I need to track head orientation in a moving vehicle (car,plane, etc). Obviously, vehicle motion will affect the MEMS IMU. Theoretically, one could use two MEMS IMUs to isolate the head movement from the vehicle motion effects. Other than the research community, has anyone successfully implemented this using MEMS IMUs? (I realize this problem is solved for jet fighters like the F-35, using very advanced, precise, and expensive subsystems). What challenges am I likely to face? MEMS IMUs are attractive for their size and price.