JPH0223109A - Synchronous control method for conveying means - Google Patents

Abstract

PURPOSE:To prevent misalignment between works by optimally, visually confirm a specified portion of a first work from a second conveying means side to detect the amount of misalignment between the first work and a second work, and correcting the misalignment by variance of the amount of travel of a first conveying means and the second conveying means during the detecting operation of the misalignment in synchronous operation of dependent conveyors, etc. CONSTITUTION:An optical detection means 22 consisting of a distance sensor 19, a two-dimensional camera 20, and a light source 21 is attached to a second conveying means 5 to visually confirm a drain hole 12 of a first work 2, and misalignment between the first work 2 and a second work 4 is detected by a specified calculating operation. On the other hand, while the optical detection means 22 detects and outputs the misalignment of the works, each amount of travel of a first conveying means 3 and the second conveying means 5 is respectively detected by a first detection means 34, and a second detection means 40 so as to obtain the amount of misalignment caused by output delay of the optical detection means 22. Based on the amount of misalignment, the misalignment optically obtained is then corrected. By this constitution, the misalignment between the works can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control method for synchronously operating mutually independent transport means such as conveyors, and in particular, to eliminate the occurrence of positional deviation between both eye transport means. The present invention relates to a method for synchronously controlling conveying means.

[Prior Art] In an automobile assembly device, the body of the automobile is supported by a first conveyor, and parts such as an engine are attached to a second conveyor. Parts such as an engine are attached to the body of the automobile while both conveying means are operated synchronously.

By the way, in the assembly apparatus that operates synchronously in this manner, when the first conveyor supports the automobile body, the position of the body often changes due to deflection of the conveyor chain or the like. For this reason, even though both conveying means are synchronized, misalignment between the body and the parts mounting device is likely to occur, and the engine cannot be assembled to the body as it is.

Therefore, in order to compensate for such positional deviation, various methods have been proposed in the past for synchronously controlling both conveying means.

As an example of this, for example, Japanese Patent Laid-Open No. 62-34868 is known. The control method disclosed in this publication performs the same ttlJ control of a vehicle body being conveyed by a conveyor and a parallel running device running alongside the vehicle body. In this control method, light is irradiated onto the vehicle body from an optical detection means installed on the side-by-side running device, and the illuminance of the anti-copper light is 15
is measured by an optical detection means, a specific position on the car body is detected from the illuminance distribution, and by aligning the specific position with the reference position of the parallel running device, the conveyor and (
It is possible to run in synchronization with the Jf running device.

[Problems to be Solved by the Invention] As mentioned above, among the optical detection means used for synchronous control of conveyors, etc., the following are currently in the practical stage:
There are two-dimensional cameras as linear sensors and visual sensors. Linear sensors take about 1 to 2 ram S from image capture to output, and there is no problem in substantially synchronously controlling the conveyance means, but since linear sensors cannot perform linear (one-dimensional) measurements, It is sensitive to vertical deviations and has a limited range of application.

On the other hand, with a two-dimensional camera, problems such as Niasen 4's structure can be solved, or the number of image elements to be processed is large, so the output time (processing time) is 1,760 to 1,730 yen.
The speed is delayed to 0 seconds, and it is not possible to determine what kind of speed change occurred on the vehicle body during that time. For example, when assembling workpieces using a transport conveyor that transports a car body and a parallel running device that moves in synchronization with the conveyor, suppose that the transport speed changes little by little due to surging of the transport conveyor, etc.
When a two-dimensional camera is used, the parallel running device performs speed control based on the camera only after one output time at the earliest, and the relative positional deviation between the vehicle body and the parallel running device increases during this time. Therefore, it becomes difficult to align the intermediate position with the parts to be attached to the vehicle body, resulting in a problem that work efficiency is significantly reduced.

The present invention is a method for synchronous control of transport means using an optical detection means such as a two-dimensional camera, and can improve the responsiveness of synchronous control when the transport speed of one transport means changes little by little. , it is an object of the present invention to provide a control method that can minimize positional deviations that occur between workpieces.

[Means for solving the problem] Synchronous control N+1 of the conveying means according to the present invention in accordance with this purpose
The method includes causing a second conveying means for conveying a second workpiece to travel synchronously with a first conveying means for conveying a first workpiece, and assembling the first workpiece and the second workpiece. In the synchronous control method of the conveyance means, the pA of a specific part of the first workpiece is detected by an optical detection means provided on the second conveyance means, so that the first workpiece and the second workpiece can be synchronously controlled. The amount of positional deviation is detected, the amount of movement of the first conveyance means is detected by the first detection means, and the second I
The amount of movement of the I & transport means is detected by a second detection means, and the positional deviation amount obtained by the optical detection means is detected between the first transport means and the second II within the processing time of the optical detection means.
It consists of something that corrects based on the amount of positional deviation with the R feeding means.

[Function] In this method of synchronous control of conveyance means, first,
The amount of positional deviation between the first workpiece and the second workpiece is detected by an optical detection means. In this case, the speed of the second conveying means may be controlled by j*iI based on the amount of positional deviation obtained by the optical detecting means, but since there is an output delay in the optical detecting means, the first The amount of movement of the Ill transport means and the second transport means is detected, and the positional deviation obtained by the above-mentioned optical detection means is corrected based on the small positional deviation at this time. This allows synchronization i
The responsiveness of i'l r+ll+ is increased, and the second one-shell feeding means can be synchronized with the first one (throwing means) with high accuracy. Therefore, the positions of the first workpiece and the second workpiece can be The amount of deviation is suppressed to an extremely small amount, and the first workpiece of the second workpiece
Easy to attach to the workpiece.

[Example] Hereinafter, a preferred example of a first method for controlling transfer means according to the present invention will be described with reference to the drawings.

1 to 3 show an embodiment of the present invention, and particularly show an example where the invention is applied to an automobile assembly line. A rail 1 is attached to a ceiling beam in an assembly factory, and a first conveying means 3 for conveying a car body 2 as a first work runs on this rail 1. The first +ta transport means 3 has arms 3a that hold the vehicle body 2 at the four corners, and the first transport means 3 is configured to travel at a preset constant speed (control 1).

A second conveying means 5 that can run synchronously with the first conveying means 3 is located below the first 100 conveying means 3 . The second conveyance means 5 is a parallel running device that runs on a traveling rail 7 provided on the floor i7i'16 of the assembly factory. An automatic work assembly device 8 for automatically attaching the liner 4 to the vehicle body 2 is loaded.

The automatic work assembly device 8 is composed of a slide rail section 9, a floating table 1G, a fender liner fixing pin (positioning pin) 11, a lifting device 12, a drive arm 13, and a tightening unit 14. The slide rail section 9 is directly attached to the second conveyance means 5, and the slide rail section 9 allows the floating table 10 to move in a direction perpendicular to the traveling direction. The floating table 10 is movable back and forth along the traveling direction, and the floating table 1
The fender liner fixing pin 11 is attached to the upper surface of the floating table 10 and is used to position the fender liner 4 as the second workpiece. It is something to do. Further, a drive arm 13 having a tightening unit 14 attached to its tip is fixed to the upper surface of the floating daple 10, and the drive arm 13 moves the tightening unit 14 to a designated location.
It is designed to tighten the tapping screw.

In this automatic workpiece mounting, the speed of the second transport means 5 loaded with the device 8 is controlled by a control device to be described later, so that it can travel in synchronization with the first transport means 3, which always travels at a constant speed. - A pole 18 extending upward is attached to the second conveyance means 5, and a distance sensor 19 and a two-dimensional camera 10 as a visual sensor are installed at the tip of the pole 18. Optical detection means 22 consisting of a light source 21 for the sense sensor is provided. The distance sensor 19 measures the distance between the first conveyance means 3 and the second conveyance means 5, and the two-dimensional camera 20 measures the drainage hole 12 formed at the bottom of the vehicle body 2. It is necessary to visually check and detect the positional deviation of the second conveying means 5 with respect to the drainage hole 12. The visual sensor light source 11 includes water 1 as a visual detection unit.
This is to illuminate the hole 23 and improve the reliability of the two-dimensional camera.

The second 1fEt feeding means 5 is driven by a servo motor 33 provided at the rear of the second conveying means 5. A rotary encoder 40 for position detection and a tacho generator 33 for speed detection are connected to the servo motor 33. The servo motor 33, the rotary encoder 401 and the tachometer generator 35 are
A control device 3 that controls the general transport means 3 and the second transport means 5
6. Similarly, the distance sensor 19, two-dimensional camera 20, and visual sensor light source 21 attached to the pole 18 are also connected to the control device 36. On the rail 1 of the first conveyance means 3, a limit switch 37 for detecting the start position and a limit switch 3 for detecting the position of the synchronization line 1 are provided.
8 and a rotary encoder 34 as a first detection means for detecting the moving distance of the first transport/transfer means 3 are installed at a predetermined interval, and both limit switches 37 and 38 are also controlled by the control device. 36.

FIG. 2 shows a block diagram of the synchronous control device for the conveying means according to this embodiment.

When the vehicle body 2 is transported to a predetermined position by the first transport means 3, the start position detection limit switch 37
The second transport means 5 is caused to run in parallel with the first lfl transport means. In this case, 2 as a visual sensor
The dimensional camera 20a5 and the distance sensor 19 measure the positional deviation ΔX of the specific part (the water drain hole 23), and after the calculation process, it is output to the control device 36. Immediately during the optical detection means 22, the encoder 34 attached to the first conveying means 3 side and the second conveying means 5 (11+1 encoders 40) running in parallel detect the positional deviation of each conveying means. Δya-Δyb is detected, and this positional deviation amount Δya-Δyb is added to the positional deviation amount ΔX by the optical detection means 22, and the gain G141 in the position δ loop is
is input.

On the other hand, the gain G243 in the speed loop contains the movement i! of the vehicle body 2 caused by the encoder 34 on the first conveyance means 3 side! The velocity ya obtained by differentiating the Jl suspension Δya with the differentiator 42 is input.

Therefore, the D/A (digital/analog) converter 45 has the velocity element and the position element added (Δχ
+Δya−Δyb)xG1+YaXG2 is transmitted.

After being converted into analog by the D/A converter 45,
The servo motor 33 is driven by this speed element via the servo driver 46.

Next, the operation in the above-described method for synchronously controlling the conveying means will be explained based on the flowchart shown in FIG.

Figure 3 shows a different method for determining velocity gain,
Cycle time 33.3 s, Gt = 3 [1/s
ec], G2 = 1 [1/sec].

First, in step 50, the start position detection limit switch 37 provided on the rail 1 is turned on by the first conveying means 3, and the process proceeds to step 51, where the automatic workpiece assembly device assembles the fender liner 4. The second transport means 5 loaded with 8 is started. When both conveying means 5 move in a predetermined direction (in the direction of the arrow), the process proceeds to step 52 and the distance between the vehicle body 2 and the second conveying means 5 is measured by the distance sensor 1) 19.

At almost the same time, as shown in step 53, the two-dimensional camera 20 as a visual sensor detects the amount of relative positional deviation of the second conveying means 5 with respect to the water bale hole 23 of the vehicle body 2 based on the measured value of the distance sensor 919. used.

Next, the process proceeds to step 55, and a difference is calculated from the moving amount for one cycle of the encoder 40 on the first conveying means 3 side and the encoder on the second conveying means 5 side running parallel to the first conveying means 3. In step 57, the difference in movement amount is added to the relative displacement fence shown in step 54.

In step 57, it is determined whether or not the positional deviation determined in step 54 is the same as the positional deviation determined in the previous determination. That is, in this step, the first conveying means 3
It is determined whether or not a steady state exists in which the small positional deviation of the conveyance means 5 in item 2 is constant.

As a result, if it is not in a steady state, proceed to step 58;
The servo motor 33 is controlled so that the speed of the second transport means 5 matches the speed of the first transport means 3, and step 5
Return to 2.

In step 57, if it is determined that the steady state is maintained, the process proceeds to step 59, where it is determined whether or not the second conveying means 5 is behind the first conveying means 3.

In step 60, if the second conveyance means 5 is behind the first conveyance means 3 by, for example, 3 m, the process proceeds to step 61, and the speed gain G2 is set to G2/100.
G2-〇, 70? ), proceed to step 63.

In step 63, the servo motor is controlled based on the corrected speed gain, and the second conveying means 5 is operated at a synchronous speed. Then, the process proceeds to step 64, where measurement is performed using the distance sensor υ19, and then roughly proceeds to step 65, where measurement is performed using the two-dimensional camera 20. Then, in step 66, the relative positional deviation between the first conveying means 3 and the second conveying means 5 is screened out, and the process proceeds to step 67.

In step 67, as in step 55, the water difference is calculated from the movement amount for one cycle of the encoder 34 on the first conveying means 3 side and the encoder 40 on the second conveying means 5 side running parallel to the first conveying means 3. It will be done. This difference in movement amount is tightened to the relative sliding suspension L2 in step 68, and then the process returns to step 59 again.

If it is determined in step 60 that the second conveying means 5 is not moving forward with respect to the first conveying means 3, the process proceeds to step 69, and a synchronizing signal is output to the control device 36. Then, the process proceeds to step 70, and measurement using the distance sensor +)9 is performed. In other words, proceeding to step 70 indicates a state in which the moving speeds of the first eleven transport means 3 and the second transport means 5 almost completely match.
In this state, the fender liner 4 as the second workpiece loaded on the second conveying means 5 is attached to the vehicle body 2.

Even in this state, as in the case above, the distance sensor 19 performs measurement in step 70, and the two-dimensional camera 20 as a visual sensor performs measurement in step 71.

In step 48, the relative deviation is calculated based on the fixed values on both sides, and in step 73, a difference is calculated from the movement i of one cycle of each encoder 34.40, and this difference in movement amount is added to the relative deviation ff1L3 in step 74. Ru. At step 75, the same gate speed control of the second conveyance means 5 is performed. When the second transport means 5 moves by a predetermined distance, the synchronization end position detecting limit switch 18 attached to the rail 1 is turned on by the first transport means 3.

In step 76, it is determined whether the synchronization end position has been detected. That is, it is determined whether the above-mentioned synchronization end position detection limit switch 38 is turned on, and as a result, if the synchronization end position has not been reached yet, the process returns to step 70 and the synchronization end position has been reached. If so, the process proceeds to step 77 and the synchronous operation of the second conveying means 5 is stopped.

When the synchronous operation is started, the servo motor 33 of the second conveyance means 5 is reversed, and the second conveyance means 5 is returned to its original position. Then, the process advances to step 79 and the control ends.

In this way, in steps 59 and 60, the delay or advance of the second conveying means 5 in the steady state is determined, and the value calculated in step 63 is output to the servo motor 33, and the amount of positional deviation is determined in steps 64 to 68. By repeating the loop from steps 59 to 68 again, a velocity feedforward gain G2 with a positional deviation of ±0rrvn is obtained. Then, by inputting this speed feedforward gain G2 as an optimum value to step 70, synchronous operation control is performed until step 79 with almost no positional deviation occurring.

Next, the operation of the apparatus for automatically assembling the workpieces loaded onto the second conveying means 5 will be explained with reference to FIG.

As shown in step 69 of the flow chart of FIG.
When entering a loop in which the relative positional deviation is ±OIM1, a signal indicating that synchronization is in progress is input to the control device 36. As a result, the automatic work assembly device 8 is activated in step 80 of FIG. 4, and the floating table 10 is raised in step 81. Subsequently, in step 82, the fender liner fixing pin 11 is raised, and the fender liner 4 is fixed. Once the fender liner 4 is fixed,
Proceeding to step 83, a screw (tapping screw) is supplied to the unit 14 for tightening. In step 84, the drive arm 13 is moved to the taught position, and in step 85, the unit 14 performs hiss tightening. Thereafter, this series of tightening operations is performed at a plurality of positions up to step 91.

When the screws at the specified positions are tightened, the fender
A liner 4 is fixed to the vehicle body 2. When the fender liner 4 has been assembled, the process proceeds to step 92, where the fender liner fixing pin 11 is lowered, and then step 93.
The floating table 10 is lowered. When the automatic work assembly of the fender liner 4 is completed by the device 8, the process proceeds to step 94, where a work completion signal is output to the control device 36, and at step 95, the automatic assembly control is completed.

FIG. 5 shows the measurement start signal from the control device 36 to the visual sensor and the output timing of the servo driver l\. As shown in the figure, when a measurement start signal @S1 is issued from the control device 36, measurement S2 by the two-dimensional camera 20 as a visual sensor and measurement S4 by the distance sensor 19 are executed, and based on these data, image data is Process S3 is carried out, and reading S5 of the two encoders 34, 40 is carried out simultaneously with the output. Then, from the results of image data processing S3 and reading S3 of each encoder, an output countermeasure 1se is made to the driver, and the output value @S
7 is output to the servo driver 46.

In this way, in the present invention, the response delay of the Domei control due to the output delay of the two-dimensional camera 20 is corrected by the signals from the encoders 34 and 40 provided on each Ifa sending means side, so that, for example, the response delay of the Domei control due to the output delay of the two-dimensional camera 20 is Even if the first conveyance means 3 changes little by little during the time from intake to output, the occurrence of positional deviation between the first conveyance means 3 and the second conveyance means 5 is eliminated.

[Effects of the Invention] As explained above, when using the synchronous control method of the conveyance means according to the present invention, the positional deviation mother obtained by the optical detection means is calculated as the first value within the processing time of the optical detection means. Since the correction is made based on the amount of positional deviation between the first conveying means and the second conveying means,
The response delay of synchronous control can be eliminated. In other words, the responsiveness of synchronous control can be improved compared to conventional methods.
The second conveyance means can be made to accurately follow the first conveyance means.

As a result, the second workpiece (fender liner) can be easily assembled to the first workpiece (vehicle body), and the workpiece assembly can be automated without manual work.

In addition, by being able to eliminate position errors in synchronous operation,
Assembly can also be applied to work processes that require precision.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an automobile line to which a synchronous control method for conveying means according to an embodiment of the present invention is applied, FIG. 2 is a block diagram of speed control in the apparatus of FIG. 1, and FIG. is a flowchart showing the flow of speed control for the device shown in FIG. This is a time chill route that indicates the timing of signal output, etc. 2.....First work (vehicle body) 3.
......First conveyance means 4...
...Second workpiece (fender liner) 5...Second conveyance means 19...
・・・・・・・・・Distance sensor 20・・・・・・・・・
...Visual sensor (2D camera) 22...
...Optical detection means 23...
・Water hole (visual detection part) 33...
・υ-Pomotor 34... First detection means (rotary encoder) 35... Tacho generator 36.
......Control device 40...
...Second detection means (rotary encoder) Whistle 3 Figure 5

Claims (1)

[Claims] 1. A second conveyance means for conveying a second workpiece is caused to travel synchronously with a first conveyance means for conveying a first workpiece,
In the synchronous control method of a conveyance means that enables the first workpiece and the second workpiece to be assembled, a specific portion of the first workpiece is visually recognized by an optical detection means provided on the second conveyance means. As a result, the amount of positional deviation between the first workpiece and the second workpiece is detected, the amount of movement of the first conveyance means is detected by the first detection means, and the amount of movement of the second conveyance means is detected by the first detection means. The amount of positional deviation detected by the second detection means and obtained by the optical detection means is corrected based on the amount of positional deviation between the first conveyance means and the second conveyance means within the processing time of the optical detection means. A synchronous control method for a conveyance means, characterized in that: