Base-excited oscillator
= Base-excited oscillator
A <base-excited oscillator> has a moving support rather than a directly applied periodic <force>. If its <damping> depends on velocity relative to the support, $z=x-y$ obeys $m\ddot z+b\dot z+kz=-m\ddot y$. A model with damping against absolute velocity instead obeys $m\ddot x+b\dot x+kx=ky$ after subtracting its static equilibrium. These conventions give different <transfer functions>.