JP2868195B2 - Grinding robot and grinding work execution method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding robot and a method of performing a grinding operation, and more particularly to a grinding robot such as a deburring machine or a surface grinding machine as a multi-degree-of-freedom working machine based on position / force control. The present invention relates to a grinding robot for grinding all of a large number of similar grinding target portions existing at unspecified locations on a work surface using a small amount of grinding data that can be easily taught, and a method of performing the grinding operation.

[0002]

2. Description of the Related Art An industrial grinding robot includes a robot main body for executing a grinding operation by pressing a grinding tool against a portion to be ground of a work, and a control device for controlling the operation of the grinding operation of the robot main body. The robot body performs a task requiring a large degree of freedom, and the control device controls the position and force required for the grinding task. The control device has a program for performing position / force control.Based on the program, a control command is generated under given grinding conditions such as a grinding place and a grinding order, and the control command is transmitted to the robot body. give.

In order for such a grinding robot to perform a desired grinding operation, it is necessary to teach the grinding robot in advance information on the conditions of the grinding operation. Information such as position data for the grinding operation is stored in the memory of the control device.

In a teaching operation of a general teaching playback type grinding robot, an operator moves a grinding tool of the robot body to a target position where the workpiece is to be actually ground, and the order, conditions, position, etc. of the operation. Is taught to the grinding robot. In the operation of the grinding operation by the grinding robot, teaching by the operator before the operation is an important process.

[0005] Examples of conventional grinding robots disclosed in the literature include, for example, "Development of Remote Grinder Working Robot" on pages 35 to 39 of the Robot Industry Association and Industrial Robot Utilization Technology Seminar, and pages 40 to 44 of the literature. There are “Features and application examples of a trace-type grinding robot system”.

[0006]

A teaching playback type grinding robot faithfully executes a grinding operation based on position and force information taught by an operator. However, with the conventional grinding robot, the grinding operation can be performed appropriately when the grinding location on the workpiece is unchanged, but when the grinding location is changed, the position information stored in the memory must be changed each time. Must. To do so, the teaching work on different grinding locations must be performed again. To explain with a specific example, for example, in the work of grinding a weld bead repaired and piled on a work, the place where the repair work is piled up is different for each work even if the shape of the work is the same. Is unspecified. Therefore, every time the work to be ground is replaced, it is necessary to re-teach a grinding operation that matches the work each time. As described above, the conventional teaching operation is very troublesome for the operator.

[0007] Further, a grinding robot which performs a grinding operation by manual operation, which is a remote operation, requires a peripheral device separately from the grinding robot, and is expensive. Further, although the actual grinding operation itself is performed by the robot, the operator must perform the operation of the grinding operation, which has a disadvantage that the burden on the operator increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a teaching playback type grinding robot which grinds a large number of similar ground portions to be formed at unspecified locations by a simple teaching operation. To provide a grinding robot and a method for performing the grinding operation.

[0009]

A grinding robot according to the present invention has a position data storage unit for storing a plurality of position data for specifying a region to be ground which is position data of a grinding tool taught by a teaching operation device. When having a control means for generating a control command by the position-force control based on a plurality of said position data, and a robot mechanism to perform the grinding operation the grinding tool on the basis of the control command, a plurality of said position data and the reference position data for identifying an object to be ground region serving as a reference is
To be used, is taught with reference position data, the reference position
Associated with the location data and in a certain
And one point storing taught reference position representing the taught reference position storage section that less determines the actually performed position grinding operation
An execution reference position storage unit that stores an execution reference position that represents one point, and a correction value calculation that calculates a positional difference between the teaching reference position and the execution reference position given from each of the two storage units as a correction value. And a position correction unit that converts the reference position data into position data specifying the actual grinding target area using the correction value, and provides the converted position data to the position target value setting unit of the control unit. Be composed.

In the above-mentioned configuration, preferably, the control means has a force detecting means for detecting a force applied to the grinding tool and a position detecting means for detecting a position of the grinding tool. When the force applied to the grinding tool is detected by the force detection means, the position of the grinding tool is detected by the position detection means, and the position is stored in the execution reference position storage unit as the execution reference position of the grinding operation. I do.

In the above configuration, preferably, the position data storage unit stores the reference position data including a plurality of position data.
Data as one pattern and different from each other
It has a configuration for preparing and storing a plurality of patterns, and further has a selecting means for extracting and outputting reference position data of a pattern corresponding to a region to be ground from the plurality of patterns.

[0012] grinding implementation of the present invention is a working implementation method applied to teaching playback type grinding robot, before the grinding operation, the grinding target region serving as a reference
Reference position data including a plurality of position data to be specified ;
Teaching the position data of one teaching reference point attached to the reference grinding target area and having a fixed positional relationship with respect thereto, and holding these position data;
Before grinding operation starts, it teaches the position data specifying at least one execution reference point corresponding to the taught reference point in the actual vicinity of the grinding region in the actually given work, holding the position data Steps to
Position of the taught reference point and the execution reference point taught
Calculating the difference , correcting the reference position data based on the difference , and grinding the actual grinding area based on the corrected reference position data.

[0013] In the above method, preferably, the teaching position data of the execution reference position, the grinding tool of the grinding robot in a force control state by the position-force control means work
This is performed by contacting the above-mentioned point to be an execution reference point .

[0014]

In the grinding robot according to the present invention, first,
A plurality of reference position data (reference position data, for example,
P1 to P6) shown in FIG. 3 are taught. The reference position data specifies a region to be ground as a reference in the work. For this reference position data ,
A teaching reference position that is attached and has a further fixed positional relationship
(Eg, point Q shown in FIG. 3) . On the other hand, when a work is given and an actual grinding operation is performed, an actual grinding area existing at an arbitrary position on the work is taught. This actual area to be ground (for example, as shown in FIGS. 3 and 4)
In the teaching of the mode 46) , an execution reference position (for example, shown in FIG.
Point Q ') is determined, and the position data of the execution reference position is stored as corresponding to the above-described teaching reference position. For the taught reference position and the execution reference position, a correction value for the positional difference is automatically calculated, and the position data (P1 to P6) taught first using this correction value. Is converted, and the converted position data (point P shown in FIG. 4)
1 ' to P6') , the actual grinding operation of the area to be ground is performed.

In the teaching of the execution reference position, the grinding tool of the grinding robot operating in the force control state under the position / force control is brought into contact with the execution reference position of the work, so that the contact position is instantly taught. Is set.

In the teaching of the actual grinding operation after the work is actually given, it is only necessary to teach the execution reference position existing at an arbitrary position on the work. The grinding area can be ground.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall system configuration of a grinding robot according to the present invention. In FIG. 1, reference numeral 1 denotes a robot main body, and an arm 2 having a plurality of joints is attached to a base 3. A drive device such as a motor is provided at each joint, and each joint has a function of operating in a predetermined direction. Due to the movable function of each joint of the arm 2, the posture of the entire arm changes to a posture required for work, and the tip of the arm 2 moves to a position required for work. A 6-axis force sensor 5 is attached to the wrist 4 at the tip of the arm. A grinding tool 7 for performing a grinding operation on the work 6 is attached to the tip side of the force sensor 5. The grinding tool 7 is, for example, a grinder. Reference numeral 8 denotes a controller, and the controller 8 is formed of, for example, a computer. The controller 8 has a control program for calculating a preset arithmetic expression or the like for controlling the position and the force, and uses this control program, parameters relating to given conditions, and teaching contents,
The operation of the robot body 1 is controlled. A program for controlling the grinding operation of the robot main body 1 includes a controller 8
Is stored in the memory.

The controller 8 gives a command for controlling the operation of the grinding operation to the robot body 1 through a signal line 9. Further, the controller 8 is provided with a detection signal regarding a force and a moment applied to the grinding tool 7 from the force sensor 5, that is, a force signal 10. Reference numeral 11 denotes a teaching operation device for assigning various conditions relating to a grinding operation to be performed to the controller 8 of the grinding robot and setting the conditions in a memory thereof. The operation device 11 has a numeric keypad and operation switches for giving various commands. The operating device 11 teaches, for example, teaching of a grinding operation and setting of grinding operation conditions. In particular, in the present embodiment, the teaching reference position and the execution reference position, which will be described later, are taught via the operating device 11. The operating device 11 can be configured as a portable device owned by an operator who performs a grinding operation, or can be configured as an installation device, as necessary.

Referring to FIG. 2, a detailed configuration of the control means realized by the controller 8 will be described. For the robot main body 1 performing the grinding operation, the control content for determining the content of the grinding operation is realized by software mainly using the controller 8. FIG. 2 is a block diagram showing the control elements and the connection relationship. It is needless to say that the control circuit can be configured using a hardware circuit.

A plurality of drive motors for operating each joint of the arm 2 are built in the robot body 1. A goniometer 21 for measuring a drive amount is attached to each of these drive motors. The angle meter 21 measures the axial angle data of each joint.

First, the configuration of the position / force control calculation system, which is the basic configuration, will be described. The position / force control calculation system has a configuration of a control system that executes virtual compliance control. The force signal 10 detected by the force sensor 5 attached to the tip of the arm of the robot body 1 is sent to the force calculation unit 22. The force calculation unit 22 performs gravity compensation by converting the input force signal from the sensor coordinate system to the reference coordinate system (absolute coordinate system) and subtracting the gravity of the grinding tool 7 from the force signal. Thus, the work 6 and the grinding tool 7 are
The force <f> generated at the contact point portion is calculated. Here, the symbol “<f>” means that f is a vector quantity.
In the following description, the meaning of the symbol “<>” is the same.

The force <f> obtained by the force calculator 22 is input to a subtractor 23, which subtracts the force <f> from the force target value <fr> set in the force target value setting unit 24. Done.
The output of the subtractor 23 is sent to the position / force control calculator 25 as force <f ′>. The target force value <fr> is a command value for giving a target force value in the pressing direction of the grinding tool 7.

The angle data on each axis detected by the goniometer 21 is sent to the position calculating section 27. The position calculator 27 calculates the position <x> (including the posture data) of the grinding tool 7 in the absolute coordinate system based on the input angle data. The calculated position <x> is compared with a target value <xr> of the position set by the position target value setting unit 29 in the position deviation calculating unit 28, and a position deviation <Δx> between them is obtained.

As described above, the force <f ′> obtained by the subtractor 23 and the position deviation <Δ
x> is input to the position / force control calculation unit 25.

The position / force control calculator 25 includes a subtractor 30
And a spring constant calculator 31 and a characteristic compensation calculator 32. The force <f ′> output from the subtractor 23 is
Input to 0. The position deviation <Δx> output from the position deviation calculator 28 is input to the spring constant calculator 31.
A virtual spring constant matrix K is set in the spring constant calculation unit 31. The spring constant calculator 31 calculates the input position deviation <Δ
x <> is calculated by multiplying x> by the set virtual spring constant matrix K. Spring constant calculator 31
Is output to the subtractor 30. The subtractor 30 calculates <f ′> − K <Δx>. The operation result obtained by the subtractor 30 is provided to the characteristic compensation operation unit 32.

The controller gain Kc is set in the characteristic compensation calculating section 32. In the characteristic compensation calculating section 32, <f ′> − K <Δ inputted based on the controller gain Kc.
x> undergoes control characteristic compensation, whereby the speed command value <v> is calculated. The speed command value <v> obtained by the position / force control calculation unit 25 is supplied to the drive command unit 33. In the drive command unit 33, the speed command value <v> is a drive command of each drive motor of the robot body 1. Is converted to the value <θ>. The obtained drive command value <θ> is supplied to each drive motor of the robot body 1, and the robot body 1 operates at a desired position and posture based on the operation of each drive motor.

A control system for correcting position data, which is a feature of the present invention, is added to the basic configuration of the virtual compliance control described above. Reference numeral 40 denotes a position data correction unit. The position data correction unit 40 includes a position data storage unit 41, a teaching reference position storage unit 42, an execution reference position storage unit 43, a correction value calculation unit 44, and a position correction unit 45.

The position data storage section 41 is a section for holding position data for performing a grinding operation. The position data is data for specifying a reference grinding area in the work, and is data taught by an operator. The operator inputs the position data into the position data storage unit 41 by operating the teaching operation device 11.

The teaching reference position storage section 42 is a section for holding position data relating to the teaching reference position accompanying the position data stored in the position data storage section 41. The teaching reference position is a reference position associated with the position data stored in the position data storage unit 41 so as to have a certain positional relationship, and is position data when a reference grinding area in the work is set. is there. Position data related to the teaching reference position is also input via the operating device 11 according to the teaching of the operator.

The execution reference position storage section 43 is a section for holding position data relating to the execution reference position. The execution reference position is a reference position for setting a region to be ground on which a grinding operation is actually performed on a work. When this execution reference position is set in the execution reference position storage section 43, when the grinding tool 7 is brought into contact with the vicinity of a portion of the work to be ground in a state where the work is set on the robot body, The position of the grinding tool 7 at the moment of contact is input to the execution reference position storage unit 43 as an execution reference position. Therefore,
As is clear from FIG. 2, the output signal of the force calculation unit 22 and the output signal of the position calculation unit 27 are input to the execution reference position storage unit 43, as is clear from the connection relationship between the connection terminals. According to this configuration, when a predetermined force signal is generated from the force calculation unit 22, the position data output from the position calculation unit 27 is held. Note The method for contacting the grinding tool 7 to the workpiece 6, or a method of contacting by operating the grinding robot in based power control state to the position-force control described above, by operating the robot body by the operator of the manual operation, grinding There are methods for bringing the tool 7 into contact.

The position data of the teaching reference position storage section 42 and the position data of the execution reference position storage section 43 are input to the correction value calculation section 44. The correction value calculation unit 44 determines a difference between the teaching reference position and the execution reference position value as a correction value. This difference is a difference between the position representing the teaching reference position and the point representing the execution reference position, and is described as a difference in each direction in the position coordinates or a vector representing a distance and a direction connecting two points. When the execution reference position is the same as the teaching reference position, the value output from the correction value calculation unit 44 is zero.

The position correction section 45 includes a position data storage section 4
1 and the difference data output from the correction value calculator 44 are input. When actually performing the grinding operation, the position correction unit 45 corrects the position data relating to the area to be ground sent from the position data storage unit 41 with the correction value obtained by the correction value calculation unit 44, and Convert to position data for performing grinding work. The position data obtained by the position correction unit 45 is given to a position target value setting unit 29, where it is set as a position target value.

The above-described basic control system and position data correction unit 4
The control executed by 0 will be described with reference to FIGS. In the present embodiment, as the grinding operation of the portion to be ground on the workpiece 6, first, position data defining a reference grinding region is determined, and a part of this position data is used as position data covering the grinding region. The position is stored in the position data storage unit 41, and the other parts are stored in the teaching reference position storage unit 42 as position data for determining the position of the area to be ground. The execution reference position data for determining the actual position of the area to be ground in the work 6 is determined each time by the above-described method before the grinding operation is performed, and the position data is stored in the execution reference position storage unit 43. . In the state where the teaching data is held, the correction value calculation unit 44 and the position correction unit 45 operate to automatically change the setting contents of the position target value setting unit 29, and the grinding area generated at an arbitrary position on the workpiece 6 is determined. A grinding operation is performed.

FIGS. 3 to 3 are images of the above operation.
FIG. 3 and 4 show plan views of the work 6, in which plane coordinates by an X axis and a Y axis are defined. FIG. 5 shows another embodiment in which the work is viewed from the side, and the plane coordinates by the X axis and the Z axis in the figure are defined.

Referring to FIG. 3, a case in which a bead 46 existing on the work 6 is ground will be described. Bead 46
Form the actual area to be ground. First, points P <b> 1 to P <b> 6 that define a reference grinding area on the surface of the work 6
And a point Q are set. Points P <b> 1 to P <b> 6 are points that set an area that covers the area to be ground as a reference. As indicated by the arrows, the grinding is performed in the order from the point P1 to the point P6. The position data of the points P1 to P6 is stored in the position data storage unit 41 based on the teaching work of the operator. Point Q is a teaching reference position and is set at a position close to points P1 to P6. The position data of the point Q representing the teaching reference position is stored in the teaching reference position storage unit 42 based on the teaching work of the operator. The reference grinding area defined by the points P1 to P6 and the point Q can be set at an arbitrary position on the surface of the work 6, and strictness is not required. Therefore, when the work 6 is determined, the operator can perform the setting by a relatively easy teaching operation.

Next, when the workpiece 6 on which the bead 46 to be ground is formed is provided, the operator
6, a point Q 'representing an execution reference position having a fixed positional relationship with the bead 46 is determined, the position data of the point Q' representing the execution reference position is taught to the grinding robot, and stored in the execution reference position storage unit 43. I do. In the teaching operation, as described above, the position of the point Q 'is detected by moving the grinding tool 7 to the point S and bringing it into contact with the point Q' under force control as shown in FIG. 6, for example. As is apparent from FIG. 4, the point Q 'is located at a position displaced with respect to the point Q in the X and Y axial directions.

In the state where the position data of the points P1 to P6, the position data of the point Q, and the position data of the point Q 'are set, the correction value calculator 44 calculates the coordinates based on the position data of the points Q and Q'. The above difference is obtained, and the position correction unit 45 converts the position data of the points P1 to P6 into the position data of the points P1 'to P6' based on the difference obtained by the correction value calculation unit 44. Point P
The position data of 1 'to P6' is, as shown in FIG.
This is the actual grinding execution position data covering the area where the beads 46 are formed. The position data of the obtained points P1 'to P6' is set in the position target value setting unit 29. When the position data of the points P1 'to P6' are stored in the position target value setting section 29, the basic control system uses the grinding tool as shown by the arrow in FIG. 4 based on the position data of the points P1 'to P6'. 7 moves, and the operation of grinding the bead 46 is performed.

The embodiment of FIG. 5 shows an example in which there is a difference in the height direction between point Q and point Q '. Also in this case, the difference between the two points is obtained using the position data of the point Q and the point Q '. Using this correction value, the reference teaching position data is converted to obtain the actual execution position data of the grinding operation. Can be calculated.

In the above embodiment, an example in which one bead exists on the surface of the work has been described. However, the number of beads existing on the surface of the work 6 is not limited to one.
For example, as shown in FIG.
0 may be scattered at arbitrary positions on the workpiece surface. In such a case, each bead 47 ~
Execution reference positions Q1 to Q4 are set corresponding to 50, and these are taught to the grinding robot. Each execution reference position Q1 to Q4
Are sequentially stored in the execution reference position storage unit 43. The method of teaching each execution reference position is the same as the method described in the above embodiment. In the grinding operation, beads 47
~ 50 are ground in the order taught.

In each of the above embodiments, the position data P1 to P
6, and the plane on which the basic grinding area defined by Q exists and the plane on which the grinding area defined by the execution reference position Q 'and the position data P1' to P6 'converted by the correction value exist. Although the relationship is parallel, it is possible to perform conversion between non-parallel surfaces by performing coordinate rotation conversion.

FIG. 8 shows another embodiment. In this embodiment, the position data storage unit 41 stores position data P1 to P1.
The pattern formed of P 6 are from the first provided with a plurality of patterns of the n. The first to n-th patterns are appropriately selected and output by the switch 51 in accordance with the region to be ground or the type of work. Switch 51
Is controlled by the switching controller 52.

[0043]

As is apparent from the above description, according to the present invention, in a grinding robot having a position / force control unit and executing position and force control, the position / force control unit corrects the grinding position data. With the addition of a part, it is only necessary to teach the position data, which is the basis of the grinding operation, once. For the actual grinding area, the grinding area can be specified by simple teaching each time before the start of the work. In addition, the grinding operation can be performed with short-time teaching. Even if there are a plurality of actual grinding regions at arbitrary positions on the work, all the grinding regions can be ground with a simple teaching.

In addition, a plurality of patterns can be stored as position data for defining a region to be ground as a reference, and position data of an arbitrary pattern can be used as necessary. A high grinding robot can be realized.

In the teaching of the execution reference position for determining the actual area to be ground, the teaching can be performed simply by bringing the grinding tool operating in the force control state into contact with the execution reference position on the work, so that the teaching can be easily performed. . Further, since the position is corrected including the wear amount of the grinding tool, a function for correcting the wear of the grinding tool is not required.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an overall system of a grinding robot according to the present invention.

FIG. 2 is a block diagram illustrating an internal configuration of a control device.

FIG. 3 is a plan view showing position data defining a bead on a workpiece and a reference grinding area.

FIG. 4 is a plan view showing a relationship between an actual area to be ground on the workpiece and a reference area to be ground;

FIG. 5 is a side view of a work having a step.

FIG. 6 is a diagram for explaining a method of teaching an execution reference position.

FIG. 7 is a plan view illustrating an embodiment in which a plurality of beads are provided on a work surface.

FIG. 8 is a block diagram illustrating a configuration of a position data storage unit including position data of a plurality of patterns.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Robot main body 2 ... Arm 5 ... Force sensor 6 ... Work 7 ... Grinding tool 8 ... Controller 11 ... Operating device 22 ... Force calculation part 24 ... Force target value setting part 25 ... Position / force control calculation part 27 ... Position calculation part 29 position target value setting unit 40 position data correction unit 41 position data storage unit 42 teaching position storage unit 43 execution reference position storage unit 44 correction value calculation unit 45 position correction units 46 to 50 beads 51 ... Switch 52… Switch controller

Continuation of the front page (56) References JP-A-62-109102 (JP, A) JP-A-4-13530 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23Q 15 / 00 305 B23Q 15/00 309 B24B 27/00 B24B 49/16

Claims (5)

(57) [Claims] 1. A position data storage means for storing a plurality of said position data for specifying an object to be ground region a position data of the grinding tool to be taught in the teaching means, a plurality of said position de
Possess a control means for generating a control command by the position-force control based on each of chromatography data, and a robot mechanism to perform the grinding work the grinding tool based on the control command, a plurality of
The position data is used to specify the area to be ground as a reference.
In the grinding robot is used as a reference position data, it is taught together with the reference position data, the reference position data
One that is attached to and has a fixed positional relationship with the
Teaching reference position storing means for storing a teaching reference position representing a point, and at least determining a position at which the grinding operation is actually performed.
An execution reference position storing means for storing an execution reference position representing one point, and a positional difference between the teaching reference position and the execution reference position given from each of the two storage means.
Correction value calculating means for calculating the difference as a correction value, and converting the reference position data into position data for specifying an actual grinding area using the correction value, and converting the converted position data to a position A grinding robot, comprising: a position correcting means for giving to a target value setting unit. 2. The grinding robot according to claim 1, wherein
The control unit has a force detection unit that detects a force applied to the grinding tool, and a position detection unit that detects a position of the grinding tool, and makes the grinding tool contact a position where a grinding operation is actually performed, When the force applied to the grinding tool is detected by the force detection means, the position of the grinding tool is detected by the position detection means, and the position is stored in the execution reference position storage means as the execution reference position of the grinding operation. Characterized grinding robot. 3. The grinding robot according to claim 1, wherein
The position data storage unit is configured to store a plurality of position data
Is stored as one pattern.
And a plurality of patterns different from each other
Paid by grinding robot, characterized in that it further includes an output selecting means retrieves the reference position data of the pattern corresponding to the ground region. 4. A method for performing a grinding operation of a teaching playback-type grinding robot, wherein a plurality of grinding target areas to be a reference are specified before the grinding operation .
Reference position data consisting of position data and position data of one teaching reference point attached to the grinding target region and having a fixed positional relationship with the reference position data are taught, and these position data are held. a step, before the grinding operation starts, the actual in the vicinity of the actual grinding target area in a given workpiece to specify at least one execution reference point corresponding to the taught reference point taught position data, the position Holding data, and the positional relationship between the taught reference point and the execution reference point taught.
Determining a significant difference , correcting the reference position data based on the difference , and grinding the actual ground area based on the corrected reference position data. Method. 5. The grinding operation execution method according to claim 4, wherein the teaching of the position data of the execution reference point is performed by executing a grinding tool of a grinding robot in a force control state by a position / force control unit on the work. A method for performing a grinding operation, wherein the method is performed by contacting a point to be a reference point .