JP2003251584A - Locus control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a locus control device which can depict a small circle or the like with high accuracy even by a robot control device without any high accuracy. <P>SOLUTION: The locus control device which is fitted to an arm tip of a robot body having an articulated structure and can move an equipped tool 5 to an arbitrary position with respect to the robot body comprises a first rotating body 12 which can be supported in a rotatable manner to the robot body, and operated by a first axis-drive motor 1, a second rotating body 22 which is supported in a rotating and revolving manner with respect to the first rotating body 12, and operated by a second axis-drive motor 2, a table mechanism 31 connected to the second rotating body 22 via a bearing 23, and a bracket 32 which is connected to the table mechanism 31 and holds a tool 5. The table mechanism 31 has an operational mechanism which is operable in the horizontal direction of two degrees of freedom with respect to a casing of the locus control device. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trajectory control device adapted to control a trajectory of a small trajectory machining tool or the like when attached to the wrist of an industrial robot.

[0002]

2. Description of the Related Art For example, in a manufacturing process of a body panel of an automobile, a locus control device is provided at an arm tip of an industrial robot having an articulated structure, and the locus control device is equipped with a laser gun, a plasma gun, a water jet. By attaching a gun or the like, a round hole, an elongated hole, or a polygonal small hole cylinder is formed in the body panel.

In the machining of small holes such as weaving trajectories of arc welding and arc welding or marking work by such industrial robots, the trajectory accuracy of the tool becomes a problem. However, for industrial robots, the robot arm tip with large inertia and low rigidity must be controlled, and since the trajectory interpolation calculation is performed by multiple joint axes, the interpolation cycle is long and the interpolation interval becomes coarse for small trajectories. For this reason, it is difficult to secure sufficient trajectory accuracy under normal conditions. Therefore, in order to secure a high trajectory accuracy, for example, Japanese Patent Laid-Open No. 7-266296 and Japanese Patent Laid-Open No. 5-266296.
As disclosed in Japanese Patent No. 318347, a tip of the robot arm is equipped with a trajectory control device.

[0004]

However, JP-A-7-2
In the trajectory control device disclosed in Japanese Patent No. 66296,
For example, as shown in FIG. 10 and FIG. 14 of the publication, since the structure has a large hollow hole for passing a cable, the structure of the device is complicated, and maintenance of the tool and the trajectory control device is difficult. There is a problem that a large tool cannot be attached due to the restriction of the hollow hole. In addition, the tool attachment part at the tip of the trajectory control device is accompanied by unnecessary rotation movement in addition to the revolution movement for generating the trajectory required for the tool to work, so the tool cable is twisted. As a countermeasure against this, a tool is supported by bearings to allow the rotation motion to escape, but for this purpose, it was necessary to accurately align the tool drive shaft and the tool axis. Furthermore, since it is necessary to match the axes, it is impossible to attach a large tool to the outside of the trajectory control device with a bracket or the like.

Further, in the trajectory control device disclosed in Japanese Patent Laid-Open No. 5-318347, for example, FIG.
With the structure as shown in FIG.
Although the problem of -266296 has been solved, the advantage of being able to draw a small circle by the simple control of constant speed driving of a biaxial motor is impaired, and if a locus of equivalent accuracy is drawn, higher accuracy is achieved. A motor control device (robot control device) was needed.

The present invention has been made in order to solve the problems of these prior arts, and the tool attached to the trajectory control device can be easily maintained, a large tool can be attached, and the robot control is not highly accurate. It is an object of the present invention to provide a trajectory control device capable of drawing a small circle or the like with high accuracy in the device.

[0007]

In order to achieve the above object, in the invention according to claim 1, the tool 5 attached to the arm tip of the robot body having an articulated structure and equipped with the tool 5 is attached to the robot body. In a trajectory control device that can be moved to an arbitrary position, a first rotating body 12 that is rotatably supported by a robot body and is operated by a first axis drive motor 1, and a first rotating body 12 A second rotating body 2 which is rotatably and revolvably supported with respect to and is operated by a second shaft drive motor 2.
2 and the second rotating body 22 are connected via a bearing 23 to a table mechanism 31, and a bracket 3 connected to the table mechanism 31 and adapted to hold the tool 5.
2 is provided, and the table mechanism 31 has an operation mechanism that is movable in the horizontal direction of two degrees of freedom with respect to the housing of the trajectory control device. In the present invention, the “horizontal direction” refers to a direction orthogonal to the rotation axes of the first rotating body 12 and the second rotating body 12.

With the structure according to claim 1, the bracket 32 holding the tool 5 is horizontally or rotationally operated by controlling the drive of the first axis drive motor 1 and the second axis drive motor 2. As a result, the tool 5 gripped by the bracket 32 can be moved to an arbitrary position without operating the robot body. Further, since the tool 5 is connected to the main body of the trajectory control device via the bracket 32, replacement and maintenance of the tool 5 are easier than in the case where the tool 5 is directly connected to the main body of the trajectory control device. In addition to the ease of use, a tool having a volume large enough to interfere with the main body of the trajectory control device can be attached in the conventional art. Further, since the cable / hose 6 connected to the tool 5 can be directly connected to the tool 5 without being laid on the surface of the trajectory control device or on the inside of the housing, the cable / hose 6 can be replaced or maintained. It will be easier.

An example of an operating mechanism that can move horizontally in two degrees of freedom with respect to the housing of the trajectory control device is, for example,
It suffices to have two linear guides 35 and 36 that are movable in different horizontal directions with respect to the housing of the trajectory control device (claim 2). The two linear guides 35 and 36 do not necessarily have to be arranged in an orthogonal relationship with each other, but if they are arranged in an orthogonal relationship with each other, movement of the tool 5 with respect to the operable range of the linear guides 35, 36 will be described. Since the possible range is maximized, the operating mechanism can be made compact (claim 3). Further, as another operation mechanism, there is one including link mechanisms 35a and 36a which are horizontally movable with two degrees of freedom with respect to the housing of the trajectory control device (claim 4). By using the link mechanism, it is possible to eliminate the linear guide portion, and by using a bearing or the like in the rotating portion of the link, the dustproof property can be improved.

The second shaft drive motor 2 and the second rotary body 22 may be connected via an internal gear 21 (claim 5). By using the internal gear having a high transmission efficiency of the driving force, the driving force can be efficiently transmitted to the rotating body arranged such that the center of rotation is eccentric.

The first rotating body 12 is connected to the first rotating body 12 via a speed reducer 15.
The second rotary body 22 may be operated by the second shaft drive motor 2 via the speed reducer 25 while being driven by the shaft drive motor 1. Reducer 15,
By using 25, the rotating bodies 12, 22 can be operated by the drive motors 1, 2 having a large reduction ratio and a small output. Further, since the outputs from the speed reducers 15 and 25 are directly connected to the rotating bodies 12 and 22 without passing through gears or the like, there is an advantage that the backlash is small and the rigidity is high. Therefore, it is possible to generate a small trajectory with higher accuracy.

The first axis drive motor 1 and the second axis drive motor 2 may be servo motors, and may be controlled as an additional axis of the joint axis drive motor of the robot body (claim 7). A servo motor is generally used as the joint axis drive motor of the robot body, but the first axis drive motor 1 and the second axis drive motor 2 are the same servo motors as the joint axis drive motor of the robot body. 1st and 2nd
By synchronously controlling the axis drive motor 2 with the joint axis drive motor of the robot body, the trajectory control device can be operated while operating the joint axis of the robot body, so that efficient operation control is possible.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view and a plan sectional view of a trajectory control device according to an embodiment of the present invention. The trajectory control device shown in FIG. 1 is provided at the arm tip of a robot body having a multi-joint structure (not shown). The trajectory control device has a first axis drive motor 1 and a second axis drive motor 2 as its drive mechanism. Both the first axis drive motor 1 and the second axis drive motor 2 are servo motors, and as an additional axis of the joint axis drive motor of the robot body not shown, like the joint axis drive motor of the robot body, robot control not shown The device is synchronously controlled.

Here, controlling as an additional axis of the joint axis drive motor of the robot body means, for example, when the robot body has a multi-joint structure of 6 axes, the first axis drive motor 1
It means that the second axis drive motor 2 is controlled in synchronization with the six joint axis drive motors of the robot body as the seventh axis and the eighth axis of the robot body, respectively. By synchronously controlling the first axis drive motor 1 and the second axis drive motor 2 with the joint axis drive motor of the robot body, the trajectory control device can be operated while operating the joint axis of the robot body. Good motion control is possible.

When the first shaft drive motor 1 is driven, the gear 3 on the output shaft of the first shaft drive motor 1 operates, and when the gear 3 operates, the first shaft drive gear 11 operates. The rotating body 12 rotates about its rotation axis.
The second rotating body 22 is rotatably and revolvably supported by the tip end portion of the first rotating body 12, and is located at a position separated from the rotation axis of the first rotating body 12 by a predetermined distance.
Has its axis of rotation parallel to that of. This second
Since the rotating body 22 is connected to the first rotating body 12 via the rotary bearing, the second rotating body 22 revolves around when the first rotating body 12 operates around its rotation axis.

On the other hand, when the second shaft drive motor 2 is driven, the gear 4 on the output shaft of the second shaft drive motor 2 operates, and when the gear 4 operates, the first shaft drive gear 11 is eccentrically mounted. The biaxial drive gear 21 operates, whereby the second rotating body 22 rotates about its rotation axis. Therefore, the second rotating body 22 performs the revolution operation by the drive of the first axis drive motor 1 and the rotation operation by the drive of the second axis drive motor 2. In addition, it is desirable to use an internal gear as the second shaft drive gear 21 in order to enhance the transmission efficiency of the drive force.

Reference numeral 31 is a table mechanism attached to the housing of the trajectory control device via the base 40. 5
Is a tool such as a laser gun or a plasma gun attached to the table mechanism 31 via a bracket 32. Reference numeral 6 denotes a cable / hose that transmits energy to the tool 5, and is laid outside the main body of the trajectory control device. As shown in FIG. 1, in the present invention, the tool 5
Is attached to the main body of the trajectory control device via a plate-shaped bracket 32 having the horizontal direction as the longitudinal direction. Therefore, the attachment position of the tool 5 is a position remote from the main body of the trajectory control device in the horizontal direction. There is. Therefore, the cable / hose 6 connected to the tool 5 can be directly connected to the tool 5 without being laid on the housing surface of the trajectory control device or inside the housing.

The configuration according to this embodiment is called a compass mechanism. If this is compared to a multi-joint robot in which the second arm is provided at the tip of the first arm, the first rotating body 12 corresponds to the first arm driven by the first axis drive motor 1, and the second rotating body Reference numeral 22 corresponds to a second arm driven by the second shaft drive motor 2 attached to the tip of the first rotating body 12. Each of these is equipped with a mechanism corresponding to a compass, and is rotated by three rotary bodies 12 and 22 corresponding to two arms in the XY direction and rotation θ in a plane.
It has a degree of freedom.

Next, the structure of the table mechanism 31 will be described. FIG. 3 is a mechanism diagram showing the structure of the table mechanism 31. The table mechanism 31 is a linear guide 35 that is movable in a horizontal direction (X direction in FIG. 3) with respect to a base 40 that is fixed to the housing of the trajectory control device, and its operation with respect to the linear guide 35. Linear guide 3 that is operable in the horizontal direction (Y direction in FIG. 3) orthogonal to the direction
6 and 6. That is, the bracket 32 to which the tool 5 is attached is attached to the base 40 fixed to the housing of the trajectory control device via the table mechanism 31. By the way, the second rotating body 22 described above is also connected to the bracket 32 via the bearing 23. Therefore, by controlling the drive of the first axis drive motor 1 and the second axis drive motor 2, the tool 5
It is possible to horizontally or rotationally move the bracket 32 holding the bracket. Then, as a result, the tool 5 attached to the bracket 32 does not operate the robot body, and as shown at 50 in FIG. With the compass mechanism having three degrees of freedom in the plane added with, the locus control device operates.

As described above, in this embodiment, the two linear guides 35, 36 are arranged so as to be orthogonal to each other, but this is the linear guide 3.
The movable range of the tool 5 with respect to the movable ranges of 5 and 36 is maximized, whereby the operating mechanism is made compact. However, the present invention can be implemented without an orthogonal relationship as long as the operating mechanism has two degrees of freedom and can be operated in the horizontal direction. Further, the present invention is not limited to the compass mechanism as shown in FIG. 3 described above.
For example, as shown in FIG. 4A, by using link mechanisms 35a and 36a composed of a combination of parallel links or the like, two free movements such as XY of a plane to cancel a rotation motion of a compass structure and generate a trajectory. You may take out the degree. Further, as shown in FIG. 4B, a link mechanism having an operation amount proportional to the operation amount of the compass mechanism may be used. That is, the table mechanism according to the present invention has two degrees of freedom in the X and Y directions of a plane that cancels the above-described degree of freedom θ of rotation of the compass axis having three degrees of freedom and forms a locus of a small figure. It refers to the mechanism that can take out.

FIG. 5 shows an example of a locus such as a small circle or a small irregular shape generated by the locus control device according to the present invention. These small irregular shapes are generated by numerical information such as radius and side length, and are not limited to the shapes shown in FIG. Specifically, the table mechanism 3 driven by the rotating bodies 12 and 22.
The plane including the two operation axes (X, Y) of 1 is used as coordinates, and the tip of the tool 5 is rotated so that the tip of the tool 5 has a desired trajectory according to the radius information of the circle and the irregular shape, the long side, and the short side. The bodies 12 and 22 may be controlled.

By the way, in the present invention, it is possible to incorporate a speed reducer in the drive path. 2 is different from the one shown in FIG. 1 described above in the drive path.
5 is an example of a trajectory control device having a compass mechanism including No. 5, and is a front sectional view and a plan sectional view thereof. In the trajectory control device shown in FIG. 2, the first
The rotating body 12 is operated by the first axis drive motor 1 via the speed reducer 15, and the second rotating body 22 is operated by the second axis drive motor 2 via the speed reducer 25. Reducer 15,
By using 25, the rotating bodies 12 and 22 can be operated by the drive motors 1 and 2 having a large reduction ratio and a small output. Further, since the outputs from the speed reducers 15 and 25 are directly connected to the rotating bodies 12 and 22 without passing through a gear or the like, there is an advantage that the backlash is small and the rigidity is high. Therefore, it is possible to generate a small trajectory with higher accuracy. Note that, in FIG. 2, the configuration other than the speed reducers 15 and 25 is the same as that in FIG. 1 described above, and thus detailed description thereof is omitted.

The embodiments of the present invention have been described above. According to the present embodiment, even if the control device is not highly accurate by the compass mechanism, it is possible to draw a small circle with high accuracy by driving and controlling the drive motors 1 and 2. Further, since the tool 5 is connected to the main body of the trajectory control device via the bracket 32, replacement and maintenance of the tool 5 are easier than in the case where the tool 5 is directly connected to the main body of the trajectory control device. In addition to the ease of use, a tool having a volume large enough to interfere with the main body of the trajectory control device can be attached in the conventional art. Further, since the cable / hose 6 connected to the tool 5 can be directly connected to the tool 5 without being laid on the surface of the trajectory control device or on the inside of the housing, the cable / hose 6 can be replaced or maintained. It will be easier.

[0024]

According to the present invention, the trajectory control of the tool is performed by taking out the two degrees of freedom desired to generate the trajectory using the table mechanism from the three degrees of freedom including the rotation of the output shaft of the compass mechanism. Therefore, even if the robot control device is not highly accurate, it is possible to draw a small circle with high accuracy by driving and controlling the drive motor. In addition, since the cable and hose can not be inserted into the hollow path inside the trajectory control device and the tool can be installed outside the trajectory control device, the tool and the trajectory control device can be easily maintained, for example, the tool and the trajectory control device. Even if the device breaks down and these devices are replaced, the replacement work can be performed in a short time. Also, tools with a large outer shape can be easily attached by using an adapter or the like.

[Brief description of drawings]

FIG. 1 is a front sectional view and a plan sectional view of a trajectory control device according to an embodiment of the present invention.

FIG. 2 is an example of a trajectory control device having a compass mechanism having reduction gears 15 and 25 in a drive path according to another embodiment of the present invention, showing a front sectional view and a plan sectional view thereof. is there.

FIG. 3 is a mechanism diagram showing a structure of a table mechanism 31.

FIG. 4 is a mechanism diagram showing a table mechanism 31 using a link mechanism instead of a compass mechanism.

FIG. 5 is generated by the trajectory control device according to the present invention,
It is explanatory drawing which showed the example of a locus | trajectory, such as a small circle and a small irregular shape.

[Explanation of symbols]

1st axis drive motor 2 Spindle drive motor 3 gears 4 gears 5 tools 6 Cables and hoses 11 1st axis drive gear 12 First rotating body 15 reducer 21 2nd axis drive gear (internal gear) 22 Second rotating body 23 Bearing 25 reducer 31 table mechanism 32 bracket 35 Linear guide 35a parallel link 36 Linear guide 36a parallel link 40 base

Claims (7)

[Claims] 1. A trajectory control device which is attached to an arm tip of a robot body having an articulated structure and which can move an equipped tool 5 to an arbitrary position with respect to the robot body. While being rotatably supported,
The first rotating body 12 operated by the first shaft drive motor 1.
The second rotary body 22 supported by the first rotary body 12 so as to be rotatable and revolvable and driven by the second shaft drive motor 2, and the second rotary body 22 via a bearing 23. A table mechanism 31 connected to the table mechanism 31 and a bracket 32 connected to the table mechanism 31 and adapted to hold the tool 5. 2
A trajectory control device having an operation mechanism that is operable in a horizontal direction with a degree of freedom. 2. The trajectory control according to claim 1, wherein the operating mechanism is composed of two linear guides 35 and 36 which are movable in different horizontal directions with respect to the housing of the trajectory control device. apparatus. 3. The trajectory control device according to claim 2, wherein the two linear guides 35, 36 are arranged so as to be orthogonal to each other. 4. The link mechanism 3 is capable of moving horizontally in two degrees of freedom with respect to the housing of the trajectory control device.
The trajectory control device according to claim 1, wherein the trajectory control device comprises 5a and 36a. 5. The trajectory control device according to claim 1, wherein the second shaft drive motor 2 and the second rotary body 22 are connected via an internal gear 21. . 6. The first rotating body 12 is operated by a first shaft driving motor 1 via a speed reducer 15, and the second rotating body 22 is driven by a second shaft driving motor 2 via a speed reducer 25.
6. The method according to claim 1, wherein
2. The trajectory control device according to any one of 1. 7. The first axis drive motor 1 and the second axis drive motor 2 are servo motors, and are controlled as additional axes of a joint axis drive motor of a robot body. 7. The trajectory control device according to any one of 1 to 6.