hello sir my aim is to show and study the different controller. i make a physical model of a robot arm using a dc servomotor gear trains and for arm connect a strip of iron (i make it second order system).i want to control it position through p, pi ,pid controllers through making a program on computer in c.for interfacing pc to physical model i use AD-DA convertor.i am using position as a feed back.now problem is "coding" .if any one have an idea or any sugust plz help me. or if i plot the graph between position and time how i get it transfer function. thanking u. a student manoj

-- manoj (manoj_dun@yahoo.com), November 06, 2004