DE102004018213A1 - Supply line for an industrial robot has a number of cables and pipes within a hose sleeve and an optical fiber sensor held in a loose envelope within the hose sleeve so that deformation presses it against the side of the envelope - Google Patents

Abstract

Supply line (2), especially a hose package, for an industrial robot has a number of cables (6A, 6B) and or pipes (8A, 8B) as well as in integrated monitoring sensor (12) for monitoring the deformation of the supply line. The sensor comprises a cladding-free optical fiber that is enclosed in a sleeve, such that when a force acts on the hose the sleeve is pressed against the optical fiber. The fiber has a coupling point at which light is coupled into it and is connected to an evaluation unit. An independent claim is made for a device with a supply hose package, especially an industrial robot.

Description

The The invention relates to a method for monitoring the deformation of a Supply line and a supply line for such monitoring is formed and a device with such a supply line.

In many technical areas will be supplying power in Part of heavily loaded areas are used and guided So sometimes exposed to extreme environmental conditions. Especially when connecting moving machine parts, the supply line a sufficiently high elasticity or Biegeschlaffheit to the movements of the machine part to be able to follow.

One such high-stress area of application is, for example in a particular multi-arm industrial robot before, as he used in many industries for automation purposes becomes. In an industrial robot, the supply line, the as so-called hose package with a variety of individual Line components is equipped, over several relative to each other movable robot arms to a tool head, for example a Welding machine, guided. In the hose package are usually electrical supply and Data cables, optical cables and fluid lines for the supply of Gases or liquids arranged. The failure of an industrial robot, for example due to a wire break in an electrical cable, may cause high downtime and thus lead to high costs. Such a Wire break occurs, for example, in the case of an impermissible bending load of the hose package, when the electrical cable over an allowed yield strength is stretched. Such an impermissible bend therefore constitutes an inadmissible Deformation of the elastic, limp hose package is.

Of the Invention is based on the object such an impermissible deformation to capture with simple means.

The Task is according to the invention solved by a method according to claim 1. Thereafter, it is envisaged that in the elastic or pliable Supply line a monitoring sensor for the detection of an impermissible Deformation is integrated. To form the monitoring sensor is here integrated into the supply line a cladding-free optical fiber, surrounded by a shell. In operation, the fiber optic fiber Led light, so that on the outer surface of the optical fiber so-called evanescent field trains. In case of impermissible deformation a pressure is applied to the sheath so that the sheath pressed against the fiber, causing the evanescent field and thus the light propagation disturbed becomes. This disorder will as a change in intensity recorded and evaluated as needed.

These Embodiment is based on the knowledge that in the light propagation in an optical fiber near the near surface, the evanescent field forms, so that the electromagnetic waves are in this shallow Spread out area. conventional Optical fibers are surrounded by a so-called cladding, which a cladding or coating of the optical fiber (optical fiber) represents and the desired Total reflection by choosing a refractive index smaller than that of Optical fiber ensures. The invention is further based on the finding that a disorder of the Light wave propagation in the area of the evanescent field to a measurable intensity change leads, which can be evaluated. Starting from this is the embodiment of the monitoring sensor essential that the optical fiber fiber is cladding free to pressurize to enable that the sheath pressed against the cladding-free optical fiber becomes so that the Evanescent field is disturbed.

outgoing from this sensor principle is in the present invention, the Integration of such a trained monitoring sensor in a supply line intended. If the supply line is deformed impermissibly, this leads namely causing the sheath to be pressed against the optical fiber, so that a change in intensity recorded and evaluated. A significant advantage of the monitoring sensor is to be seen in that he already without deformation of the optical fiber is sensitive. It is sufficient therefore, when the sheath for abutment with the optical fiber comes.

at the monitoring sensor it is therefore a pressure-sensitive sensor. For his Effect is crucial that by pressing the Sheathing against the optical fiber, the light propagation is impaired. This is done by the sheath preferably having a refractive index which is larger than the fiber optic, so the condition for total reflection is interrupted when the jacket is applied. Alternatively, the Sheathing a high damping or absorbency on, so that - yourself if the condition for the total reflection is given - that Light in the near-surface Range through which a high attenuation Shroud must spread and thereby weakened.

In the normal, so unloaded condition to allow a largely trouble-free propagation of light, the optical fiber is preferably surrounded by the gap leaving a gap. Conveniently, an impermissible bend is detected in the supply line and the monitoring sensor is located outside a neutral fiber of the supply line.

According to one preferred development is the intensity profile of the detected light stored in an evaluation device. By saving it is possible, also to any later Time causes for a damage to understand the supply line. Due to the partial high economic damage in case of failure of a production plant This is special due to a faulty supply line relevant with regard to guarantee and warranty claims. By this measure has namely the manufacturer or supplier of the supply line has the option an invalid and not under the warranty prove falling use. The stored intensity gradients are if necessary, read out of the memory and evaluated. For this Preferably, a remote diagnosis is also provided.

There dependent from the respective application of the supply line this one complex structure and also for different applications may be provided, the monitoring sensor according to a appropriate training, initially calibrated. For this purpose, the Supply line with the integrated monitoring sensor at the Use of the supply line is exposed to any permitted loads. The inevitable occurring intensity changes of detected light are considered admissible Reference curves saved. This will be zweckereienlichereweise in a table for different operating modes different reference curves, if necessary stored with tolerance deviations, so that the entire work profiles and the entire work spectrum of, for example, an industrial robot are covered. To determine whether an inadmissible charge took place has, then recorded in the operation intensity characteristics the reference curves compared. A deviation above predetermined thresholds then becomes as inadmissible Load evaluated.

Around a trouble-free Ensuring operation of a plant process is the monitoring sensor Conveniently connected to a process monitoring and at Occurrence of an impermissible Loading is by process monitoring an error signal is issued. As an error signal here is an optical, acoustic or a shutdown signal delivered, which is a forced shutdown leads the plant, for more damage to avoid. In a preferred embodiment, the monitoring sensor used in a so-called hose package of an industrial robot.

The Task is according to the invention still solved by a supply line according to claim 8, for monitoring on impermissible Deformation of the monitoring sensor having.

Around to allow a simple production is expediently the supply line or a line component extruded from it together with the optical fiber. That the Supply line and the optical fiber are inexpensive than Manufactured by the meter.

According to one alternative embodiment is the monitoring sensor, comprising the fiber optic cable and the sheath, with further line components stranded to form the supply line.

Conveniently, is the fiber optic fiber in a sheath of the supply line integrated. This has the advantage that the optical fiber in the outdoor area is arranged, in which the deformation and thus the pressure on the monitoring sensor is greatest. Preferably, the jacket at the same time also forms the sheath of the Fiber. The sheath and the optical fiber are in this case in particular coextruded.

Around a high sensitivity is to ensure the sheath in particular easily formed deformable and has a low inherent rigidity. According to a preferred embodiment the cladding is here as a surrounding the optical fiber Hose formed in which this particular loose fitting guided is. The design with the loose-fitting fiber is due their ease of manufacture very inexpensive. The fiber is here guided in a somewhat serpentine inside the tube and clings to the reversal points on the shell. At pressure load come larger sections the optical fiber with the sheath in contact.

Alternatively, the fiber is foamed to form the sheath. In particular, this forms the foam at the same time also the jacket of the supply line or a line component of the supply line. Conveniently, in this case an open-pore foam is used, so that the casing is not fully supported on the fiber optic fiber. A closed cell foam can be used if the refractive index of the foam material is smaller than that of the optical fiber. In this case, at ei ner pressure, so the pressing of the sheath against the optical fiber, the foam compresses, whereby its damping behavior is greatly changed, which leads to the change in intensity.

The Task is according to the invention still solved by a device, in particular an industrial robot according to claim 17. The device is in this case in particular a machine or a plant in which two relatively movable machine parts are provided and the supply line over this time - or on this led along is. Those with regard to the procedure and the supply line cited Advantages and preferred embodiments are mutatis mutandis to transfer the device.

embodiments The invention will be explained in more detail below with reference to the drawing. It show each in schematic and sometimes greatly simplified representations:

1 a hose package with several different line components and several integrated monitoring sensors,

2A to 2C different embodiments of the monitoring sensor,

3 a fluid line with several integrated optical fibers,

4 an electrical cable with integrated monitoring sensor, and

5 a highly schematic representation of an industrial robot with a supply line with integrated monitoring sensor and an evaluation.

In the figures are the same acting parts with the same reference numerals Mistake.

In the 1 illustrated supply line 2 is used in particular as a so-called hose package in industrial robots for supplying a tool head with electrical or optical signals, with an electrical power supply and for supplying various media such as gases, liquids, etc. The supply line 2 includes an outer, trained as a protective jacket jacket 4 that surrounds multiple line components of different types. In the exemplary embodiment, electrical cables are different types for the line components 6A . 6B , Fluid lines 8A . 8B as well as filling strands 10 intended.

The illustrated supply line 2 has a plurality of monitoring sensors 12 on. Four of them are in the coat 4 the supply line 2 integrated, two more are with the other line components 6A . 6B . 8A . 8B . 10 stranded, a monitoring sensor is in the electrical cable 6A integrated, and two fluid lines 8A again each have four monitoring sensors 12 on. In order to be located at a bend in a pressure-loaded area, the monitoring sensors are located outside of a neutral fiber (shown only in the drawing) 18 the supply line 2 and the fluid line 8A and the electric cable 6A ,

In 1 the monitoring sensors are shown only as an example. By integrating into the coat 4 or by the stranding with the other line components is the monitoring of the supply line 2 as such allows. Through the integration in the individual line components, for example in the fluid line 8A or in the electrical cable 6A , these can be additionally monitored. Alternatively, only one or more line components are monitored without a monitoring sensor 12 in the coat 4 integrated or stranded with.

Examples of the training of the monitoring sensors are in the 2A to 2C shown. The monitoring sensor 12 necessarily includes an inner fiber optic fiber 14 and a surrounding sheath 16 ,

In the two monitoring sensors according to the 2A and 2 B is between the fiber optic fiber 14 and the sheath 16 a space filled in particular with air 20 provided so that the optical fiber 14 from the sheath 16 is spaced. The fiber optic fiber 14 relies here only on individual points on the casing. According to the 2 B are supporting webs for this purpose 22 provided that part of the sheathing 16 form. The jacket 16 therefore has a kind of internal profiling. This can also be achieved by a particularly large surface roughness.

According to 2A is the sheath 16 formed as a tube in which the optical fiber 14 Loosely fitting is guided, so this over the longitudinal extent of the monitoring sensor 12 considered in the tube is arranged serpentine or arcuate and only at their reversal points in each case on the casing 16 supported.

In the third embodiment of the monitoring sensor 12 according to 2C is not a gap 20 intended. Rather, the lies jacket 16 directly on the fiber optic fiber 14 at.

For the effectiveness of the monitoring sensor in the action of a pressure caused by a deformation of the supply line 2 , is on the one hand essential that the optical fiber has no so-called cladding. The cladding is usually a coating or a fiber cladding, which has a smaller refractive index than the optical fiber 14 so that the condition for the Totelreflexion in the boundary region between the fiber and the cladding is guaranteed. A farther, with the sheath 16 provided protective coating in this case has no effect on the light propagation. The opposite is the present monitoring sensor 12 the influence of the sheathing 16 crucial. In fact, the so-called evanescent field is formed during the propagation of light in the near-surface outside area. The penetration depth of the same into the outside area amounts to a few μm. The effect of the monitoring sensor is based on the fact that the evanescent field and thus the light propagation is impaired. According to a first variant, in this case, the sheath 16 a higher refractive index than the optical fiber 14 on, allowing the light from the fiber optic fiber 14 quasi decoupled and no longer reflected, as soon as the sheathing 16 to the fiber 14 inspired. In particular, the embodiment variants according to FIGS 2A and 2 B out. The prerequisite for this is that the sheath is sufficiently elastic, so that in a pressure load, this in addition to the support points flat to the fiber 14 snugly.

A change in intensity is caused in a second alternative in that only a damping of the evanescent field and thus the light propagation takes place. The embodiment is based on this effect 2C , In this case, the boundary condition for the total reflection can continue to be satisfied, ie the refractive index of the cladding is smaller than that of the fiber 14 , It is essential that the damping behavior of the sheath 16 is changed under pressure load. This is achieved by the fact that the material of the casing 16 is compressible and, for example, foamed material. When pressure is applied, the sheath becomes 16 compressed, so that the damping is increased. If an open-pore foamed material is used, which does not have a closed surface, but has a surface with a pore structure, then these pores form quasi individual interstices to the optical fiber 14 ,

In contrast to the embodiments according to the 2A to 2C is the cross-sectional geometry of the monitoring sensor 12 not necessarily round.

In 3 is again the fluid line 8A with the integrated monitoring sensors 12 shown. These are as in the hose jacket 26 the fluid line 8A integrated fiber optic fibers 14 educated. The hose jacket 26 therefore forms at the same time the sheath 16 , The monitoring sensors 12 are here around the circumference of the fluid line 8A distributed approximately evenly so that the bends of the fluid line 8A can be detected in different directions without further ado. The 4 shows the electrical cable 6A , in which - together with the individual electrical wires or wires not shown here - a monitoring sensor 12 integrated, in particular distributed or interwoven.

In 5 is a simplistic industrial robot 40 with several relatively movably mounted robot arms 42 shown. The supply line 2 is from a connection interface 44 at the individual robot arms 42 along led to a tool head, not shown here, to supply this. The industrial robot 40 performs in operation sometimes very complex movements, so that the elastic supply line 2 Bending and torsional stresses is exposed. Is the permissible load of the supply line 2 exceeded, for example, by an excessive extension or over-rotation of the robot arms 42 , this leads to an inadmissible deformation of the supply line 2 Such as stretching, compression or bending, which form localized areas with increased compressive stress, resulting in a response of the monitoring sensor 12 to lead.

The change in intensity of the detected light at a deformation of the supply line 2 This is due to the fact that in the areas outside the neutral fiber 18 the supply line 2 Regions with increased tensile or increased compressive stress are present. As a result of such a particular due to egg ner bending caused compressive stress, the sheath 16 of the monitoring sensor 12 against the optical fiber 14 pressed, reducing the intensity of the in the monitoring sensor 12 propagating light as described.

In operation, to monitor an impermissible deformation of the supply line 2 via a feed-in point 28 Light in particular a light emitting diode in the optical fiber 14 coupled, which via a decoupling unit 30 is decoupled again. The light intensity of the coupled-out light is detected by a sensor, not shown here, in particular a diode. The feed-in point 28 and the decoupling unit 30 are with a control and evaluation unit 32 via signal lines 33 In this, the intensity change between the coupled and the decoupled light is detected and evaluated as needed. The evaluation unit 32 in this case includes in particular a memory 34 in which the ascertained intensity profiles are stored. At the same time reference curves are stored in the memory, which reflect the intensity curves at a normal and allowable stress. For further evaluation, the detected or stored intensity profiles are evaluated in particular by comparison with the reference curves. This is done either within the evaluation unit 32 or the data is transmitted via a data interface 36 to an external evaluation unit 38 for example, wirelessly transmitted.

Preferably, an online monitoring is provided during operation as part of a process monitoring in order to detect damage early on. In this case, the intensity profiles are evaluated continuously or at regular intervals. If an impermissible load is detected, then an error signal F from the evaluation unit 32 delivered and for example via another signal line 33 to the industrial robot 40 transmitted and displayed there acoustically or visually. In case of a serious error can be via the signal line 33 also a forced shutdown of the industrial robot 40 be made.

The monitoring of a supply line 2 can be used in many technical areas, where the supply line 2 is exposed to mechanical loads. This is especially the case when using the supply line 2 moving machine parts are supplied. This applies, for example, cranes and crane systems, in so-called drag chains guided supply lines 2 Electrical wiring harnesses for wind turbines, gasoline or fluid lines for tanks or refueling systems, gas lines for welding equipment, electrical cables for elevators, mechanically loaded control lines or power supply lines, such as in the automotive sector, etc.

2

supply line

4

coat

6A, B

electrical electric wire

8A, B

fluid line

10

filling strand

12

monitoring sensor

14

Optical fiber

16

jacket

18

neutral fiber

20

gap

22

supporting web

26

hose mantle

28

infeed

30

outcoupling

32

evaluation

33

signal line

34

Storage

36

Data Interface

38

external evaluation

40

industrial robots

42

robot arm

44

Connection Interface

F

error signal

Claims (17)

Method for monitoring the deformation of a supply line ( 2 ), in which to form a monitoring sensor ( 12 ) into the supply line ( 2 ) a cladding-free optical fiber ( 14 ), which in the unloaded state of a casing ( 16 ) surrounded by the optical fiber ( 14 ) Light and when deformed on the sheath ( 16 ) a pressure is applied, so that these against the light optical fiber ( 14 ) is pressed, so that on the outer surface of the optical fiber ( 14 ) Evanescent field is disturbed and this disorder is detected as a change in intensity and evaluated as needed. Method according to Claim 1, in which the optical fiber ( 14 ) leaving a gap ( 20 ) in the casing ( 16 ) is guided. Method according to Claim 1 or 2, in which the supply line ( 2 ) is monitored for an impermissible bend and the monitoring sensor ( 14 ) outside a neutral fiber ( 36 ) of the supply line ( 2 ) runs. Method according to one of the preceding claims, in which the intensity profile of the light emitted by the optical fiber ( 14 ) guided light in an evaluation device ( 32 ) is stored. Method according to one of the preceding claims, in which the monitoring sensor ( 12 ) is calibrated by the supply line ( 2 ) with the integrated monitoring sensor ( 12 ) when using the supply line ( 2 ) is exposed to permitted loads and the occurring intensity changes are stored as permissible reference values. Method according to one of the preceding claims, in which the monitoring sensor ( 12 ) is connected to a running process monitoring and an error signal is deducted from the process monitoring if an impermissible load occurs will give. Method according to one of the preceding claims, in which the monitoring sensor ( 12 ) is used in a hose package of an industrial robot. Supply line ( 2 ) for carrying out the method according to one of the preceding claims, with an integrated monitoring sensor ( 12 ) containing a cladding-free optical fiber ( 14 ) covered by a sheath ( 16 ) is surrounded in such a way that, when force is applied against the optical fiber ( 14 ), the optical fiber ( 14 ) with a feed point ( 28 ) for coupling in light and with an evaluation device ( 32 ) is connectable. Supply line ( 2 ) according to claim 8, wherein the optical fiber ( 14 ) in the unloaded state to form a gap ( 20 ) of the sheath ( 16 ) is surrounded. Supply line ( 2 ) according to claim 8 or 9, wherein this or a portion of it together with the optical fiber ( 14 ) is extruded. Supply line ( 2 ) according to claim 8 or 9, wherein the monitoring sensor ( 12 ) with further line components ( 6A , B; 8A , B; 10 ) is stranded. Supply line ( 2 ) according to one of claims 8 to 11, comprising a jacket ( 4 ) into which the optical fiber ( 14 ) is integrated. Method according to claim 12, wherein the jacket ( 4 ) at the same time the sheath ( 16 ) of the optical fiber ( 14 ). Supply line ( 2 ) according to one of claims 8 to 13, in which the sheath ( 16 ) is easily deformable and has a low inherent rigidity. Supply line ( 2 ) according to one of claims 8 to 14, in which the Ummanntelung ( 16 ) as the optical fiber ( 14 ) surrounding tube is formed, in which the optical fiber ( 14 ) is guided in particular loose fitting. Supply line ( 2 ) according to one of claims 8 to 15, in which the optical fiber ( 14 ) for the formation of the sheath ( 16 ) is foamed. Device, in particular an industrial robot ( 40 ), with a supply line ( 2 ) and one in this integrated monitoring sensor ( 12 ) for monitoring the deformation of the supply line ( 2 ) containing a cladding-free optical fiber ( 14 ), which in the unloaded state, in particular with formation of a gap of a sheath ( 16 ) is surrounded in such a way that it is pressed against the fiber when force is applied, the optical fiber ( 14 ) with a feed point ( 28 ) for coupling in light and with an evaluation device ( 32 ) for detecting by the optical fiber ( 14 ) guided light is connected.