Complementary Observer for Body Segments Motion Capturing by Inertial and Magnetic Sensors

TLDR

The authors propose a quaternion‑based complementary observer for rigid‑body attitude estimation as an alternative to the extended Kalman filter. The observer processes data from a compact inertial/magnetic sensor module using a two‑layer filter that applies Levenberg‑Marquardt preprocessing of acceleration and magnetic measurements, then fuses these outputs with angular rates for attitude estimation, and is evaluated on an industrial robot and a commercial IMU during human segment motion. Experimental results show the observer’s design is greatly simplified and its performance is promising for human motion applications, particularly ambulatory monitoring.

Abstract

This paper presents a viable quaternion-based complementary observer (CO) that is designed for rigid body attitude estimation. We claim that this approach is an alternative one to overcome the limitations of the extended Kalman filter. The CO processes data from a small inertial/magnetic sensor module containing triaxial angular rate sensors, accelerometers, and magnetometers, without resorting to GPS data. The proposed algorithm incorporates a motion kinematic model and adopts a two-layer filter architecture. In the latter, the Levenberg Marquardt algorithm preprocesses acceleration and local magnetic field measurements, to produce what will be called the system's output. The system's output together with the angular rate measurements will become measurement signals for the CO. In this way, the overall CO design is greatly simplified. The efficiency of the CO is experimentally investigated through an industrial robot and a commercial IMU during human segment motion exercises. These results are promising for human motion applications, in particular future ambulatory monitoring.