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  2. Active disturbance rejection control - Wikipedia

    en.wikipedia.org/wiki/Active_Disturbance...

    This disturbance rejection feature allows users to treat the considered system with a simpler model insofar as the negative effects of modeling uncertainty are compensated in real time. As a result, the operator does not need a precise analytical description of the base system; one can model the unknown parts of the dynamics as internal ...

  3. Proportional–integral–derivative controller - Wikipedia

    en.wikipedia.org/wiki/Proportional–integral...

    His goal was stability, not general control, which simplified the problem significantly. While proportional control provided stability against small disturbances, it was insufficient for dealing with a steady disturbance, notably a stiff gale (due to steady-state error), which required adding the integral term. Finally, the derivative term was ...

  4. Direct stiffness method - Wikipedia

    en.wikipedia.org/wiki/Direct_stiffness_method

    The structure’s unknown displacements and forces can then be determined by solving this equation. The direct stiffness method forms the basis for most commercial and free source finite element software. The direct stiffness method originated in the field of aerospace. Researchers looked at various approaches for analysis of complex airplane ...

  5. Error vector magnitude - Wikipedia

    en.wikipedia.org/wiki/Error_Vector_Magnitude

    The degradation in dynamic EVM is due to the PA transient response affecting the preamble at the start of the packet and causing an imperfect channel estimate. Studies have shown that dynamic EVM with a 50% duty cycle square wave applied to PA Enable to be worse than the static EVM (PA Enable with 100% duty cycle).

  6. Stability derivatives - Wikipedia

    en.wikipedia.org/wiki/Stability_derivatives

    The stiffness does not only depend on the static stability term , it also contains a term which effectively determines the angle of attack due to the body rotation. The distance of the center of lift, including this term, ahead of the centre of gravity is called the maneuver margin .

  7. Structural engineering theory - Wikipedia

    en.wikipedia.org/wiki/Structural_engineering_theory

    Stiffness depends upon material properties and geometry. The stiffness of a structural element of a given material is the product of the material's Young's modulus and the element's second moment of area. Stiffness is measured in force per unit length (newtons per millimetre or N/mm), and is equivalent to the 'force constant' in Hooke's Law.

  8. Stiff equation - Wikipedia

    en.wikipedia.org/wiki/Stiff_equation

    These are all examples of a class of problems called stiff (mathematical stiffness) systems of differential equations, due to their application in analyzing the motion of spring and mass systems having large spring constants (physical stiffness). [5] For example, the initial value problem

  9. Guyan reduction - Wikipedia

    en.wikipedia.org/wiki/Guyan_reduction

    In computational mechanics, Guyan reduction, [1] also known as static condensation, is a dimensionality reduction method which reduces the number of degrees of freedom by ignoring the inertial terms of the equilibrium equations and expressing the unloaded degrees of freedom in terms of the loaded degrees of freedom.