Compliance Mechanics Design of Lower Extremities Exoskeleton

Phang, Xiao Qi (2020) Compliance Mechanics Design of Lower Extremities Exoskeleton. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Mechanically, exoskeleton refers to electromechanical devices that can be wear by human and it supposed to assist the physical performance of wearer. Improved load carrying capacity, able to run at faster speeds or longer distances and lower metabolic outflow are considered as increasing the physical performance. There are many lower extremities exoskeleton in the market which are designed with electrical controller. Some current designs with electrical controllers are not waterproof and not able to fulfil whole day usage without the replacement of power source. Other than that, current designs only able to support weight of 10 to 15kg. The objective of this study is to help patients or other individuals that suffers from injuries on their lower body to recover or provide support to wearer that requires to handle heavy objects during daily life or during work by increasing the supporting weight to the range of 20 to 25kg while electrical controllers are not needed. Wearer could be elders that have weak knees or workers that need to squat and stand up to carry heavy load. In this report, Finite Element Analysis was used to create a new design and carry out relative simulations. The new design will be remodel based on ideas come from some of existing lower extremities exoskeleton that are available on market and some examples of compliance mechanics such as Iris. FEA analysis will be used to analyse the maximum weight that can be supported by this lower extremity exoskeleton. 3D model of lower extremities exoskeleton was drawn in SolidWorks. Based on the simulation, the simulation starts to fail when the members of internal spring have very high stress at its tips and bottom which leads to extremely high stress in the whole simulation. When it is rigid body simulation, every point on that body will have the same angular velocity. As the internal spring rotate, the rigid body motion caused the strain to have value even though the internal spring have not touched the casing.