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New Scale Technologies has used its Squiggle micro motor technology to develop new rotary piezoelectric motors.

The rotary micro motors were custom developed for NASA Jet Propulsion Laboratory’s “Cobra” fibre positioner, part of the Wide-Field Multi Object Spectrometer (WFMOS) to be commissioned on the Subaru Telescope on Mauna Kea, Hawaii in 2013.

New Scale developed two custom miniature rotary motors optimised for high torque and precision.

The two piezoelectric motors, measuring only 2.4 x 2.4mm and 4.6 x 4.6mm, offer better than 0.1 degree step-resolution and twice the torque of similar-sized DC micro motors.

Each Cobra fibre positioner comprises one SQR-2.4 and one SQR-4.6 rotary piezo motor in a two-stage theta-phi configuration.

Overall positioner dimensions are 8mm in diameter and 85mm in length.

The WFMOS will have 2400 Cobra positioners in a close-packed hex array pattern on 8mm centres.

New Scale can design and integrate custom rotary piezoelectric-motors for anywhere that miniature rotary motors are used, including electronic locks, micro pumps and scanning systems.

New Scale rotary piezo-motors can be optimised for other design parameters including smaller size or higher speeds.

The Squiggle motor design consists of piezoelectric plates that are activated to generate ultrasonic vibrations in a hollow metal stator tube.

These vibrations directly drive a rotor in the tube using friction as the driving force.

This design eliminates the need for gear-reduction mechanisms and enables direct-drive rotary motors with small size, high peak-torque at sustained speeds, high holding torque and high precision without windup or backlash.

The Cobra is a two-degree-of-freedom mechanism that can position an optical fibre in the prime focus of the telescope to a precision of 5um.

The theta-phi style positioner contains two custom rotary Squiggle motors with one offset from the other, enabling the optic fibre to be placed anywhere in a 9.5mm diameter patrol region.

The patrol diameter of the actuator is large enough to obtain 100 per cent sky coverage with the close-packed hex array pattern of 2400 positioners on 8mm centres.

The Cobra, named because it resembles a snake ready to strike, allows red shift observations of 2400 cosmological targets simultaneously.

It allows, for the first time, large-scale galactic archeology and dark energy surveys, helping to unlock the secrets of the universe.

New Scale Technologies

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