Pulse width modulated servo valve enabled by single crystal piezoelectric

Active Signal Technologies and Moog propose to demonstrate a solid state pulse width modulated pilot stage for a servo valve enabled by single crystal PMN-PT. The basic mechanism and labor intensive fabrication processes used to build conventional servo valves remain largely unchanged since the device was launched in 1951, resulting in high cost and limited bandwidth. A digitally controlled valve has been long sought but has not materialized because of the limitations of available drivers -- low frequency capability of magnetic torque motors and solenoids, and stroke limitations of "high strain" solid state materials such as Terfenol and PMN. However, the advent of single crystal PMN-PT with over 2 times the strain of conventional solid state materials and low hysteresis can supply the 10X bandwidth improvement needed to realize a truly digital valve. The new servo valve will not only be smaller and low cost, but will be more readily integrated with digital control, especially for adaptive structural control using distributed actuation. In Phase I we will build a working pilot stage valve and demonstrate its switching speed capability, and in Phase II we will develop a fully integrated high speed servo valve using this technology.