Walking motion trajectory of hip powered orthotic device using quintic polynomial equation

In lower limb exoskeleton system walking motion profile generation, cubic polynomial is commonly used to generate smooth walking profile on flexion angle, velocity and acceleration data of three joint movements (ankle, knee and hip joints). However, cubic polynomial does not closely matched human motion. For this reason, a higher-order-polynomial i.e. quintic polynomial is proposed to gene- rate walking motion profile. Error analysis was conducted to measure how closely quintic polynomial could represent human walking motion profile. Result shows that quantic polynomial could closely represent human walking trajectory with maximum RMS error of 0.2607rad occurred during mid-swing phase.