JP2015136772A - Polishing robot and track formation method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing robot and a track formation method therefor capable of facilitating setting of teaching of a tool attitude and a robot operation track, when a workpiece processing position is in a narrow part.SOLUTION: A restraining point p designated in a space and restraining a posture of a tool rotary shaft z is stored. Based on shape data of a workpiece 1, track data D including a normal vector v at a point position r and the point position r on the track along a processing surface 2 of the workpiece 1, is created. In the restraining plane including the restraining point p and the normal vector v, a side surface of a tip end 12a and the processing surface 2 of the workpiece 1 are made parallel, by setting a posture of a processing tool 12 (direction of a shaft center z of the tip end 12a).

Description

  The present invention relates to a polishing robot for polishing a workpiece and a method for generating a trajectory thereof.

In a processing robot that processes a workpiece by attaching a processing tool to the end of the robot arm and moving it along the processing path, interference between the robot and the workpiece or between the tool and the workpiece becomes a problem when processing a narrow part.
For example, Patent Documents 1 and 2 have already been proposed as processing means for such a narrow portion.

  The “robot mechanism control method” of Patent Document 1 calculates a non-interference area of a grinding tool for a three-dimensional model of a work object, calculates an operation path of the grinding tool, and sets a tool posture and a variable for compliance control. It is planned off-line and transferred to the robot controller to perform processing such as grinding.

  The “grinding posture generation device for a grinding robot” in Patent Document 2 is a grinding robot that moves a grinding tool based on position data of a grinding path taught before a grinding operation to grind an object to be ground. The form of the object is detected, and the robot grinding posture is generated based on the detected form data.

Japanese Patent No. 3670700 JP-A-5-318280

The conventional narrow section machining means described above teaches the tool posture and via points for the workpiece offline.
However, particularly when the machining position of the workpiece is in a narrow portion (for example, inside the narrow mouth), teaching of the tool posture with respect to the workpiece is complicated.

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a polishing robot capable of facilitating teaching of a tool posture and setting of an operation trajectory of the robot and a method of generating the trajectory when the machining position of the workpiece is in a narrow part. is there.

According to the present invention, a polishing robot that polishes a work surface of a workpiece with a processing tool that processes at a tip portion, and the processing surface is located inside a narrow opening of the work that passes the processing tool,
A robot arm that moves the machining tool in a three-dimensional space;
An attitude control device that controls the attitude of the machining tool based on the machining surface shape of the workpiece,
The attitude control device includes:
A storage unit that is stored in a space and stores a restraint point that restrains the posture of the tool rotation axis;
From the shape data of the workpiece, a trajectory data creation unit that creates trajectory data consisting of a point position on the trajectory along the work surface of the workpiece and a normal vector at the point position;
A posture setting unit that sets a posture of a machining tool so that a side surface of the tip portion and a machining surface of a workpiece are parallel to each other in a constraint plane including the constraint point and the normal vector. A polishing robot is provided.

Further, according to the present invention, there is provided a method for generating a trajectory of a polishing robot that polishes a processing surface of a workpiece with a processing tool processed at a tip portion, and the processing surface is positioned inside a narrow opening of the workpiece that passes the processing tool. And
A robot arm that moves the machining tool in a three-dimensional space;
Preparing an attitude control device for controlling the attitude of the machining tool based on the machining surface shape of the workpiece,
The restraint point that is designated on the space (A) by the posture control device and restrains the posture of the tool rotation axis is stored,
(B) From the shape data of the workpiece, create trajectory data including a point position on the trajectory along the work surface of the workpiece and a normal vector at the point position;
(C) In a constraining plane including the constraining point and the normal vector, a posture of a processing tool is set so that a side surface of the tip portion and a processing surface of a workpiece are parallel to each other. A trajectory generation method is provided.

The shape of the tip is a cylindrical shape centered on the axis,
In the above (C),
Obtaining a first vector perpendicular to a constraint plane including the constraint point and the normal vector;
Next, a second vector perpendicular to the normal vector and the first vector is obtained,
It is preferable that the posture of the second vector is set as the posture of the processing tool.

The shape of the tip is a conical shape having an inclination angle with respect to the axis,
In the above (C),
Obtaining a first vector perpendicular to a constraint plane including the constraint point and the normal vector;
Next, a second vector perpendicular to the normal vector and the first vector is obtained,
It is preferable that an attitude having the inclination angle inward of the narrow mouth with respect to the second vector as a center is set as an attitude of the machining tool.

  The posture of the machining tool is the posture of the tool rotation axis.

According to the apparatus and method of the present invention, since the posture of the machining tool is set so that the side surface of the tip of the machining tool and the machining surface of the workpiece are parallel, the state where the side surface of the tip is in close contact with the machining surface of the workpiece The workpiece can be polished (polished).
Also, since the machining tool posture is set in the constraint plane including the constraint point in space (for example, inside the narrow mouth or its upper and lower spaces) and the normal vector at the point position on the trajectory, the constraint point is set appropriately. By doing so, when machining the machining area, the shape of the space through which the machining tool passes can be changed, and interference between the workpiece and the machining tool can be avoided.
Therefore, since the trajectory data, which is the point position on the trajectory along the machining surface, and the attitude of the machining tool can be automatically calculated from the workpiece shape data (for example, a CAD model), the teaching work can be saved.
Furthermore, the constraint condition that the side surface of the tip of the processing tool (for example, cylindrical shape or conical shape) is brought into close contact with the processing surface of the workpiece can be satisfied at the same time.

It is a whole block diagram of the grinding robot of the present invention. It is a schematic diagram of the workpiece | work which this invention makes object. It is a whole flowchart of the orbital generation method of the present invention. It is a schematic diagram in case the shape of the front-end | tip part of a processing tool is a cylindrical shape centering on an axial center. It is a schematic diagram in case the shape of the front-end | tip part of a processing tool is a cone shape which has an inclination angle with respect to an axis.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is an overall configuration diagram of a polishing robot 10 according to the present invention.
In this figure, a polishing robot 10 is a device that polishes a processing surface 2 of a workpiece 1 with a processing tool 12 that processes at a tip portion 12a, and includes a robot arm 20 and a posture control device 22.

2A and 2B are schematic views of the workpiece 1 targeted by the present invention, in which FIG. 2A is a front sectional view, and FIG. 2B is a side sectional view taken along the line BB.
As shown in this figure, a work 1 targeted by the present invention has a narrow opening 1a through which a processing tool 12 is passed, and the machining surface 2 of the work 1 is inside the narrow opening 1a (downward in this figure). positioned. As long as the narrow opening 1a can pass the processing tool 12, a shape and a magnitude | size are arbitrary.
In this example, the “narrow part” is the inside or the inside of the narrow opening 1 a, but the present invention is not limited to this, and may be a narrow part of the work 1.

In this example, the work 1 is a member to be processed whose surface 2 is polished by the tip 12a of the processing tool 12, and is made of a hard material such as cast iron.
In this example, the work 1 is accurately fixed at a predetermined position by the work holding device 3. The predetermined position is a position set in advance within the operating range of the robot arm 20 of the polishing robot 10.

In FIG. 1, a polishing robot 10 attaches a processing tool 12 to the tip of a robot arm 20 and moves the workpiece 1 along a processing path.
The robot arm 20 moves the processing tool 12 in a three-dimensional space.
The polishing robot 10 is an articulated robot in this example, but the present invention is not limited to this and may be other robots.

The processing tool 12 is attached to the tip of the robot arm 20 and processes the workpiece 1.
In this example, the processing tool 12 includes a tip end portion 12a for processing the workpiece 1 and a driving device 13 for driving the tip portion 12a.
In this example, the processing tool 12 is a rotary tool, and the driving device 13 is an electric spindle motor or an air motor. Moreover, the front-end | tip part 12a is a grindstone, a cemented carbide cutter, a brush, a cushion sander (resin sponge containing abrasive grains), and the like.
The processing tool 12 is not limited to a rotary tool, and may be a tool that reciprocates the tip 12a in the axial direction.

In FIG. 1, a force sensor 14 is attached to the tip of a robot arm 20, and a processing tool 12 is attached to the force sensor 14.
The force sensor 14 is a load cell, for example, and detects an external force acting on the processing tool 12.
The external force detected by the force sensor 14 is preferably an external force having six degrees of freedom (a force in three directions and a torque around three axes), but the present invention is not limited to this, and the pressing force against the workpiece 1 As long as it can be detected, other force sensors may be used.

  The polishing robot 10 includes a robot controller 16. The robot controller 16 is a numerical control device, for example, and controls the tip of the robot arm 20 to six degrees of freedom (three-dimensional position and rotation about three axes) by a command signal.

In FIG. 1, the posture control device 22 includes a storage unit 23, a trajectory data creation unit 24, and a posture setting unit 25, and controls the posture of the machining tool 12 based on the machining surface shape of the workpiece 1.
In the following description, the attitude of the machining tool 12 means the attitude of the tool rotation axis z.

The storage unit 23 stores a restraint point p that is designated in the space and restrains the posture of the tool rotation axis z. The position (three-dimensional position) of the constraint point p is set based on the shape data (for example, CAD data) of the workpiece 1. This setting may be input from the outside, or may be automatically set from the shape of the workpiece 1 to its centroid or the like. Appropriate automatic or manual input may be used.
Here, the “space” is preferably a space in which the narrow opening 1a can be directly viewed, for example, a space above the narrow opening 1a in FIG.
For example, when the workpiece 1 has a shape having a specific narrow part (for example, the inside of the narrow opening 1a in FIG. 2), the restraint point p is set to the middle of the narrow part (for example, the inside of the narrow opening 1a) or its upper and lower spaces. It is easy to avoid the tool axis from interfering with the narrow part.
The storage unit 23 further stores trajectory data D including the position, posture, and pressing direction of the processing tool 12.
The trajectory data D is represented by, for example, the three-dimensional position (x, y, z) and posture (a, b, c) of the machining tool 12 in the workpiece coordinate system, and the posture parameters a, b, c are, for example, Euler angles. Etc. Further, the pressing direction of the machining tool 12 is represented by a unit vector (vx, vy, vz) in the workpiece coordinate system.
In the present invention, as long as the position, posture, and pressing direction of the processing tool 12 can be set, these coordinate systems and posture parameters are defined (generally, various definition parameters are used for posture expression). It is not limited to.

The trajectory data creation unit 24 and the posture setting unit 25 are, for example, a control PC.
The trajectory data creation unit 24 creates trajectory data D including a point position r on the trajectory along the machining surface 2 of the work 1 and a normal vector v at the point position r from the shape data (for example, CAD data) of the work 1. To do.
The posture setting unit 25 is configured so that the side surface of the tip 12a and the machining surface 2 of the workpiece 1 are parallel to each other in a plane including the constraint point p and the normal vector v (hereinafter, “constraint plane”). The posture (axis center z of the tip 12a) is set.
The trajectory data D and the attitude data of the processing tool 12 are output to the robot controller 16.
In this example, the posture control device 22 is provided separately from the robot controller 16, but the robot controller 16 and the posture control device 22 may be configured by the same control PC.

FIG. 3 is an overall flowchart of the trajectory generation method of the present invention.
In the trajectory generation method of the present invention, the above-described apparatus is prepared, and steps (steps) S1 to S3 are performed.

  In step S1 (constraint point storage step), a restraint point p that is designated on the space (for example, inside the narrow mouth 1a or its upper and lower spaces) and restrains the posture of the tool rotation axis z is stored.

In step S2 (trajectory data creation step), trajectory data D including a point position r on the trajectory along the machining surface 2 of the workpiece 1 and a normal vector v at the point position r is created from the shape data of the workpiece 1.
Note that step S1 and step S2 are not limited to this order, and may be reversed or simultaneous.

In step S3 (posture setting step), the posture (tip portion) of the machining tool 12 is set so that the side surface of the tip portion 12a and the machining surface 2 of the workpiece 1 are parallel to each other in the constraint plane including the constraint point p and the normal vector v. Set the axial center z) of 12a.
In step S3, the trajectory data D including the point position r on the trajectory along the machining surface 2 and the normal vector v at the point position r and the posture of the machining tool 12 are automatically determined from the shape data (for example, CAD model) of the workpiece 1. Can be calculated. The “trajectory data D and the attitude of the machining tool 12” are the trajectories generated by the present invention.

FIG. 4 is a schematic diagram when the shape of the tip end portion 12a of the processing tool 12 is a cylindrical shape centered on the axis z.
When the processing tool 12 is a rotary tool, the axis of the rotary shaft 12b of the tip end portion 12a coincides with the cylindrical axis z. In this case, it is necessary to satisfy the constraint condition that the side surface of the distal end portion 12a (columnar shape) of the processing tool 12 is in close contact with the processing surface 2 of the workpiece 1 as shown in the figure.
Here, “close contact” means a state in which the side surface shape of the tip 12 a of the processing tool 12 is in contact with the processing surface 2 of the workpiece 1.

  When the distal end portion 12a has a cylindrical shape, the above-described step S3 (posture setting step) includes steps (steps) S3-1 to S3-3.

In step S3-1, a first vector u perpendicular to the constraint plane including the constraint point p and the normal vector v is obtained. The first vector u can be obtained by Expression (1). Note that (p−r) is a vector and x is an outer product.
u = (p−r) × v (1)

The first vector u is preferably a unit vector. In this case, the first vector u can be obtained by Expression (2).
u = ((pr) × v) / | (pr) × v | (2)

Next, in step S3-2, a second vector w perpendicular to the normal vector v and the first vector u is obtained.
The second vector w can be obtained by Expression (3).
w = v × u (3)

  Next, in step S3-3, the posture of the second vector w is set as the posture of the machining tool 12 (the axis center z of the tip portion 12a).

The first vector u is a vector perpendicular to the constraint plane including the constraint point p and the normal vector v, and the second vector w is a vector perpendicular to the normal vector v and the first vector u. The two vectors w are on the constraint plane including the constraint point p and the normal vector v, and are in a direction orthogonal to the normal vector v.
Accordingly, by setting the posture of the second vector w as the posture of the machining tool 12, the machining tool 12, that is, the tip portion 12a, is such that the side surface of the tip portion 12a of the machining tool 12 and the machining surface 2 of the workpiece 1 are parallel to each other. Can be set.

FIG. 5 is a schematic diagram when the shape of the tip 12a of the processing tool 12 is a conical shape having an inclination angle α with respect to the axis z.
When the processing tool 12 is a rotary tool, the axis of the rotary shaft 12b of the tip end portion 12a coincides with the cylindrical axis z. In this case, it is necessary to satisfy the constraint condition that the side surface of the distal end portion 12a (conical shape) of the processing tool 12 is in close contact with the processing surface 2 of the workpiece 1 as shown in the figure.

When the distal end portion 12a has a conical shape, step S3 (posture setting step) described above includes steps (steps) S3-1 to S3-3.
Steps S3-1 and S3-2 are the same as in FIG.
That is, in step S3-1, the first vector u perpendicular to the constraint plane including the constraint point p and the normal vector v is obtained, and in step S3-2, the first vector u perpendicular to the normal vector v and the first vector u is obtained. 2 vector w is obtained.

Next, when the distal end portion 12a has a conical shape, in step S3-3, an inclination angle α inward of the narrow portion (for example, inside the narrow port 1a) with respect to the second vector w with the direction of the first vector u as the center. Is set as the posture of the machining tool 12 (axis center z of the tip portion 12a).
The posture of the machining tool 12, that is, the direction vector Z of the axis z of the tip end portion 12a can be obtained by Expression (4).
Z = (R · w) / | R · w | (4)
Here, R is a rotation matrix, and is expressed by Equation (5) of Equation 1.

The first vector u is a vector perpendicular to the constraint plane including the constraint point p and the normal vector v, and the second vector w is a vector perpendicular to the normal vector v and the first vector u. The two vectors w are on the constraint plane including the constraint point p and the normal vector v, and are in a direction orthogonal to the normal vector v.
Further, the posture of the machining tool 12, that is, the direction of the axis z of the tip 12a is inclined inward of the narrow portion (for example, inside the narrow opening 1a) with respect to the second vector w with the direction of the first vector u as the center. Since the posture has the angle α, it is possible to set the posture of the machining tool 12, that is, the axis center z of the tip portion 12 a so that the side surface of the tip portion 12 a of the machining tool 12 is parallel to the machining surface 2 of the workpiece 1. it can.

According to the above-described apparatus and method of the present invention, the posture of the machining tool 12 is set so that the side surface of the tip 12a of the machining tool 12 and the machining surface 2 of the workpiece 1 are parallel to each other. The workpiece 1 can be polished (polished) while being in close contact with the processing surface 2 of the workpiece 1.
Further, since the posture of the machining tool 12 is set in the constraint plane including the constraint point p inside the narrow aperture 1a and the normal vector v at the point position r on the trajectory, the machining tool 12 passes near the constraint point and narrows. Interference between the mouth 1a and the processing tool 12 can be avoided.
Accordingly, since the trajectory data D, which is the point position r on the trajectory along the machining surface 2, and the posture of the machining tool 12 can be automatically calculated from the shape data (for example, CAD model) of the workpiece 1, the labor of teaching work can be saved. .
Furthermore, the constraint condition that the side surface of the tip 12a (for example, cylindrical shape or conical shape) of the processing tool 12 is brought into close contact with the processing surface 2 of the workpiece 1 can be satisfied at the same time.

  In addition, this invention is not limited to embodiment mentioned above, is shown by description of a claim, and also includes all the changes within the meaning and range equivalent to description of a claim.

p constraint point, r point position, v normal vector, u first vector,
w second vector, D orbit data, z axis (tool rotation axis),
1 workpiece, 1a narrow opening, 2 machining surface, 3 workpiece holding device,
10 polishing robot, 12 processing tool, 12a tip,
13 drive device, 14 force sensor, 16 robot controller,
20 robot arms, 22 attitude control devices, 23 storage units,
24 orbit data creation unit, 25 attitude setting unit

Claims (4)

A polishing robot that polishes the processing surface of a workpiece with a processing tool that processes at the tip, wherein the processing surface is located inside a narrow opening of the workpiece that passes the processing tool,
A robot arm that moves the machining tool in a three-dimensional space;
An attitude control device that controls the attitude of the machining tool based on the machining surface shape of the workpiece,
The attitude control device includes:
A storage unit that is stored in a space and stores a restraint point that restrains the posture of the tool rotation axis;
From the shape data of the workpiece, a trajectory data creation unit that creates trajectory data consisting of a point position on the trajectory along the work surface of the workpiece and a normal vector at the point position;
A posture setting unit that sets a posture of a machining tool so that a side surface of the tip portion and a machining surface of a workpiece are parallel to each other in a constraint plane including the constraint point and the normal vector. A polishing robot. A method for generating a trajectory of a polishing robot that polishes a processing surface of a workpiece with a processing tool that processes at the tip, wherein the processing surface is located inside a narrow opening of the workpiece that passes the processing tool,
A robot arm that moves the machining tool in a three-dimensional space;
Preparing an attitude control device for controlling the attitude of the machining tool based on the machining surface shape of the workpiece,
The restraint point that is designated on the space (A) by the posture control device and restrains the posture of the tool rotation axis is stored,
(B) creating trajectory data including a point position on the trajectory along the work surface of the workpiece and a normal vector at the point position from the workpiece shape data;
(C) In a constraining plane including the constraining point and the normal vector, a posture of a processing tool is set so that a side surface of the tip portion and a processing surface of a workpiece are parallel to each other. Orbit generation method. The shape of the tip is a cylindrical shape centered on the axis,
In the above (C),
Obtaining a first vector perpendicular to a constraint plane including the constraint point and the normal vector;
Next, a second vector perpendicular to the normal vector and the first vector is obtained,
The method of generating a trajectory for a polishing robot according to claim 2, wherein the posture of the second vector is set as the posture of the machining tool. The shape of the tip is a conical shape having an inclination angle with respect to the axis,
In the above (C),
Obtaining a first vector perpendicular to a constraint plane including the constraint point and the normal vector;
Next, a second vector perpendicular to the normal vector and the first vector is obtained,
3. The polishing according to claim 2, wherein a posture having the inclination angle inside the narrow opening with respect to the second vector as a center with respect to a direction of the first vector is set as a posture of the processing tool. Robot trajectory generation method.

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