JP2019202372A - Robot system and control method for robot - Google Patents

Abstract

To create a movement trajectory more accurate than a conventional one.SOLUTION: A robot system comprises: a robot comprising a predetermined processing tool; and a control device that acquires a movement trajectory of the processing tool during a teaching mode. The robot comprises a force sensor that detects external force acting on the processing tool. The control device acquires the movement trajectory by moving the processing tool while pressing the processing tool against a work, such that external force detected by the force sensor during the teaching mode has a constant value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot system and a robot control method.

  Patent Document 1 below discloses an industrial robot mechanism that performs a copying operation such as grinding and polishing on a work target having a three-dimensional free-form surface with a tool attached to a hand portion. This industrial robot mechanism performs so-called teaching playback control in which a copying operation is performed on a work object by moving a tool along a movement path manually taught by an operator in advance.

Japanese Patent No. 3670700

  By the way, the teaching of the moving path varies depending on the teaching ability of the operator. Therefore, an accurate movement path cannot be taught, and the industrial robot mechanism may not be able to move the tool along the accurate movement path.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to create a more accurate movement route than before.

  In order to achieve the above object, in the present invention, as a first solving means related to a robot system, a robot having a predetermined processing tool, and a movement trajectory of the processing tool are acquired in a teaching mode, and A robot system including a control device that controls the robot based on a movement trajectory, wherein the robot includes a force sensor that detects an external force acting on the processing tool, and the control device is configured to perform the operation in the teaching mode. A means is adopted in which the processing tool is moved while being pressed against the surface of the workpiece so as to acquire the movement locus so that the external force detected by the force sensor becomes a constant value.

  In the present invention, as the second solving means relating to the robot system, in the first solving means, the control device adopts a means for controlling the robot based on the movement locus in the playback mode.

  In the present invention, as the third solving means relating to the robot system, in the first or second solving means, the control device presses the movement trajectory in the direction in which the processing tool is pressed against the surface of the workpiece or in the pressing A method is adopted in which a movement path is created by offsetting in a direction opposite to the direction, and the robot is controlled based on the movement path.

  In the present invention, as a fourth solving means relating to the robot system, in any one of the first to third solving means, the processing tool is pressed against the surface of the workpiece with the force of the constant value. The teaching tool is formed of a material having rigidity that does not deform.

  In the present invention, as a fifth solving means related to the robot system, in the first to fourth solving means, means that the processing tool is a tool for performing the predetermined processing is adopted.

  In the present invention, as a sixth solving means related to the robot control method, the robot control method includes a predetermined processing tool and a force sensor that detects an external force acting on the processing tool. An acquisition step of acquiring a movement trajectory of the processing tool. In the acquisition step, the processing tool is moved while being pressed against the surface of the workpiece so that the external force detected by the force sensor becomes a constant value in the teaching mode. A means of acquiring the movement trajectory is adopted.

  In the present invention, as a seventh solving means relating to the robot control method, in the sixth solving means, in the playback mode, a control step of controlling the robot based on the movement trajectory acquired in the acquisition step is provided. Furthermore, the means of including is adopted.

  According to the present invention, it is possible to create a more accurate movement route than before.

It is a block diagram which shows the structure of the robot system A which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus 2 which concerns on one Embodiment of this invention. It is a figure which shows the flow of operation | movement of the industrial robot 1 and control apparatus 2 which concern on one Embodiment of this invention. It is a figure explaining operation | movement of the teaching mode which concerns on one Embodiment of this invention. It is a figure which shows the structure of the tool which apply | coats and inject | pours an adhesive agent to the workpiece | work W which concerns on one Embodiment of this invention. It is a figure showing composition of a tool which wipes off adhesive on the surface of work W concerning one embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The robot system A according to this embodiment includes a robot 1 and a control device 2 as shown in FIG.
The robot 1 is a robot that performs a predetermined process on the workpiece W while moving along a movement path R along the surface shape of the workpiece W fixed by the jig F.
Here, the predetermined treatment includes deburring, C chamfering, round edge processing, application of liquid such as an adhesive, pouring or wiping.

The robot 1 includes a robot arm 3, a hand unit 4, a processing tool 5, and a force sensor 6.
The robot arm 3 has a plurality of multi-joint mechanisms. Each joint of the robot arm 3 is provided with a motor that drives each joint. The robot arm 3 can move in, for example, a three-dimensional space when the motor is driven by the control device 2. Each joint is provided with an encoder for detecting the rotation angle of the motor.

The hand unit 4 removably connects the processing tool 5 to the robot arm 3.
The processing tool 5 is attached to the tip of the robot arm 3 by the hand unit 4. The processing tool 5 can move its position and posture in the three-dimensional space by driving the robot arm 3. The processing tool 5 is formed of a material that does not deform even when pressed with a predetermined force. The predetermined force is a pressing force with which the processing tool 5 presses the workpiece W. The processing tool 5 is attached to the tip of the robot arm 3 by an operator when creating the movement path R in the teaching mode. The processing tool 5 may be a tool that performs the predetermined processing in the playback mode, or may be a dedicated teaching tool for creating the movement path R in the teaching mode.

  The force sensor 6 detects an external force Ft acting on the processing tool 5. Then, the force sensor 6 outputs the detected external force Ft to the control device 2. For example, the force sensor 6 is attached between the robot arm 3 and the processing tool 5 that are movable in three dimensions. The force sensor 6 detects, for example, the forces in the three orthogonal axes and the torque around each axis. However, the force sensor 6 is not limited to this, and may be other force sensors as long as the pressing force against the workpiece W can be detected.

The control device 2 stores the movement trajectory of the processing tool 5 and the operation data of the robot 1 in the teaching mode, and controls the robot 1 based on the movement trajectory and the operation data in the playback mode. Below, the structure of the control apparatus 2 is demonstrated concretely.
As illustrated in FIG. 2, the control device 2 includes a robot control unit 21, a storage unit 22, a trajectory acquisition unit 23, and a route creation unit 24.

  The robot control unit 21 acquires an external force Ft acting on the processing tool 5 from the force sensor 6. Then, the robot control unit 21 is set in advance while pressing the processing tool 5 against the surface of the workpiece W by controlling the driving of the motor provided in the robot arm 3 so that the acquired external force Ft becomes a constant value. To each teaching point T. That is, the robot control unit 21 can copy the processing tool 5 to the surface shape of the workpiece W while controlling the pressing force of the processing tool 5 against the surface of the workpiece W. Here, the direction (pressing direction) of pressing the processing tool 5 against the surface of the workpiece W is, for example, the normal direction of the surface of the workpiece W. However, the pressing direction is not limited to the normal direction on the surface of the workpiece W, and may be a direction shifted from the normal direction in order to avoid interference between the workpiece W and the processing tool 5. In addition, the direction (moving direction) in which the processing tool 5 can follow the surface shape of the workpiece W is, for example, a direction perpendicular to the pressing direction.

  The storage unit 22 stores the preset teaching point T. A plurality of teaching points T are set on the surface of the workpiece W. For example, the teaching point T includes a start position and a stop position of the processing tool 5 for copying the surface shape of the workpiece W.

  The trajectory acquisition unit 23 acquires the trajectory of the position where the processing tool 5 has moved (movement trajectory) and the operation data (position and posture) of the robot arm 3 for each position. For example, the trajectory acquisition unit 23 calculates the movement trajectory of the processing tool 5 and the operation data of the robot arm 3 on the movement trajectory based on the rotation angle of the motor acquired from the encoder provided in the robot arm 3.

  The route creation unit 24 creates a travel route R from the travel track acquired by the track acquisition unit 23. For example, the route creation unit 24 creates the travel route R by offsetting the movement track acquired by the track acquisition unit 23 in the pressing direction or the direction opposite to the pressing direction. For example, the offset amount is determined based on the shape of the processing tool 5. For example, when the teaching tool is attached to the tip of the robot arm 3 and the movement path R is created, the length in the pressing direction of the teaching tool and the tip of the robot arm 3 to perform the above-described processing are performed. The offset amount is set based on a difference value with the length in the pressing direction of the tool to be attached. Then, the route creation unit 24 stores the created travel route R and the operation data acquired by the trajectory acquisition unit 23 in the storage unit 22 in association with each other.

  For example, when applying or injecting adhesive to the workpiece W as the predetermined processing, the nozzle (tool) attached to the tip of the robot arm 3 is separated from the workpiece W by a predetermined distance. While copying, the adhesive is discharged from the nozzle. In this case, the route creation unit 24 creates the movement route R by offsetting the trajectory acquired by the trajectory acquisition unit 23 by a predetermined distance in the direction opposite to the pressing direction.

  On the other hand, for example, when the adhesive on the surface of the workpiece W is wiped off as a predetermined process, the adhesive is wiped off by copying a spatula (tool) attached to the tip of the robot arm 3 while pressing it against the workpiece W. In this case, the route creation unit 24 creates the travel route R by offsetting the travel track acquired by the track acquisition unit 23 by a predetermined distance in the pressing direction.

  Next, operations of the robot 1 and the control device 2 will be described in detail with reference to FIGS.

The operator attaches a teaching tool as the processing tool 5 to the tip of the robot arm 3. Then, the worker roughly teaches the plurality of teaching points T _{1 to} T ₄ to the control device 2 along the shape of the workpiece W (step S101). The teaching points T _{1 to} T ₄ may be taught by the operator manually moving the processing tool 5 on the surface of the workpiece W, or the operator stores desired coordinates on the surface of the workpiece W. You may teach by making it store in the part 22. FIG. You may teach offline using the 3D CAD model of the workpiece W. The teaching point T ₁ is the start position of the locus that the processing tool 5 follows, and the teaching point T ₄ is the stop position of the locus that the processing tool 5 follows. In addition, the teaching points T ₂ and T ₃ indicate positions between the start position and the stop position of the locus followed by the processing tool 5.

When teaching of the teaching points T _{1 to} T ₄ is completed, the robot control unit 21 controls the robot arm 3 so that the external force Ft acquired from the force sensor 6 becomes a constant value, while the processing tool 5 It is moved at a low speed so as to follow the order of T ₁ , teaching point T ₂ , teaching point T ₃ , and teaching point T ₄ (step S102). For example, when the surface of the workpiece W has a three-dimensional shape, the robot control unit 21 controls the processing tool 5 to follow the surface of the workpiece W while controlling the force in one direction of pressing. The low speed is a speed lower than the moving speed of the tool when the predetermined processing is performed.

  The trajectory acquisition unit 23 acquires the movement path of the processing tool 5 and the operation data of the robot arm 3 based on the rotation angle of the motor acquired from the encoder provided in the robot arm 3 in step S102 (step S103). Note that the creation of a movement trajectory that the processing tool 5 has moved on the surface of the workpiece W means that the surface shape of the workpiece W is acquired.

  The route creation unit 24 creates the movement route R by offsetting the trajectory acquired by the trajectory acquisition unit 23 by a predetermined distance in the pressing direction or the direction opposite to the pressing direction (step S104). Then, the route creation unit 24 stores the created travel route R in the storage unit 22 in association with the operation data. Thereby, in this embodiment, it becomes unnecessary for an operator to create the exact movement route R, and the movement route R can be created automatically. Thereby, even if the workpiece | work W is complicated shapes, such as a three-dimensional shape, the path | route creation part 24 can acquire the shape (trajectory on the surface of the workpiece | work W) of the workpiece | work W correctly. The route creation unit 24 can create an accurate travel route R based on the acquired shape data.

  When the movement path R is created, the operator removes the teaching tool and attaches the tool to the tip of the robot arm 3. Then, the robot control unit 21 performs a predetermined process on the workpiece W by controlling the tool so that the tool moves on the movement path R stored in the storage unit 22 (step S105).

  Thus, the robot system A according to the present embodiment acquires the surface shape of the workpiece W by copying the surface shape of the workpiece W with the processing tool 5. Then, the robot system A creates a movement route R based on the acquired surface shape of the workpiece W. Thereby, even when the position where the workpiece W is fixed or the size of the workpiece W is deviated, an accurate movement route R can be created for each workpiece W.

  In addition, since the robot system A according to the present embodiment automatically creates the movement path R regardless of the operator's teaching, the robot system A can handle a workpiece W having a complicated shape such as a three-dimensional shape that is difficult to accurately teach. Also, an accurate movement route R can be created.

  Further, for example, when the robot system A according to the present embodiment performs a predetermined process on the workpiece W using a tool, the robot system A operates while performing position control in one direction along the movement path R. Therefore, it can be operated quickly and accurately. For example, when applying and injecting an adhesive onto the workpiece W using a tool, the tool is moved a predetermined distance from the surface of the workpiece W, and the moving direction of the tool is operated by position control. Thereby, the quality in application | coating and injection | pouring of an adhesive agent can be stabilized, keeping the distance of a tool and the surface of the workpiece | work W constant.

  Further, the robot system A according to the present embodiment may extrapolate both ends of the movement path R by a predetermined distance when the predetermined processing is sufficiently performed up to the end of the workpiece W in the playback mode. Thereby, the robot system A can apply or wipe off the adhesive sufficiently to the end of the workpiece W with a tool, for example.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the robot control unit 21 may generate the pressing direction from the 3D CAD model of the workpiece W stored in the storage unit 22 in advance.

(2) In the above embodiment, as a tool for applying / injecting an adhesive to the workpiece W, a tool as shown in FIG. For example, the tool includes an air tube 11, a cartridge 12, and a nozzle 13. The air tube 11 allows a dispenser (not shown) and the cartridge 12 to communicate with each other. The adhesive filled in the cartridge 12 is discharged from the nozzle 13 to the outside by compressed air fed from the dispenser through the air tube 11.

(3) In the above embodiment, as a tool for wiping off the adhesive on the surface of the workpiece W, an elastic spatula 14 may be attached to the tip of the robot arm 3 with the hand portion 4 as shown in FIG. Thereby, it becomes possible to push the spatula 14 into the surface of the workpiece | work W, the float of the spatula 14 can be suppressed, and the adhesive residue can be reduced.

DESCRIPTION OF SYMBOLS 1 Robot 2 Control apparatus 3 Robot arm 4 Hand part 5 Processing tool 6 Force sensor 11 Air tube 12 Cartridge 13 Nozzle 14 Spatula 21 Robot control part 22 Memory | storage part 23 Trajectory acquisition part 24 Path | route creation part

Claims (7)

A robot system including a robot including a predetermined processing tool and a control device that acquires a movement trajectory of the processing tool in the teaching mode,
The robot includes a force sensor that detects an external force acting on the processing tool,
The control device acquires the movement trajectory by moving the processing tool while pressing it against the surface of a workpiece so that an external force detected by the force sensor becomes a constant value in a teaching mode. .   The robot system according to claim 1, wherein the control device controls the robot based on the movement locus in a playback mode. The control device creates a movement path by offsetting the movement locus in a direction in which the processing tool is pressed against the surface of the workpiece or in a direction opposite to the pressing direction, and controls the robot based on the movement path. The robot system according to claim 1 or 2, wherein: 4. The teaching tool according to claim 1, wherein the processing tool is a teaching tool formed of a material that does not deform even when pressed against the surface of the workpiece with the force of the constant value. 5. The robot system according to claim 1. The robot system according to claim 1, wherein the processing tool is a tool that performs a predetermined process. A robot control method comprising a predetermined processing tool and a force sensor for detecting an external force acting on the processing tool,
Including an acquisition step of acquiring a movement locus of the processing tool in the teaching mode;
In the acquisition step, the movement trajectory is acquired by moving the processing tool while pressing it against the surface of a workpiece so that the external force detected by the force sensor becomes a constant value in the teaching mode. Control method.   The robot control method according to claim 6, further comprising a control step of controlling the robot based on the movement trajectory acquired in the acquisition step in the playback mode.

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