JPH01245108A - Calibrating method for work positioning device - Google Patents

Abstract

PURPOSE:To shorten the time required for deriving the accuracy after the installation by measuring an operating position of a positioning robot of a work positioning device after it has been installed in a use place, by a measuring robot and executing a calibration, based on its result. CONSTITUTION:An operation instructing signal is applied to a controller 8 from a main controller 14, and by a program which has been inputted to the controller 8 in advance, a robot 5 is moved so that a reference point of a work receiving jig 6 is positioned, based on the position relation at the time when the directions of each orthogonal coordinate axis of a positioning robot 5 and a frame 4 have coincided with each other. Subsequently, by the program, an operation instructing signal is applied to a measuring robot controller from the controller 8, and a probe of a contact type sensor of a measuring robot 15 is operated so as to come into contact with a detecting block which has been protruded from the side face of the jig 6 which is stopping. In such a way, an actual position of the reference point of the jig 6 at the time when the robot 5 has been operated so that the reference point of the jig 6 is positioned can be derived from a result of calibration of operating position data of the robot 15.

Description

Detailed Description of the Invention (Industrial Application Field) This invention moves and arranges a plurality of gauge parts for positioning workpieces based on the operation of a plurality of positioning robots, and positions a plurality of workpieces relative to each other. The present invention relates to a method for calibrating the operating position of the positioning robot of a workpiece positioning device.

(Prior Art) As an example of the above-mentioned workpiece positioning device, there is one previously disclosed by the present applicant in Japanese Patent Laid-Open No. 144595/1983.

FIG. 5 shows the above device installed on an automobile body assembly line.
This is a perspective view showing a configuration using a Cartesian coordinate robot as a positioning robot, which is applied to the assembly stage of the main parts of the car body, which almost determines the assembly accuracy of the car body, and 1 in the figure is the stage for assembling the main parts of the car body. The workpiece positioning device is shown in the figure.

In this assembly line, car body panels such as the main floor, left and right side panels, rear panels, cowl top assembly, shelf panel, etc. are delivered to the main body part assembly stage, and the body panels are assembled at that stage. The workpiece positioning device 1 positions the panel at a relative position that satisfies a predetermined assembly accuracy, and then, on the same stage, the positioned panels are temporarily joined together by spot welding to improve the assembly accuracy of the car body. After that, the main body part 2 determined to be assembled is assembled, and then the main part 2 of the car body is transported to other stages (not shown) by the shuttle conveyor 3, and additional spot welding is performed on the main part 2 of the car body at those stages. At the same time, vehicle body panels such as front and rear roof rails and roof panels are further assembled to assemble the vehicle body, and the assembly accuracy of the vehicle body is measured in the subsequent stage (not shown). In order to position each of the constituent body panels, the workpiece positioning device 1 includes a frame 4, a number of orthogonal coordinate type positioning robots 5 attached to the frame 4, and a -base positioning robot 5 as a hand portion thereof. One or more workpiece receivers are each equipped with a jig 6, and the positioning robot 5 is also equipped with an air cylinder-driven workpiece clamping device 7 as a hand section as required.

Here, as shown in FIG. 6, the workpiece receiver jig 6 moves a large number of adjacent strips one by one forward and backward in the same direction using a servo motor, and shapes the tip edges of the strips into a predetermined shape. By fixing the strips together with a fixing device, it is possible to form a gauge section 6a as a positioning means that can position and hold the workpiece. No. or patent application 1986-12193
(Refer to No. 1), using this function, the workpiece positioning device 1 adjusts the shape of each of the numerous positions to be positioned on each body panel constituting the main part 2 of the car body, and the workpiece holder corresponding to that position is fixed. By making the shapes of the gauge portions 6a of the tools 6 match each other, and at the same time, by the operation of each positioning robot 5, the workpiece receivers are placed in the predetermined positions of the jigs 6, and by extension, the gauge portions 6a thereof, respectively. The vehicle body panels can be positioned relative to each other and fixed by operating each work clamp device 7.

Then, the control device 8 of the positioning robot 5 controls the sixth positioning robot 5.
As shown in the figure, a calculation unit 9 consisting of a normal CPU, a memory 10 used for storing operation instruction signals and calculation processing,
The workpiece holder is an interface 11 for inputting an operation instruction signal including position data of the gauge part 6a of the jig and outputting an operation confirmation signal, and the servo motor and workpiece holder provided for each coordinate axis direction of the positioning robot 5 are connected to the jig. The servo controller 12 controls the operation of the servo motor for driving the strips of 6 through the amplifier unit 3, and the workpiece holder is connected to the jig 6.
It is equipped with a controller (not shown) for controlling the operation of the strip fixing device and each work clamping device 7, and is connected from the main control device 14 of the workpiece positioning device 1 to the interface 11.
Each positioning robot 5 and workpiece receiver controls the operation of the jig 6 and workpiece clamping device 7 based on the operation instruction signal inputted through the robot, and outputs an operation confirmation signal when the operation is completed.

(Problems to be Solved by the Invention) By the way, when installing the workpiece positioning device 1 on the vehicle body main part assembly stage, in order to ensure sufficient positioning accuracy of each gauge part 6a, the operating position of each positioning robot 5 is adjusted. needs to be calibrated to correspond to the coordinate system of the main body part assembly stage. Conventionally, this calibration work was first performed for each positioning robot 5.
Calibration data is obtained by measuring the operating position in the direction of the three orthogonal coordinate axes with a measuring device such as a three-dimensional measuring device,
Next, these positioning robots 5 are assembled at predetermined positions of the frame 4 assembled with a predetermined precision so that the direction of each coordinate axis of the positioning robot 5 matches the direction of the three orthogonal coordinate axes of the frame 4, and then The frame 4 is installed on the main body assembly stage so that the direction of each coordinate axis of the frame 4 coincides with the direction of the three orthogonal coordinate axes of the stage, and then the frame 4 is installed or transported to that stage. This was done by correcting the distortion of the frame 4 while measuring it with a surveying device, and then obtaining calibration data for converting the coordinate system of the frame 4 to the coordinate system of the stage.

However, in the above method, in order to guarantee the operating position of each robot after assembly to the frame 4, the accuracy of the installation of the frame 4 to the main body part assembly stage and the distortion of the frame 4 after installation are required. Corrections must be made with extremely high precision, and since the frame 4 is an extremely large structure, it is extremely difficult and time consuming to make the corrections accurately.

The present invention provides a calibration method that advantageously solves these problems.

(Means for Solving the Problems) A method for calibrating a workpiece positioning device according to the present invention involves moving and arranging a plurality of gauge parts for positioning the workpieces based on the operations of a plurality of positioning robots. When calibrating the operating position of the positioning robot/nod of the workpiece positioning device that positions each other, the measuring robot whose operating position has been calibrated in advance is adjusted to the working range of the measuring robot and the workpiece positioning device installed at the place of use. The robot is transported to a position where the operating range of the positioning robot at least partially overlaps with the coordinate system of the measuring robot and the coordinate system of the location of use has a predetermined positional relationship, and is removably fixed at that position. Then, actuate the positioning robot and actuate the measurement robot, measure the position of the gauge section after movement due to the operation of the positioning robot by the measurement robot, and based on the measurement result of the measurement robot. The present invention is characterized in that the operating position of the positioning robot is calibrated.

(Function) According to this method, the operating position of the positioning robot of the workpiece positioning device after it has been installed at the place of use is calibrated in advance, and the positional relationship between its coordinate system and the coordinate system of the above-mentioned place of use is determined. The identified measurement robot measures within the range where the operating ranges of these robots overlap, and the operating position of the positioning robot is calibrated based on the measurement results, so it is easy to install the frame of the workpiece positioning device that supports the positioning robot. The accuracy required for distortion correction can be reduced while guaranteeing the operational accuracy of the positioning robot, and the period required for achieving accuracy of the workpiece positioning device after installation can be significantly shortened.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a perspective view showing an embodiment in which the workpiece positioning device calibration method of the present invention is applied to the workpiece positioning device shown in FIG. 5. In the figure, the same parts as the device shown in FIG. It is indicated by the same code.

That is, 1 in the figure indicates a workpiece positioning device, and this workpiece positioning device 1 is used to place workpieces such as a floor main, left and right side panels, a rear panel, a cowl top assembly, and a shelf panel on a main body assembly stage of an automobile body assembly line. It is installed to mutually position vehicle body panels such as for temporary fixing, and as shown in FIG. The servo motor (M) 5a for each coordinate axis direction of each positioning robot 5 and the servo motor (M) 6b for driving the strip of the jig 6 serve as the workpiece holder.
It also controls the operation of the work clamp device 7.

To install this workpiece positioning device 1 on the stage, first, the workpiece positioning device 1 is mounted on the frame 4, and the workpiece holder is equipped with a jig 6 and a workpiece clamping device 7 as a hand portion as required. Temporarily assemble the robots 5 so that the directions of the orthogonal coordinate axes of the robots roughly match the directions of the orthogonal coordinate axes set on the frame 4,
Thereafter, the frame 4 is transported from the assembly location to the vehicle main part assembly stage and fixed to the stage so that the direction of the orthogonal coordinate axes of the frame approximately coincides with the direction of the orthogonal coordinate axes of the stage. It is being done.

When calibrating the operating position of each positioning robot 5 of the workpiece positioning device 1, in this example, first, as shown in FIG. 1, using the shuttle conveyor 3 of the assembly line,
A Cartesian coordinate type measuring robot 15 is carried into the frame 4, and preferably the measuring robot 15 is moved so that the Cartesian coordinate system of the measuring robot 15 has a predetermined relationship with the Cartesian coordinate system of the main body part assembly stage. The direction of the orthogonal coordinate axes of the measuring robot 15 matches the direction of the orthogonal coordinate axes of the stage, and the values on each coordinate axes of the stage are obtained by adding or subtracting a predetermined value to the values on each coordinate axes of the measuring robot 15. 5 is removably fixed to the stage.

As shown in FIG. 2, the measurement robot 5 here includes a base 16, a movable base 17, a column 18, and an arm 19. An unillustrated X-axis drive mechanism driven by a ball screw, for example, is provided to move the stage 17 back and forth in the transport direction of the shuttle conveyor 3, that is, in the horizontal Y-coordinate axis direction (indicated by arrow Y in the figure). An arm 19 is placed inside a support 18 erected on the stage in the vertical Z-axis direction (arrow Z in the figure).
For example, a ball drive X
A shaft drive mechanism is provided in the arm 19 to drive the arm 19.
This stage is moved horizontally and reciprocally in the direction of the X coordinate axis (indicated by arrow X in the figure), which is perpendicular to the direction of the Y coordinate axis,
For example, a ball-driven X-axis drive mechanism is provided, and contact distance sensors 20 are provided at both ends of the arm 19, respectively.

Here, as shown in FIG. 3, the X-axis drive mechanism, the X-axis drive mechanism, and the The contact sensor 20, which is connected to a measurement robot control device 23 having a configuration similar to that of the control device 8 shown in FIG. The contact sensor 20 can be moved within a range that includes the operating range of all the positioning robots 5 provided in the measuring robot 4, and the movement position of the contact sensor 20 due to the operation of each of the above-mentioned drive mechanisms of this measuring robot is measured in advance by a three-dimensional measuring device. and calibrated.

After the measurement robot 15 is placed and fixed on the vehicle body main part assembly stage, the measurement robot control device 23 is
is connected to the control device 8 so that the operation of the measuring robot 15 can be coordinated with the positioning robot 5.

Here, an operation instruction signal is given to the control device 8 from the main control device 14, and the directions of the orthogonal coordinate axes of the positioning robot 5, the frame 4, and the stage are aligned with each other according to a program input into the control device 8 in advance. Based on the positional relationship between the positioning robot 5 and the workpiece holder it is equipped with, the reference point set on the jig 6 is set to the positioning robot 5 as shown in FIG.
Points 101 to 120, three on each side, defining a cube or rectangular parallelepiped that extends to near the operating limit of the stage, and the direction of each side coincides with the coordinate axis direction of the stage.
The measuring robot is operated so as to move along a sequential route and stop for a certain period of time at those points, and according to the above program, an operation instruction signal is given from the control device 8 to the measuring robot control device 23, and the measuring robot 15, as shown in FIG. 2, the workpiece receiver while the probe 20a of the contact sensor 20 is stopped at each of the above points comes into contact with three mutually perpendicular surfaces of the cubic detection block 6c protruding from the side surface of the jig 6. Activate it.

As a result, when the positioning robot 5 is operated so that the reference point of the workpiece holder jig 6 is located at each point 101 to 120 in the coordinate system of the main body assembly stage, the workpiece holder is placed on the jig. The actual position of the reference point 6 is determined from the calibration result of the operating position data of the measuring robot 15,
Thereafter, the actual positions of these reference points are sent from the measurement robot control device 23 to the control device 8, and the control device 8
Based on the error between the actual position of the reference point and the position instructed to the positioning robot 5, data for calibrating the specified position, and even the operating position, is determined and stored, If there is a deviation from the coordinate axis direction, try to eliminate the deviation.
The positioning robot 5 is mounted on the frame 4 by correcting its posture, and then, based on the above calibration data, perform the above procedure again for representative points 101°105 and 115.110 among the above points to confirm the calibration data. do.

By performing this procedure for all the positioning robots 5, it is possible to obtain highly accurate calibration data for making the movement positions of all the positioning robots 5 of the workpiece positioning device 1 correspond to the coordinate system of the main body part assembly stage. Moreover, according to this method, the positioning robot 5 can be mounted on the frame 4 without significantly increasing the accuracy and the accuracy of the installation position of the frame 4 on the stage, and with little or no distortion correction of the frame 4. Since the operating position of the positioning robot 5 can be guaranteed at any time, the accuracy of the workpiece positioning device 1 at the place of use can be easily achieved in a short period of time.

Furthermore, according to the method of the above example, since the work procedure is stored in advance as a program in the control device 8, the work of collecting calibration data of all the positioning robots 5 can be performed automatically without human intervention. can.

After the collection of calibration data is completed, the workpiece positioning device 1 can be used by removing the measurement robot 15 from the main body assembly stage and transporting it out of the stage by the shuttle conveyor 3.

Although the above description has been made based on the illustrated example, the present invention is not limited to the above-mentioned example. Of course, the invention is applicable, and the measurement of the operating position of the positioning robot by the measuring robot may be performed using a non-contact type sensor.

(Effects of the Invention) Thus, according to the method of the present invention, the operating position of the positioning robot of the workpiece positioning device after it is installed at the base of use is measured by the measurement robot, and calibration is performed based on the result, so that the workpiece positioning The accuracy required for installing the frame that supports the positioning robot and correcting distortion of the device can be reduced while guaranteeing the operating accuracy of the positioning robot, and the time required to improve the accuracy of the workpiece positioning device after installation can be significantly reduced. Can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the workpiece positioning device calibration method of the present invention, FIG. 2 is a configuration diagram showing the structure of the workpiece positioning device and measuring robot used in the above example, and FIG. FIG. 4 is a path diagram showing the operating path of the positioning robot in the above example; FIG. 5 is a perspective view illustrating a conventional example and a workpiece positioning device used in the above example; FIG. 6 is a configuration diagram showing the configuration of the workpiece positioning device. 1... Workpiece positioning device 5... Positioning robot 6... Workpiece holder is jig 6
a... Gauge section 8... Control device 14...
・Main controller 15...Measuring robot 20...
・Contact sensor patent applicant Nissan Motor Co., Ltd. Figure 4

Claims (1)

[Scope of Claims] 1. A workpiece positioning device in which a plurality of workpiece positioning gauge parts are moved and arranged based on the operation of a plurality of positioning robots, and a plurality of workpieces are mutually positioned. When calibrating the working position, the measuring robot whose working position has been calibrated in advance is operated so that the working range of the measuring robot and the working range of the positioning robot of the workpiece positioning device installed at the place of use at least partially overlap; and the coordinate system of the measuring robot and the coordinate system of the place of use have a predetermined positional relationship, and are removably fixed at that position, and then the positioning robot is operated and the measuring robot is The measuring robot measures the position of the gauge section after movement due to the operation of the positioning robot, and calibrates the operating position of the positioning robot based on the measurement result of the measuring robot. , a method for calibrating a workpiece positioning device.