In addition, the gyroscope offset was continuously recalibrated. This reduces the integration drift that originates from errors in the angular velocity signal. The correction was performed using an inclination estimate continuously obtained using the signal of the 3D accelerometer. The presented orientation estimation algorithm continuously corrected orientation estimates obtained by mathematical integration of the 3D angular velocity measured using the gyroscopes. An IMU containing three single-axis accelerometers and three single-axis micromachined gyroscopes was assembled in a rectangular box, sized 20×20×30 mm. The aim of the paper was to develop and validate a method for accurate measurement of the orientation of human body segments using an inertial measurement unit (IMU). Current methods for ambulatory measurement of body orientation have limited accuracy when the body moves.

In the medical field, there is a need for small ambulatory sensor systems for measuring the kinematics of body segments.