Development of crossover-free fiber optic gyroscope sensor coils

The DoD goals for inertial sensors have included achieving high accuracy performance and small size at a low cost. This goal has always been a challenging endeavor, since small size and high accuracy have often been costly and technically difficult to achieve. In 1998, the Army patented a fiber sensor coil winding concept that would facilitate the opportunity to make the Fiber Optic Gyroscope (FOG) more competitive in cost with relation to the commonly-used Ring Laser Gyro (RLG). Recent advances in FOG sensor coil winding techniques appear to show great promise in the improved performance. The novel Crossover-Free (CF) winding technique eliminates fiber crossovers and allows the use of inexpensive single-mode fiber (SMF). Experiments were conducted with the use of an analog, open-loop testbed, which was characterized with a 1 km quadrupolar SM sensor coil. Various sensor coil configurations were spliced into the FOG testbed and bias drift tests were conducted. Different fiber lengths, coil diameters, and fiber wind configurations were evaluated. The Crossover-Free sensor coils were precision wound by a semi-automated Fiber Placement Machine (FPM) developed by Stanley Associates. The Crossover-Free sensor coils test results are compared to standard precision wound coils. The bias errors caused by the fiber crossovers in standard SM sensor coils are also discussed and compared to the near elimination of the crossovers in the CF design.