Maneuver at Micro Scale: Steering by Actuation Frequency Control in Micro Bristle Robots

This paper presents a novel steering mechanism, which leads to frequency-controlled locomotion demonstrated for the first time in micro bristle robots. The miniaturized robots are 3D-printed, 12 mm × 8 mm × 6 mm in size, with bristle feature sizes down to 400 µm. The robots can be steered by utilizing the distinct resonance behaviors of the asymmetrical bristle sets. The left and right sets of the bristles have different diameters, and thus different stiffnesses and resonant frequencies. The unique response of each bristle side to the vertical vibrations of a single on-board piezoelectric actuator causes differential steering of the robot. The robot can be modeled as two coupled uniform bristle robots, representing the left and the right sides. At distinct frequencies, the robots can move in all four principal directions: forward, backward, left and right. Furthermore, the full 360 ◦ 2D plane can be covered by superimposing the principal actuation frequency components with desired amplitudes. In addition to miniaturized robots, the presented resonance-based steering mechanism can be applied over multiple scales and to other mechanical systems.