What is meant by feedback and feed forward control?

I think you are talking about positive and negative feedback in a servo. The servo is trying it's best to keep speed where it has been set at by the technician. Perfect speed is impossible so when it leads then negative feedback is automatically ordered by the resolver. When it lags the the resolver orders positive feedback. The motor and resolver are mechanically linked together so the feedback is almost instantanious.What is meant by feedback and feed forward control?
Feed-forward is a term describing an element or pathway within a control system which passes a controlling signal from a source in the control system's external environment, often a command signal from an external operator, to a load elsewhere in its external environment. A control system which has only feed-forward behavior responds to its control signal in a pre-defined way without responding to how the load reacts; it is in contrast with a system that also has feedback, which adjusts the output to take account of how it affects the load, and how the load itself may vary unpredictably; the load is considered to belong to the external environment of the system.





Some prerequisites are needed for control scheme to be reliable by pure feed-forward without feedback: the external command or controlling signal must be available, and the effect of the output of the system on the load should be known (that usually means that the load must be predictably unchanging with time). Sometimes pure feed-forward control without feedback is called 'ballistic', because once a control signal has been sent, it cannot be further adjusted; any corrective adjustment must be by way of a new control signal. In contrast 'cruise control' adjusts the output in response to the load that it encounters, by a feedback mechanism.





These systems could be in control theory, physiology or computing.