Based on nine-axis micro-electro-mechanical system（ MEMS） positoning system

analyze and compensate on displacement plane deflect error caused by gyroscope zero-bias. By experiment and formula derivation

quantitative analysis on deviation is firstly given

and establish a mathematic model for error propagation; to estimate deviation

design a new simplified extended Kalman filtering（ SEKF） technology

which has state vector containing gyroscope zero-bias only

overcome the estimation deviation problem without accelerometer

reduce calculations amount

this algorithm can nicely meet the online estimation demand for displacement. By hardware experiment

nine-axis MEMS system can accurately estimate the displacement of cyclical movement in limited range

after bias compensation

the accuracy of magnitude positioning reaches 90 %. The system can be used for unmanned aerial vehicle（ UAV）

robot localization

and other fields.