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Technology

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iSiOS
uses the native precision of the laser


The patented
functional principle of iSiOS
is based on scanning some precisely straight laser beam with the robot. When the robot hand is moved along the laser beam, smallest deviations from the straight line are detected easily. Measurements of these deviations yield a precise model of the robot by elaborate mathematical algorithms. The identified robot model contains all entities which influence the position of the robot hand. Deformations of the robot arm, zero offsets of the joints or gravity-induced displacements of the hand are compensated completely and sustainably in the whole workspace.
iSiOS uses this principle usually in reverse set-up: the compact, light-weight laser is carried by the robot and the sensor is placed fixedly near the workcell boundary.

Accuracy

Small errors of the robot are mapped in full size onto the sensor over the whole range of the laser beam. This is the foundation of the conceptually high sensitivity and precision of the system, which could easily be increased further if needed - e.g. for the calibration of micro-mechanisms. With two or three sensors placed and distributed properly on the boundaries of the workcell, iSiOS calibration provides maximum robot positioning accuracy throughout the complete workspace.

The fundamentally new approach yields decisive technical advantages which were reserved to costly laser trackers before

  • The large errors caused by gravitation-induced elasticities and deflections are identified and compensated precisely. Only measurements along the total reachable area of the laser beam enable reliable results and accuracy for varying load situations.
  • The appropriately sized, patented Isios carbon fiber etalon with two cost-efficient sensors yields sufficient error dampening to determine absolute robot lengths precisely in contrast to measurements within a restricted area or single spot.
  • During set-up, iSiOS does not require the use of an additional laser tracker anymore, which was needed up to now to measure the exact poses of obligatory reference devices w.r.t the robot whenever demanding precision goals had to be met.
  • iSiOS is highly sensitive also to orientational errors. When the laser is mounted on the robot hand or tool, the laser beam functions as an immaterial lever, which amplifies orientation errors proportional to distance, yielding maximum orientational accuracy after calibration.
In all its accuracy statements, Isios always takes the user defined tooltip (TCP) into account. For certain types of universal, industrial 6-joint robots, absolute positioning errors at some 200 mm tooltip can be kept below 0,15 mm in the whole workspace including arbitrary changes in the joint-configuration (i.e. shoulder left or right, elbow up or down, handflip); the average error ranges around a minimum of 0,05 mm. Counter-examination with high precision measurement gauges (laser tracker) yields highly similar calibration results.

Depending on type, the average overall of industrial robots with workspace radius below 3 m and payload below 300 kg can be raised up to the range of 0,3 mm. The overall accuracy is the effective accuracy at the workpiece when the hand pose is specified relative to the workpiece only. In this case, the absolute pose of the hand with respect to the world is unknown beforehand but is automatically identifed by the iSiOS system with the calibrated robot.


Cost-efficiency

The outstanding scalable sensitvity and high resolution of the system is founded in the tehcnological concept of the system, not in costly measurement equipment. Therefore, regular robust and compact components exceed the requirements of the system easily.


Control of the calibrated robot

Once the parameters of the robot model are identified exactly, the robot can be controlled exactly. This only requires appropriate calculations - the so called inverse transformation - before each precision move of the robot but no additional measurements during runtime. Calculation is done either by the robot control system or by the extremely fast iSiOS realtime-precision-control module which may be executed on the robot controller or independently on a remote computer.
The exact inverse transformation can be evaluated at run time or offline beforehand in case that offline simulation systems are used.


Compare iSiOS

  • iSiOS does not need elaborate, sensitive optics or precision measurement gauges. The scalable sensitivity of the system and its particular concept guarantee maximum robot accuracy within the complete workspace - not only for typical articulated-joint robots but also for cartesian robots, SCARA-robots and special purpose gantry mechanisms with combinations of rotary and prismatic joints.
  • All compact components of iSiOS inline calibration systems, remain installed in the workcell and are readily available when needed. Only the stationar
    • installation enables features like instant, synchronous error-diagnosis of all robots of a production line within a matter of minutes,
    • permanent monitoring of all production devices including mechanisms like rotary tables,
    • automatic recalibration and restoration of maximum accuracy after minor collisions or exchange of robots within approx. 5 minutes, or
    • compensation of wear and tear or temperature effects concurrent with production.
  • Robustness and compactness as well as contactfree, seamless integration and function in rough obstructed environments and under low visibility conditions are decisive advantages in demanding industrial applications.
  • The system generates a large part of its cost already during set-up and initial calibration of the original production line or workcell, resp. Teach-In costs can be saved. iSiOS is laid out and priced for fast amortisation of stationary installations in all accuracy-critical cells of a production line.

Compare accuracy, advantages and cost

Are you planning benchmark tests? Isios appreciates to support a critical evaluation of iSiOS features and resulting robot accuracy as well as comparative tests with other calibration principles.


           
           
    DerThing Medienpool Isios GmbH