A positioning system to position a movable object having a body, the positioning system includes an object position measurement system, an object actuator, and an object controller, wherein the positioning system further includes a stiffener to increase the stiffness and/or to damp relative movements within the body of the object, the stiffener including; one or more sensors, wherein each sensor is arranged to determine a measurement signal representative of an internal strain or relative displacement in the body, one or more actuators, wherein each actuator is arranged to exert an actuation force on a part of the body, and at least one controller, configured to provide on the basis of the measurement signal of at least one of the sensors, an actuation signal to at least one of the actuators to increase the stiffness and/or to damp movements within the body.