JP6323744B2 - Polishing robot and its control method - Google Patents

Description

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

  For example, Patent Documents 1 and 2 have already been proposed as techniques for performing processing while controlling force on a workpiece in a processing robot that processes a workpiece by attaching a tool to the tip of the robot arm and moving it along the machining path ing.

The “polishing method” of Patent Document 1 compensates for the deviation between the target track and the workpiece by performing processing while controlling the pressing force of the tool to be constant.
Patent Document 2 “Workpiece Processing Apparatus and Control Method Therefor” maintains machining accuracy and prevents tool breakage even when shocking machining reaction force occurs.

Japanese Patent No. 2852828 JP 2010-253613 A

  Here, in the conventional method described above, for example, even when a workpiece including a first surface and a second surface connected at an inner angle of less than 180 degrees is machined, a force is applied only in the normal direction of one surface. Processing is performed under control. However, in order to avoid the collision of the tool with the other surface during machining, the machining range needs to be set at a position where a sufficient clearance is secured from the boundary line between the first surface and the second surface. It was.

Therefore, for example, when polishing a workpiece, it is difficult to polish the vicinity of the boundary line of the workpiece, so that there is a problem that a range in which the polishing cannot be performed becomes wide.
In particular, when polishing a workpiece having a variation in shape, it is necessary to further secure a clearance from the boundary line.

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to prevent a collision between a workpiece and a machining tool regardless of variations in the shape of the workpiece when machining a workpiece including the first surface and the second surface connected at an inner angle of less than 180 degrees. An object of the present invention is to provide a polishing robot that can perform polishing in the vicinity of the boundary line of a workpiece while avoiding it, and a control method thereof.

According to the present invention, the workpiece includes a first surface and a second surface that are connected at an inner angle of less than 180 degrees, and a boundary line between the first surface and the second surface is a curved line and is processed at a tip portion. A polishing robot for polishing the first surface or the second surface with a processing tool,
A force sensor for measuring an external force acting on the processing tool;
A robot arm that moves the machining tool in a three-dimensional space;
A robot controller that stores trajectory data and controls the robot arm, and
The robot controller is
The machining tool to the first surface and the second surface 2 direction perpendicular both to the, or the resultant force is in force control in two directions toward the boundary line, so modeled after the tip along said boundary line, A trajectory acquisition unit that stores trajectory data of the tip part;
A polishing control unit for controlling the force of the machining tool in one direction orthogonal to the first surface or the second surface and polishing the workpiece at a position where the tip portion is separated from the boundary line based on the trajectory data; A polishing robot characterized by comprising:

The trajectory acquisition unit measures a workpiece by hybrid control using a trajectory created based on teaching work or shape data of a design drawing as a target trajectory.

  The polishing control unit polishes a workpiece by hybrid control in which a trajectory displaced in a direction away from the boundary line is used as a target trajectory.

Further, according to the present invention, the workpiece includes the first surface and the second surface that are connected at an inner angle of less than 180 degrees , the boundary line between the first surface and the second surface is a curve , A method for controlling a polishing robot for polishing the first surface or the second surface with a processing tool to be processed,
A force sensor for measuring an external force acting on the processing tool;
A robot arm that moves the machining tool in a three-dimensional space;
Preparing a robot control device for storing trajectory data and controlling the robot arm;
By the robot control device,
(A) the two directions perpendicular to the machining tool in both the first surface and the second surface, or the resultant force is in force control in two directions toward the boundary line, the leading end portion along the boundary line Copy, memorize the locus data of the tip,
(B) The force of the machining tool is controlled in one direction orthogonal to the first surface or the second surface, and the workpiece is polished at a position where the tip portion is separated from the boundary line based on the trajectory data. A control method for a polishing robot is provided.

In (A), the trajectory data of the tip is measured by hybrid control using the trajectory created based on the teaching work or the shape data of the design drawing as the target trajectory.

  In (B), the workpiece is polished by hybrid control with the trajectory displaced in a direction away from the boundary line as a target trajectory.

According to the present invention, the machining tool is force-controlled in two directions orthogonal to both the first surface and the second surface, or in two directions where the resultant force is directed toward the boundary between the first surface and the second surface, By tracing the tip along the boundary line, it is possible to obtain the trajectory data of the boundary line of the workpiece regardless of the variation in the shape of the workpiece. Further, the locus data of the tip is stored, the force of the machining tool is controlled in one direction orthogonal to the first surface or the second surface, and the workpiece is polished at a position where the tip is separated from the boundary line based on the locus data. As a result, it is possible to avoid collision between the other surface and the processing tool during polishing.
Therefore, when machining a workpiece including the first surface and the second surface that are connected at an internal angle of less than 180 degrees, the workpiece boundary is avoided while avoiding the collision between the workpiece and the machining tool regardless of variations in the workpiece shape. Polishing in the vicinity of the line can be performed.

It is a block diagram of the grinding robot of this invention. It is explanatory drawing of the workpiece | work grind | polished with the grinding | polishing robot of this invention. It is a whole flowchart of the control method of the present invention. It is explanatory drawing of step S2 by the control method of this invention. It is explanatory drawing of step S3 by the control method of this invention.

  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 a configuration diagram of a polishing robot 10 of the present invention.
In this figure, 1 is a work (member to be processed), 2 is a work holding device, 3 is a processing tool, 10 is a polishing robot, and 20 is a robot control device.

  The workpiece 1 is a workpiece to be deburred, chamfered, or rounded by the machining tool 3 and is made of a hard material such as cast iron. In the present invention, it is assumed that the workpiece 1 is polished by the processing tool 3.

Specifically, as shown in FIG. 2, the workpiece 1 to be polished by the polishing robot 10 of the present invention is intended to include a first surface 1a and a second surface 1b connected at an internal angle θ of less than 180 degrees. The inner angle θ is preferably about 60 ° to 120 ° formed by a plane or a curved surface, and more preferably 90 °.
Further, in this example, the workpiece 1 is accurately fixed at a predetermined position by the workpiece holding device 2. The predetermined position is a position set in advance within the operating range of the polishing robot 10.

The polishing robot 10 attaches the machining tool 3 to the tip of the robot arm 12 and moves the workpiece 1 along the track (machining path).
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 3 is attached to the tip of the robot arm 12 and processes the workpiece 1.
In this example, the processing tool 3 includes a tip portion 3a for processing the workpiece 1 and a driving device 3b (in this example, an electric spindle motor) that rotationally drives the workpiece.
The tip 3a is a brush, a cushion sander (resin sponge containing abrasive grains), a grindstone, a cemented carbide cutter, or the like.
The drive device 3b can be replaced with a drive device that moves in various directions such as vertical, horizontal, and circular, and the electric spindle motor can be replaced with an air motor.

In FIG. 1, the force sensor 14 is attached to the tip of the robot arm 12, and the processing tool 3 is attached to the force sensor 14.
The force sensor 14 is, for example, a load cell, and is attached to the tip of the robot arm 12 that can move in a three-dimensional space, and detects an external force acting on the tip.
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 is Other force sensors may be used as long as they can be detected.

  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 12 to six degrees of freedom (three-dimensional position and rotation about three axes) by a command signal.

  In FIG. 1, a robot control device 20 according to the present invention stores trajectory data D and controls a robot arm 12, and in this example, includes a control PC 25.

In this example, the control PC 25 includes a storage device 21, a trajectory acquisition unit 22, and a polishing control unit 23, and controls the robot arm 12 via the robot controller 16.
Although the control PC 25 is provided separately from the robot controller 16 in this example, the robot controller 16 and the control PC 25 may be configured by the same control PC.

The storage device 21 stores trajectory data D including the position, posture, and pressing direction of the processing tool 3.
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 3 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 3 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 3 can be set, these coordinate systems and posture parameters are defined (in general, various definition parameters are used for posture expression). It is not limited to.

The trajectory acquisition unit 22 controls the force of the machining tool 3 in two directions orthogonal to both the first surface 1a and the second surface 1b, and follows the tip 3a along the boundary line 1c. Is stored in the storage device 21.
Here, the direction of force control is not limited to “two directions orthogonal to each other”, but may be two directions in which the resultant force is directed toward the boundary line 1c between the first surface 1a and the second surface 1b. Further, “toward the boundary line 1 c” does not have to be strictly toward the boundary line 1 c, but may be in a direction approaching the boundary line 1 c.
In the case where the trajectory data D is already stored in the storage device 21, a corrected version is stored.

In particular, the trajectory acquisition unit 22 preferably measures the trajectory data of the tip portion 3a by hybrid control in which a trajectory created based on teaching work or shape data of a design drawing or the like is used as a target trajectory.
“Hybrid control” refers to control in which force control and position control are performed simultaneously, and the trajectory acquisition unit 22 performs force control in the normal direction of the first surface 1a and the second surface 1b, Position control in other directions. However, since the normal direction is not constant when the first surface 1a and the second surface 1b are curved surfaces, it is necessary to change the direction of force control in synchronization with the operation.

The polishing control unit 23 performs force control in one direction orthogonal to the first surface 1a or the second surface 1b and polishes the workpiece 1 at a position where the tip 3a is separated from the boundary line 1c based on the trajectory data D. is there.
In particular, it is preferable that the polishing control unit 23 polishes the workpiece 1 by hybrid control using a trajectory displaced (shifted) in the direction away from the boundary line 1c as the target trajectory.

In the polishing control unit 23, force control is performed in the normal direction of the first surface 1a or the second surface 1b, and position control is performed in other directions in the space. However, since the normal direction is not constant when the first surface 1a or the second surface 1b is a curved surface, it is necessary to change the direction of force control in synchronization with the operation.
“Synchronized with operation” means that when the normal is a curved surface or the like, the method of applying force differs depending on the direction of the normal, and thus the method of applying force is adjusted in conjunction with the direction of the normal.

FIG. 3 is an overall flowchart of the control method of the present invention.
The apparatus mentioned above is prepared and the control method of this invention implements each step (process) of S1-S3.
In step S1 (trajectory data generation step), for example, the trajectory data D is generated by a CAD model or teaching of the workpiece 1 and stored in the storage device 21.

  In step S2 (copying step), the machining tool 3 is force-controlled in two directions in which the machining tool 3 is orthogonal to the first surface 1a and the second surface 1b or the resultant force is directed toward the boundary line 1c between the first surface 1a and the second surface 1b. Then, the tip portion 3a is copied along the boundary line 1c, and the locus data D of the tip portion 3a is stored (corrected).

FIG. 4 is an explanatory diagram of step S2 according to the control method of the present invention.
FIG. 4A is an explanatory view showing the workpiece 1 and the machining tool 3 in step S2, and FIG. 4B is a cross-sectional view of the A plane in FIG. 4A.
In this example, as shown in FIG. 4B, the processing tool 3 controls the force by the pressing force F1 with respect to the normal direction of the first surface 1a, and in the normal direction of the second surface 1b. On the other hand, force control is performed by pressing force F2. Furthermore, position control is performed along the trajectory data D about the boundary line 1c between the first surface 1a and the second surface 1b (in the direction of the broken line arrow in FIG. 4A).

  In the control in step S2, the force is controlled so that the force in the pressing direction of the machining tool 3 becomes the target value, and the direction orthogonal to the pressing direction or the resultant force is directed to the boundary line 1c between the first surface 1a and the second surface 1b. Controls the position so as to follow the trajectory data D.

  In step S <b> 2, instead of the processing tool 3, a copying jig (not shown) having the same shape as the processing tool 3 may be attached to the hand side flange surface of the robot arm 12. As long as the workpiece 1 is not machined, the machining tool 3 may be used as it is as a copying jig.

  In step S3 (polishing step), after step S2, the processing tool 3 is force-controlled in one direction orthogonal to the first surface 1a or the second surface 1b, and the tip 3a is moved to the boundary line 1c based on the trajectory data D. The workpiece 1 is polished at a position away from the workpiece.

FIG. 5 is an explanatory diagram of step S3 according to the control method of the present invention.
FIG. 5A is an explanatory diagram when the trajectory data D is acquired in accordance with step S2. As described above, by controlling the force on the first surface 1a and the second surface 1b, the trajectory data D obtained as a result of the tip portion 3a of the processing tool 3 moving along the boundary line 1c is acquired.
FIG. 5B is an explanatory diagram of the first embodiment of step S3, and FIG. 5C is an explanatory diagram of the second embodiment of step S3.
FIGS. 5A to 5C show a case where the second surface 1b is polished at a position away from the boundary line 1c while performing force control on the first surface 1a.

In the first embodiment shown in FIG. 5B, while performing force control on the first surface 1a, (1) the trajectory displaced in the direction away from the boundary line 1c is set as a new target trajectory. (2) Polishing is performed along the new target trajectory at the displaced position, and polishing is performed by alternately repeating (1) and (2).
The polishing performed along the target trajectory created from the trajectory data D may be a method of reversing the direction in which polishing is performed each time, as shown in FIG. 5B, and polishing in the same direction every time. It may be a method of processing.

  Further, the process of creating the target trajectory for polishing is not limited to the displacement of the trajectory data D, but may be a boundary line of the region where the trajectory data D is processed as shown in FIG. 5C (second embodiment). ).

The polishing in step S3 may be performed by displacing a tool reference point (TCP: Tool Center Point) or a reference coordinate system.
Further, when the variation in the shape of the workpiece 1 is small, the workpiece 1 may be polished without measuring the trajectory data D on the condition that the workpiece 1 is accurately positioned.
Further, if there is no influence on the non-polished surface of the first surface 1a and the second surface 1b (if there is no risk of contact with the processing tool 3), the polishing is performed while acquiring the trajectory data D. It may be a thing.

According to the present invention described above, the machining tool 3 is applied in two directions orthogonal to both the first surface 1a and the second surface 1b, or in two directions in which the resultant force is directed toward the boundary line between the first surface 1a and the second surface 1b. The locus data D of the boundary line 1c of the workpiece 1 can be acquired regardless of the variation in the shape of the workpiece 1 by controlling and following the tip 3a along the boundary line 1c. Further, the locus data D of the tip portion 3a is stored, the force of the machining tool 3 is controlled in one direction orthogonal to the first surface 1a or the second surface 1b, and the tip portion 3a is moved from the boundary line 1c based on the locus data D. By polishing the workpiece 1 at the separated position, it is possible to avoid collision between the other surface and the processing tool 3 during polishing.
Therefore, the vicinity of the boundary 1c of the workpiece 1 can be polished while avoiding the collision between the workpiece 1 and the processing tool 3 regardless of the variation in the shape of the workpiece 1.

  Further, in the present invention, since polishing can be performed based on the trajectory data D acquired by the polishing control unit 23, polishing is performed without performing accurate calculation on the contact position of the processing tool 3 and the workpiece 1. Can do.

  The vicinity of the boundary line 1c (for example, a range of about 5 to 10 mm from the boundary line 1c) may be polished by the polishing robot 10 according to the present invention, and the other range may be polished by conventional means. .

  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.

1 work (member to be processed), 1a first surface, 1b second surface, 1c boundary line,
2 Workpiece holding device, 3 processing tool, 3a tip, 3b drive device,
10 grinding robot, 12 robot arm, 14 force sensor,
16 robot controller, 20 robot controller,
21 storage device, 22 locus acquisition unit, 23 polishing control unit, 25 control PC

Claims (6)

The workpiece includes a first surface and a second surface that are connected at an internal angle of less than 180 degrees, a boundary line between the first surface and the second surface is a curve, and the first tool is a processing tool that processes at a tip portion. A polishing robot for polishing a surface or the second surface,
A force sensor for measuring an external force acting on the processing tool;
A robot arm that moves the machining tool in a three-dimensional space;
A robot controller that stores trajectory data and controls the robot arm, and
The robot controller is
The machining tool to the first surface and the second surface 2 direction perpendicular both to the, or the resultant force is in force control in two directions toward the boundary line, so modeled after the tip along said boundary line, A trajectory acquisition unit that stores trajectory data of the tip part;
A polishing control unit for controlling the force of the machining tool in one direction orthogonal to the first surface or the second surface and polishing the workpiece at a position where the tip portion is separated from the boundary line based on the trajectory data; A polishing robot comprising: The polishing robot according to claim 1, wherein the trajectory acquisition unit measures a workpiece by hybrid control with a trajectory created based on teaching work or shape data of a design drawing as a target trajectory.   The polishing robot according to claim 1, wherein the polishing control unit polishes the workpiece by hybrid control in which a trajectory displaced in a direction away from the boundary line is used as a target trajectory. The workpiece includes a first surface and a second surface that are connected at an internal angle of less than 180 degrees, a boundary line between the first surface and the second surface is a curve, and the first tool is a processing tool that processes at a tip portion. A polishing robot control method for polishing a surface or the second surface,
A force sensor for measuring an external force acting on the processing tool;
A robot arm that moves the machining tool in a three-dimensional space;
Preparing a robot control device for storing trajectory data and controlling the robot arm;
By the robot control device,
(A) the two directions perpendicular to the machining tool in both the first surface and the second surface, or the resultant force is in force control in two directions toward the boundary line, the leading end portion along the boundary line Copy, memorize the locus data of the tip,
(B) The force of the machining tool is controlled in one direction orthogonal to the first surface or the second surface, and the workpiece is polished at a position where the tip portion is separated from the boundary line based on the trajectory data. A polishing robot control method characterized by the above. 5. The polishing robot according to claim 4, wherein, in (A), the trajectory data of the tip portion is measured by hybrid control using a trajectory created based on teaching work or shape data of a design drawing as a target trajectory. Control method. 5. The method of controlling a polishing robot according to claim 4, wherein, in (B), the workpiece is polished by hybrid control with a trajectory displaced in a direction away from the boundary line as a target trajectory. 5.

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