Active tuned vibration absorber

An active tuned vibration absorber for reducing vibrations in a structure, the vibration absorber comprising:

• a mount for attachment to the structure;
• a moveable mass;
• a spring arrangement connected between the mass and the mount;
• an actuator arrangement for applying a force between the mass and the mount;
• a force sensor attached to or proximate the mount for outputting a measurement indicative of a force exerted between the structure and the mount;
• and
• a control system for generating a drive signal for the actuator arrangement using the measurement, the actuator drive signal being generated to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device such that the active tuned vibration absorber dissipates energy transferred from the structure,
• wherein only one of the spring arrangement and actuator arrangement is directly connected between the mass and the mount via the first sensor, and
• wherein, in isolation from the actuator arrangement and control system, the moveable mass and the spring arrangement form a first resonant system having a first Q factor and, when controlled by and combined with the actuator arrangement and control system, the moveable mass and the spring arrangement form a second resonant system with a second Q factor, and wherein the second Q factor is larger than the first Q factor.

A method of reducing vibrations in a structure, comprising:

• providing a mount for attachment to the structure;
• providing a moveable mass;
• providing a spring arrangement connected between the mass and the mount;
• providing an actuator arrangement for applying a force between the mass and the mount;
• providing a first sensor for providing a first measurement indicative of a force exerted between the structure and the mount;
• providing a second sensor for providing a second measurement indicative of an acceleration of the structure at or proximate to the mount;
• and
• providing a control system for generating an actuator driving signal for driving the actuator using the first and second measurement,
• wherein only one of the spring arrangement and actuator arrangement is directly connected between the mass and the mount via the first sensor, and
• wherein the control system is operable to generate the actuator driving signal to cause the first measurement and second measurement to conform to a target relationship such that the active tuned vibration absorber dissipates energy transferred from the structure, and
• wherein, in isolation from the actuator arrangement and control system, the moveable mass and the spring arrangement form a first resonant system having a first Q factor and, when controlled by and combined with the actuator arrangement and control system, the moveable mass and the spring arrangement form a second resonant system with a second Q factor, and wherein the second factor is larger than the first Q factor.