Figure 6.

Gyro Integration-Based Orientation Filter (GIOF). $a_{i_k}$ ($i=x,y,z)$ is the acceleration of $i$ axis measured at time stamp k; $g_{k_z}$ and $g_{{\left(k-1\right)}_z}$ are gyroscope $z$ axis reading measured at time stamps k and (k − 1); $t_k$ and $t_{k-1}$ are the time values of time stamps k; and (k − 1); ${\theta }_{k-1}$ is the previous estimation of thigh angle and ${\theta }_k$ is the current estimation of thigh angle.