Autonomous Ceiling Robots

Involved People
Timo OverboomPhD student
Johan SmeetsPhD student
Prof. dr. E.A. Lomonova, M.Sc.First promotor

XY-positioning systems consisting of stacked linear actuators suffer from high power losses and bad  dynamic performance due to their large moving mass.  As an alternative, magnetically levitated planar actuators have already been researched for lithographic applications [ASPA].  These actuators consist of a single moving translator which is levitated above a stationary frame and propelled in the xy-plane by means of magnetic fields.
For the inspection or assembly of printed circuit boards, however, it is desirable to suspend the moving translator underneath a stationary frame (ceiling).  In this case the inverted planar actuator, or so called ceiling actuator, uses an attractive normal force to suspend the translator, whereas the aforementioned planar actuator uses an repulsive normal force. Furthermore, unlike the planar actuator, the ceiling actuator requires a passive normal force. It is necessary to reduce the dissipated power losses for magnetic suspension, to clamp the translator against the ceiling when it is not in use, and to guarantee fail-safe operation in case of power black-outs.
Power needs to available on the moving translator for propagation and functionality, for example to power a camera for inspection.  The energy can be fed by a cabled connection, but this connection would limit the acceleration, the stroke, and  the position accuracy of the moving translator. Therefore, energy will be transferred wirelessly between the stationary frame and moving translator, by means of an inductive coupling (transformer with an air-core). The goal is to develop a contactless energy transfer system which transfers a constant amount of energy for independent of the translator's position.
For the actuation of the actuator, it is important to know the position of the moving translator. Therefore, a position detection system (6 DOF) will be integrated in the system. The position sensors will be placed on the ceiling and the moving translator, a wireless communication link will transfer the position data between both sides.
The  focus of this research project is the realization of a proof-of-principle for the ceiling actuator with integrated contactless energy transfer and position detection. This novel actuator concept (Fig. 1) combines the following features:

  • Single-sided active magnetic bearing with control over six degrees-of-freedom (DOF).
  • Magnetic propulsion of multiple moving translators over an unlimited stroke in the xy-plane. 
  • A passive attraction force, Fz,0, between the ceiling and translator for fail-safe operation (mg<Fz,0 m=mass).
  • Position independent contactless energy transfer from the stationary ceiling to the moving translator.
  • Autonomous operation and 6-DOF position detection of each moving translator.

The project is split into two parts: Timo Overboom focuses on the magnetic suspension and actuation, while Johan Smeets dedicates his research to the integration of the contactless energy transfer and position detection.