Principles of Control Systems

Open loop and closed loop systems, Servomechanism, Basic structure of a feedback control system.Dynamic Models and ResponsesDynamic model of an RLC network, State variable model, Impulse response model, Transfer function model, Standard test/disturbance signals and their models, Transfer function model and dynamic response of a second order electrical system.Control System ComponentsBasic units of feedback control system, Reduction of system block diagrams, Signal flow graph, Mason's gain rule, Block diagram reduction using Mason's gain rule, Operational amplifier used as an error detector, Servo potentiometer, DC and AC servomotors, Tachogenerator, Stepper motor, Synchros, Block diagram model of a typical control system using simplified sub-system, Transfer function blocks.Feedback Control System Characteristics Stability, Sensitivity, Disturbance rejection, Steady state accuracy, Transient and steady state responses of a second order system, Effect of additional zeros and poles, Desired closed loop pole locations and dominant poles, Steady state error constants, System type numbers and error compensation.System Stability Analysis and Compensator DesignSystem stability bounds, Routh stability criterion, Relative stability and range of stability, Root locus concept, System characteristic equation, Plotting root loci, Design of cascade lag-lead compensation, Minor loop (rate) feedback compensation.Nyquist Criterion and Stability MarginsNyquist stability criterions, Nyquist plot, Gain and phase margins, Bode plot of magnitude and phase and determination of stability margins.Feedback System PerformancePerformance specifications in frequency domain, Correlation between frequency domain and time domain specifications, Constant - M circles, Nichols chart, Stability margins from sensitivity function. Design of cascade lag-lead compensation using Bode plot. Minor loop (rate) feedback compensation.