E. Keskinen (Finland) and M. Cotsaftis (France)
Motion planning, dispensing robotics, elastic rotors, dynamic balancing
To avoid damaging vibrations, the problem of accurately balancing long cylindrical rotors is becoming very important with higher performance requirements in today industry. A method is proposed here to solve this problem for hollow rotors currently used in many industrial plants, based on the possibility to directly measure rotor imbalance by adequate sensors. From observations, the mass defect responsible of actual rotor imbalance is then exactly evaluated analytically everywhere along rotor inner surface. A robotic mass dispensing system is further proposed to compensate the missing mass according to calculated imbalance defect. It consists of a movable beam introduced inside the rotor along geometric longitudinal axis, on which is mounted the dispensing system consisting of a second arm perpendicularly linked to the primary beam at the end of which is fixed the dispensing head spraying the mass through a calibrated nozzle by oscillatory. The control problem associated with the robotic dispensing task has been analysed and some resulting constraints are discussed. One is that the nozzle diameter is upper-bounded, so the material has to be launched as a fluid with well-defined and constant viscosity and weight characteristics. A numerical example from hollow rolls in paper mill use is discussed which shows the adequacy of the proposed system.
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