JPS6235864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position and orientation detection device for a welding robot.
This makes it possible to accurately detect the position and orientation of the welding torch regardless of the shape of the object to be measured.

Generally, when welding objects to be welded using an automatic welding robot, the relative positional relationship between the welding torch supported at the tip of the robot arm and the object to be welded is detected, and the robot arm is adjusted based on the detected value. Movement needs to be controlled. The conventional position detection device for this type of welding robot is as shown in Fig. 1a.
A welding torch 2 is supported at the tip of the robot arm 1, and a vertical position sensor 3 and a horizontal position sensor 4 are provided at the tip of the robot arm 1, respectively, to determine the position relative to the objects to be measured (workpieces) 5 and 6. The welding torch 2 of the robot arm 1 is moved by detecting it with each position sensor 3, 4, respectively. In addition, 7 is a welding part.

However, according to the conventional position detection device, since the position sensors 3 and 4 are installed apart from the welding torch 2, position detection or welding may become impossible depending on the shape of the objects to be measured 5 and 6. For example, as shown in Figure b, if the object to be measured 6' is short, the position cannot be detected by the horizontal position sensor 4, and as shown in Figure c, if the object to be measured 6' is short. If the upper end of the welding torch 2 protrudes toward the welding torch 2 side, the tip of the welding torch 2 cannot be guided to the welding part 7 due to interference between the horizontal position sensor 4 and the object to be measured 6'', and welding cannot be performed. There will be no.

Furthermore, the attitude of the welding torch 2 cannot be detected.

With the above points in mind, the present invention enables the position and orientation of a welding torch in three-dimensional space to be detected with a simple configuration, and includes a robot arm of a welding robot that freely moves in three-dimensional space,
a welding torch supported at the tip of the robot arm, an excitation coil that is directly attached to the outer periphery of the welding torch at equal intervals and generates an eddy current in the object to be measured, and a differentially wound excitation coil that generates an eddy current induced by the eddy current. A plurality of position sensors each consisting of a detection coil that detects a voltage detected by the welding torch, each of which has a detection direction inclined at an equal angle with respect to the axis of the welding torch, and a tertiary sensor of the welding torch that processes the output signals of each of the position sensors in time series. This is a welding robot position and orientation detection device characterized by comprising a signal processing circuit that detects a position and orientation in a source space.

Therefore, according to the present invention, in addition to being able to detect the position of the welding torch with respect to the object to be measured, a plurality of position sensors are arranged at equal intervals around the outer circumference of the welding torch, and the output signals of the respective position sensors are processed in time series. Therefore, the position and orientation of the welding torch in three-dimensional space can be easily detected.

First, Figures 2 and 3 show the position detection means.
The diagram will be explained.

In these drawings, 8 is a welding torch supported at the tip of the robot arm 1 of the automatic welding robot;
Reference numeral 9 denotes a position sensor which is directly attached to the outer periphery of the tip of the welding torch 8 and whose detection direction 9' is equal to the axial direction of the welding torch 8. It consists of two differentially wound detection coils with the same number of turns.

10 is an oscillation circuit, and when a voltage is applied from the oscillation circuit 10 to the excitation coil of the position sensor 9,
Eddy currents are generated in the object to be measured 11 in the axial direction of the welding torch 8 due to the magnetic lines of force generated in the excitation coil.
The magnitude of this eddy current varies depending on the distance or relative angle between the position sensor 9 and the object to be measured 11, and a minute voltage induced by the eddy current is detected in the detection coil of the position sensor 9. 12 is an amplifier circuit that amplifies the output voltage of the detection coil of the position sensor 9 to a predetermined level, 13 is an absolute value circuit that rectifies the output of the amplifier circuit 12, and 14 is a low-pass circuit that converts the output of the absolute value circuit 13 into a DC component. , 15 are output circuits for converting the levels of the signals processed by the amplifier circuit 12, the absolute value circuit 13 and the low-pass circuit 14, and for outputting the detected and processed signals as input signals to the control device of the welding robot. Operates as an interface circuit. In addition, 12
15 constitute a signal processing circuit 16 that detects the position of the welding torch 8 based on the output signal of the position sensor 9.

Therefore, the output obtained from the position sensor 9 varies depending on the distance or relative angle between the position sensor 9 integrated in the welding torch 8 and the object to be measured 11.
By signal processing the output of the position sensor 9,
The position of the welding torch 8 can be detected, and the same effects as described above can be obtained.

Next, the present invention will be explained with reference to the drawings from FIG. 4 showing an embodiment thereof.

First, FIG. 4 and FIG. 5 showing one embodiment will be explained.

In these drawings, the same symbols as above indicate the same things, and the difference is that three position sensors 17, 18, 19 consisting of an excitation coil and a detection coil are provided, and each position sensor 17, 18, 19 is welded. In addition to being attached directly to the outer circumference of the torch 8, the detection directions 17', 18' of each position sensor 17, 18, 19,
19' is inclined at 45 degrees with respect to the axis of the welding torch 8, and the detection directions 17', 18', 19' of each position sensor 17, 18, 19 have a mutual interval of 120 degrees on the circumference. The points are arranged like this.

Further, in FIG. 5, 20 is a multiplexer, 21 is a demultiplexer, and the oscillation circuit 1
The signals from 0 are sequentially input to the excitation coils of the position sensors 17 , 18 , and 19 by switching the multiplexer 20 , and the detection outputs of the respective detection coils are input to the signal processing circuit 16 via the multiplexer 20 . The switching of the multiplexer 20 and the demultiplexer 21 is performed by the control circuit 22, and the output signals of the position sensors 17, 18, 19 are sequentially scanned by the switching signal from the control circuit 22, and the welding torch 8 is Position and orientation are detected. Here, when the welding torch 8 is arranged perpendicularly to the planar workpiece 11, the outputs from each position sensor 17, 18, and 19 become equal, and the output level at this time causes the welding torch 8 and the workpiece to be measured. When the distance to the object 11 is detected and the welding torch 8 is tilted relative to the object 11 to be measured, the output level of each position sensor 17, 18, 19 changes individually, and due to the change, the welding torch 8 is The attitude, ie, the angle, with respect to the measurement object 11 is detected.

Next, FIG. 6 showing another embodiment will be explained.

In the one shown in FIG. 6, four position sensors 23, 24, 25, and 26, each consisting of an excitation coil and a detection coil, are arranged at equal intervals around the outer periphery of the tip of the welding torch 8. 23, 24, 2
5, 26 respectively detection directions 24', 25', 2
6' are perpendicular to the axis of the welding torch 8 and are arranged at 90° intervals on the circumference.

Therefore, each position sensor 23, 24, 25,
By processing the output signals of 26 in time series in the same manner as described above, it becomes easy to detect the position of the welding torch 8 in three-dimensional space.

As described above, according to the welding robot position/attitude detection device of the present invention, not only the position but also the attitude of the welding torch can be easily detected with a simple configuration.

[Brief explanation of the drawing]

Figures 1a, b, and c are block diagrams of a conventional position detection device for a welding robot, Figures 2 and 3 show position detection means, and Figures 2a and b are a front view and a front view of a welding torch. A side view, FIG. 3 is an electrical block diagram, FIG. 4 and the following drawings show an embodiment of the position/orientation detection device for a welding robot according to the present invention, and FIGS. 4 and 5 show the first embodiment. Figure 4a
5 is an electrical block diagram, and FIGS. 6a and 6b are front and side views of a welding torch according to another embodiment. 1... Robot arm, 8... Welding torch, 9,1
7, 18, 19, 23, 24, 25, 26...Position sensor, 16...Signal processing circuit.

Claims (1)

[Claims] 1. A robot arm of a welding robot that moves freely in three-dimensional space, a welding torch supported at the tip of the robot arm, and a welding torch that is directly attached to the outer circumference of the welding torch at equal intervals and generates an eddy current in the object to be measured. a plurality of position sensors each including an excitation coil and a differentially wound detection coil for detecting the voltage induced by the eddy current, each of which has a detection direction inclined at an equal angle with respect to the axis of the welding torch; A position/orientation detection device for a welding robot, comprising: a signal processing circuit that processes output signals of each position sensor in time series to detect the position and orientation of the welding torch in a three-dimensional space.