MECH 466 - Lecture5-DCMotors-2009W

4 5 2 sec4 negative feedback system negative ea

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: stem Negative Ea Encoder (Sec.4-5-3) (Sec.4- Fact: Ki=Kb. Ki=Kb. 2008/09 Feedback system MECH466 : Automatic Control 9 Ex: Derivation of transfer functions 2008/09 MECH466 : Automatic Control 10 DC motor: Transfer functions (TF) Compute transfer functions from R(s) to Y(s). R(s) Y(s). Ea Ea 2nd order system Ea 2008/09 Ea MECH466 : Automatic Control 11 2008/09 MECH466 : Automatic Control 12 3 Course roadmap DC motor: Transfer functions (cont’d) Modeling Note: In many cases La<<Ra. Then, an approximated TF is obtained by setting La=0. Analysis Laplace transform Transfer function Models for systems • electrical • mechanical • electromechanical 2nd order system 1st order system Linearization Time response • Transient • Steady state Frequency response • Bode plot Stability • Routh-Hurwitz Routh• Nyquist Design Design specs Root locus Frequency domain PID & Lead-lag LeadDesign examples Matlab simulations & laboratories 2008/09 MECH466 : Automatic Control 13 2008/09 What is a linear system? Real systems are inherently nonlinear. (Linear Real systems do not exist!) Ex. f(t)=Kx(t), v(t)=Ri(t) Ex. f(t)=Kx(t), v(t)=Ri(t) TF models are only for linear time-invariant (LTI, TF timesee next slide) systems. Many control analysis/design techniques are Many available for linear systems. Nonlinear systems are difficult to deal with Nonlinear mathematically. Often we linearize nonlinear systems before Often analysis and design. How? System A nonlinear system does not satisfy the principle of superposition. MECH466 : Automatic Control 14 Why linearization? A system having Principle of Superposition system Principle 2008/09 MECH466 : Automatic Control 15 2008/09 MECH466 : Automatic Control 16 4 Time-invariant & time-varying A system is called time-invariant (time-varying) system time(timeif system parameters do not (do) change in time. if Example: Mx’’(t)=f(t) & M(t)...
View Full Document

Ask a homework question - tutors are online