Miniature Motor Squiggles into Small Precision Devices

Look at small motors for a product design and you’ll find a gap between small DC motors and micro electromechanical systems (MEMSs) fabricated on a silicon wafer. New Scale Technologies has helped filled that gap by designing squiggle-motion motors, or squiggle motors, for engineers who need a tiny motor in miniature and subminiature applications. You can find out more at: http://www.newscaletech.com/motorsforoem.html.

The people at New Scale loaned me one of the DK-1.8-SS-TRK-33 developer’s kits so I could see first hand how the motor works. In 2007, I wrote a short article on motor dev kits in which I covered one of the early squiggle-motor devices, so two years on it seemed worth taking another look. The kit requires no assembly because it comes put together with a closed-loop SQUIGGLE motor and a TRACKER position sensor. Two AA-size batteries power the kit and two pushbuttons let you move the motor’s leadscrew left or right.

The image above shows the Squiggle Motor demonstration unit. I added the arrow that points to the small motor.

New Scale developed a NSD-1202 ASIC that controls the motion of the squiggle element that drives a leadscrew. The kit includes a CD-ROM with software and manuals and a USB cable that lets a host PC control motor actions. The Quick Start Guide I received leaves a bit to the imagination. Steps don’t always match menu choices, and a note recommends saving relevant manuals from the CD, but it never explains which manuals relate to this kit. I installed the USB-motor-control software, but without going through a 70-page manual, there’s not much to do except jog the motor back and forth. Engineers who want to investigate farther should print the manual. It seems to offer a lot of motor-control information.

The New Scale motors, which capitalize on the piezoelectric effect to move the small leadscrew, offer resolutions of a few nanometers and they can move a leadscrew from a slow speed of one micrometer per second to as fast as 10 mm/sec, and some models can produce a force as high as five Newtons. You can watch a short video of two squiggle motors that independently move tiny lenses at: www.youtube.com/watch?v=4vFn7nRgQUA.

Within the kit I received, a squiggle motor pushes two small spring-loaded stages to the left or right. The Tracker non-contact position sensor offers half-micron resolution by using a Hall-effect sensor that detects the movement of a string of alternating north/south magnet poles attached to the moving stages. Although the sensor acts much like a linear incremental encoder, it counts pulses internally and communicates with a host controller via an I2C channel. New Scale also offers a development kit for the Tracker sensor alone.

The underlying electronics include a baseboard that communicates with a host PC via a USB port, a daughter card that supplies the squiggle-motor controller ASIC, and a second small board that converts the tracker sensor’s flexible-circuit conductors to header contacts that attaches to the baseboard.

If you have ideas for miniature devices that require motion, a Squiggle motor might do the job. In addition to complete squiggle-motor kits, New Scale also sells two motor types for OEMs and the company can customize motor designs, too. –Jon Titus