Control of Micrometer Size Robots

Scientific Coordinator: Aude Bolopion     –

Non contact robotics is as a promising solution to handle objects of less than 500 micrometers. Due to the small scale, on board actuation or sensing is not possible. Remote actuation, using for example magnetic fields, enables to power these microrobots. Several actuation principles can be used depending on the properties of the objects that should be controlled. However, major challenges, such as the closed loop control of 3D trajectories or the integration of manipulation tools, must still be faced to perform advanced tasks.

Non contact actuation based on the use of magnetic fields. Magnetic microrobots, in blue, are used to sort objects inside a fluidic environment.

Compared to classical approaches where the tools plus the objects should be moved, the use of remote force fields enables moving only the object. At small scales the inertia of the objects decreases drastically, which leads to important accelerations. The works performed in Minarob team focus on exploiting this property to increase the velocity of the displacements of the objects, while maintaining a good precision of the trajectory control. Several challenges must be faced on different topics:

  • Modeling: accurate models of the system that can be inverted in real time to perform trajectory control must be defined.
  • Design: the actuation platforms must be designed to maximize the force applied on the objects, which introduces important non linearity.
  • Fabrication: micrometer size robots must be fabricated in clean room facilities.
  • Sensors: high frequency position feedback of the objects is necessary, which can necessitate the use of original position sensors.
  • Control: control laws robust to the perturbation must be implemented at high frequency.

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