thanks SunnySkyguy. but in the case where the DC motor block has been used is not actually controlled but just driving it. although it helped me alot. i want to ask other thing, that why there is been an inertia block is been connected to the dc motor where as it has inertia parameter build-in, in dc motor. and why is the terminator block is been used? one thing more could you help me in finding a block in simulink which could convert angular velocity to electrical signal so that i could use it as feedback for my controller.thanks again for responding.