Design and analysis of lower limb exoskeleton with external payload

The lower limb exoskeletons are mainly used in the field of medical assistance for gait rehabilitation and military for maximizing user’s strength and endurance. This work is inspired by the work of “Bionic Boot”, invented by Keahi Seymour that enables to run faster with ostrich back-leg framework. The leg structure of ostrich can store double the elastic energy per step than human, due to their long elastic tendons. The existing Bionic Boot design aids in gaining speed while running without any external payloads. The objective of this work is to design and analyse lower limb exoskeleton that can carry external payload by reducing the consumption of metabolic energy during the motion. The entire mechanical structure of exoskeleton is designed in SolidWorks 3D modeling platform using three materials: aluminium alloy, stainless steel and titanium alloy. Finite element analysis of the design is performed in the same modeling package simulating the human running gait cycle for different phases to examine the stability of the structure. The deformations in aluminium and titanium alloy were larger by 66% and 40% than stainless steel respectively. However, in terms of maximum stress, stainless steel and titanium alloy experienced respectively 3.8% and 1.3% higher compared to aluminium alloy. The design is further analysed for sustainability with a view of minimizing its impact on the environment. The environmental impact parameters indicated that, stainless steel had minimal impact on the environment compared to aluminium and titanium alloy. Thus, these type of exoskeletons can reduce the dependence on the fossil-fuel powered vehicles, thereby reducing environmental pollution.