Robot

a robot is a universal, programmable processing machine. These robots are conceived for the employment in the industriellen surrounding field (e.g. Automobile manufacturing).

KUKA joint arm robot with 6 axles

the processing machine consists generally of the manipulator, the control and a Effektor (tool, grip arm, etc.). Often becomeRobot also equipped with different sensors. This machine in a the position is once programmed to accomplish a work routine autonomously or to vary the execution of the task based on sensor information within limits.

The manipulator or bionic arm is a multi-functional Handhabungsautomat, which from a set of rigidMembers exists, which are interconnected by trick or prismatic joints, whereby the joints can be adjusted by steered drives. An end of this “link chain” is the basis, while the other end is freely mobile and with a tool or grip arm is equipped by production work for execution.The origin of the robots is to be looked for in the reactor engineering, where one used already early from handsteered manipulators for tasks within radioactively endangered area. The first robots in the automobile industry were equipped with hydraulic cylinders as power sources. In the middle of seventies became on electrical control driveswith microprocessor price increase reequipped.

Robots are supplied to different remarks and by different manufacturers. They are usually purchased as standardized basic equipment and adapted with user-specific tools to their respective task.

Table of contents

tool coordinate system

(Tool ) on the basis the used kinetics:

  • Serial kinetics
    • joint arm robot:
      • 6-Achs-Roboter with 6 rotation axles (comparable with human arm)
      • palletizing robot with 4 propelled rotation axles and mechanical blockage of wrist orientation
      • SCARA robot with 3 parallel rotation axles and a linear axle
    • portal robot with 3 linear axles (movement in a cartesian coordinate system x/y/z, comparably goliath crane) and possiblya rotation axle directly at the grip arm.
  • Parallel kinetics:
    • Hexapod robot (griech. “Sechsfüsser”) with 6 linear axles, often also with flight simulators uses (picture).
    • Delta robot with 3 gestellfest installed rotation axles and spatial parallelogram guidance of the drilling platform. (Picture)

an important characteristic of robots is the load. Thisdescribes the mass, which can be maximally fastened to the end of the manipulator. With joint arm robots there is thereby at present a range from 2,5 to 500 kilograms.

history

was invented the robot of George Devol 1954 and in this year also toPatent announced. Together with Joseph F. Engelberger creates Devol 1956 those world-wide first robotics company and develops a functional robot. For the first time such a robot was used 1961 with general of engine in a production line.

The first use of robots in Japan took place 1967 and in Germany 1970with Mercedes Benz in automobile production.

There are most robots at present (2004) in the triad countries. In Japan (Economist, 29. October 2005) gives it altogether to 356 Tsd. Robot. 2004 came 37 Tsd. in addition. 121 Tsd. Robot gives it in Germany, to 115 Tsd. into thatThe USA. Into Germany 2004 13 Tsd came., in the USA 12 Tsd. New installations in addition. All other countries have clearly less robot, Italy follow next country with 53 Tsd. Robots.

areas of application

Gelenkarmroboter mit Schweißpistole
joint arm robots with welding gun

to be used robots in the range:

structure and structure of robots (IR)

Struktur eines IR

the structurea robot (IR) contains:

  • Control: It supervises and gives the movement and actions of the IR. This presupposes a programming .
  • Drives: The drive moves the members of the kinematic chain and consists of engine, transmission and regulation. The drive can electrically, hydraulically ortake place pneumatically.
  • internal sensor technology: This supplies information about the position of the kinematic chain. It is used from the control to the alignment between being and actual position. Internal sensors can e.g. incremental rotation transducers, interference samples or light barrier functions its.
  • Kinetics: It places the physical realization of the read-basicStructure and creates the spatial allocation between tool/workpiece and manufacturing equipment. It consists of rotatorischen and translatorischen axles. Usually at least 3 degrees of freedom are to be able to reach necessarily around each space point. Requires at least 3 movement axles.
  • Grab systems: A grab system places the connection betweenWorkpiece and IR ago. This can be made by force mating, form mating or material matching.
  • external sensor technology: It gives a feedback over the environment to the IR. It makes thereby a flexible reaction possible to not planned changes. External sensors can e.g. Image processing systems, Lichschrankenfunktionen and ultrasonic sensors its.

Programming from robots

to the production of robot programs gives it the procedures to on-line programming and the off-line programming, which are often also combined used.

Most robotic controls permit also a large programming. So the behavior of the robot can be adapted to external influences: Different partscan be recognized by sensors, and be differently worked on by the robot. For example “Pick and Place” robot can sort a mixed bulk material from different chocolates by means of a video system into a Bonbonniere box.

Robotic control is frequently attached to a SPS. This regulates interaction between thatRobot and the surrounding equipment technology.

on-line programming

among the procedures of on-line programming rank:

  • Teach in procedure
  • Playback procedure
  • manual input over keys and switches (become outdated)

Teach in procedures

with Teach in procedures (short: Teachen) drives the programmer the robot with a tax console into thosedesired position and stores these in the control. This step is repeated until the entire intended movement is described by salient points.

Thus develops a succession of space points, which the robot drives off successively. For the movement between the individual points parameters can be entered.Like that the speed and acceleration are adjustable. The movement between the points can take place on a straight line, a circular path, or on, a geometrically however accurately not specified course particularly favorable for the robot.

After the Teachen the movement can reconstructed by the robot autonomouslybecome.

Playback procedure

of the programmers drives off the intended course by direct leading of the bionic arm. The robot repeats exactly these movements.

off-line programming

among the procedures of the off-lines programming rank:

  • textuelle programming
  • of CAD supported programming
  • of macroprogramming
  • acoustic programming

textuelle programming

the tasks becomedescribed on the basis of a problem oriented language. The procedure is comparable with programming in a higher programming language.

Advantages of textuellen programming:

  • The program can be changed easily and documented well.
  • The program can be prepared without use of the robot.

Disadvantages of textuellen programming:

  • For programming a qualified programmer is necessarily
  • almost any manufacturer uses its own programming language.

CAD supported procedure

with the CAD supported programming is programmed the robot on a PC job (often also Unix - workstations) on basis by construction designs and Simulationen.

The entire course of motionthereby already at the PC in a three-dimensional screen environment one specifies. Usually the environment of the robot and its tools are likewise shown. Thus different investigations can be accomplished:

  • Are the desired operating points at all attainable?
  • How long the robot needs for this course of motion
  • comesit with this program for collisions with the environment?

Advantages of the CAD supported programming (in connection with simulation):

  • The programming of the robot can already take place, if this is still not at all developed.
  • Planning and constructional defects can be promptly recognized. Necessary changes can in thisStage still at the computer to be made and it is not an expensive change on the building site necessarily
  • extensive changes at robot programs is partly substantially more simply possible than direct at the robot
  • in the 3D-Umgebung at the computer can each part of the robot environment of all sides be regarded. Inthe reality are often covered or with difficulty accessible operating points of the robot.

Disadvantages of the CAD supported programming:

  • The exact environment often does not exist as 3d-Modell. Basic elements of the workshop installation such as column, carrier, cross beams o.a. are difficult therefore to consider.
  • All devices and tools must accurately thatCorrespond to models in the computer.
  • The Teaching is often simpler and faster.
  • Flexible supply lines (compressed air - feed, Kühlwasserschläuche, welding current supply or adhesive supply, pin supply with Studwelding) can at the computer be illustrated only insufficiently, cause however substantial movement restrictions of the material Industieroboters.

In the CAD gestützen programming providedProgram will transfer into the robot by data media or network and can be implemented then immediately. Normally however still various adjustments (robot calibration) are necessary, since the simulated environment agrees exact never with the reality. Also the binding to the SPS takes place usually only“locally”.

Macroprogramming

with frequently returning jobs macros are provided, which represent frequently used instruction sequences in shortened form. The macro is once programmed and inserted afterwards at the necessary places of the control program.

acoustic programming

here is made the programming of the program text by the natural speech alsoAssistance of a microphone. The system can confirm the instructions acoustically and make so control possible of the correct collection.

Advantages of acoustic programming :

  • Avoidance of input errors
  • larger freedom of movement of the operator
  • adjustment to the used natural communication form

of disadvantages of acoustic programming :

  • relative high error rate today'sSpeech recognition systems

of coordinate systems

the position of a robot can be oh-referred either or described spacereferred.

oh-referred: For each individual (linear or rotatorische) axle of the robot one indicates, in which position it is. From it a clear position of the robot tool at the end resultsthe kinematic chain. As soon as rotatorische axles are present, it is however difficult to bring the TCP by indication of oh values to the desired situation.

spacereferred: The tool position of a robot is described over its TCP in such a way specified (Tool center POINT). This is a meant point of reference, which is in suitable place at the tool. In order to describe, which situation is to take the robot tool, it is sufficient, to define the position of the TCP in the area and its twist.

It is specified here by the programmer, to which place in the area the robot tool drivenwill is and like it is aligned. Robotic control calculates then over the so-called Denavit Hartenberg transformation, which position the individual robot axles must take in addition. See in addition also inverse kinetics, direct kinetics.

For the spacereferred description of the robot position different coordinate systems are available,those the programmer depending upon need to use can. The designation can vary depending upon robotic control:

absolute Cartesian coordinate system

the absolute Cartesian coordinate system (WORLD

)

has spacereferred robot coordinate systems [work on] its origin usually in the rotatorischen center of the first axle (basic axle, basic frame). It is the main coordinate system, which constantlyin the area lies. On this coordinate system all different are referred.

basis coordinate system

the basis coordinate system (COUSIN) is mostly used on the workpiece or workpiece admission, in order to teachen point coordinates in the purchase for the piece of who or workpiece admission. Thus the point of origin of the basis coordinate system can be shifted and the pertinentPoint coordinates move also. In the default condition the basis coordinate system is congruent with the absolute Cartesian coordinate system (cousin x 0, y 0, z 0, A 0, b 0, C 0). In the robot system several of these coordinate systems can be put on and stored with names. When programming can thus between the different basic systemsare switched.

tool coordinate system (Tool)

the tool coordinate system is at the tool of the robot. Its situation is defined by the TCP (Tool center POINT), which in suitable place of the tool is. Its orientation becomes by the so-called. Direction of attack of the tool as well as second,tool tools freely which can be selected fixed. Situation and orientation of the who things coordinate system are defined as translatorische and rotatorische shift to the “Ur-ZKP” in the center of the robot flange.

Because the tool coordinate system with the tool moves, lies it relative to this always directly, even if its situation in the areais variable. When defining meaningful of the TCP the programmer can turn the tool in such a way around its operating point or accomplish linear movements exactly suitably the tool situation. That comes to meet the human function and facilitates so the Teachen.

In a robotic control several tool tools can be normally put on,over a tool number to be selected can. Like that it is possible, with several different tools to work (e.g. two differently formed welding tongs). These can be at the same time at the robot cultivated, which however possibly leads to problems with weight and accessibility. Alternatively a tool change system can be used,with that the robot different tools on and abdockt.

A special application of the tool coordinate system forms the “external Tool in such a way specified”. Here the TCP is defined not at the robot tool, but at the operating point of a stationary tool. The points of the robot program are not thereby firmly in the area, but“stick” at the workpiece moved by the robot and with this to the being certain tools are induced.

The robot thus e.g. moves in this case. not the pliers to the sheet metal, but advance the sheet metal held in a grip arm to the being certain pliers.

cousin coordinate system

The cousin coordinate system can be positioned by the programmer freely in the area, e.g. parallel to one diagonally in the area standing device. Situation and orientation are independent of other coordinate systems, refer however computationally to the absolute Cartesian coordinate system. If a robot program is defined in the cousin coordinate system, then it leaves itself easyshift in the area and turn, as the situation of the coordinate system is only changed, but without only one point of program must become again GET eight (see basis coordinate system).

oh configuration

the movement of the robot tool by inverse kinetics leads to some characteristics. During itself from a certain positionthe axles clearly a position of the tool results in, is not the position of the axles for a certain tool situation clear always. The system is computationally over-certain.

Depending upon situation of the goal and the mechanics of the robot there are often several oh configurations, which lead to the desired tool tools.The selection of the most suitable configuration is task of the programmer. The control must place then surely that this configuration is as for a long time as possible maintained during the movement. The change between two configurations can lead otherwise to the fact that for a minimum tool motion a very large movement of the entireRobot takes place. This unexpected movement costs time and is often not not collision-free possible.

With some Roboterkinematiken (e.g. 6-achsiger joint arm robot) gives it space points, which lead to so-called singularities. Here there are infinitely many oh positions, which lead to the same tool tools. Some controls break the program when driving throughsuch a point off.

security

security of persons has a high meaning in the robotics. Already in the 50's Isaac Asimov in its Science Fiction novels set up three robot rules, which mean in the reason that humans by a robot or a itsInactivity to damage to come may not. Today there is laws (in Europe the machine guideline 98/37/EG) and international standards (e.g.: DIN EN 775), whatever specifies the safety standards of machines and thus to robots.

The dangers, which proceed from the robot, exist in for humansoften completely unforeseeable, complex movement samples and rapid changes of speed, with at the same time enormous set free forces. Working beside an unsecured robot can end fast deadly.

As the first preventive measure therefore the separation of the movement area from humans and robot mostly stands by grilles with secured protective doors or light barriers.Opening the protective door or an interruption of the light barrier lets the robot stand still immediately. In special modes of operation, where humans must enter the danger area of the robot (e.g. with the Teachen), agreement aster must be operated, in order to permit movements of the robot expressly. At the same time the speeds must the robot on a safe measure limited its.

Newer developments (Assistenzroboter) go into the direction that the robot recognizes an approximation of a foreign object or humans by means of sensor technology in time and its movement slowed down, stop, or even automatically back-yields. Thus becomes in the futurea common co-operation with the robot in its direct proximity possible.

All control circuits with functions for person security are usually redundantly implemented and supervised, so that also errors (like short-circuits) cannot lead to the safety loss.

manufacturer

important manufacturers of robotsare among other thingsABB, COMAU, Denso, Fanuc, KUKA, Güdel, Epson, Yaskawa/Motoman, Neuronics, Nidec Sankyo, Stäubli, rice Robotics, Kawasaki, Nachi, SEF, OTC and VOLKSWAGEN.

Nearly each manufacturer exerts itself own controls, in its programming, efficiency and the attainableCourse accuracy of the robot differentiate between.

Besides there are numerous system houses, which the robots, in individual, on which respective customer's requests arouse adapted plants to the life. In Großproduktionen, wie z.B. the automobile manufacturing, often only robots of only one manufacturer are used. The number makes smaller on supply toospare parts holding. In addition it is not necessary to train the coworkers on different systems. However more and more car manufacturer to give to the most favorable robot offerer the addition over and thus the concerning the price dependence on only one manufacturer ignore a too one-sided robot populationto reduce.

research institutes

of research institutes in the German-speaking countries are among other things (in alphabetical order):

literature

  • Alois Knoll, Thomas's Christian all: Robotics. Fischer publishing house. Frankfurt, 2003. ISBN 3-596-15552-5
  • Wolfgang weber: Robot. Methods of the control and regulation.Specialized publishing house Leipzig (Carl Hanser publishing house). Leipzig, 2002.ISBN 3-446-21604-9

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