JPH0760666A - Work passage following device - Google Patents

Abstract

PURPOSE:To improve following accuracy of a tool by calculating an observation point vector and an information reliability factor in response to the movement of a manipulator according to sensor information, finding a passage function by adjusting a weighting function to the observation point vector by the reliability factor, and determining a positional posture orbit of the tool by the passage function and a passage following condition. CONSTITUTION:Prior to a tool 8, cross-sectional data of a work passage 9 is detected by a sensor head 101. According to this data, a signal processing part 2 calculates reliability of sensor data, and a formation discriminating part 3 calculates a position of a passage characteristic point and respective directional vectors, and finds an observation point vector. A passage creating part 4 converts the observation point vector into reference point coordinates by using positional information of a manipulator 7. This procedure is repeated according to the movement of the manipulator 7, and a weighting function is adjused to an obtained observation point vector group by a reliability factor, and a passage function of the next section is created, and is stored in a memory 5. A positional posture orbit of the tool is determined by the passage function and a passage following condition imparted beforehand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining path follow-up device for detecting a machining path by a sensor and causing a tool to follow the path with high accuracy based on the information.

[0002]

2. Description of the Related Art Conventionally, as a machining path follow-up device of this type, there is an automatic machining device disclosed in Japanese Patent Laid-Open No. 63-114853, which performs automatic machining by a sensor.

In this example, the case of application to the welding robot apparatus shown in FIG. 3 has been described. That is, FIG. 4A shows detection points P ₁ , P ₂ , on the welding line WL captured by the image sensor 16 of the visual sensor 15 of the robot 11.
P ₃ ... P _j ... P _n are shown, and these detection points are converted into position data (again, P ₁ , P ₂ , P ₃ ... P _j ... P _n ) on the robot coordinate system by the coordinate conversion device 17. The coordinates are converted and stored in the FIFO device (first-in first-out storage device) 18 described with reference to FIG. 3 as shown in FIG. 4B. In this storage, movement route interpolation information is added. It is assumed that the welding torch 13 has just arrived at the detection point P ₁ , this time is t ₁ , and the moving speed of the welding torch 13 is v (mm / sec). When the welding torch 13 arrives at the detection point P ₁ , [1] The robot controller 19 reads the position data P ₂ of the next detection point from the FIFO device 18 and detects the detection point P ₁
The movement path L ₁₂ of the welding torch 13 between −P ₂ is specified as shown in FIG. 4C based on a predetermined interpolation formula.

[2] When the moving route L ₁₂ is specified, the moving route L ₁₂ is set to 1, 2, as shown in FIG. 4 (c).
3 ... N is divided into N moving target points. The coordinates of each division point are P ₁ , P ₂ , P ₃ ... P _n .

[3] After setting the movement target points P ₁ , P ₂ , P ₃ ... P _N (= P) on the movement path L ₁₂ , 1
A division path (hereinafter, referred to as a movement vector) along which the welding torch 13 should move every control cycle T _0.

[Equation 1] That is, the movement vector

[Equation 2] Is calculated.

[4] Movement vector

[Equation 3] When the calculation of is completed, the movement vector to the current position P = P ₁

[Equation 4] Position vector

[Equation 5] Is sent to the joint angle conversion unit 20 as the next movement target point.
The joint angle converter 20 is a position vector

[Equation 6] Joint angle conversion matrix

[Equation 7] By the joint angle vector

[Equation 8] Convert to.

[5] In this way, the welding torch 13
Arrives at the detection point P ₂ , the next welding line position data P ₃
Is read from the FIFO device 18, and the above [1] to [4] are read.
Perform the operation of. After that, this operation is repeated.

As described above, this device specifies the tool path between two adjacent sensor detection points by calculation and sets the movement target value based on this.
It is intended to control the position of the tool. In such a method, due to the nature of using two adjacent sensor detection points, if there is an error in the detection data of either one or a large detection error, the specified route itself is Since the machining line is significantly different from the original machining line, the tool is controlled to an incorrect target as a result. Therefore, such a method, which uses the position detected by the sensor having a certain limit in reliability as the definite information, has an essential drawback that sufficient reliability cannot be ensured even as an apparatus.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in the prior art, means for estimating a reliable route with high reliability in response to a decrease in reliability of sensing or a malfunction of a sensor. Because it does not provide any
It is an object of the present invention to solve the problem that it was difficult to cause a manipulator to follow a path with high accuracy, and to provide a processing path follow-up device that allows a tool to follow a processing path with high accuracy.

[0010]

In order to achieve the above object, the machining path follow-up device of the present invention represents the coordinates of the detected point on the machining path from the machining path section data obtained by processing the sensor information. The observation point vector, which consists of both the position vector and the direction vector that characterizes the machining path cross-sectional shape, and the reliability factor, which represents the accuracy of the sensor information, are sequentially calculated in correspondence with the movement of the manipulator. By fitting a plurality of observation point vector groups with weighting functions using their respective reliability factors, the path function of the next section that satisfies the predetermined connection condition with the already created path function Is generated, and the position / orientation trajectory of the tool is determined based on the path function and the predetermined tool path following condition, and these steps are performed sequentially. Tool machining path, characterized in that to operate the manipulator so that can continuously follow the.

The conventional technique is that the observation point vector of the machining route is utilized together with the reliability factor, and that the route function is sequentially generated by the weighting function adaptation considering the reliability factor. The difference is that the position / orientation trajectory of the tool is determined based on the function and the working conditions.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 is a sensor portion comprising a sensor head 101 mounted at the tip of a manipulator, for example, a laser section sensor of the optical cutting type. And 2 is a signal processing unit, 3 is a shape identification unit, 4 is a path generation unit, 5 is a memory unit, 6 is a motion control unit, 7 is a manipulator, 8 is a processing tool such as a welding torch, and 9 is an overlapping section. A recognizable machining path represented by 10 is a workpiece.

Next, the initial operation of the manipulator will be described.

Consider a work in which the position and orientation of the work point on the machining path 9 can be represented by path functions. At this time, the manipulator 7 uses the route parameters s = s _i−1 to s = s.
_i- th arbitrary path function P representing a piecewise path to i
The tool 8 is controlled to be positioned at a predetermined relative position and orientation on the machining path 9 on the workpiece along a predetermined trajectory given based on (s _i ) and the path function Q (s _i ) of the attitude.

In the sensor unit 1, at this time, the sensor head 101 held at the hand of the manipulator 7 scans the machining path 9 so as to move ahead of the tool 8 to acquire sensor data. By using the sensor unit 1 such as a light-section type laser sensor, the cross-sectional data of the processing path 9 can be detected with high accuracy.

The signal processing unit 2 calculates highly accurate two-dimensional cross-section data by filtering the sensor data. At the same time, the reliability of the sensor data is calculated based on the main information such as the laser power fluctuation and the signal level fluctuation.

The shape identification unit 3 calculates the position vector of the route feature point and the direction vector of that point in the sensor coordinate system from the cross-section data, and each observation point vector u
_{Let i + m} and v _{i + m} . For example, in a groove machining operation in which the groove portion of the cross-sectional shape of the path is approximated to a V-shaped pattern, the intersection of two ridge lines forming the groove portion can be regarded as a feature point, and therefore the position vector of this intersection and one of By using the ridge as a reference, the direction vector that characterizes the cross section can be determined (see FIG. 2). The shape identifying unit 3 can also calculate the reliability by, for example, monitoring the magnitude of the variation of the calculated observation point vector from the previous sample.

The path generation unit 4 uses the position information of the manipulator 7 to convert the observation point vector into reference point coordinates. For example, the position vector u of the observation point is converted into the vector U of the reference coordinate system. In this way, the observation point vector groups U _{i + 1} and U _{i + m} combined with the observation point vectors that have already been observed / calculated / converted in the same procedure and stored in the memory unit 5 are calculated by, for example, the least squares method. It is compatible with the polynomial function used. At this time, s of the path function P (S _i )
= S _i, the terminating condition, such as the position vector or the tangent vector, is made continuous, and each observation point vector is weighted by the reliability given simultaneously. For the path function generated in this way, s = s
For the section from _i to s = s _{i + 1} , the piecewise path function is adopted again as the (i + 1) th path function P (s _{i + 1} ). A path function Q (s _{i + 1} ) is similarly created for the direction vector v of the observation point.

By the above procedure, the tangent vector in the path direction and the direction vector perpendicular to the tangent vector and capable of specifying the groove shape in the path cross section are determined again at the generated arbitrary point on the machining path 9. .

The memory unit 5 sequentially stores the generated piecewise path function parameters together with the operation information of the manipulator 7 corresponding to the path parameter s, and sequentially sends them to the motion control unit 6 of the manipulator 7 based on a command. .

The final motion control section 6 refers to the tangent line and the normal line at an arbitrary point on the path 9 obtained by using the generated path function, and refers to the relative positions of the processing path 9 and the processing tool 8. Based on work conditions that define the speed and the like, the continuous position / orientation trajectory of the machining tool 8 mounted on the manipulator 7 is determined, and the manipulator 7 is operated with this as a target value.

By sequentially repeating the above procedure, the generation paths are sequentially connected, and as a result, the machining tool 8 smoothly follows the predetermined machining path 9.

Regarding the follow-up start point, one or more path functions may be set in the vicinity of the start of the machining path 9, and the path generated by the sensor unit 1 may be connected thereto. . If the reliability of the detected sensor information is equal to 0, it is possible to use the path function of the previous section as it is without generating a path using it.

Due to such a structure, even if the sensor unit 1 detects erroneous data due to a short defect,
A probable route is estimated based on the reliability calculated at the same time as the data, and as a result, the manipulator trajectory with high accuracy is always determined.

[0026]

As described above, according to the present invention, even if the sensor intermittently detects erroneous data, a probable route is estimated based on the reliability calculated at the same time as the data. Since a highly accurate manipulator trajectory is always determined as, the high-precision path following of the tool is not hindered because there is no reliable means for path generation unlike the conventional method. The effect that a reliable and highly accurate machining path follow-up device is realized is produced.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of an observation point vector by sensing according to the present invention.

FIG. 3 is a configuration explanatory view showing a conventional welding robot apparatus.

FIG. 4 is an explanatory diagram for explaining the operation of FIG.

[Explanation of symbols]

1 ... Sensor unit, 2 ... Signal processing unit, 3 ... Shape identification unit, 4 ...
Path generation unit, 5 ... Memory unit, 6 ... Motion control unit, 7 ... Manipulator, 8 ... Machining tool, 9 ... Machining path, 10 ... Machining work, 11 ... Robot, 13 ... Welding torch, 15 ... Visual sensor, 16 ... Image processing device 17, coordinate conversion device 17,
18 ... FIFO device, 19 ... Robot control device, 20 ...
Joint angle converter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G05D 3/12 S 9179-3H K 9179-3H // G05B 19/19 H 9064-3H (72) Inventor Tadashi Mohri 1-6, Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Toru Kaneko 1-1-6, Uchisaiwai-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Koji Otani 1-6, Saiwaicho, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Naoki Takekawa 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A tool for machining an object, a sensor for detecting a machining path prior to the tool, and a manipulator for holding the sensor, and the tool on the machining path based on the information detected by the sensor. A machining path tracking device that moves a manipulator so as to track the position vector representing the coordinates of the detection point on the machining path and the direction characterizing the machining path cross-sectional shape from the machining path cross-section data obtained by processing the sensor information. The observation point vector composed of both the vector and the reliability factor that represents the accuracy of the sensor information, and a means for sequentially calculating the manipulator movement and a plurality of calculated observation point vector groups. , By fitting the weighting function using the respective confidence factors, A means for generating a path function for the next section that satisfies a predetermined connection condition, and a position / orientation trajectory of the tool is determined based on the path function and a predetermined path following condition of the tool, and these steps are sequentially performed. A machining path tracking device having means for operating a manipulator so that a tool can follow the machining path continuously.