ℋ2 synthesis for active vibration isolation

Vibration isolation is used routinely to reduce unwanted transmission of force or motion from one mechanical subsystem to another. However, in some applications, passive isolation is not sufficient. Active isolation improves performance, but requires actuators, sensors, and control. Although active control of isolation systems is application specific, compensator design is fundamental for given sensor/actuator configurations. State space modelling of simple plants with sensor and performance outputs and disturbance and control inputs is presented. Linear quadratic Gaussian (LQG) control is applied as a compensator design tool to meet the common ℋ₂ performance requirements. Frequency weighting is explored as a method of shaping the desired transmissibility. Finally, several experimental active isolation systems are used to highlight the common real world limits to control