Real time measurements of drill bit attitude while drilling are the key factors for guiding of horizontal directional drilling.Aiming at shortcomings of existing algorithms

a new method is introduced to measure inclination

azimuth

and tool face angle using gyroscope.Through quaternion-based all attitude complementary filter algorithm

accelerometers and magnetometers are used to compensate for the measurement error due to the drift of the gyroscope output over time.The detailed theoretical analysis and calculation process are presented.The results show that quaternion-based all attitude complementary filter algorithm based on sensor combination can effectively eliminate gyroscope drift error

and obtained azimuth measurement precision is better than ±0.3°.