JPS59116011A - Measuring method of size and shape by robot - Google Patents

Abstract

PURPOSE:To improve the degree of accuracy in measurement by correcting an intended locus according to the positional deviation between the intended locus and the surface of a material to be inspected, and measuring the size and shape of the surface of the object to be inspected from the corrected locus and the spacing between the corrected locus and the surface of the material to be inspected. CONSTITUTION:A gap sensor 20 is first moved at an intended locus 32 and the deviation in a measuring object is known from the result of the measurement with the sensor. More specifically, a peak part is determined from an actually measured curve 36, and a deviation l is determined in terms of the difference between the X value thereof and the X value in the intended peak part. A command is then given to a robot to shift and locus 32 by the distance l. If the gap is measured by moving the sensor along the corrected locus 33, the surface shape and size of a steel pipe are exactly measured by the measured gap and the locus 33. The correct measurement having the actual bead part 31 at the center of the locus is made possible. The accuracy in the measurement is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the size and shape of large members such as UO steel pipes using an industrial robot.

UO steel pipes are made by bending a thick steel plate into a pipe shape and butt-welding the edges on both sides.To ensure quality, bead width, bead height, pipe diameter, etc. are measured after pipe making to check whether they are within acceptable ranges. do. Measurement of the bead area, such as bead width, is carried out by laying the tube horizontally with the heated part directly above it (
Measure the pipe diameter at two diameters at 45° to the vertical line (not necessarily directly above), then rotate the pipe 45° from that position, and then measure the pipe diameter at 45° to the vertical line again. Measure on two diameters of the tube, and use these measurements as the tube diameter.

This is because the UO steel pipe has a large diameter, so if it is placed horizontally, it will bend in the first direction, and for this reason, the pipe diameter should be measured at the above-mentioned position, which is the neutral point. In addition, UO steel pipes are often used for purposes such as connecting multiple pieces together to construct a pipeline, and in such cases, the pipe ends are beveled, but the shape of the bevel is measured during product inspection. , inspection is also important. Traditionally?
Measurements and inspections were performed manually. However, this method introduces individual differences in measurement and test results, making it difficult to maintain high accuracy and is not suitable for saving labor. If industrial robots could be used to perform force measurements and inspections, these types of problems could be solved at once.

In order to carry out measurement and inspection using a robot, it is conceivable to transport the UO steel pipe that has been welded or beveled to a robot installation location, and then operate the robot there to perform measurement and inspection. In this case U.

Steel pipes have large diameters and long lengths, so it is difficult to achieve precision in movement and rotation stop positions (large capital investment is required to achieve high precision).
. However, robots generally use a teaching-back method, in which they repeat what they have been taught over and over again to perform the required movements. Therefore, when the UO steel pipe moves to a different position than planned and stops rotating, Roboso 1~ will measure and inspect the unplanned part of the steel pipe.

To measure dimensions and shapes with a robot, a gap sensor is attached to the robot's arm, and the sensor is moved along a fixed trajectory along the surface of the material to be inspected to measure the distance between the sensor and the surface of the material to be inspected. is valid. In this case, the above trajectory is the one taught to the robot and is constant, so
If the position of the material to be inspected shifts, there will be a problem that the trajectory will deviate from the part to be measured of the material to be inspected, and the sensor will start at one end of the trajectory and stop at the other end, resulting in poor measurement accuracy at the starting and stopping part. Therefore, it is preferable to perform measurements in the middle of the trajectory.
For this reason, it is preferable that the part to be measured of the material to be measured be located in the middle of the 1 lil trace, but a problem arises in that this condition is no longer satisfied.

The present invention seeks to address such problems. In other words, when installing a gap sensor on the arm of an industrial robot to measure the dimensions and shape of large components such as large diameter UO steel pipes,
This is an attempt to solve the problem of poor stopping precision of large members and poor measurement precision when starting and stopping a robot.

In the present invention, a gap sensor is attached to the arm of an articulated robosol l-, and the distance between the sensor and the surface of the material to be inspected is measured while moving it along a predetermined trajectory on the surface of the material to be inspected. In the method of measuring the dimensions and shape of the surface of the material to be inspected from , correct the planned trajectory according to the positional deviation, move the sensor along the corrected trajectory, measure the distance between the corrected trajectory and the surface of the material to be inspected, and measure the distance and correction 11i1 from the trace. The method is characterized by measuring the dimensions and shape of the material surface, which will be explained in detail below with reference to the drawings.

Figure 1 shows the procedure for measuring the dimensions and shape by
0 is an articulated industrial robot, with a pedestal part 11, arm parts 12 ~
14, the pedestal moves in one direction on a horizontal plane (forward,
arm 12 stands vertically and is rotatable about a vertical axis; arm 13.14 is pivotally connected to arm 12.13 and rotatable about its pivot axis; Both of these movements and rotations are performed by respective motors. A gap sensor 2o is rotatably attached to the tip of the robot's arm, and moves along a predetermined trajectory of the object to be inspected, in this example, a UO steel pipe 3o, to measure the distance between the sensor and the surface of the thin tube. do. As the gap sensor 2o, in addition to the gap sensor 2o described in the specification filed separately by the present applicant, other suitable sensors can be used.

The movement trajectory of the robot is determined by a command signal given to the robot, and is grasped by the robot. If the distance from the known trajectory to the steel pipe surface is measured by the sensor 20, the steel pipe surface shape can be easily determined.

To explain this with reference to Figure 2, 3o is the 006m pipe, 3
1 is the heat generated in the welded part. 32 is a sensor locus, which in this example is an arc concentric with the Uo steel pipe 3o and having a diameter larger than the diameter of the steel pipe. The command signal given to the robot is a rotation angle command signal for each joint of the robot.
If it is an axis type robot 1-, it can be expressed as x, y, z, α, β, etc. Although the circular locus 32 is instructed by a command signal, a straight line, an arc, etc. are types of trajectories that can be easily generated. Once the 11Nt trace 32 is determined and the sensor 2o measures the distances δl, δ2, etc. between the trace and the surface of the steel pipe, the shape of the surface of the steel pipe can be determined, and the bead etc. can also be grasped accordingly. Bead width, heat height, etc. can be calculated from the measurement data.

In the figure, the distance measured by the sensor 20 is in the vertical direction. This is because the attitude of the sensor is controlled so that it always faces in the vertical direction, and if the attitude of the sensor is controlled so that it faces the center of the steel pipe 30, the distance measured is in the radial direction. However, considering the deviation between the locus 32 and the steel pipe 30, attitude control to direct the sensor toward the center of the steel pipe becomes very difficult.

As mentioned above, the stopping accuracy of UO steel pipes is not good.

Therefore, as shown in FIG. 2, the heat that should be at the top, as indicated by 31', may be shifted as indicated by 31. If the deviation is large and exceeds the range of the trajectory 32, measurement of the bead portion will be impossible, and even if the deviation is not so large, if the deviation is at the beginning or end of the trajectory 32, the measurement accuracy will deteriorate.

The present invention is intended to deal with the problem of deviation, and first, the sensor is moved on a scheduled track #32 and measured, and the deviation of the part to be measured is determined from the measurement results. That is, as shown in FIG. 3, if we take the starting end of the trajectory 32 as Xo and the ending end as Xn, and take the measured gap length G on the vertical axis, a curve 35 is the expected measurement result if there is no positional deviation, but, If the actually measured result is the curve 36, the distance %llllff is the amount of deviation.

The distance l is determined by determining the peak portion from the actual measurement data and finding it as the difference between the X value of the peak portion and the expected X value of the peak portion. Once the distance l is determined, the robot is instructed to shift the trajectory 32 by the distance l1ittp. In this way, the trajectory changes to 33 in Figure 2, and if the sensor is moved along this corrected trajectory to measure the gap, the measurement result, that is, the gap and the corrected trajectory, can be used to determine the exact surface shape and dimensions of the steel pipe. Measurement becomes possible.

Correct measurement can be performed with the actual heat section 31 centered on the trajectory.

In this example, the shift amount β is simply moving the circular arc 32 by a length β in the direction of the circular arc, but it is also possible to add a shift in the radial direction. That is, by comparing curves 35 and 36, the deviation in the radial direction as well as the deviation in the circumferential direction can be determined (G
The trajectory VIF 32 may be moved in the radial direction of the steel pipe according to the deviation (depending on the magnitude or smallness of the curve), and in this way, accurate measurement can be performed with the distance between the trajectory and the surface of the steel pipe set to a predetermined value.

Conventional teaching playbank type robots need to accurately stop the target material in a predetermined position, but in the steel industry, etc., the target material is large and heavy, so it is not possible to accurately position the target phase.

In this respect, intelligent robots that have sensors attached to their hands and can perform tasks by changing the starting point and direction of a predetermined trajectory are extremely effective.

FIG. 4 is a block diagram showing the configuration of a device that performs the above-mentioned control. 4o is a control unit of the robot 1o, which includes a command value generation unit 41, a comparator 42, a D/A converter 43, and a servo amplifier 4.
4, a counter 45, and a coordinate conversion device 46. 15 is a motor that drives each joint of the robot, and 16 is an encoder that measures and outputs the amount of rotation of each joint. Although only one of these is shown in the figure, there are actually the same number of joints. When the position of the robot arm tip, that is, the sensor 2o, is given to the comparator 42 from the command value generator 41 as drive command signals X, 'y, Z, α, β (in the case of 5-axis type) for each joint, the signal becomes D. After being converted into an analog quantity by the /A converter 43, the signal is input to the ZARPO amplifier 44, where it is amplified and applied to the motor 15.

The amount of rotation of the motor and therefore the amount of joint rotation is detected by the encoder 16 and output in the form of a pulse number. A counter 45 counts these pulses and feeds back the counted value, that is, the rotation amount to the comparator 42. The comparator 42 outputs the difference between this feedback signal and the command value, and drives the motor 15 until the difference becomes zero, so that the sensor 20 eventually moves according to the command value. The output of the counter 45 is also given to a coordinate conversion device 46, which determines the coordinates of the current sensor position.

Further, 50 is a dimension/shape calculation device, which includes an A/D converter 51, a heat position identification device 52, a bead position comparison device 53, a bead position reference value output device 54, and a shift +-i calculation device 5.
5. As described above, the sensor measures the distance between the locus and the surface of the steel pipe, which is converted into a digital value by the A/D converter and then input to the bead position identification device 52. The output of the coordinate conversion device 46, that is, the sensor locus is also input to the identification device 52, from which the perfume surface shape is determined, and then the bead position is determined. The detected bead position is input to a comparison device 53 and compared with a bead reference position from a reference value output device 54. The comparator 53 outputs the difference between them, that is, the above-mentioned deviation l, and in response to this, the arithmetic unit 55 calculates the trajectory shift amount. The aforementioned x, y, z...
The shift amount expressed in the form is input to the command value generation section 41 or the comparator 42, and the locus is shifted.

As explained above, according to the present invention, even if the object to be inspected has poor stopping accuracy and deviates from the planned position, it is possible to measure the dimensions and shape with high accuracy using the teaching play puncture type robot saw 1-.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the procedure for dimension and shape measurement by a robot, Fig. 2 is an explanatory diagram of positional deviation, Fig. 3 is an explanatory diagram of a method for correcting positional deviation, and Fig. 4 is an illustration of an apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration. In the drawing, jO is an articulated robot, 20 is a gasop sensor, 32 is a planned trajectory, and δ1. δ2 is the interval, l is the positional deviation,
33 is the corrected trajectory. Applicant Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi

Claims (1)

[Claims] A gear sensor is attached to the arm of an articulated robot, and the distance between the sensor and the surface of the material to be inspected is measured while moving it along a predetermined trajectory on the surface of the material to be inspected. In the method of measuring the dimensions and shape of the surface of a material to be inspected from seek,
The planned trajectory is corrected according to the positional deviation, the sensor is moved along the corrected trajectory, the distance between the corrected trajectory and the surface of the material to be inspected is measured, and the distance between the corrected trajectory and the surface of the material to be inspected is determined from the distance and the corrected trajectory. A method for measuring dimensions and shapes using a robot, characterized by measuring dimensions and shapes.