AnAutomatic Digital Recorder forTiming Sequential Events
Stanley M. BLOCKt · 1959
L IVESthere aresearcher withsoul sodead, whonever ILtohimself hassaid, There ought tobeaneasier waytocollect andanalyze data? Outofthenecessity ofendless hoursoffilmandstrip-chart analysis, SEMTAR wasconceived asautomation's gift tothetired researcher. SEMTAR automatically records time-interval dataina form(punched-tape) which canserveasinput toavariety ofcommercially-available translating andcomputing equipment. SEMTAR istheabbreviated namefor Sequential Electronic Motion TimerandRecorder. Specifically, SEMTAR wasinvented bythewriter for motion-study research, wherethetimetaken bysubjects to perform eachofaseries ofmotion-elements inrepetitive workcycles undervariable isofgreat interest. Inorder todrawstatistically-va lid conclusions, theresearcher mustaccumulate andanalyze large samples of datatodistinguish variations inperformance timecaused byvariables underinvestigation, fromtimevariations caused bydifferences inskill, practice, effort, chance, etc. Noneoftheother knowntechniques available formotiontimeresearch permit accurate recording andidentification ofsequential, relatively short (less thanonesecond) time intervals inmachine language (that is, a formsuchas punched tapewhichcanbeautomatically readbymachines fortranslation orcomputation). Thispaper ispresented inthehopethat there areareas Fig. 1-SEMTARrecording hand-motion research. ofmedical andbiological research, unknown tothewriter, inwhichSEMTAR canbeofgreat value inautomatically input (sensing) units, electronic switches, two identifying andrecording timeintervals associated with(oscillator), ic unte s,election swices, two events ofsignificance totheresearcher. Withproper inputpairs ofelectronic counters, Identification devices acontransducers, itwouldbepossible tosetcertain maximumtrol unit, coding andamplifying units, andapaper-tape desirable conditions (such astemperature, pressure, force,punch. (SeeFlg. 2.) etc.) andautomatically torecord eachtime this maximum'SEMTAR2 eliminates observer errorandtediumby isexceeded andhowlongitisexceeded. Onecould alsosensing andinterpreting theclosing andopening of useSEMTAR very readily torecord thereaction timebe- appropriate transducers, suchasbridge circuits, phototween astimulus andoneormoreresponsesa electric cells, microswitches, strain gages, etc. Thepresent SEMTARs ispresently asemi-portable unit, mountedmodelcanaccommodate uptofive pairs oftransducers. SEMTR i