C´mon part, do the local motion!

We describe a new control method for vibrations-based planar manipulation. We\´ve developed a device-the Universal Planar Manipulator (UPM)-based on a single, horizontally-vibrating plate. Though minimalist in construction (one moving part), the UPM can manipulate several parts on its surface in parallel, simply using friction. The authors previously showed (1998) that a sequence of rigid plate rotations can be computed which produces pre-specified part displacements. Here we present a new method based on a special motion primitive-the "jet"-which displaces a chosen part in a desired direction while keeping all others still. Parallel manipulation then reduces to a round-robin application of jets. This technique is both faster and more robust than the old rotations-based method. Experiments on parallel trajectory following and part sorting are presented. With jets, the UPM becomes a practical technology for applications such as part singulation, feeding, sorting, food handling, product displays, and interactive devices such as active desks and toys.