KR920008141B1 - Robot performance measuring system - Google Patents

Abstract

The apparatus comprises a carrier frame (12), a horizontal and vertical rotatable shaft (13) mounted in the frame, a support, a linear bearing guide (18,19) on one end of the horizontal shaft, a linear scale (14) caried by the support (17) and bearing guides, a rotary position transducer (15) connected to each end of the shafts, a universal joint and an electronic control unit. An up/down counter reads detected positions or position changes of the central point of a machine tool. The counter and a machine control unit are connected to a computer with software for computation of position coordinates and for performing power measurement and calibration.

Description

Robot performance measurement and counting device

1 is a schematic configuration diagram showing the connection between the performance measurement and coefficient recognition tester and the measuring robot and the peripheral device of the present invention.

Figure 2a, b is a longitudinal cross-sectional view of the performance measurement and coefficient recognition tester of the robot cut in a direction perpendicular to each other.

3 is an enlarged longitudinal sectional view of the universal joint.

4 is a configuration diagram of a selection screen of a program for measurement and analysis of the device of the present invention.

5 is a flow chart of electrical operation in accordance with the present invention.

6 to 11 show the repeatability, linear accuracy, circular accuracy, position accuracy and positioning accuracy measured and analyzed by the performance measurement and coefficient recognition device of the robot of the present invention. Figures showing Velocity Behavior.

12 is a view showing an operation for coefficient recognition.

* Explanation of symbols for main parts of the drawings

1: Robot performance measurement and coefficient recognition tester 2: Universal joint

3: robot 4: robot controller

5: port 6: print

7: computer 8: counter

13, 13 ': axis of rotation 14: linear scale

15: rotary encoder

The present invention relates to a performance measurement and calibration device (calibration) of the robot.

With the recent trend of factory automation, the role of robots in the production line has been diversified and its importance is increasing. As the use of robots gets wider, the demand for flexibility and reliability of robots is increasing, and the importance of measuring devices and counting devices is also increasing.

Such a device occupies an important position as a judgment system for quality inspection, performance improvement and application for a robot manufacturer or a user, and when an off-line programming system is introduced into a robot system in the future, one coefficient It can also be used as a recognition device.

Conventional robot performance measurement and coefficient recognition devices have been used in various forms, depending on the application. Especially, a device using a camera or an interferometer or theodolite has been used. . However, most of these devices have the disadvantages such as high price and limited use area.

Therefore, the present invention has been proposed to solve the above-mentioned drawbacks, and its object is to provide a performance measurement and coefficient recognition device for a robot which can be operated in a simple manner, has a wide range of applications, can be made compact, and can be operated at low cost.

The performance measurement and coefficient recognition device of the robot according to the present invention comprises a mechanical movement part composed of a combination of a main body consisting of two rotational axes and one translational axis, and a universal joint consisting of three rotational axes, The sensor unit includes an encoder and a linear scale, and software that calculates the position coordinates of the robot from the position data input through the counter, and performs performance measurement and coefficient recognition of the robot.

The apparatus of the present invention configured as described above has the following features.

-Select and use any robot as kinematic data

Measurement accuracy within 10μm at the tool center point

Basically, it has two axes of rotation and one axis of translation.

-Connect the 3 axis universal joint to the connection part with the robot to form a system with 6 degrees of freedom as a whole.

Define the absolute coordinate system of the robotic system,

-Measure the repeatability of the robot

To measure the path accuracy during continuous path exercise,

Measure the speed error and acceleration error of the robot,

-Measure response characteristics (overshoot, vibration, settling time) when robot motion is stopped,

-Provides robot motion coefficient recognition algorithm.

Hereinafter, with reference to the accompanying drawings, the configuration and effect of the present invention will be described in detail.

1 is a configuration of the overall system of the robot performance measurement and coefficient recognition tester according to the present invention, as shown in the robot performance measurement and coefficient recognition tester is a robot ( 3), the robot 3 is connected to the robot controller 4 and the robot controller 4 is connected to the computer 7 through a port (for example, RS232C port) 5 and the The performance measurement and coefficient recognition tester 1 is directly driven by the robot 3 and connected to an up-down counter 8 so that the change amount can be read at a desired measuring point, and the up-down counter 8 is connected to the computer 7. The printer 6 is connected to the computer 7 so as to print the measurement and coefficient recognition results.

2a, b is a longitudinal cross-sectional view showing the configuration of the performance measurement and coefficient recognition tester which is the main part of the present invention in a direction orthogonal to each other. Referring to this, the performance measurement and coefficient recognition tester according to the present invention basically has several legs (11). Support frame 12 having a, a rotating shaft 13 provided in the vertical direction to the support frame 12, a rotating shaft 13 'provided in the horizontal direction in the upper portion thereof and the rotating shaft provided in the upper end ( 13 ') and a linear scale (translation shaft) 14 rotating in a 360 ^° range around the rotary encoder 15 and rotary encoders 15 respectively connected to the ends of the rotating shafts 13 and 13'. It is measured by the rotary encoder 15 and the linear scale 14.

Both ends of the rotating shaft 13 are fixed by support bearings 16, which are combined in three stages to prevent shaking during rotation.

The rotary encoder 15 is preferably attached to the rotary shaft 13 (13 '13) to use a 25 times divider (divider) to obtain a rotational accuracy. The basic pulse is 135,000 pulses / rev, and 540,000pluse is obtained after four times of dividing.

The linear scale 14 is linearly moved through the linear bearing guides 18 and 19 on the support 17, and mechanical switches 110 are provided at the ends of the support 17 and the linear bearing guide 19. ) And the stopper 111 are fixed, and the zero point detector 112 is fixed to the middle portion of the support 17.

The linear scale 14 provides a resolution of 1 μm (option 5 μm) and an accuracy of 4.8 μm. Thus, perfect counting of the instrument itself ensures an accuracy of 15 μm at the tip of the instrument (800 mm).

In FIG. 2, reference numerals 113 and 113 ′ denote moving parts.

3 is a longitudinal cross-sectional view of the universal joint connecting the measuring instrument of the robot, as shown in the universal joint (2) is composed of three rotating shafts to improve the mobility in the connection with the robot, two flanges (21, One end of the connecting rods 22 and 23 is supported by the ball bearings 26 and 28, and the other ends of the connecting rods 22 and 23 are connected to each other via a connecting pin 24 and a ball bearing 27. Are interconnected.

In Figure 3, 29 shows the support.

On the other hand, since the output of the rotary encoder 15 and the linear scale 14 is a pulse train proportional to the displacement, a circuit for counting this is required. Since both the encoder 15 and the linear scale 14 function in both directions, a counter board is manufactured to perform up and down counting, and the counter 15 and the linear scale 14 are set to count 10 ⁷ so as to sufficiently secure the motion area.

In addition, National Instruments Labwindows is used to facilitate the processing and analysis of measurement data. The software features C and Quick BASIC languages, and features a library of statistical functions, curve fitting, and two-dimensional graphics.

These libraries are used to perform analysis and graphical display of measurement data.

The software that forms part of the robot and the performance measurement and counting device basically uses the C language and consists of a menu system as shown in FIG.

5 shows an operational flow diagram in terms of electrical aspects of the measurement system according to the present invention.

The apparatus of the present invention as described above, the performance measurement and coefficient recognition tester 1 is driven directly by the robot 3 to up and down the amount of change detected by the linear scale 14 and the encoder 15 at the desired measurement point. The absolute coordinates of the robot tool tip (Tool Center Poling = TCP) are measured by reading through the counter 8 and calculating the position coordinates of the robot 3 from the measured position data. The points read from the up-down counters 8 connected to the encoders 15 and the linear scales 14 respectively store the file type in the computer 7 and then perform processing of Labwindows, a software dedicated to measurement data processing. Is analyzed in the computer 7 through. In addition, transmission and reception of the start and stop signals of the robot 3, program menu selection, and file transfer are performed by the robot controller 4, and the measurement and coefficient recognition results are output through the printer 6.

Next, a data processing flowchart from the output of the sensor unit such as the rotary encoder 15 and the linear scale 14 to the performance measurement and the coefficient recognition will be described.

The menu was configured using Microsoft's Windows (MS-DOS) Development Toolkit, and the user can select menu pulldown using the mouse. Details of each menu are as follows.

File: Select File from the menu to perform the following functions.

-Open: Open an existing file.

-New: Open a new work file.

-Floppy: Copy the generated file to a floppy diskette.

-Save: Save the work file.

-Delete: deletes the existing file.

-Print: Print job file to printer.

-Quit: End the operation.

Robot Kinematics: All the robot's motion data are stored in the file. When the robot is selected, the robot's motion data file is read. The initial exercise data file must be input by the user, and the values are updated after the coefficient recognition process.

Send rovbot program: The robot program generated along the designated path is converted into a robot code and sent to the robot controller 4. Each program code sent in this way is assigned a unique number, and the robot is actually driven by selecting this number. Robot programs can also be created by teaching-in the robot directly. This communication takes place via the RS-232C port (5).

Measurement and Measurement: The robot moves along the determined path, and the ultimate goal of the system is to measure and analyze the movement. This is where the measurement takes place. First, when the measurement target is selected, the robot program number of the path corresponding thereto is sent to the robot controller 4 to move the robot, and the position value of the robot's working tool tip (TCP) is read from the measuring instrument.

The measured values are saved in a file, and after the measurement, the values are processed for analysis. The items that process and represent the data obtained from the meter are:

Repeatability: The robot's repeatability is the most basic performance specification of the robot and the most important factor that determines the performance in the touch play back operation most commonly used in the robot.

In this system, it is possible to analyze the repeatability accuracy in various ways, and in particular, it is possible to measure the approach direction in several directions at the same time. When a measurement signal is input from the robot 3, the count value of the up-down counter 8 at that time is read, changed into the robot coordinates, and the next signal is waited. When the end signal comes from the robot, the count value of the up-down counter 8 is read and processed, and the measured results are displayed on the screen in the form of X-Y, Y-Z, Z-X plane (X, Y, Z are coordinate axes). At this time, the average value, the maximum measured value, the average value +30 deviation, the command point, and the calculated average point on the plane are simultaneously displayed (FIG. 6). Next, the measurement results for each axis are displayed on the screen (Fig. 7). Finally, the analysis results for each axis and plane are displayed on the screen numerically and the work is finished.

Linear Accruracy: Linear path error measurement is a method to measure the performance of the robot's continuous path movement. When the measurement start signal is received from the robot 3, the position values are continuously read and stored according to the sampling rate determined by the computer 7, and when the end signal is received from the robot, the reading operation is terminated and the analysis is started. . Since the rectangle drawn by the robot's path is a path in arbitrary space, the mapping of the robot to the plane is preceded.

The screen simultaneously shows the ideal rectangular path mapped on the plane, the path of the measured robot, and the fitted lines that linearly fit the measurement path for each line segment (Figure 8). Next, when the measured path is mapped to a plane, the screen shows the amount of deviation from the plane. Finally, the result of analysis is displayed on the screen and the work is finished.

Circular path error measurement: The circular path error measurement is very important in that it can represent the error when the robot performs the curved motion. When the measurement start signal is received from the robot 3, the position values are continuously read and stored according to the standard extraction rate determined by the computer 7, and when the end signal is received from the robot, the reading operation is terminated and the analysis is started.

Since the circle drawn by the robot's path is a path in arbitrary space, the work of mapping it to a plane is preceded. The screen simultaneously shows the ideal path and center point mapped on the plane, the path of the robot measured, and the circle and center point fitting the measured paths (Fig. 9). Next, when the measured path is mapped to a plane, the screen shows the amount of deviation from the plane. Finally, the analysis results are displayed on the screen numerically and the work is finished.

Positioning Accuracy: Positioning accuracy is measured at the same time when measuring the point to point of the robot (3), rising time, settling time, maximum overshoot and normal. The purpose of this study is to measure the state error and to measure the robot's important performance specifications.

When the measurement signal is received from the robot 3, the position values are continuously read and stored according to the sampling rate determined by the computer 7, and when the signal is received from the robot, the reading operation is terminated and analysis starts. . First, the error positioning command, the actual positioning command and the measuring position are simultaneously displayed in the axis unit on the screen, and each of them is displayed on the screen again. Finally, the analysis results are displayed on the screen numerically and the operation ends (figure 10).

Velocity Behavior: Velocity behavior is a measure of the tendency of the robot (3) to move in accordance with the speed command. It only obtains information about one axis in one measurement. First, the user determines the speed for one axis and passes it to the robot.

When the measurement start signal is input from the robot 3, the position value is read, and when the end signal is received, the reading operation is terminated.

After converting the read position data into the robot coordinate system, the values of the designated axis are differentiated according to the sample extract. The data obtained through this process is displayed on the screen together with the command, and then the operation is finished (Fig. 11).

12 is a view showing the operation for coefficient recognition, based on the concept of the kinematic program as follows.

의 최소화방법으로 해결할 수 있다.In this method, first, by using the least square method from the points obtained by rotating the respective joints, the plane of rotation and the center of rotation are evaluated, and from the plane of rotation, a vector (a) representing the joint axis corresponding to the unit standard vector of this plane is obtained. From the center of rotation, find the point (p) through which the joint axis passes. The motion parameters of the modified motion model are obtained from the obtained a and p. As can be seen from the illustrated schematic diagram, when the points obtained by rotating only the i-th joint are referred to as P _ij (j = l, ... m), the i-th rotation plane and the i-th rotation from the position data of these measured points Find the center. The problem of obtaining the i th rotation plane and the i th rotation center from the measured position data of the points (P _ij ) is that the points corresponding to the points on the rotation plane for which X _i are to be calculated, a are the unit standard for this rotation plane. If the vector, P _i , _c is the i-th center of rotation, a function with

This can be solved by minimizing

The transformation matrix is formed by defining the link coordinate frame presented in the rotation plane, the rotation center, and the deformation motion model obtained above. In this case, the deformation matrices obtained because the position data used are the coordinate values of the sensor subordinate frame. Deformation matrix indicating the i th coordinate frame with respect to the sensor subordinate frame.

The resulting deformation matrix

라고 하고 이로부터

를 구하면,Finally, the resulting deformation matrix is rotated from the joint to the first joint in turn.

From this

If you find,

로부터

를 구하는 것은 로봇 기준좌표에 대한 센서부좌표의 위치가 임의적이고, 센서부 좌표에 대한 센서부좌표의 위치가 임의적이고, 센서부 좌표에 위치를 로봇 기준 좌표에 대한 정확히 정의하기가 어렵다는 면에서 합당하다.Where for the sensor subordinate

from

Finding is reasonable in that the position of the sensor coordinates relative to the robot reference coordinates is arbitrary, the position of the sensor coordinates relative to the sensor coordinates is arbitrary, and it is difficult to accurately define the position of the sensor coordinates relative to the robot reference coordinates. Do.

As described above, the robot performance measurement and coefficient recognition device of the present invention is considered to have a great industrial use value, and thus, a robot manufacturer has a basis for improving the performance of a robot along with performance measurement and coefficient recognition processing of the manufactured robot. It is used as a measurement test equipment, and users of the robot can thoroughly inspect the robot's performance and measure the coefficients to improve absolute accuracy.

It can also be used as a counting device for plant machinery.

While the measurement system developed for the conventional robot performance measurement and coefficient recognition is limited in the measurement object, one system cannot meet the measurement objectives and ranges above, but also has a lot of limitations in terms of price and algorithm. The robot performance measuring and counting device of the present invention is inexpensive in terms of price and convenience, and meets the above measurement target. In particular, the robot performance measurement and coefficient recognition device of the present invention focused on securing the mobility of the measuring device, which is a driven part by design, but can also detect minute changes in the driving part.

Claims (3)

Supported by the support frame 12, a pair of rotary shafts 13, 13 ', which are in contact with the support frame 12 in the vertical and horizontal directions, and the support 17 and the linear bearing guides 18, 19 The robot measures the performance measurement and coefficient recognition tester 1 and the performance measurement and coefficient recognition tester 1 having a linear scale 14, an encoder 15 attached to the rotary shafts 13 and 13 ', respectively. Universal joint (2) for joint movement to (3) and up-down counter (8) for reading the position change amount of the tool tip of the robot (3) detected by the encoder (15) and linear scale (14) And a robot controller 4 for controlling the driving of the robot 3, a computer 7 to which the up-down counter 8 and the robot controller 4 are connected, and the computer 7 from the up-down counter 8; The position coordinates of the robot 3 can be calculated based on the transmitted position data to perform performance measurement and coefficient recognition of the robot 3. Robot performance measurement and counting device, characterized in that it consists of software to lock. According to claim 1, wherein the rotary shaft 13 is supported at both ends by a support bearing 16 to prevent shaking during rotation, the linear scale 14 is installed to rotate about the rotary shaft 13 ' The universal joint 2 is connected to a pair of flanges 21 and 25 by one end of the connecting rods 22 and 23 supported by ball bearings 26 and 28, and the connecting rod 22 ( 23) the other end of the robot performance measurement and coefficient recognition device, characterized in that interconnected via a connecting piece 24 and the ball bearing (27). 2. The software according to claim 1, wherein the software analyzes and evaluates the repeatability, linear accuracy, arc accuracy, position accuracy and speed error of the robot 3 from the position data transmitted from the up-down counter 8 to the computer 7. Robot performance measurement and counting device, characterized in that to display.

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