16-05-2012, 12:29 PM
Ch3 Feedback control system characteristics
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Open-loop and closed-loop control systems
Benefits:
Reduce error (eliminating the error)
Reduce sensitivity or Enhance robustness
Disturbance rejection or elimination
Improve dynamic performance or adjust the transient response (such as reduce time constant)
Sensitivity of system to parameter variations
System are time-varying in its nature because of inevitable uncertainties such as changing environment , aging , and other factors that affect a control process.All these uncertainties in open-loop system will result in inaccurate output or low performance. However, a closed-loop system can overcome this disadvantage.
Disturbance in a feedback control system
Disturbance signal is an unwanted extraneous input signal that affects the system’s output signal, such as noise for amplifier,wind gusts for radar antennas,etc.
Feedback control can completely or partially eliminate the effect of disturbance signal.
Summary
Decrease the sensitivity to parameter variation
Improve transient or dynamic performance
Enhance the robustness
Reduce the steady-state error
[attachment=22126]
Open-loop and closed-loop control systems
Benefits:
Reduce error (eliminating the error)
Reduce sensitivity or Enhance robustness
Disturbance rejection or elimination
Improve dynamic performance or adjust the transient response (such as reduce time constant)
Sensitivity of system to parameter variations
System are time-varying in its nature because of inevitable uncertainties such as changing environment , aging , and other factors that affect a control process.All these uncertainties in open-loop system will result in inaccurate output or low performance. However, a closed-loop system can overcome this disadvantage.
Disturbance in a feedback control system
Disturbance signal is an unwanted extraneous input signal that affects the system’s output signal, such as noise for amplifier,wind gusts for radar antennas,etc.
Feedback control can completely or partially eliminate the effect of disturbance signal.
Summary
Decrease the sensitivity to parameter variation
Improve transient or dynamic performance
Enhance the robustness
Reduce the steady-state error