Patent ID: 8482719

Claim:
A positioning system configured to position a movable object having a body, the positioning system comprising: an object position sensor configured to measure a position quantity of the object; an object actuator configured to exert an actuation force on the object; an object controller configured to provide an object actuation signal for the actuator on the basis of a difference between a desired position quantity and the measured position quantity; and a stiffener configured to increase the stiffness and/or to damp a relative movement within the body of the object, the stiffener comprising an optical sensor configured to determine a measurement signal representative of an internal strain or relative displacement in the body, the optical sensor configured to measure a change in distance between two parts of the body, said body being transparent to radiation emitted by the optical sensor to allow said radiation to travel between the two parts, an actuator configured to exert an actuation force on a part of the body, and a controller configured to provide, on the basis of the measurement signal of the sensor, an actuation signal to the actuator to increase the stiffness and/or to damp the movement within the body.