US 2008077258 A1 abstract a twisted wire actuator whereby the shortening of the length of a wire or a bundle of wires as it is twisted is used to control the motion of an actuated element achieving sub micron motion resolution the control can be performed robotically the high resolution can be achieved without the use of gears sliders or high precision lead screws thus enabling a simplified actuation system and eliminating sources of friction the use of wires operating in opposing directions and having oppositely directed rotations significantly reduces the non linearity effect inherent in twisted wire actuation resulting in a system having a good level of motion linearity as a function of control input impulse the use of multiple twisted wires attached to the actuated element at different angles enables the implementation of robotic systems with multiple degrees of freedom several experimental actuators verify these results application_number US 59553004 A description reference is now made to fig1 which illustrates schematically how a wire made of any number of strands 10 12 shortens in length as it is twisted the actual shortening length is now calculated for a wire with two strands as shown in fig1 where the unshortened length is marked l and the shortened length for a specific twist angle is marked s u2032 the calculation method shown below is however also.