Dec 19, 2018

Using three-axis magnetic solution combined with three-axis accelerometer, affected by external force acceleration is very big, in the sports/vibration environment, output direction Angle error is bigger, moreover magnetic sensor has faults, it is the absolute reference lines of magnetic force of the geomagnetic field, geomagnetic is characteristic of wide use range, but strength is low, some tenths of gauss, very vulnerable to the interference of other magnets, if is a blend of Z axis of gyroscope instantaneous Angle, can make the system more stable data.Acceleration measures the direction of gravity. In the case of no external acceleration, the ROLL/PITCH two-axis attitude Angle can be accurately output and there will be no cumulative error at this Angle, which is accurate in a longer time scale.But the disadvantage is that the acceleration sensor Angle acceleration sensor is actually a tiny deformation caused by MEMS technology is used to inspect inertia force, the inertia force and gravity essence is the same, so the accelerometer could not distinguish between acceleration of gravity and acceleration force, when the system variable motion in three-dimensional space, its output is not correct

Gyro output angular velocity, instantaneous flow, angular velocity on the posture balance cannot be used directly, angular velocity and Angle of time integral calculation, get the Angle of the variation and the initial Angle, get the target Angle, the smaller the integration time of Dt, the more accurate the output Angle, but the principle of the gyroscope will determine the measurement of the benchmark is itself, is not absolute reference system, combined with infinitesimal Dt is impossible, so the accumulation of integral error will increase as time goes by quickly, eventually lead to do not tally with the actual output Angle, so gyroscope can only work in a relatively short time scale.

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