DE102013204282B4 - Method for measuring an adjustable end effector and arrangement for carrying out such a method - Google Patents

Abstract

Method for measuring a spatial orientation of modules (8) of an adjustable end effector (5) with a plurality of modules (8) which are connected to one another with the aid of multi - axial joints, characterized in that in each case a cylindrical surface with an optical radiation (14, 15 ) is applied and a reflection signal is evaluated, in each case at two in the extension direction of a longitudinal axis (6) of the cylindrical surface spaced positions (P1, P2) measurements in two coordinate axes are performed to a spatial orientation of the longitudinal axis (6) of the cylindrical surface determine.

Description

The invention relates to a method for measuring a spatial orientation of modules of an adjustable end effector with a plurality of modules which are interconnected by means of multi-axis joints and arrangement for carrying out such a method.

From the DE 20 2007 004 999 U1 a positioning device is known for structures, in particular tools, wherein the positioning device is multiaxially adjustable and has at least two arms which are connected to one another and with a base and a headboard articulated and lockable and the positioning device for a mechanical adjustment, z. B. by means of one or more manipulators or robots is designed to show a simpler and better positioning technology for structures, in particular tools.

From the DE 10 2007 039 384 A1 a handling device is known for multi-axis handling machines, in particular robots for handling different components with a support member to which at least one provided with at least one passive joint arm is attached, at the end of a tool is arranged, wherein the at least one joint a clamping device for fixing it is assigned in pre-selectable position and wherein in the unfixed state, the at least one joint is freely movable to provide a handling device for a multi-axis handling machine, especially for robots, to handle different components, the high flexibility with less technical effort compared to conventional active kinematics have comparable flexibility.

From the DE 10 2007 055 119 A1 For example, a robot is known comprising a robot arm, a tool disposed on the robot arm, a hinged connection that movably connects the tool between different relative positions with the robot arm and has a hinge axis with respect to which the tool and the robot arm have at least one degree of freedom of movement relative to each other , and a fixing device for releasably fixing the tool in either one of the relative positions, the tool being freely movably connected to the robot arm when the fixing is released via the articulated connection in the at least one degree of freedom of movement in order to provide operational flexibility of a robot to improve on short set-up times in a cheap way.

From the document DE 10 2010 039 945 A1 For example, a method for determining a position is known, wherein a light beam is directed via a movable mirror and a rotationally symmetrical optical element to a reflector, which detects the light beam reflected by the reflector, and a position of an object is determined on the basis of the detected reflected light beam.

The document EP 1 804 034 A1 relates to a system for monitoring a nozzle position of a processing tool for spraying liquids. The system includes a light source, a reflector, and a photodetector. The light source and the photodetector are fixedly arranged. The reflector is fixedly mounted to the nozzle to reflect a light beam from the light source.

From the document US Pat. No. 6,775,013 B2 For example, a method and apparatus are known for measuring a displacement or movement error in a rotating object, such as a machine tool spindle, by means of a laser beam directed at a preferably curved reflecting surface.

The invention has for its object to improve a method mentioned above. In particular, a contactless measurement should be possible. In particular, measurement errors are to be reduced. In particular, an absolute measurement should be made possible independently of a starting point. In particular, an influence of vibrations should be reduced. In particular, an influence of a temperature should be reduced. In particular, a measurement effort should be reduced. In particular, a measurement accuracy should be increased. In particular, a measurement speed should be increased. In particular, a mechanical coupling during measurement should be avoided. In particular, problems should be avoided by ferromagnetisehe or conductive parts. In particular, a measurement should be reliably enabled indoors. In addition, the invention has for its object to provide an arrangement for carrying out such a method.

The object is achieved by a method for measuring a spatial orientation of modules of an adjustable end effector with a plurality of modules, which are connected to each other by means of multi-axis joints, wherein for measuring a respective cylindrical surface is exposed to an optical radiation and a reflection signal is evaluated, in each case Measurements can be made in two coordinate axis directions at two positions spaced apart in the direction of extension of a longitudinal axis of the cylindrical surface in order to determine a spatial orientation of the longitudinal axis of the cylindrical surface.

Reference measurements can be made for the entire end effector, ie for all modules and there for All measurements are performed to compensate for manufacturing, assembly and similar tolerances. The adjustment can then not be made against ideal values, such as measuring tubes axially parallel to the reference coordinate system, but against real values from the reference measurement of the end effector. The reference values for pitch and yaw angles of a module may be used, the reference value for the roll angle is preferably used.

In order to determine a rotation of a module about an axis parallel to a longitudinal axis of the cylindrical surface, one measurement can be carried out in each case and set in relation to a reference measurement.

A received reflection signal can trigger storage of position coordinates. The position coordinates can be provided by an industrial robot. The position coordinates can be provided by an external position measuring device. By means of an external position measuring device, a module measuring device can be calibrated.

A measurement result may be provided for subsequent adjustment of the end effector. Adjustment of the end effector can be carried out automatically. Adjustment of the end effector may be performed on an adjuster.

In addition, the solution of the problem underlying the invention with an arrangement for carrying out such a method comprising an industrial robot with a control device and an adjustable end effector, the end effector comprising a plurality of modules which are interconnected by means of multi-axis joints, the modules each having a joint main axis and a Measuring cylinder having a longitudinal axis and a reflective cylindrical surface and a module measuring device with aligned in two different coordinate axis measuring modules for performing reflection-based measurements, wherein the measurement modules each having a light source.

The industrial robot may have a manipulator. The industrial robot can be a 6-axis robot. The industrial robot may have position sensors. The industrial robot may have a control device. The control device signals of the position sensors can be available. The end effector may be disposed at a free end of the manipulator.

The modules of the end effector may be arranged along a line. The line can be straight or curved. The line can be spatially curved. The line can be curved several times. The modules of the end effector can be connected by means of ball joints. The modules may each have two opposing connecting sections for connection to an adjacent module. The main hinge axes of the modules may each extend between the connecting sections. The modules of the end effector may each comprise a gripper for gripping a workpiece. The modules of the end effector can each have a suction gripper. The modules with the measuring cylinders can each be designed geometrically at least approximately equal.

The end effector may be geometrically adaptable to different workpieces. The end effector can be used to handle flexible workpieces. The end effector can be used to handle blanks. The end effector can be used for handling fiber materials, in particular carbon fibers. The end effector can be used in the manufacture of fiber composite workpieces.

The measuring cylinders can each extend at least approximately over the entire width of a module. The measuring cylinders can be arranged such that their cylindrical surface is at least approximately free on all sides for carrying out measurements. The measuring cylinders can each consist at least superficially of a material which has a high optical reflection. The measuring cylinders can each consist at least superficially of a material which has a diffuse optical reflection. The measuring cylinders can each have a polished surface. The measuring cylinders may each have a surface with a reflective coating. The measuring cylinders can each have a bright surface. The measuring cylinders can each have a surface with a light, for example white, coating. The surface of the measuring cylinder may be dull, d. H. she does not reflect judged. This prevents the laser beam from being reflected away from the detector (angle of incidence = angle of reflection on curved surface).

The module measuring device can have a frame. The measuring modules can be arranged on the frame. The measuring modules can each have a light source and a light sensor. The light source may be a laser. The measuring modules can each have a local electronic arrangement. The measuring modules can each have a housing. The measuring modules can each be electrically signal-conducting connected to the control device of the industrial robot.

The main hinge axes of the modules and the longitudinal axes of the measuring cylinders may each be parallel to each other and spaced from each other. The measuring modules can be aligned with each other at least approximately at right angles.

The arrangement may comprise an external position-measuring device, in particular a tracking interferometer. Using the external position measuring device, a position of the manipulator can be determined independently of the position sensors of the industrial robot. The external position measuring device enables a more accurate position determination than the internal position sensors of the industrial robot.

In summary and in other words, the invention thus provides, inter alia, a determination of a position and / or orientation of a multiaxially adjustable end effector.

A light sensor can be used for non-contact measurement of a modular, flexible end effector. For a measurement of a single module, in each case one component "measuring cylinder" can be arranged on each individual module. A measuring device can record the position of the measuring cylinder of each individual module and make it possible to determine the orientation as a function of a neighboring module.

As long as a measurement accuracy within a robot accuracy is sufficient, sole use of this measuring device (light sensors) in conjunction with a 6-axis manipulator (robot) can be sufficient. With increased accuracy requirements, an external guide can be used in addition to the 6 degrees of freedom of the robot. This external guidance can be done by laser tracker. Thus, a higher accuracy in the position recording can be achieved. This higher accuracy of an external guide can also be used for a calibration of the measuring device.

For measurement, a measuring cylinder can be moved along an axis in the direction of a light beam. The measuring cylinder can be part of a single module.

As soon as the measuring cylinder reflects the beam of the light sensor, the position and orientation of the coordinate system of the individual module can be stored in a reference coordinate system in the measuring device. This detection can be made in several places on the measuring cylinder and with sensors that radiate in two different directions. The orientation of the respective module can then be calculated from the measured points.

The light sensor can only trigger a storage of coordinates, with the help of which then an orientation of the modules is calculated later. The measurement information can be generated from the 6-axis system and only the measurement time can be determined by the light sensors.

Two laser sensors and a 6-axis manipulator (robot) can be combined to accurately detect a hitherto unknown position and orientation of an end effector module.

Actual information (position and orientation) can be automatically generated for a downstream, automated setting process. It can be a manual or a fully automated implementation.

A light sensor-based measuring device can be connected to an external guide of the 6-axis manipulator (robot). This allows a highly accurate measurement of position and orientation. By combining the external guidance with the 6-axis manipulator (robot), the measuring device can be calibrated with high precision.

By "may" in particular optional features of the invention are referred to. Accordingly, there is an embodiment of the invention each having the respective feature or features.

With the invention, a contactless measurement is possible. Measurement errors are reduced. An absolute measurement independent of a starting point is made possible. An influence of vibrations is reduced. An influence of a temperature will be reduced. A measuring effort is reduced. A measuring accuracy is increased. A measuring speed is increased. A mechanical coupling during measurement is avoided. Problems due to ferromagnetic or conductive parts are avoided. Measuring is also possible reliably indoors. In addition, an arrangement for carrying out such a method is provided.

Hereinafter, embodiments of the invention will be described with reference to figures. From this description, further features and advantages. Concrete features of these embodiments may represent general features of the invention. Features associated with other features of these embodiments may also constitute individual features of the invention.

They show schematically and by way of example:

1 a measuring device with two measuring modules,

2 an industrial robot with an adjustable end effector on a measuring device,

3 a measuring process to determine a spatial orientation of a longitudinal axis of a measuring cylinder,

4 a measuring process to determine a spatial orientation of a longitudinal axis of a measuring cylinder,

5 a measuring process to determine a spatial orientation of a longitudinal axis of a measuring cylinder,

6 a reference measurement with aligned adjustable end effector,

7 a measuring operation to determine a rotation of a module about a hinge axis and

8th a measuring operation to determine a rotation of a module about a hinge axis.

1 shows a measuring device 1 with two measuring modules 2 . 3 , 2 shows an industrial robot 4 with an adjustable end effector 5 at the measuring device 1 , 3 - 5 shows a measurement process to a spatial orientation of a longitudinal axis 6 a measuring cylinder 7 to determine 6 shows a reference measurement with aligned adjustable end effector 5 and 7 - 8th shows a measuring process to a rotation of a module 8th around a joint main axis 9 to determine.

The industrial robot is programmable. The industrial robot is a 6-axis robot. The industrial robot 4 has a control device. The industrial robot 4 has a manipulator 10 on. The industrial robot 4 has position sensors. The control device signals of the position sensors are available. The manipulator 10 has a free end with a connection flange.

The end effector 5 has several modules, like 8th , on. For example, the end effector points 5 nine modules 8th on. The modules 8th are arranged along a line. The line can be straight or curved. The line may be spatially and / or multiply curved. The modules 8th are successively arranged adjacent to each other. The modules 8th are with each other using ball joints, like 11 , connected. This is the modules 8th each spatially adjustable. Every module 8th has a suction pad, like 12 , on. The end effector 5 has a connection portion for connection to the connection flange of the manipulator 10 on. The connection section is at the end effector 5 arranged in the middle. The end effector 5 is with its connection section on the connecting flange of the manipulator 10 arranged. The end effector 5 may also be referred to as a "snake gripper" or "grapple Gen2".

The adjustability of the end effector 5 allows a geometric adaptation to different workpieces. In particular, the adjustability of the end effector allows 5 a handling of different fiber material blanks in the manufacture of fiber composite workpieces.

Basically, the end effector 5 both manually and automatically adjustable on an adjustment. For automated adjustment, the end effector 5 using the manipulator 10 with his modules 8th each guided to the adjustment and by a corresponding movement of the manipulator 10 become the modules 8th adjusted. To the modules 8th To be able to correctly guide and adjust the setting device, the control device must have the spatial orientation of the modules 8th be known.

The measuring device 1 serves the spatial orientation of the modules 8th to eat. The measuring device 1 has a frame 13 on. On the frame 13 are the measurement modules 2 . 3 arranged. The measuring modules 2 . 3 each have a laser and a light sensor. Using the laser, one laser beam at a time 14 . 15 to be sent out. By means of the light sensor, a reflection signal of the emitted laser beam 14 . 15 be received and evaluated. The measuring modules 2 . 3 are arranged such that their beam directions are arranged at least approximately at right angles to each other. The measuring modules 2 . 3 are with the control device of the industrial robot 1 signal-conducting connected.

The modules 8th of the manipulator 10 each have a measuring cylinder, such as 7 , on. The measuring cylinder 7 are at the modules 8th each of the suction pads 12 arranged opposite. The measuring cylinder 7 are at the modules 8th arranged to carry out measurements each free. The measuring cylinder 7 each have a reflective cylindrical surface. The measuring cylinder 7 are with their longitudinal axes 6 each parallel and spaced from the main axis of the joint 9 arranged.

In a measurement process, the end effector 5 using the manipulator 10 positioned and oriented so that the measurement modules 2 . 3 the measuring device 1 the module to be measured 8th the end effector 5 with his measuring cylinder 7 can capture.

As a prerequisite for the later calculation of the orientation of the individual modules 8th become the modules 8th initially defined and the location of each individual module 8th is with the measuring device 1 detected in a reference measurement, see 6 , These determined values for position and orientation are used as reference values in the subsequent calculations. The alignment is on two modules 8th in example 6 shown.

In a subsequent measurement process are per module 8th two measurements at two measuring points each and a third measurement with a measuring point carried out around the orientation of the module 8th in the room. First, the orientation of the module 8th unknown. This situation is exemplary in 3 shown.

The module 8th will now be under the measurement module 2 so long in the direction of the arrow moves, see 4 until the laser beam is at a point, e.g. Eg here P1 in 5 , is reflected and the sensor of the measuring module 2 the reflection signal is received. At this moment, the position of a defined coordinate system 16 stored in a reference coordinate system. The same process is repeated for P2. This is now the actual orientation of the module 8th be determined in a horizontal plane and the module 8th is now from the industrial robot 4 aligned axially parallel in the plane.

The measuring procedure described above now becomes vertical with the second measuring module 3 , please refer 1 , repeatedly and again the position of the coordinate system is stored at two points. Thus, the orientation can be determined in a vertical plane and the module 8th is aligned axially parallel in this plane.

After these two alignments, the last degree of freedom is the rotation of the module 8th around the main axis of the joint 9 , This direction of rotation is in 5 with an arrow 17 shown. In order to compensate for this last twist, reference is once again made to the one-time reference measurement described above.

As in 6 The modules were shown for this reference measurement 8th previously aligned in one direction and on one level. Then, during a measurement, the reference point becomes Psoll for each module 8th recorded as a reference. This reference point will now be used to determine the rotation of the respective modules 8th used.

For the last setting, so the module 8th , as in 7 represented, paraxial under the measuring module 2 emotional. If the sensor of the measuring module 2 the reflection signal is received, the position of the coordinate system is stored at this time and using the existing data, reference points Psoll, the rotation of the modules 8th calculated.

This is the spatial orientation of the module 8th completely determined. The measurement process will be for each module 8th carried out. Below is the end effector 5 be adjusted automatically at the setting.

LIST OF REFERENCE NUMBERS

1

measuring device

2

measurement module

3

measurement module

4

industrial robots

5

end effector

6

longitudinal axis

7

measuring cylinders

8th

module

9

Hinge main axis

10

manipulator

11

ball joint

12

Suction pads

13

frame

14

laser beam

15

laser beam

16

coordinate system

Claims (11)

Method for measuring a spatial orientation of modules ( 8th ) of an adjustable end effector ( 5 ) with several modules ( 8th ), which are connected to each other by means of multi-axis joints, characterized in that for measuring in each case a cylindrical surface with an optical radiation ( 14 . 15 ) is applied and a reflection signal is evaluated, in each case at two in the extension direction of a longitudinal axis ( 6 ) of the cylindrical surface spaced apart positions (P1, P2) measurements in two coordinate axis directions are performed to a spatial orientation of the longitudinal axis ( 6 ) of the cylindrical surface. Method according to at least one of the preceding claims, characterized in that for determining a rotation of a module ( 8th ) about a longitudinal axis ( 6 ) of the cylindrical surface parallel axis ( 9 ) is carried out in each case a measurement and set in relation to a reference measurement. Method according to at least one of the preceding claims, characterized in that a received reflection signal triggers a storage of position coordinates. Method according to Claim 3, characterized in that the position coordinates of an industrial robot ( 4 ) to provide. Method according to one of claims 3 or 4, characterized in that the position coordinates are provided by an external position measuring device. Method according to at least one of the preceding claims, characterized in that a module measuring device is calibrated by means of an external position-measuring device. Method according to at least one of the preceding claims, characterized in that a measurement result for subsequent adjustment of the end effector ( 5 ) is made available. Arrangement for carrying out a method according to at least one of claims 1 to 4 and / or 7, comprising an industrial robot ( 4 ) with a control device and an adjustable end effector ( 5 ), the end effector ( 5 ) comprising several modules ( 8th ) connected to each other by means of multi-axis joints, the modules ( 8th ) each having a joint main axis ( 9 ) and a measuring cylinder ( 7 ) with a longitudinal axis ( 6 ) and a reflective cylindrical surface and a module measuring device ( 1 ) with measuring modules aligned in two different coordinate axis directions ( 2 . 3 ) for performing reflection-based measurements, wherein the measurement modules ( 2 . 3 ) each have a light source. Arrangement according to claim 8, characterized in that the joint main axes ( 9 ) of the modules ( 8th ) and the longitudinal axes ( 6 ) of the measuring cylinder ( 7 ) are mutually parallel and spaced from each other. Arrangement according to one of claims 8 or 9, characterized in that the measuring modules ( 2 . 3 ) are aligned at least approximately at right angles to each other. Arrangement according to at least one of claims 8 to 10, characterized in that the arrangement comprises an external position-measuring device, in particular a tracking interferometer.

Images