JPH08252785A - Force control robot - Google Patents

Abstract

PURPOSE: To provide a force control robot to prevent the non-machined area or an excessive machined area from being generated even when a working objective substance has a corner part. CONSTITUTION: In a force control robot to move an end effecter along the surface of a working objective substance while the end effecter 12 is controlled so as to be pressed against the surface of the working objective substance whose surface shape is known with the target pressing force, a control mans to reduce the speed and force which reduces the advancing speed of the end effecter and reduces the target pressing force in the prescribed range before and behind a corner part when the working objective substance is provided with the corner parts 20a, 20b and the corner parts have the angular change Δθover the prescribed value is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force control robot for performing work such as chamfering, deburring or grinding.

[0002]

2. Description of the Related Art It has been proposed to use a force control robot to perform operations such as chamfering, deburring or grinding of cast parts, sheet metal parts and the like.

As an example of machining, a cast part is shown in FIG. In FIG. 7, the cast component 20 is machined to attach other components or to attach itself to the machine body, creating a machined surface 24. A ridge line 26 or a contour line 26 is generated between the machined surface 24 and the casting surface 22 or sheet metal surface (not shown) generated during casting, and burrs are generated at the contour line 26.

FIG. 9 shows in detail the occurrence of machining burrs. In FIG. 9B, which is an enlarged view of the Z portion in FIG. 9A, the generated burr 28 is shown. These burrs 28 need to be removed because they may damage the assembler and the end user.
Normally, the burrs 28 are removed by chamfering the ridge lines 26.

As shown in FIG. 10, the ridge 26 is considered to be a contour defined on the machining plane 24. The cutter 32 as an end effector moves while being position-controlled in the A direction along the contour line 26 on the machining plane 24, and is force-controlled so as to be pressed with a constant force in the B direction substantially orthogonal to the A direction. Operate and chamfer, burr 28
Is excluded.

Conventionally, a tool device having mechanical compliance has been used in the processing of objects to be processed such as cast parts and sheet metal parts.

It is also possible to use a force control type robot which corrects the tool trajectory by force control or compliance control using a feedback signal from a force sensor to machine. In this case, in order to respond to the change in the machining shape of the cast parts etc., the movement operation is performed while controlling the position toward the target value, and the force is controlled in the direction substantially orthogonal to the traveling direction to make the pressing force constant. Thus, it operates according to the surface shape.

[0008]

As shown in FIG. 6, the corners 20a, 2 of the object 20 to be machined are subject to a sudden change in angle.
When 0b is present, there are the following problems. Normally, the cutter 32 as an end effector is controlled to move as fast as possible so as to improve work efficiency,
The force is controlled in the direction orthogonal to the traveling direction.

However, since the movement control of the end effector requires a finite response time, the cutter 32 cannot follow the angle change in the corner portions 20a and 20b, and
During this response time, the vehicle tries to proceed in the same traveling direction as before before reaching the corners 20a and 20b. For this reason,
In the convex corner portion 20a, as shown in FIG. 6 (a), the cutter 32 separates from the object to be processed 20 to form an unmachined area 21a, and in the concave corner portion 20b, As shown in FIG. 6B, the cutter 32 bites into the object to be processed 20 and an excessively processed area 21b is generated.

In this case, the corner portions 20a, 20b are reduced by reducing the traveling speed.
The cutter 32 can be made to follow the change in the angle. However, if the traveling speed is simply reduced, the machining time in the deceleration region becomes longer than that in the non-deceleration region, resulting in excessive machining.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to prevent an unmachined region or an excessively machined region from occurring even when a machining target has a corner portion. Is to provide.

[0012]

In order to achieve the above object, a force control robot according to the present invention controls an end effector so as to press it with a target pressing force against the surface of a processing target object whose surface shape is known. In a force control robot that moves the end effector along the surface of the processing target object, when the processing target object has a corner part and the corner part has an angle change of a predetermined value or more, the corner part And a deceleration / reduction control means for reducing the advancing speed of the end effector and reducing the target pressing force in a predetermined range before and after.

[0013] Preferably, the deceleration reduction control means greatly reduces the advancing speed of the end effector and the target pressing force as the angle change of the corner portion increases.

Preferably, the end effector includes a force sensor for detecting a reaction force received from the processing object.

Preferably, the end effector is an end effector that performs operations such as chamfering, deburring or grinding.

[0016]

Since the surface shape of the object to be machined is known, the deceleration and deceleration control means detects that the end effector has moved to a predetermined position in front of the corner portion, and a predetermined predetermined distance before and after the corner portion is specified. Within the range, the advancing speed of the end effector is reduced and the target pressing force is reduced.

In a predetermined range before and after the corner portion, not only the advancing speed of the end effector is decreased but also the target pressing force is decreased. Therefore, even if the advancing speed of the end effector is decreased, the workpiece is excessively processed. There is nothing to do.

[0018]

Embodiments of the force control robot of the present invention will be described below with reference to the drawings. A deburring process for removing burrs generated on a ridgeline between a casting surface and a machined surface in machining a cast component will be specifically described based on an embodiment using a force control robot.

FIG. 2 shows a schematic structure of the main body 1 of the force control robot. The robot main body 1 is a 6-degree-of-freedom cylindrical robot and has a force control function. Robot body 1
In, the turning unit 3 is fixed on the base plate 2 fixed to the floor. A column 4 is rotatably supported by the swivel unit 3 to form a Θ axis.
A saddle 5 is slidably installed on the column 4 and constitutes a Z axis. An arm (not shown) is slidably arranged on the saddle 5 to form an R axis. The wrist portion 7 is arranged at the tip of the arm, and the posture control axes of the α axis, the β axis, and the γ axis are configured.

A 6-axis force sensor 10 is provided at the tip of the wrist 7.
Is arranged, and a deburring tool 12 is attached to the tip of the force sensor 10 as an end effector. The force sensor 10 detects a reaction force that the deburring tool 12 receives from the processing object 37.

Next, with reference to FIG. 1, a schematic configuration of this embodiment will be described. The robot body 1 is a robot controller 13
Controlled by. The robot controller 13 executes a predetermined operation command according to the teaching data 14 based on the reaction force detected by the force sensor 10. The robot control device 13 includes a deceleration and deceleration control means for reducing the advancing speed of the deburring tool 12, which is an end effector, and the target pressing force within a predetermined range before and after the corner of the workpiece 20. It is equipped with 15.

Next, the teaching data 14 will be described. The processing target 20 has a known surface shape, and has, for example, the shape shown in FIG. As shown in FIG. 3, the object to be processed 20 has corner portions of a convex (TOTSU) portion and a concave (OU) portion, and each of the convex (TOTSU) portion and the concave (OU) portion has LARG with corner angle greater than 90 degrees
There are corners of E, REC with an angle of 90 degrees, and SMALL with an angle of less than 90 degrees. As shown in FIG.
Starting teaching points P1, P2, ... P10 are designated in advance before each corner portion. In addition, start teaching points P1, P2 ...
Corresponding to P10, end teaching point Q1, across the corner,
Q2 ... Q10 are designated in advance. Teaching data 14
, Start teaching points P1, P2, ... P10 and end teaching point Q
It includes data such as 1, Q2, ... Q10.

Next, the deceleration reduction control means 15 will be described. As shown in FIGS. 2A and 2B, the deburring tool 12 is controlled to move at the moving speed V until reaching the start teaching point P and is pressed to the surface of the object to be processed by the pressing force F. ing. Deburring tool 12 starts Teaching point P
At this point, the deceleration reduction control means 15 causes the deburring tool 12
The deceleration / reduction force is controlled so that the moving speed of V is reduced to v smaller than V and the pressing force is reduced to f smaller than F. This deceleration reduction control is performed by the deburring tool 1
2 is performed until the end teaching point Q is passed. Where V
And v, F, and f, and the angle change Δθ of the corner portion will be described. The angle change Δθ is an angle indicating a change in the traveling direction of the deburring tool 12, as shown in FIG. The angle change Δθ takes a smaller value as the angle of the corner portion in the various corner portions shown in FIG. 3 increases. A relationship of v / V = m · Δθ (1) f / F = n · Δθ (2) is set between the deceleration rate v / V, the weight removal rate f / F, and the angle change Δθ. m and n are, for example, integer proportional coefficients, and as shown in the equations (1) and (2), the angle change Δθ
Is set to be larger, the deceleration rate v / V and the weight removal rate f / F are set to be larger. It should be noted that the proportional coefficients m and n do not have to be constant in all ranges of the angle change Δθ, and a suitable proportional coefficient may be set for each range of the angle change Δθ.

Next, the operation of this embodiment will be described.
The robot control device 13 refers to the teaching data 14 and controls the movement of the deburring tool 12 while pressing the deburring tool 12 against the workpiece 20 based on the reaction force detected by the force sensor 10 with the set target pressing force. Deceleration reduction control means 15
Deburring tool 12 starts teaching points P1, P2 ... P1
When it is detected that 0 has been reached, the end teaching points Q1, Q2
.. Until reaching Q10, the deburring tool 12 is controlled according to the equations (1) and (2) to reduce the traveling speed of the deburring tool 12 and reduce the target pressing force. The deburring tool 12 has a constant response time to a control command received from the robot controller 13, and by reducing the traveling speed, it is possible to reduce the range of the unmachined area and the excessively machined area in the corners 20a and 20b. . Further, not only the progressing speed is reduced, but also the pressing force is reduced. Therefore, it is possible to prevent excessive machining which may occur because the processing time in the deceleration region becomes longer than that in the non-deceleration region due to the reduction in the traveling speed. You can

As described above, according to the configuration of this embodiment, the deceleration and deceleration control means 15 is provided, so that even if the path of the workpiece 20 traced by the deburring tool 12 changes suddenly, a predefined program Accordingly, the contour line can be deburred continuously and smoothly.

In the description of the above-mentioned embodiments, an example in which the force control robot is used for deburring has been described, but the present invention is not limited to this, and processing other than deburring such as chamfering and grinding. Can also be applied in.

[0027]

As described above, according to the configuration of the present invention, since the deceleration and deceleration control means is provided, even if there is a rapid angle change in the path of the object to be traced by the end effector, it is defined in advance. The end effector can be continuously and smoothly controlled with respect to the workpiece according to the program.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a force control robot according to the present invention.

FIG. 2 is a diagram illustrating an example in which control of deceleration and deceleration by a deceleration and deceleration control unit is applied to a convex corner portion (a) and a concave corner portion (b) and a definition of an angle change Δθ.

FIG. 3 is a diagram showing various corners of a processing object classified into convex corners (a) to (c) and concave corners (d) to (f).

FIG. 4 is a view showing various corner portions of a processing object.

FIG. 5 is a front view showing a schematic configuration of a robot body of a force control robot.

FIG. 6 is a diagram showing that an unmachined region and an excessively machined region are generated in a corner portion in a conventional force control robot.

FIG. 7 is a perspective view illustrating an example of machining a cast component.

8A and 8B are views for explaining the occurrence of burrs in machining and a partially enlarged view thereof.

FIG. 9 is a perspective view for explaining a ridge line as a contour figure on a machining plane.

[Explanation of symbols]

 1 Robot Main Body 10 Force Sensor 12 End Effector (Deburring Tool) 13 Robot Controller 14 Teaching Data 15 Deceleration Reduction Control Means 20 Machining Targets 20a, 20b Corners

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Ozaki 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center

Claims (4)

[Claims] 1. A force control robot for moving the end effector along the surface of the object to be processed while controlling the end effector to press the surface of the object to be processed having a known surface shape with a target pressing force. When the processing object has a corner portion and the corner portion has an angle change of a predetermined value or more, the advance speed of the end effector is reduced in a predetermined range before and after the corner portion. A force control robot comprising a deceleration reduction control means for reducing the target pressing force. 2. The deceleration reduction control means greatly reduces the advancing speed of the end effector and greatly reduces the target pressing force as the angle change of the corner portion increases. The force control robot described in. 3. The force control robot according to claim 1, wherein the end effector includes a force sensor that detects a reaction force received from the processing object. 4. The force control robot according to claim 1, wherein the end effector is an end effector that performs work such as chamfering, deburring, or grinding.