Experimental characterization of Drobot: Towards closed-loop control

Abstract

This paper presents advances in the development of a microrobotic platform actuated by three liquid droplets in a gaseous environment (Drop-bot or Drobot). Drobot builds on the bubble robotics concept earlier introduced by Lenders [1]. A new platform design is described allowing three actuated degrees of freedom : one translational (vertical) and two rotational (tilt). The platform-supporting droplets are generated by pushing liquid out of a tank through linear actuators. Preliminary kinematic (output/input ratio), static (compliance) and dynamic (response time and evaporation time) characterizations of Drobot are reported, as well as promising experiments with an ionic liquid, whose negligible volatility is suitable for vacuum or hot environments. Additionally, a method to deduce the platform attitude from the measurement of the electrical resistance of the droplets is discussed. This work contributes toward the automatic control of the platform, which will be fully addressed in a following publication.