JPH08118278A - Force-controlled robot - Google Patents

Abstract

PURPOSE: To optimize the force control of a force controlled robot for each kind of work, etc., by selecting the force component suitable for the force control among the detection forces according to the selected kind of work, shape of a working object, etc., and designating the pushing direction of the designated pushing force of an end effector, separately from the selected force component. CONSTITUTION: A robot language interpretation device 10 is installed on a controller 2, and a plurality of parameters necessary for selecting and executing a desired work are interpreted. The interpretation device 10 is equipped with a pushing direction table 12 and a detection force table 13. Each parameter of the pushing direction table 12 and the detection force table 13 is designated by a parameter designating means 11. The force component suitable for the force control among the detection force is designated by the detection force table 13. The pushing direction table 12 designates the pushing direction for a working object by an end effector, and outputs the value to an arm controller 6.

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, and more particularly, to a force control robot for performing work by force-controlling an end effector with a designated pressing force onto a surface of a work target by using a force sensor. Regarding

[0002]

2. Description of the Related Art Various operations such as deburring of a work object are performed using a force control robot. In these cases,
In the force control robot, force control is performed so that the end effector at the robot hand is pressed against the surface of the work target with a specified pressing force, and the work is performed by moving the end effector along the surface.

The force with which the end effector presses the work object is detected by the force sensor in the vicinity of the end effector at the robot hand. The detection result of the force sensor is used for force control so that the end effector is pressed against the surface of the work target object with a specified pressing force.

[0004]

The movement of the robot hand in the working space is generally affected by inertial force due to acceleration and often accompanied by vibration. Further, the force sensor is attached to the tip of the hand of the robot or the like. Therefore, the force sensor receives an acceleration or a vibration with reference to the base of the hand part as the robot hand moves. The force actually detected by the force sensor is not limited to the reaction force that the end effector receives from the work object, but various noise-like forces are mixed in addition to the force required for force control. There is.

The direction in which the end effector is pressed against the work object does not necessarily match the direction of the force detected by the force sensor, and therefore the end effector is moved in the direction opposite to the direction of the force detected by the force sensor. It doesn't have to be pressed.

When various kinds of work are selected and executed using the force control robot, in order to perform force control so that the end effector is pressed against the surface of the work object with a specified pressing force, the selected work type and work are selected. It is necessary to use an appropriate force component of the force detected by the force sensor for force control according to the shape of the object.

For this reason, the direction in which the end effector is pressed against the work object and the force component used for force control are thoroughly studied, and a robot operation program is created based on the result of this study. In order to specify the force component used for force control, it is necessary to specify the coordinate system, the pressing direction of the end effector, the type of force, and the like.

Conventionally, every time a work is performed by a force control robot, a robot operation program is created by examining the direction in which the end effector is pressed against the work object, the force component used for force control, and the like. There are also cases where it is necessary to change the designation during the work, and in this case it was difficult to change immediately.

As described above, every time the work is started or during the work, the direction in which the end effector is pressed against the work object and the force component used for the force control are examined to create the robot operation program, or the work is performed. It is not preferable to change the setting due to complicated procedure in the middle of operation because of the work efficiency.

Therefore, an object of the present invention is to provide a force control robot which solves the above problems of the prior art and can easily specify and execute a suitable force control according to the type of work and the shape of a work target. Is to provide.

[0011]

In order to achieve the above object, a force control robot according to the present invention uses a force sensor provided at a robot hand to press an end effector against a surface of a work object with a designated pressing force. Force control like
In a force control robot that performs work by moving the end effector along this surface, a robot language interpreter that interprets a plurality of parameters necessary for selecting and executing a desired work is provided, and the robot language interpreter is ,
A pressing direction table that specifies the pressing direction of the specified pressing force, a detection force table that specifies a force component used for the force control among the detection forces detected by the force sensor, the pressing direction table and the detection force. And a parameter designating unit that designates each parameter of the table.

[0012] Preferably, the pressing direction table includes a coordinate system parameter that specifies a coordinate system to be used to specify the pressing direction, a specified direction parameter that specifies a pressing direction in this coordinate system, and a pressing direction. And a designation method parameter for designating a direction designation method.

Preferably, the designation method parameter is a direct designation method for designating any coordinate axis direction in the adopted coordinate system, a moving direction of the end effector and a selection direction selected as desired in the work space. It is characterized in that it is specified by either a vector cross product specification method specified by the vector cross product with and or an arc specification method specified by the center direction or outward direction of the arc.

Preferably, the detection power table is
In order to specify the force component used for the force control, a detection coordinate system parameter that specifies the coordinate system to be used, a detection direction parameter that specifies the direction of the force component to be detected, and the type of force component to be detected are specified. And a power parameter.

Preferably, the detected force parameter is a translational force acting in any coordinate axis direction of the adopted coordinate system, a combined force obtained by combining a plurality of force components, or the center of gravity of the end effector. It is characterized in that it is specified by any one of calculation by calculation from the moment force acting on and the distance to the point of action.

Further, it is preferable that the detection force parameter is a parameter that specifies only the magnitude of the force component to be detected.

[0017]

[Function] The direction in which the end effector is pressed against the work object does not necessarily match the direction of the force detected by the force sensor, and even if the end effector is pressed in the opposite direction of the force direction detected by the force sensor. It does not mean that you should do it. Therefore, of the forces detected by the force sensor, a force component suitable for force control is selected according to the selected work type or the shape of the work target, and the end effector is separated from the selected force component. Designate the pressing direction of the specified pressing force to press the work object.

The parameter designating unit designates the pressing direction of the designated pressing force by which the end effector presses the work object and the force component of the detection force detected by the force sensor that is used for force control.

The robot language interpreting device interprets the parameters of the pressing direction table and the detected force table, and executes force control suitable for the type of work and the shape of the work target. Parameters required for force control according to the type of work are given in a table format as a pressing direction table and a detection force table, so that suitable force control can be easily designated and executed.

[0020]

Embodiments of the force control robot according to the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing the overall configuration of the force control robot of the present invention. In FIG. 2, the force control robot includes a robot body 1, a control device 2 of the robot body 1, and a teach pendant 3 that sends an instruction to the control device 2. An end effector 5 for performing work such as grinding on a work W is attached to the tip of the hand of the robot body 1. A 6-axis force sensor 4 is provided near the end effector 5 at the hand of the robot body 1.

When the work is executed by using the force control robot, the arm control device 6 provided inside the control device 2 so as to press the end effector on the surface of the work object with the specified pressing force by using the force sensor 4. Then, as the force control method, for example, the force is controlled according to the equation (1). Vd = Kf (Fd−F) (1) Here, Fd is the target designated pressing force, F is the force component of the detection force detected by the force sensor 4, which is used for force control,
Kf is a force control gain, and Vd is a speed command value indicating the speed of the end effector 5 in the pressing direction. The force component F of the detected force in Expression (1) and the pressing direction that gives the speed command value Vd are specified in the pressing direction table 12 and the detected force table 13 of the robot language interpretation device 10.

As shown in FIG. 1, the control device 2 is provided with a robot language interpreting device 10 which interprets a plurality of parameters necessary for selecting and executing a desired work.

The robot language interpreter 10 includes a pressing direction table 1 for specifying a pressing direction in which the end effector 5 presses the surface of the work W with a specified pressing force.
2, a detection force table 13 that specifies a force component used for force control among the detection forces detected by the force sensor 4, a parameter specifying unit 11 that specifies each parameter of the pressing direction table 12 and the detection force table 13. It has and.

The pressing direction table 12 is, as shown in FIG. 4 or FIG. 7, a coordinate system parameter for specifying the coordinate system to be adopted, a specified direction parameter for specifying the pressing direction in this coordinate system, and a method for specifying the pressing direction. And a specification method parameter for specifying.

The coordinate system parameters include, for example, a work coordinate system ΣW in which a coordinate system is set for the work W and a tool coordinate system ΣT in which a coordinate system is set for the end effector 5. The designated direction parameter is any coordinate axis direction in the coordinate system set by the coordinate system parameter.

The designation method parameter includes, for example, a direct designation method, a vector cross product designation method, or a circular arc designation method. The direct designation method is a method of directly designating one of the coordinate axis directions in the coordinate system set by the coordinate system parameter, and is effective when the shape of the work object is simple. The vector cross product specification method is the end effector 5
This is a method of designating by the vector cross product of the moving direction of the and the selected direction selected in the work space. The desired selection direction is, for example, the normal direction of the surface of the work target W. The vector cross product designating method changes the pressing direction of the end effector 5 according to the shape of the work object during the work, such as polishing work on a curved surface or chamfering work on the edge of the work object with irregularities. Even in the case of a work that needs to be performed, it is not necessary to change the designation of the pressing direction of the end effector from the beginning to the end of the work, and the operation program can be generated very easily. The arc designating method is a method of designating the center direction or the outward direction of the arc, and is effective when the work W has many arc-shaped portions.

The power table 13 is shown in FIG. 5 or FIG.
As shown in, the detection coordinate system parameter relating to the adopted coordinate system, the detection direction parameter designating the direction of the force component to be detected, and the detection force parameter designating the type of the force component to be detected are included.

The detected coordinate system parameters include, for example, a work coordinate system ΣW in which a coordinate system is set for the work W and a tool coordinate system ΣT in which a coordinate system is set for the end effector 5. As the detection direction parameter, there is any coordinate axis direction in the coordinate system set by the detection coordinate system parameter.

The detected force parameter is designated by, for example, a translational force, a synthetic force, or a force calculated from a moment. For these force components, it is sufficient to simply specify the magnitude regardless of whether the sign is positive or negative.

Here, the designation of the translational force is designated as a force acting in any coordinate axis direction of the adopted coordinate system, and when the work object W has a simple shape, the end effector 5 is This is effective when the direction of the reaction force received from the work target W can be easily determined. The designation of the combined force is to specify it as a combined force of a plurality of force components, and is effective when the work W has a shape that cannot be specified by a single translational force. The designation of the force calculated from the moment is to specify the force calculated from the moment force acting around the center of gravity of the end effector 5 and the distance to the point of action. If the moment force around the center of gravity of the end effector 5 is MGX and the distance from the center of gravity position to the point of action of the end effector 5 in the direction perpendicular to F is L, the force F calculated from the moment is F = MGX / L ( 2) is obtained as. When the end effector 5 is accelerated or receives an inertial force, it is possible to detect a highly reliable force signal that is not easily affected by external noise (see Japanese Patent Laid-Open No. 4-164585).

Next, specific examples of the present invention will be described below. First, a first embodiment of the present invention will be described with reference to FIGS. The robot body 1 includes a cylindrical rotary grinder as the end effector 5. The work object W1 includes a flat surface 15 having a flat plate shape in the longitudinal direction and flat surfaces 16 and 17 parallel to each other in the lateral direction.
Have and. In addition, the normal direction of the flat surface 15 and the flat surface 16
It has a relationship orthogonal to the normal direction of. The cylindrical side surface of the rotary grinder 5 is force-controlled so as to be pressed against the flat surface 15 with a specified pressing force, and the direction of the moving direction vector V1 shown in FIG.
In the Y direction), polishing work is performed.

FIG. 4 shows the pressing direction table 12 designated in this embodiment. By specifying the table number, the corresponding pressing direction table 12 is specified. In FIG. 4, the work coordinate system ΣW is designated as the coordinate system parameter, and -Z is designated as the designated direction parameter.
The direction is specified, and the direct specification method is specified as the specification method parameter.

Since the robot language interpreting apparatus 10 is provided with various pressing direction tables 12 in advance, the desired parameter can be obtained by designating the table number as 1 without designating each of these three parameters. Is equivalent to setting.

FIG. 5 shows the power table 13 designated in this embodiment. By specifying the table number, the specific contents of the power table 13 are set.
In FIG. 5, the tool coordinate system ΣT is specified as the detection coordinate system parameter, the translational force is specified as the detection force parameter, and the Y direction is specified as the detection direction parameter. Here, the Z-axis direction of the work coordinate system ΣW is set to the normal direction of the flat surface 15, and the Y-axis direction is set to the longitudinal direction of the work target W1. The Z axis of the tool coordinate system ΣT is set in the rotation axis direction of the rotary grinder 5.

In the case of a flat surface polishing operation, the end effector 5 is pressed against the flat surface 15 of the work W1. In this case, since it is certain that the end effector 5 is pressed vertically against the flat surface 15, it is appropriate to use the reaction force that the end effector 5 receives from the flat surface 15 as the force component used for force control. . Therefore, the detection direction of the force component used for force control is set in the Y direction of the tool coordinate system ΣT, and since the end effector 5 is pressed in the normal direction of the flat surface 15, the −Z direction is specified as the specified direction parameter. Has been done.

Although the translational force is specified as the detection force parameter, the force F = M calculated by the moment is calculated.
GX / L may be specified. In the pressing direction table 12, the pressing direction is the work coordinate system ΣW.
-Z direction and the sign are specified. For this reason,
Of the detected forces detected by the force sensor 4, the magnitude of the force component used for force control is compared with the target pressing force, and it suffices to know only the magnitude of the difference, and the positive and negative signs of the force component. You don't have to consider. This eliminates the need to worry about the direction of the detection power when setting the detection power table 13, and the setting can be performed easily.

Next, a second embodiment of the present invention will be described with reference to FIGS. The robot body 1 includes a conical cutter as the end effector 5. The work object W2 has a flat surface 18 and a curved surface 19, and the flat surface 1
A work end portion 20 is formed as a line of intersection between 8 and the curved surface 19. The workpiece end 20 forms a coplanar curve. In addition, the normal direction of the flat surface 18 and the curved surface 19
It has a relationship orthogonal to the normal direction of. Cone type cutter 5
The conical surface is controlled so that it is pressed against the work end 20 with the target pressing force, and the work is moved in the direction of the moving direction vector V2, and the work end 20 is chamfered.

FIG. 7 shows the pressing direction table 12 designated in this embodiment. In this embodiment, the pressing direction table 12 is specified by specifying the table number 2.

In FIG. 7, the work coordinate system ΣW is designated as the coordinate system parameter, the + Z direction is designated as the designated direction parameter, and the vector cross product designation method is designated as the designation method parameter.

Since the robot language interpreting apparatus 10 is provided with various pressing direction tables 12 in advance, it is possible to specify the desired parameter by simply specifying the table number 2 without specifying these three parameters. Is equivalent to setting.

FIG. 8 shows the power table 13 designated in this embodiment. By specifying the table number 2, the specific contents of the power table 13 are set. In FIG. 8, the tool coordinate system ΣT is designated as the detection coordinate system parameter, the synthetic force is designated as the detection force parameter, and the direction of the XY plane is designated as the detection direction parameter. In this embodiment, the work coordinate system ΣW
In, the Z direction is set to the normal direction of the flat surface 18, and the Z direction of the tool coordinate system ΣT is set to the rotation axis direction of the conical cutter.

In the present embodiment, in the vector cross product designating method designated as the designating method parameter, the selection direction in the working space is selected to be the direction of the surface normal direction vector N2 of the flat surface 18. The predetermined pressing direction of the end effector 5 is set to the direction of the pressing direction vector F2 expressed by the equation (3). The pressing direction vector F2 is
An outer product of the vector V2 and the vector N2 is given by F2 = V2 × N2 (3).

In the case of the chamfering work of the work end portion 20, the direction of the reaction force received from the work object W2 changes depending on the progress of the work. Therefore, it is necessary to change the direction of the force detected by the end effector 5 accordingly.
However, if the shape of the work end portion 20 is not known in advance, it is difficult to change the designation of the detection force according to the work progress situation. Therefore, in the case of the present embodiment, the combined force in the XY plane of the tool coordinate system ΣT is designated as the force component used for force control of the detected force detected by the force sensor 4. As a result, even if the direction of the reaction force received from the work target W2 changes according to the progress of the work, it is not necessary to worry about it.

Further, regarding the designation of the pressing direction of the end effector 5, when the end effector 5 goes around the work end portion 20, the pressing direction of the end effector 5 may change. However, the end effector 5
Even when the pressing direction of is changed, according to the vector cross product specifying method, the pressing direction is set to the traveling direction vector of the end effector 5 and the direction vector set in the working space (here, the normal direction N2 of the flat surface 18 is By designating as a direction orthogonal to both the + Z direction in a certain work coordinate system ΣW), the work can be executed from the beginning to the end of the work without changing the designation of the pressing direction. As a result, the work end portion 2 of the work target W2 during work
In chamfering work that needs to change the pressing direction of the end effector 5 according to the curve shape of 0, it is not necessary to change the specification of the pressing direction of the end effector 5 from the beginning to the end of the work, and it is very easy to generate the operation program. Can be done easily.

As described above, according to the configuration of the first or second embodiment, by setting appropriate values in the pressing direction table 12 and the detection force table 13, the polishing operation and the work end portion 20 can be controlled. When performing various different works such as chamfering work, a force control method suitable for each work can be easily set. As a result,
Force control suitable for different work can be easily performed.

In the above description of the embodiment, the robot language interpretation device 10 is provided in the control device 2, but it may be provided in the teach pendant 3, or the control device 2 and the teach pendant 3 are provided. It may be provided over both.

Further, the axis configuration of the robot body 1 does not have to be a 6-axis cylindrical coordinate type, but may be any configuration such as an articulated type, a polar coordinate type or a rectangular coordinate type. Further, the force sensor of the hand portion is not limited to the 6-axis force sensor 4 and may have another configuration as long as it can detect the force acting on the end effector 5.

[0048]

As described above, according to the configuration of the present invention, the robot language interpreting apparatus includes the pressing direction table for specifying the pressing direction of the specified pressing force and the force among the detection forces detected by the force sensor. It is equipped with a detection force table that specifies the force component used for control, and parameter specifying means that specifies each parameter of the pressing direction table and detection force table, so it is suitable according to the type of work and the shape of the work target. Force control can be easily specified and executed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a detailed configuration of a robot language interpretation device in a force control robot according to the present invention.

FIG. 2 is a perspective view showing the overall configuration of a force control robot.

FIG. 3 is a diagram illustrating that a flat surface polishing operation is performed in the embodiment of the present invention.

FIG. 4 is a diagram showing the contents of a pressing direction table in the first embodiment of the present invention.

FIG. 5 is a diagram showing the contents of a power table in the first embodiment of the present invention.

FIG. 6 is a diagram for explaining the chamfering work of the work end portion in the second embodiment of the present invention.

FIG. 7 is a diagram showing the contents of a pressing direction table in the second embodiment of the present invention.

FIG. 8 is a diagram showing the contents of a power table in the second embodiment of the present invention.

[Explanation of symbols]

 1 Robot Main Body 2 Control Device 3 Teach Pendant 4 Force Sensor 5 End Effector 6 Arm Control Device W, W1, W2 Work Object 10 Robot Language Interpreter 11 Parameter Designation Means 12 Pressing Direction Table 13 Detecting Power Table

Front page continuation (72) Fumio Ozaki Inventor Fumio Ozaki 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center (72) Inventor Yasuhiko Tamada 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Stock Company Numazu Office

Claims (6)

[Claims] 1. A force sensor provided on a robot hand is used to perform force control so that an end effector is pressed against a surface of a work target with a designated pressing force, and the end effector is moved along the surface to perform work. In the force control robot to perform, a robot language interpreting device that interprets a plurality of parameters necessary for selecting and executing a desired work is provided, and the robot language interpreting device is a pressing direction table that specifies a pressing direction of the specified pressing force. And a detection force table that specifies a force component used for the force control among the detection forces detected by the force sensor, and parameter specifying means that specifies each parameter of the pressing direction table and the detection force table. A force control robot characterized by comprising. 2. The pressing direction table, in order to specify the pressing direction, a coordinate system parameter that specifies a coordinate system to be used, a specified direction parameter that specifies the pressing direction in this coordinate system, and a method for specifying the pressing direction. The force control robot according to claim 1, further comprising: a designation method parameter for designating 3. The designation method parameter is a direct designation method for designating one of the coordinate axis directions in the adopted coordinate system, and a vector cross product of the moving direction of the end effector and a selected direction selected in the working space. 3. The force control robot according to claim 2, wherein the force control robot is designated by any one of a vector cross product designating method designated by (1) and a circular arc designating method by which the center direction or the outward direction of the circular arc is designated. 4. The detection force table includes a detection coordinate system parameter that specifies a coordinate system to be used to specify a force component used for the force control, and a detection direction parameter that specifies a direction of the force component to be detected. The force control robot according to claim 1, further comprising: a detection force parameter that specifies a type of a force component to be detected. 5. The detected force parameter is a translational force acting in any coordinate axis direction of the adopted coordinate system, a combined force obtained by combining a plurality of force components, or a moment acting around the center of gravity of the end effector. The force control robot according to claim 4, wherein the force control robot is designated by one of a force calculated by a force and a distance to an action point. 6. The force control robot according to claim 4, wherein the detection force parameter is a parameter that specifies only the magnitude of a force component to be detected.