Nearly 1,50 0 total run s on different m echani sms were cond ucted over a  six month pe riod of time. Havin g  a softwa re tool that collected, an alyze d, and  display ed d ata real time mad e it practi cal to  change one  variable at a time in orde r to clea rly und ersta nd ho w that variable a ffected the mech anism. It also ma de it  easy to coll ect a numb er of sample s and verify that the results were co nsistent and not a prod uct of a   transi ent phe nomen on.   

Early testing reveale d a sharp vel ocity disturban ce at an input fre quen cy of 40  kHz, which was qui ckly  dismi ssed as electri cal noise in th e data acquisition due to the  sinusoidal volta ge used to excite the piezo  element s. After furthe r test ing and u nsuccessful atte mpts to elimi nate the erro r with elect rical shiel ding it  was reveale d that the di sturbance i s actually me chanical vibration an d not simply ele ctrical noi se. Thi s  vibration can be filtere d mechanically u sing springs in the cube corne r mounts but careful  consi deration   must be give n to this input when de aling with mecha nisms that are sen sitive to disturb ances over su ch a  wide fre quency rang e. 

Conclu sions  

A new lin ear transl ation mech anism h as been d evelope d that will allo w the  PAOS instru ment to offer   improve d performan ce and lower ma ss co mpared to existing  spaceborne spectromete rs. The low mass  (< 1 kg) of this me chanism is a direct  result of  the enablin g technolo gy rep resented by the ultra sonic  piezo motor. These motors provid e a new alte rnative for linear space me chanisms and of fer smo oth,  precise moti on, inhe rent redu ndancy, low m ass, a nd simplified  integration. The kinem atic Vespel rail   system p rovides a solutio n that is fault tolerant an d insensitive to stru ctural misalignme nts due to thermal   distortio n or manufa cturing tolera nces.  The de sign can easily be  adapte d to provide any stroke le ngth  over a  wide range of velocitie s. Initial  testing  sho ws consistent velocity e rror of le ss th an 0.7%  in a  mech anism that requi res no wet lubri cation and i s small enou gh to hold in a si ngle hand.  

Ackn owledgements 

We acknowledge fundi ng from the NASA Planetary Instru ment Design and Defi nition Program. Part of  this rese arch was pe rformed at the Jet Pro pulsion Lab orato ry unde r contract with NASA. We also   ackno wledge the exten sive assistance provided  by Nanomotio n Ltd. in the eval uation and implementatio n  of the piezo motors and d rives. 

Referen ces 

Kara sikov, Dr. Nir (2000 ). A Novel No n-Ma gneti c Miniature Mo tor for Ultra High Va cuum Applications ,  pape r for Nan omotion Ltd. 

Persky, M.J. A Re view of Space borne Infrared F ourier Transform  Spectrom eters fo r Rem ote Sen sing,  presented at The Ameri can Institute of Physics, Octo ber 19 95.   Roberts , E.W., et al. Development of Long-Li fe, Low-Noi se Linea r Bearin gs for Atm osphe ric  Interferom etry, pape r presented at the 3 4th Aero space Mecha nisms Symposium on May18 -20, 1994.  Toon, Dr. G .C., et al (2 001). Planetary Atm osphere Occultati on Spe ctrometer: A Mini ature High  Resolutio n Fourie r Tran sform  Infrared Spectrom eter, propo sal for Jet Prop ulsion Labo ratory. 

Burger, F., Eder, J. High Precision Point ing Devi ce for the LASCO instrum ent o n SOHO , paper presented  at the 6th Europea n Space  Mecha nisms & Tribology Symposium o n Octob er 4-6, 1995. 

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