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Steady state error in a control system is the difference between the desired output and the actual output of the system when it has reached a steady state. It is a measure of the system's performance and can be caused by disturbances, model uncertainty, or limitations in the system's design.
Steady state error is calculated by taking the difference between the desired output and the actual output at the steady state and dividing it by the desired output. This can be expressed as a percentage or a decimal value. For example, if the desired output is 10 and the actual output at steady state is 9, the steady state error would be 10-9=1, and the percentage error would be 1/10=0.1 or 10%.
The types of steady state error are zero steady state error, non-zero steady state error, and steady state oscillations. Zero steady state error occurs when the actual output at steady state is equal to the desired output. Non-zero steady state error occurs when there is a difference between the actual and desired output at steady state. Steady state oscillations occur when the system's output oscillates around the desired output at steady state.
Steady state error can be reduced by improving the system's design, reducing disturbances, and using control techniques such as integral control or feedback control. It is important to analyze the source of the error and make adjustments accordingly to improve the system's performance.
Steady state error does not take into account the transient response of the system and only evaluates the system's performance at steady state. It also assumes that the system is linear and time-invariant, which may not always be the case. Additionally, it does not consider the effects of noise or measurement errors. Therefore, it is important to consider these limitations when using steady state error as a measure of the system's performance.
