υ, means for storing a data string of one word of the trajectory of the contact immediately before the contact contacts the object; and , means for selecting the farthest point from the coordinate data from the trajectory data string, and means for selecting the farthest point from the coordinate data, and determining whether the trajectories have approached the object based on the coordinate data and the selected trajectory data. A coordinate measuring device characterized in that a direction is determined.