Impulse decoupled direct linear drives


Testbench for Pick-and-Place-Operations with high dynamics and impulse decoupled direct linear drives

Impulse decoupled direct linear drives to reduce mechanical oscillations

High dynamic Pick&Place Automat with impulse decoupled direct linear drives

Impulse decoupled direct linear drives to reduce mechanical oscillations

High dynamics and position accuracy are among the most prominent characteristics of linear direct drives. Due to the lack of mechanical transmission elements high acceleration are possible. On the other hand, this also promotes a direct coupling of the feed forces and the mechanical structure and leads to oscillations and position errors.

One possibility to reduce these oscillations are impulse decoupled linear direct drives. Conventional direct drives usually feature a stiff mounting of the secondary part, which carries the permanent magnets, on the structure, while the primary part is connected to the slide. For impulse decoupled systems the secondary is also flexibly mounted in a moveable way.
If the primary part is accelerated, the secondary will move in the opposite direction. And in accordance with the physical law of the conservation of momentum the secondary will also be affected by the primary’s deceleration.

To compensate for friction and process forces the connection between the secondary part and the structure is realized by an adaptive spring-damping-system. This results in a behaviour which is comparable to a single-mass-oscillator and constitutes a low pass. Thus especially the critical high frequency components can be eliminated from the excitation of the structure.

High dynamic Pick&Place Automat with impulse decoupled direct linear drives

The semiconductor industry needs highly dynamic grabbing systems for various production processes. Applications are for example the placement of parts on printed circuit boards or the packaging of IC´s. The parts have to be picked up from a supply and placed on the board with a very high speed.
To sustain this speed an to achieve a high through put the mechanical Pick & Place system has to by highly dynamic and accurate.

To further increase the dynamics of the drives the Pick & Place test bench, which has been developed at WZL, incorporates several technical aspects. The two main axes are constructed as a two dimensional parallel kinematic. A third, slower axis can be added in serics, if need. The drives for the parallel kinematic are iron-free linear direct drives, which have been chosen for their small weight and good force gradient. All moving parts of the test bench have been optimized for weight.
The drives are impuls decoupled to absorb a major part of the recoil energy of the acceleration. One of the most prominent applications for impuls decoupling so far is non-circular turning.

The control unit of the test bench uses the Real Time extension RTX to Windows NT. The target values for the movements are generated by a 10kHz RTX task and visualized on a self developed, Windows based user interface.

Papers (german only)
  • Brecher, C.; Ostermann, T. ; Weck, M.
    Pick & Place : präzise und dynamisch positionieren mit Impulsentkopplung
    In: Tagungsband "Neue Funktionalität der Ablauf- und Bewegungssteuerung an Werkzeugmaschinen- Ergebnisse- Tendenzen - Ausblicke", 3. und 4. Juni 2004, Hrsg. Großmann, K., Eigendruck IWM TU Dresden 2004, o.A.S.
  • Brecher, C. ; Ostermann, T. ; Weck, M.
    Pick&Place : Hochdynamischer Bestückungsautomat mit impulsentkoppelten linearen Direktantrieben
    In: Tagungsband "Elektrisch-mechanische Antriebssysteme -Innovationen - Trends - Mechatronik", Fulda, 6. und 7.10.2004, , Hrsg.: Binder, A. [u.a.], VDI/VDE Verlag Berlin 2004, ISBN 3-8007-2852-4, S. 317 - 328


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