Design of a flexible conveyer microrobot with electromagnetic field-based friction drive control for microfactory stations

This paper proposes and demonstrates the feasibility of a new generation of compliant piezoelectric microconveyers for microobjects based on the cooperation of arrayed direct-drive standing wave ultrasonic motors (microSWUMs). Their operating principles, which combine active frictional contact mechanisms with electromagnetic field-based friction drive control, are analyzed. A prototype of a planar-type ultrasonic motor incorporating 48 arrayed microSWUMs, whose overall dimensions are 47 × 29 mm2, has been realized through the use of a flexible active metallic sheet (stator) which acts as a mobile platform. An experimental characterization has been carried out in order to identify the main physical and technological limitations specific to millimeter scale standing wave motors. The corresponding results indicate that powerful force/speed characteristics on the millimeter scale can be expected, i.e. high output force density around 20 mN · mm-2, a carried load ratio reaching 1 kg · cm-2, a traveling distance without displacement restrictions, and a nanometer resolution of positioning.