JPH0631592A - Grinding robot and execution of grinding work - Google Patents

Abstract

PURPOSE:To carry out grinding work by a simple instruction for a short time by installing a position correction means for giving the position data after conversion to the aimed position value setting part of a control means. CONSTITUTION:The position data for specifying the grinding region instructed by an operating device is stored in a position data storage part 41. Then, the position data is set as standard position data, and the instructed standard position affiliated to the standard position data is stored in an instructed standard position storage part 42. Further, the execution standard position for determining the position for actually carrying out the grinding work by the grinding tool 7 of a robot mechanism 1 is stored in an execution standard position storage part 43. The difference between the instructed standard position given by two storage parts 42 and 43 and the execution standard position is calculated as correction value by a correction value calculation part 44. Using this correction value, the standard position data is converted to the position data for specifying the actual grinding region by a position correction part 45, and the position data after conversion is given to the aimed position setting part 29 of a control means (position/force control calculation part) 25.

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 for performing a grinding operation, and more particularly to a grinding machine such as deburring and surface polishing as a multi-degree-of-freedom working machine based on position / force control. The present invention relates to a grinding robot that grinds all a large number of similar objects to be ground existing at unspecified locations on a work surface using a small amount of grinding data that can be easily taught, and a method for performing the grinding operation.

[0002]

2. Description of the Related Art An industrial grinding robot includes a robot body for pressing a grinding tool against a portion to be ground of a workpiece to perform a grinding operation, and a controller for controlling the operation of the grinding operation of the robot body. The robot body executes work requiring multiple degrees of freedom, and the control device executes control of position and force required for grinding work. The control device has a program for performing position / force control, and based on this program, generates a control command under given grinding conditions such as the grinding location and grinding sequence, and this control command is sent to the robot body. give.

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

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

As a conventional grinding robot disclosed in the literature, for example, "Development of a remote grinder work robot" on pages 35-39 of the Robot Industry Association, Industrial Robot Utilization Technology Workshop, and pages 40-44 of the literature. "Features and application examples of tracing type grinding robot system" exist.

[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 work can be properly performed when the grinding place on the workpiece is unchanged, but the position information stored in the memory must be changed each time the grinding place is changed. I have to. To do so, the work of teaching different grinding locations must be repeated. Explaining in a concrete example, for example, in the work of grinding a weld bead repaired on a work, the location where the work is repaired 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-instruct the grinding work that matches the work each time. As described above, the conventional teaching work is very troublesome for the operator.

In addition, a grinding robot which is a remote operation and performs a grinding operation by a manual operation requires a peripheral device separately from the grinding robot, which is costly. Furthermore, although the actual grinding work itself is performed by the robot, the operator has to perform the operation of the grinding operation, which causes a problem that the operator's burden is increased.

An object of the present invention is to grind a large number of similar ground parts to be ground in an unspecified place by a simple teaching operation in a teaching playback type grinding robot. It is an object of the present invention to provide a grinding robot capable of performing the above and a method of performing the grinding work.

[0009]

A grinding robot according to the present invention includes a position data storage unit for storing position data of a grinding tool taught by a teaching operation device, the position data specifying an area to be ground. The position data includes a control unit that creates a control command by position / force control based on the position data, and a robot mechanism that causes a grinding tool to perform a grinding operation based on the control command. The teaching reference position storage unit for storing the teaching reference position associated with the reference position data, which is the teaching reference position taught together with the reference position data, and the execution reference position for determining the position where the grinding operation is actually performed. An execution reference position storage unit for storing the following, and a correction value calculation unit for calculating a difference between the teaching reference position and the execution reference position given from each of the two storage units as a correction value, It is configured to have a position correction unit that converts the reference position data into position data that specifies an actual ground region by using a positive value, and provides the converted position data to the position target value setting unit of the control unit. .

In the above structure, preferably, the control means has a force detection means for detecting a force applied to the grinding tool and a position detection means for detecting the position of the grinding tool, and the position for actually performing the grinding operation. 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 as the execution reference position for the grinding operation in the execution reference position storage unit. To do.

In the above structure, preferably, the position data storage unit has a structure for storing reference position data of a plurality of patterns different from each other, and further, the reference position of the pattern corresponding to the region to be ground from the plurality of patterns. It has a selection means for extracting and outputting data.

The grinding work execution method according to the present invention is a work execution method applied to a teaching playback type grinding robot. Before the grinding work, the position data of the reference grinding area and the reference grinding area are kept constant. Teaching the position data of the teaching reference position that has a positional relationship, and holding these position data, and before starting the grinding work, set the teaching reference position near the actual ground area in the actually applied work. Specify the corresponding execution reference position and teach the position data, and hold the position data. Find the difference between the taught reference position and the execution reference position, and correct the position data based on this difference. Then, the step of grinding the actual area to be ground based on the corrected position data.

In the above method, preferably, the teaching of the position data of the execution reference position is performed by bringing the grinding tool of the grinding robot in the force control state by the position / force control means into contact with the execution reference position.

[0014]

In the grinding robot according to the present invention, first of all,
Teaches the reference position data. The reference position data specifies a reference grinding area on the work. A teaching reference position having a further fixed positional relationship is taught to the reference position data. On the other hand, when a workpiece is given and an actual grinding operation is performed, an actual ground area existing at an arbitrary position of the workpiece is taught.
In this actual teaching of the area to be ground, an execution reference position existing in a fixed positional relationship with the actual area to be ground is determined, and the position data of this execution reference position is regarded as corresponding to the above-mentioned teaching reference position. Store. For the taught reference position and execution reference position, the correction value for the difference is automatically calculated, the position data taught first is converted using this correction value, and the position data after this conversion is used. Then, the actual grinding work of the area to be ground is executed.

In the teaching of the execution reference position, the grinding tool of the grinding robot operating under the force control under the position / force control is brought into contact with the execution reference position of the work, and the contact position is taught at the moment of contact. Is set.

In the teaching of the actual grinding work after the work is actually given, it is only necessary to teach the execution reference position existing at the arbitrary position on the work, and the workpiece to be ground formed at the 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 is a robot 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 in each joint, and each joint has a function of operating in a predetermined direction. Due to the movable function of each joint portion 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 portion 4 at the tip of the arm. On the tip side of the force sensor 5, a grinding tool 7 that grinds the work 6 is attached. The grinding tool 7 is, for example, a grinder. Reference numeral 8 is a controller, and the controller 8 is composed of, for example, a computer. The controller 8 has a control program for calculating preset arithmetic expressions for position and force control, and using this control program, parameters regarding given conditions, and teaching contents,
Controls the operation of the robot body 1. The program for controlling the grinding operation of the robot body 1 is the controller 8
Stored in memory.

The controller 8 gives a command for controlling the operation of the grinding operation to the robot body 1 through the 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 giving various conditions regarding the grinding work to be executed to the controller 8 of the grinding robot and setting the conditions in the memory. The operation unit 11 has a ten-key pad and operation switches for giving various commands. With this operation unit 11, for example, teaching of a grinding operation, setting of grinding work conditions, and the like are performed. Particularly, in the present embodiment, teaching of a teaching reference position and an execution reference position, which will be described later, is performed via the operation device 11. It should be noted that the operation device 11 can be configured as a portable device carried by an operator who performs a grinding operation, or can be configured for installation, if necessary.

The detailed structure of the control means realized by the controller 8 will be described with reference to FIG. With respect to the robot main body 1 that performs the grinding work, the control content that determines the content of the grinding work is realized by software mainly using the controller 8. FIG. 2 is a block diagram showing the control elements and connection relationships. It goes without saying that the control circuit can be configured using a hard circuit.

Inside the robot body 1, a plurality of drive motors are incorporated to operate each joint of the arm 2. An angle meter 21 for measuring the drive amount is attached to each of these drive motors. The angle data of each joint is measured by the goniometer 21.

First, the structure of the position / force control calculation system, which is the basic structure, 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 calculator 22. The force calculator 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. In this way, in the force calculation unit 22, the work 6 and the grinding tool 7 are
The force <f> generated at the contact point part of is calculated. Here, the symbol "<f>" means that f is a vector quantity.
In the following description, the symbol "<>" has the same meaning.

The force <f> obtained by the force calculation unit 22 is input to the subtractor 23, and the subtractor 23 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 calculation unit 25 as a force <f '>. The force target value <fr> is a command value for giving a force target value in the pressing direction of the grinding tool 7.

The angle data regarding each axis detected by the goniometer 21 is sent to the position calculation unit 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 the target value <xr> of the position set by the position target value setting unit 29 in the position deviation calculation unit 28, and the position deviation <Δx> between them is obtained.

As described above, the force <f '> obtained by the subtractor 23 and the position deviation <Δ obtained by the position deviation calculation unit 28.
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 calculation unit 31 and a characteristic compensation calculation unit 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 calculator 31. The spring constant calculator 31 receives the input position deviation <Δ
x <> is multiplied by the set virtual spring constant matrix K to calculate K <Δx>. Spring constant calculator 31
The K <Δx> calculated in step 3 is output to the subtractor 30. The subtractor 30 calculates <f '>-K <Δx>. The calculation result obtained by the subtractor 30 is given to the characteristic compensation calculation unit 32.

A controller gain Kc is set in the characteristic compensation calculator 32. In the characteristic compensation calculation unit 32, <f '>-K <Δ input based on the controller gain Kc.
x> is subjected to characteristic compensation in control, 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 for each drive motor of the robot body 1. 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 the 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 is 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 unit 41 is a part that holds position data for performing a grinding operation. This position data is data for specifying a reference grinding area in the work, and is data taught by the 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 the position data relating to the teaching reference position associated with the position data stored in the position data storage section 41. This teaching reference position is a reference position that is related to the position data stored in the position data storage unit 41 so as to have a fixed positional relationship, and is the position data when setting a reference ground area in the workpiece. is there. The position data relating to the teaching reference position is also input via the operation unit 11 according to the instruction of the operator.

The execution reference position storage section 43 is a portion for holding position data relating to the execution reference position. The execution reference position is a reference position for setting an area to be ground for actually performing a grinding operation on a work. When the 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 the work to be ground while 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 the 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 stored in the execution reference position storage unit 43, as is clear from the connection relationship of the connection terminals (1) and (2). Is entered. 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 retained. In addition, grinding tool 7
As a method of bringing the workpiece 6 into contact with the work 6, a method of operating the grinding robot in a force controlled state based on the position / force control to bring it into contact with the work 6 or a manual operation of an operator to operate the robot body to bring the grinding tool 7 into contact There are methods, etc.

The correction value calculation unit 44 receives the position data of the teaching reference position storage unit 42 and the position data of the execution reference position storage unit 43. The correction value calculation unit 44 obtains the difference between the teaching reference position and the execution reference position value as a correction value. This difference is the difference between the position representing the teaching reference position and the position representing the execution reference position, and is described by a difference in each direction in position coordinates or a vector representing the direction and distance connecting the 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 0.

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

The above-mentioned basic control system and position data correction unit 4
The control executed by 0 and 0 will be described with reference to FIGS. In the present embodiment, as the grinding work of the portion to be ground on the work 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. It is stored in the position data storage unit 41, and the other portion is stored in the teaching reference position storage unit 42 as position data for determining the position of the grinding area. The execution reference position data for determining the actual position of the work area in the workpiece 6 is fixed 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 content of the position target value setting unit 29, and to set the ground area that occurs at an arbitrary position on the work 6. The work of grinding is performed.

An image of the above operation is shown in FIG.
It is FIG. 3 and 4 are plan views of the work 6, in which the plane coordinates by the X axis and the Y axis are defined. FIG. 5 shows another embodiment of the work viewed from the side, and plane coordinates by the X axis and the Z axis in the drawing are defined.

In FIG. 3, the case of grinding the bead 46 existing on the work 6 will be described. Bead 46
Form the actual area to be ground. First, points P1 to P6 that define a reference area to be ground on the surface of the workpiece 6.
And the point Q is set. Points P1 to P6 are points that set a region that covers a reference region to be ground. As indicated by the arrow, grinding is performed in the order from the point P1 to the point P6. The position data of the points P1 to P6 are stored in the position data storage unit 41 based on the teaching work of the operator. The point Q is the teaching reference position and is set at a position close to the 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 ground area defined by the points P1 to P6 and the point Q can be set at any 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 work.

Next, when the workpiece 6 on which the bead 46 to be ground is formed is given, the operator operates the bead 4
A point Q'representing an execution reference position having a fixed positional relationship with the bead 46 is determined in the vicinity of 6, and 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. To do. In this teaching operation, as described above, for example, as shown in FIG. 6, the grinding tool 7 is moved to the point S and brought into contact with the point Q ′ under force control to detect the position of the point Q ′. As is clear from FIG. 4, the point Q ′ exists at a position displaced in the X and Y axial directions with respect to the point Q.

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 calculation unit 44 coordinates based on the position data of the points Q and Q '. The above-mentioned 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 ′ are as shown in FIG.
It is the actual grinding execution position data that covers the formation area of the beads 46. The obtained position data of the points P1 ′ to P6 ′ are 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 unit 29, the basic control system is based on the position data of the points P1 'to P6', as shown by the arrows in FIG. 7 moves, and the work 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 the point Q and the point Q '. Also in this case, the difference between the point Q and the point Q'is obtained using the position data, and the correction value is used to convert the reference teaching position data to obtain the actual grinding execution position data. It can be calculated.

In the above-mentioned embodiment, the example in which one bead is present 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. 7, four beads 47-5
The 0s may be scattered at arbitrary positions on the surface of the work. In such a case, each bead 47-
The execution reference positions Q1 to Q4 are set in correspondence with 50, and the grinding robot is taught this. Each execution reference position Q1 to Q4
The position data of is 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. For grinding work, bead 47
~ 50 are ground according to the order taught.

In each of the above-mentioned embodiments, the position data P1 to P
6, a plane on which a basic grinding area defined by Q exists and a plane on which a grinding area defined by position data P1 'to P6' converted by the execution reference position Q'and correction values exist. Although they are in a parallel relationship, it is possible to convert between non-parallel surfaces by performing rotational conversion of coordinates.

FIG. 8 shows another embodiment. In this embodiment, in the position data storage unit 41, the position data P1 to
The pattern formed by P2 includes a plurality of first to n-th patterns. The first to nth patterns are appropriately selected and output by the switch 51 according to the region to be ground or the type of work. Switch 51
The switching operation of 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 for controlling position and force, the position / force control unit corrects grinding position data. Since additional parts have been added, the position data that is the basis of the grinding work can be taught once, and the actual grinding area can be specified with simple teaching each time before the work starts. Moreover, the grinding work can be executed with a short time teaching. Further, even if there are a plurality of actual ground areas at arbitrary positions on the workpiece, all the ground areas can be ground with simple teaching.

With respect to the position data that defines the reference ground area, a plurality of patterns can be stored and the position data of any pattern can be used as needed, so that it is highly applicable and practical. A high grinding robot can be realized.

In the teaching of the execution reference position that determines the actual ground area, 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 it can be taught easily. . Further, since the position is corrected including the wear amount of the grinding tool, the function for correcting the wear of the grinding tool is not required.

[Brief description of drawings]

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

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

FIG. 3 is a plan view showing position data that defines a bead on a work and a reference grinding region.

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

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

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

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

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

[Explanation of symbols]

 1 ... Robot body 2 ... Arm 5 ... Force sensor 6 ... Work 7 ... Grinding tool 8 ... Controller 11 ... Manipulator 22 ... Force calculation unit 24 ... Force target value setting unit 25 ... Position / force control calculation unit 27 ... Position calculation unit 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 unit 46-50 ... Bead 51 ... Switching device 52 ... Switching controller

Claims (5)

[Claims] 1. A position data storage unit for storing the position data of a grinding tool taught by a teaching unit, the position data specifying a grinding area, and a control command by position / force control based on the position data. Control means for creating
In a grinding robot having a robot mechanism for causing the grinding tool to perform a grinding operation based on the control command, the position data is position data serving as a reference, and the position data is taught together with the reference position data. Teaching reference position storage means for storing an accompanying teaching reference position, execution reference position storage means for storing an execution reference position for determining a position at which the grinding operation is actually performed, and the above-mentioned storage means provided from each of the two storage means. A correction value calculating means for calculating a difference between the teaching reference position and the execution reference position as a correction value, and the reference position data is converted into position data for specifying an actual ground area by using the correction value, and the conversion is performed. A grinding robot, comprising: position correction means for giving subsequent position data to a position target value setting part of the control means. 2. The grinding robot according to claim 1, wherein
The control means has a force detection means for detecting a force applied to the grinding tool and a position detection means for detecting a position of the grinding tool, and brings the grinding tool into contact with a position for actually performing a grinding operation, When the force detection means detects the force applied to the grinding tool, 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. A distinctive grinding robot. 3. The grinding robot according to claim 1, wherein
A grinding robot characterized in that the position data storage means has a selection means for storing the reference position data of a plurality of mutually different patterns and for extracting and outputting the reference position data of the pattern corresponding to the area to be ground. 4. A method for performing a grinding operation of a teaching playback type grinding robot, wherein, before the grinding operation, position data of a reference grinding area and position data of a teaching reference position having a fixed positional relationship with the reference grinding area. And the step of holding these position data, and before starting the grinding work, specify the execution reference position corresponding to the teaching reference position in the vicinity of the actual ground area in the actually given work. The step of teaching the position data and holding the position data, obtaining the difference between the taught reference position and the execution reference position, correcting the position data based on this difference, and correcting the corrected position data And a step of grinding the actual region to be ground based on the position data. 5. The grinding work execution method according to claim 4, wherein the position data of the execution reference position is taught by contacting a grinding tool of a grinding robot in a force control state with the position / force control means to the execution reference position. A method of performing a grinding operation, characterized by being performed by