Applications of wearable inertial sensors in estimation of upper limb movements

A new data fusion-based tracking algorithm is proposed, based on two wearable inertial sensors that are placed around the wrist and elbow joints, respectively. Assuming that the lengths of two segments of an upper limb are known, measurements of gyro turning rates can be used to locate the wrist and elbow joints via an established kinematic model. To determine the position of a translated and rotated shoulder joint, an equality-constrained optimisation technique is then proposed to seek an optimal solution, incorporating measurements from the tri-axial accelerometers. Experimental results demonstrate that the algorithm is capable of providing consistent motion tracking of human arms without drifts in 45 s, where each standard deviation is less than half of the corresponding mean value of the Euclidean distance between the estimated joint position and the origin of the world coordinate system.