Utilising the rotational motion of machinery in a high resolution data acquisition system

Acqui r ing diver se sensor y infor mat ion fr om any machiner y, such tha t da ta fr om di ffer ent sensor s i s synchr oni sed wi th each other as wel l as wi th the ins tant angular pos i t ion of the machiner y i s a t ask fr aught wi th sever a l l ayer s of compl ica t ion. Thi s paper d i scusses the da ta acqui s i t ion se t up for a h igh speed diese l engine . Cyl inder pr essur es , vibr a t ion and acous t i c emiss ion ar e sensed fr om one cyl inder head and digi t i sed by two analogue to d igi t a l (AtoD) conver ter s , one low speed and another h igh speed. The low speed AtoD conver ter which dea l s wi th the pr essur e and vibr a t ion s ignal s i s dr iven by an exter na l clocking s ignal in the for m of t r ans i s tor to t r ans i s tor logic (TTL) pul ses fr om an opt i ca l shaft encoder which has a ver y h igh cr ank angular r esolut ion. The high speed car d uses i t s own in ter na l clock to d igi t i se the h igh fr equency acous t i c emiss ion s ignal s as wel l as the bot tom dead cent r e (BDC) infor mat ion fr om the engine . The digi t i sed s ignal s a r e then s tor ed on the har d d i sk space of a PC. It i s shown how such a sys tem can be used to success ful ly col l ect vas t amounts of da ta r epr esenta t ive of the ent i r e engine oper a t ion mat r ix . It i s a l so shown how the same da ta could be vi sua l i sed on a computer to pr ovide r ea l t ime moni tor ing of the engine oper a t ion.