What is negative feedback?  Basically in this type, the feedback signal is subtracted from the input signal in the controller. And this is the most widely used type, because of its accuracy and control in the process. Also negative feedback, which tries to reduce error by bringing input and output closer together

What is positive feedback?  Basically in this type, a feedback signal is added with the input signal in the controller. And it has less control over error.

Control System Control System Questions and Answers Q. What is the tuning of controllers? Tuning basically involves proportional adjustment. Integral and derivative parameters to get better control. The gain, time constant and dead times around the loop will determine the settings of various parameters of the controller. Q. What is the proportional control only? Proportional control attempts to return the measurement to the set point after the load is upset. It is however impossible for a standard controller to return measurements to a fixed point. You may also like this:   Control System Simulation Q. What is the use of proportional control only? It is commonly used for level control. It reduces the effect of load change but cannot eliminate it. Q. What is proportional plus reset control? A reset action is initiated to remove the offset. It will integrate the difference between the measurement and the set point and change the output of the controller until the difference between the m

 Control System Simulation The simulation of instrumentation control systems includes measuring or detecting devices, the controllers, and the actuating or manipulating output elements. Most measuring devices may be simulated by one or more simple lags for dynamic representation, with added nonlinearities for device characteristics, sensitivity, or operating point modeling. For special functions, such as logarithmic input–output relationships (such as pH measurements), the general-purpose function-generating units may be used or the functions generated by implicit techniques.  the measuring device puts out a discontinuous (pulse-type) signal, signal-generating circuits may be used, as discussed later in this section.