JPH0741417B2 - Locus interpolator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a trajectory interpolation device which is attached to a movable body and is capable of moving a tool to a desired position with respect to the movable body.

[Conventional technology]

In manufacturing automobile body parts, instrumentation parts, etc., it is necessary to form a large number of small holes for tightening screws, bolts and nuts, small holes for inserting various parts, polygonal holes, long holes, and the like. This small hole processing is generally performed by press punching, but in the case of a three-dimensional molded product such as an automobile body part, it is difficult to set it in the press die, and the model change or The shape and size of the molded product differed depending on the vehicle model, making it difficult to apply punching.

For this reason, small hole processing using a robot has been conventionally performed. FIG. 16 shows a side view of an apparatus for performing this small hole machining. A multi-degree-of-freedom robot in which a plurality of arms 1a and 1b are connected is used.
The tool 2 is attached to the tip of the. As the tool 2, for example, a laser gun, a plasma gun, a water jet gun, or the like is used, and a circular hole interpolation operation is performed based on a high-speed calculation of a controller that controls a robot, and a small hole 4 having a predetermined diameter is formed in a workpiece 3 that is three-dimensionally machined. To form.

Also, for polygonal holes, oblong holes, etc., linear interpolation,
It is formed by combining circular interpolation.

[Problems to be solved by the invention]

However, there is a problem in the circle and irregular shape trajectory interpolation control by the robot that a predetermined hole cannot be drilled for the following reasons (1) to (3).

Since the hole processing is non-contact processing, a laser gun or a plasma gun is often used as a tool, and the peripheral speed of the hole processing determined by the characteristics of these tools is much faster than the control speed of the robot.

Since the diameter of the hole to be machined is as small as 4 to 20 mm, circular interpolation is difficult.

In a structure in which a tool is controlled by an irregular shape trajectory interpolation calculation of two orthogonal axes (XY table), the unit becomes large, the cost is high, and the cable processing of the tool, the motor, etc. is difficult.

The present invention has been made to solve the above-mentioned problems, and even a robot having a slower control speed than the machining speed of a tool can be used for machining small-diameter circles and irregular-shaped holes,
It is an object of the present invention to provide a trajectory interpolating device which is small in size and which can easily handle cables for supplying energy to a tool.

[Means for solving problems]

In order to achieve the above object, the present invention is a trajectory interpolating device which is attached to a movable body and is capable of moving a tool to a desired position with respect to the movable body. A cylindrical rotation shaft rotatably supported on the rotation shaft, and a rotation center which is supported at the tip of the rotation shaft so as to be able to rotate and revolve, and which has a rotation center at a position separated from the rotation center of the rotation shaft by a predetermined distance. , An operating axis that holds the tool so that the point of action of the tool is located at a position separated from the center of rotation by a predetermined distance, and inside the axis of rotation, around an axis parallel to the axis of the axis of rotation. A cylindrical drive transmission shaft that is rotatably supported and that transmits a drive force to the operating shaft, and a cable that transmits energy to the tool are passed through the shaft center portion of the drive transmission shaft to enable the operation of the movable body. Independently controls the rotation axis and motion axis. The tool is moved along a circle and an irregularly shaped trajectory.

[Action]

Hereinafter, the outline and principle of the present invention will be described, and then the operation thereof will be described.

As shown by reference numeral 5 in FIG. 1, the trajectory interpolation device according to the present invention is basically attached to the tip of the arm 7b on the tip side of the robot 6 having a large number of arms 7a, 7b. At the same time, the tool 8 is gripped in this mounted state and operates to give various operations to the tool 8. This operation is performed independently of the robot 6 after the robot 6 positions the tool, and thus the tool 8 processes the small hole 10 having a predetermined diameter at a predetermined position in a non-contact state with the work 9. In this case, if the work 9 is a three-dimensional molded product, the mechanism of the multi-degree-of-freedom robot 6 needs to have five degrees of freedom with respect to the three-dimensional curved surface of the work. Two degrees of freedom are required for the setting mechanism (hole diameter changing mechanism at the processing point), and the system as a whole has 7 degrees of freedom.
The mechanism of freedom is a prerequisite.

On the other hand, when the work 9 is flat, the robot 6 functions in three degrees of freedom, and therefore the system as a whole has a mechanism of five degrees of freedom. The tools supported by the trajectory interpolation device 5 are:
Various tools such as YAG laser gun, carbon dioxide laser gun, plasma gun or water jet gun are selected.

The locus interpolator 5 is basically provided with numerical information such as the moving speed of the tool and the radius (or diameter) of the circular motion of the tool or the long side of an irregular shape, and the numerical value given within a preset range is given. It has a structure that changes the tool position correspondingly. The function of determining the motion speed and motion trajectory of the tool is independent of the motion of the main body of the robot 6, and the motion of the tool 8 is controlled by the trajectory interpolation device 5.

Next, the principle of circle locus interpolation in the locus interpolation apparatus according to the present invention will be described with reference to FIGS. 2, 3, and 4. FIG. 2 shows the operating locus of the circular movement, and FIG. 3 is a characteristic diagram showing the relationship between the rotation angle and the radius of the circular movement. In FIG. 2, 11
Is the center of rotation of the rotation axis rotatably supported at the tip of the robot (hereinafter, T ₁ axis). A position separated from the rotation center 11 of the T ₁ axis by a distance r is a rotation center 12 of the operation axis (hereinafter, referred to as T ₂ axis). T ₂ shaft is supported by a T ₁ shaft, if rotation is T ₁ shaft, T ₂ shaft is T ₁ shaft and rotating integrally (revolution), and, T ₂ shaft independent of the T ₁ shaft Rotate (rotate). A tool (a tool 8 is omitted in FIG. 2) is gripped on the T ₂ axis at a tool position 13 separated from the rotation center 12 by a predetermined distance. The distance from the center of rotation of the T ₂ axis to the tool position 13 is also equal to r. Then, if the T ₁ axis is held stationary and only the T ₂ axis is rotated, the tool moves along the circular locus 14. If the T ₁ axis is rotated while the T ₂ axis is kept stationary, the tool moves along the circular locus 15.

Now, a line segment connecting the rotational center 12 and T ₁ rotation center 11 of the shaft of the T ₂ shaft, if the angle between a line segment connecting the center of rotation 12 and the tool position 13 of the T ₂ shaft theta, T ₁ Axis rotation center 11 and tool position
The distance from 13 is represented by a function R (θ) of θ and has the relationship shown in FIG. The distance R (θ) is information regarding the radius of the circular motion of the tool (that is, the radius of the small hole to be machined),
It is given to the trajectory interpolation device 5. Then, R (θ) can be uniquely determined by the following equation (1).

Therefore, from the radius R (θ) of the circular motion of the tool in equation (1),
The rotation angle θ of the T ₂ axis can be calculated by the following equation (2).

On the other hand, the locus interpolation device Another information given to 5, namely the peripheral speed v of the circular operation of the tool (mm / sec) is the following formula (3) and (4) the rotational speed omega ₁ of the motor of T ₁ shaft by formula It can be converted into (the number of peripheral teeth i ₁ ) and the rotation speed ω ₂ of the motor of the T ₂ axis (the number of peripheral teeth i ₂ ).

From the above relationship, the circular motion of the tool can be controlled according to the flowchart shown in FIG. In this control, information on the radius R (θ) of the circular motion of the tool and the peripheral velocity v is first given (steps 20 and 21). Information about the radius R (theta) is converted to the amount of movement of the T ₂ shaft for supporting the tool on the basis of the above equation (2), T ₂ shaft are determined rotation angle theta is T ₂ shaft is positioned on the angle theta (Step
twenty two). On the other hand, the information about the peripheral speed v is converted into the rotational speed ω ₁ of the T ₁ -axis motor based on the above equation (3) (step 23), and the rotational speed ω ₁ of the T ₁ -axis motor is changed to the T ₂ -axis. It is converted into the rotation speed ω _{2 of the} motor (step 24). Based on this, the T ₁ axis motor and T ₂ axis motor operate simultaneously at rotational speeds ω ₁ and ω ₂ , respectively, the tool rotates 360 ° or more, and a small hole is opened in the work (step 2
Five). After this small hole is opened, the robot moves to position the tool at a predetermined position for the next small hole (step 2
6) is given information about the eyelet (step 20)
And step 21). Therefore, the circular movement of the tool is carried out quickly and smoothly by the above operation, so that small hole machining can be accurately performed regardless of the type of tool and the size of the hole diameter.

Next, the trajectory interpolation of a different shape will be described.

In the case of rectangles (including squares) and oblong holes, the shape is directional, so not only is the center of rotation of the T ₁ axis the coordinate origin of the circle locus, as in the case of circle locus interpolation, but also Fig. 5 ( a),
As shown in (b), set the start point (S) of the locus motion to T
Operate ₂ axes, T ₁ axis, teach and store. The origin (C), which is the center of the trajectory of the irregular shape, is located at the center of rotation of the T ₁ axis, as in the case of the circular trajectory. Numerical information gives side A (mm) and peripheral velocity v (mm / sec).

The trajectory formation control will be specifically described below.

As shown in FIG. 6, the center of rotation of the T ₁ axis is the coordinate origin (C).
The line connecting the coordinate origin and the start point (S) is the Y axis, and the line passing through the coordinate origin and perpendicular to the Y axis is the X axis. The trajectory forming direction passes through the start point and is perpendicular to the Y axis. Assuming that the rotation angle of the T ₁ axis is θ ₁ and the rotation angle of the T ₂ axis is θ ₂ , the coordinates of the tip of the tool 8 can be uniquely determined by the following equations (5) and (6).

X = r cos θ ₁ + r cos θ ₂ (5) Y = r sin θ ₁ + r sin θ ₂ (6) Since the start point (S) is taught, the side B is calculated from the moving angle θ ₀₂ of the T ₂ axis at that time. it can.

From the numerical information A and the calculated value B, it is possible to form a rectangle or a long hole trajectory.

Here, the information of the peripheral speed v (mm / sec), the coordinate value calculated in the control clock T (sec) interval is omitted too known, as represented in FIG. 7, the coordinate values (X ₁ ,
Y ₁ ), X ₁ = r cos θ ₁ + r cos θ ₂ (8) Y ₁ = r sin θ ₁ + r sin θ ₂ (9) From formulas (8) and (9), X ₁ −r cos θ ₁ = r cos θ ₂ … (10) Y ₁ −r sin θ ₁ = r sin θ ₂ … (11) (10) ² + (11) ^{2 From} X ₁ cos θ ₁ + Y ₁ cos θ ₁ = (X ₁ ² + Y ₁ ² ) / 2r… (12 ) Here, J = (X ₁ ² + Y ₁ ² ) / 2r X ₁ = M cos θ ₀ Y ₁ = M sin θ ₀ Then, substituting into equation (12), M cos (θ ₀ = θ ₁ ) = J cos (θ ₀ = θ ₁ ) = J / M (13) Here, when ω is defined, cos ω = J / M sinω ＝ N / M Is.

tanω = N / J, tanθ ₀ = Y ₁ / X ₁ Therefore tanθ ₁ = tan (θ ₀ = ω) = (tanθ ₀ −tanω) / (1 + tanθ ₀ · tanω) = (Y ₁ J−X ₁ N) / (X ₁ J + Y ₁ N) θ ₁ = tan-1 {(Y ₁ J−X ₁ N) / (X ₁ J + Y ₁ N)}… (14)
Substituting Eq. (14) into Eqs. (10) and (11), cos θ ₂ = (X ₁ −r cos θ ₁ ) / r sin θ ₂ ＝ (Y ₁ −r sin θ ₁ ) / r tan θ ₂ ＝ (Y ₁ −r sin θ ₁ ) / (X ₁ −r cos θ ₁ ) θ ₂ = tan-1 {Y ₁ −r sin θ ₁ ) / (X ₁ −r cos θ ₁ )… (1
5) Here, the rotation angles of the T ₁ axis and T ₂ axis for the tool to move from the start point to (X ₁ , Y ₁ ) are as shown in Fig. 8.
theta _11, can be expressed as _{θ 22, θ 11 = θ 1} -θ 01 ... (16) θ 22 = θ 22 + 180 ° -θ 1 ... (17) ( _{although, θ 01 = 180 ° -θ 02} /2 It is possible to ask.

Based on the above principle, the locus of a rectangle or an elongated hole is formed according to the flowchart of FIG.

That is, in step 91, the side A (mm) and the peripheral velocity v (mm / sec) of the tool 8 are input, and in step 92, the side B (mm) is calculated by the equation (7).

Then, in step 93, a rectangle is obtained from equations (8) and (9),
Calculate the coordinate values that form the slot, and in step 94 (14) ~
The rotation angles θ ₁₁ and θ ₂₂ of the T ₁ and T ₂ axes are calculated using Eq. (17).

In this way, by rotating so that the rotation angles of the T ₁ and T ₂ axes are θ ₁₁ and θ ₂₂ , the desired irregular-shaped trajectory is formed by the tool 8 in step 95, and steps 93 to 95 are completed until the end.
When the trajectory formation is completed, the robot moves in step 96 to correspond to another hole.

In the trajectory interpolation device of the present invention, the tool is moved from the set start point by being given information about the peripheral velocity, radius and long side of the tool. The tool is independent of the movement of a movable body such as a robot. Can be controlled directly to cause the tool to perform circular, rectangular and slotted movements.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.

FIG. 10, FIG. 11 and FIG. 12 are a longitudinal sectional view, a front view and a rear view of the first embodiment of the trajectory interpolation device according to the present invention.

The case 30 is provided with a cylindrical tip portion and a rear end portion in which the inner and outer dimensions are slightly larger and the end thereof is covered with a cover 31. One side wall of this rear end (below each of the drawings)
A flange 32 is formed integrally with the robot 32, and the flange 32 is attached to the wrist portion of the tip of the arm 7b of the robot 6. Further, the corner portion of the other side wall (upper side in the drawing) at the rear end portion has a shape similar to a rectangular tube wall protruding outward, and T ₁ is provided outside the cover 31 corresponding to this corner portion.
And T ₂ shaft motor 34 for rotating the T ₁ shaft motor 33 and the T ₂ shaft for rotating the shaft is mounted side by side.

Inside the tip of the case 30, it is arranged in the axial direction 2
A tubular T ₁ shaft (rotating shaft) 36 is rotatably attached via a _single bearing 35. The T ₁ shaft 36 has a rear end portion that is inserted inside the bearing 35 and a front end portion that projects from the case 30 in the axial direction. The rear end of the T ₁ shaft 36 has an inner surface that is substantially concentric with the center of rotation. On the other hand, the front end portion of the T ₁ shaft 36 has an outer diameter larger than that of the rear end portion and has an inner side surface that is eccentric with respect to the center of rotation. The amount of eccentricity is equal to the distance r shown in FIG. Then, a cylindrical T ₂ shaft (operating shaft) 38 is rotatably mounted inside the eccentric tip portion via two bearings 37 arranged in the axial direction.

The T ₂ shaft 38 also has an inner surface eccentric to the center of rotation. The amount of eccentricity is also equal to the distance r shown in FIG. Then, the tool 8 is attached with the position of eccentricity to the inner side of the T ₂ shaft 38, that is, the center of rotation as the point of action. In this case, for example, a laser gun is used as the tool 8, and the tool is rotatably supported by a tool mounting member 40 via two bearings 39 arranged in the axial direction. Is connected to the tip of the T ₂ axis.

On the other hand, inside the rear end of the T ₁ shaft 36, a cylindrical drive transmission shaft 41 that transmits rotational motion to the T ₂ shaft 38 is rotated via two bearings 42 arranged in the axial direction. Installed as possible.
A front end surface of the drive transmission shaft 41 and a rear end surface of the T ₂ shaft 38 oppose each other so as to be eccentrically movable, and a constant velocity coupling 43 is provided between them. That is, the rotation of the drive transmission shaft 41 is transmitted to the T ₂ shaft 38 via the constant velocity coupling 43. A hole is also formed in the axial center portion of the constant velocity coupling 43, and the cable 44 is passed through the central axis portions of the T ₂ shaft 38, the constant velocity coupling 43, the drive transmission shaft 41 and the cover 31 described above. Therefore, the processing energy can be supplied to the tool 8 without any hindrance to the eccentric movement of the tool 8.

A gear 45 is attached to the rear end surface of the drive transmission shaft 41 so as to be concentric with the center of rotation. The gear 45 has a hole through which the cable 44 is inserted. Furthermore, T ₁ axis
A gear 46 is also attached to the rear end surface of the shaft 36 concentrically with the center of rotation. The gear 46 is formed with a hole through which the T ₂ shaft 41 passes. Then, the small gear 47 attached to the output shaft of the T ₁ axis motor 33 meshes with the gear 46, and further, the T ₂ axis motor
A small gear (not shown) attached to the 32 output shafts meshes with the gear 45.

FIG. 13 is an exploded perspective view of the Oldham coupling used as the constant velocity coupling 43. This is a joint used when the two axes to be connected are parallel but not in a straight line, and flanges 43A and 43B attached to the ends of the two axes are connected via an intermediate piece 43C. At that time, the shaft end flanges 43A, 43B and the intermediate piece 43C are fitted with a groove and a projection provided in the diametrical direction, and the two sets of fittings are arranged so as to form a right angle to each other. Is. The intermediate piece 43C makes an elliptical motion and transmits the motion between two eccentric axes. Holes 48 are provided in the flanges of the shaft ends and the shaft cores of the intermediate pieces so that the cables can pass therethrough.

Incidentally, the relationship of the motion loci in FIG. 2 can be expressed similarly in FIG. 11, which enables control based on the above principle.

14 and 15 show the second part of the trajectory interpolation device according to the present invention.
It is a longitudinal cross-sectional view and a front view of the embodiment, and elements having the same effects as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Here, the T ₁ shaft 36 has a first hole and a second hole for supporting the shaft therein, respectively. The first hole is the drive transmission shaft 41
Inside, and the second hole supports the T ₂ shaft 38 inside. The axes of the first and second holes are parallel to each other and are separated from each other by a distance r. The drive transmission shaft 41 is rotatably supported in the first hole via a bearing 42, and the bearing is in the second hole.
A T ₂ shaft 38 is rotatably supported via 37. In this case, a gear 51 is formed on the outer peripheral surface of the tip end portion of the drive transmission shaft 41, and a gear 52 is also formed on the outer peripheral surface of the tip end portion of the T ₂ shaft 38, and these gears mesh with each other. Further, one end of the arm 53 is fixed to the tip end surface of the T ₂ axis with a bolt. The tool 8 is rotatably supported on the other end of the arm 53 via a bearing 39. The center of rotation of the tool 8, that is, its point of action and the center of rotation of the T ₂ axis are separated by the distance r as described above.

The rear end of the tool 8 can be moved inside the drive transmission shaft 41. The T ₁ shaft is rotated by the T ₁ shaft motor 33, and the drive transmission shaft 41 is rotated by the T ₂ shaft motor 34. By doing so, the T ₂ shaft 38 can rotate and revolve,
The relationship of the motion loci in FIG. 2 can be expressed similarly in FIG. 11, which enables control based on the above principle.

Although the laser gun is used as the tool in the above embodiment, the present invention is not limited to this, and a plasma gun, a water jet gun or the like may be used.

〔The invention's effect〕

As is clear from the above description, according to the present invention,
Even when drilling holes in 3D products such as automobile body parts, regardless of the size of the tool or the type of tool used, a circular hole, rectangular hole, or long hole with an accurate diameter can be quickly and accurately positioned. It can be formed smoothly.

Further, according to the present invention, the drive transmission shaft is supported inside the respective rotary shafts each having a tubular shape, and the shaft center portion of the drive transmission shaft is
Since the cable that transfers energy to the tool is passed through, the cable handling, which is a problem with xy tables, can be easily processed.

[Brief description of drawings]

FIG. 1 is a side view showing the basic structure of the present invention, FIG. 2 is a conceptual diagram showing a locus for determining a circular motion, and FIG. 3 is a characteristic diagram showing a relation between a rotation angle and a radius of the circular motion. FIG. 4 is a flow chart showing an example of control of a circle movement, FIG. 5 (a),
(B) is an explanatory diagram of information given for forming a trajectory in a rectangular hole or an elongated hole (an irregular shape), and FIG. 6 is a positional relationship diagram of T ₁ axis and T ₂ axis rotation centers at the time of starting the operation of the irregular shape, Figures 7 and 8 show the coordinate values and T ₁ , T at arbitrary points on irregularly shaped strips.
FIG. 9 is an explanatory view of a rotation angle of _two axes, FIG. 9 is a flowchart showing an example of control of irregularly shaped motion, FIG. 10, FIG. 11 and FIG.
1 is a longitudinal sectional view, a front view and a rear view of a first embodiment of the present invention, FIG. 13 is an exploded perspective view of a constant velocity coupling which constitutes the first embodiment, and FIGS. 14 and 15 are the present invention. FIG. 16 is a sectional view and a front view of the second embodiment of FIG. 16 and FIG. 16 is a side view of a conventional device for making small holes. 5 ... Locus interpolator, 6 ... Robot, 7a, 7b ... List, 8 ... Tool, 36 ... Rotation axis (T ₁ axis), 38 ... Motion axis (T ₂ axis), 41 ... Drive Transmission shaft, 43 ... Constant velocity coupling, 44 ... Cable.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G05B 19/414 (72) Inventor Yoshikatsu Minami 12-1 Otemachi, Kokurakita-ku, Kitakyushu, Fukuoka Stock Company Yasukawa Electric Co., Ltd. Ogura factory (56) Reference JP 63-62694 (JP, A) JP 59-174278 (JP, A) Actual development 60-11702 (JP, U) Actual 61- 31580 (JP, U) Journal "Robot" (No. 20) September 10, 1978 (corporation incorporated body) Japan Industrial Robotics Association P. 45-48

Claims (4)

[Claims] 1. A trajectory interpolating device, which is attached to a movable body and is capable of moving a tool to a desired position with respect to the movable body, wherein the trajectory interpolating device is rotatable about an axis of the movable body. A cylindrical rotation shaft (36) supported, and a rotation center supported at the tip of the rotation shaft so as to be rotatable and revolvable and at a position separated from the rotation center of the rotation shaft by a predetermined distance. Then, an operating shaft (38) for holding the tool (8) so that the point of action of the tool (8) is located at a position separated from the center of rotation by a predetermined distance, and inside the rotating shaft, A cylindrical drive transmission shaft (41) that is rotatably supported around an axis parallel to the axis of the rotary shaft and that transmits a driving force to the operating shaft. Through the cable (44) for transmitting energy to the tool, A trajectory interpolation device that controls the rotation axis and the movement axis independently of the movement of a movable body to move the tool along a circle and a trajectory of an irregular shape. 2. The rotation axis and the rotation axis of the tool are set so that the tip of the tool has a desired locus based on numerical information such as a radius of a circle and an irregular shape, a long side, and a short side. The trajectory interpolation device according to claim 1, which controls an operation axis. 3. The trajectory interpolation device according to claim 1 or 2, wherein the drive transmission shaft and the operation shaft are connected by a constant velocity coupling (43). 4. The trajectory interpolation device according to any one of claims 1 to 3, wherein the movable body is a robot.