An augmentative exoskeleton is an externally wearable orthotic device / skeletal structure worn by a healthy individual, especially soldiers, in conjunction with their existing attire / military gear for endurance enhancement and strength augmentation. Although there has been a huge impetus given to the development of augmentative exoskeletons worldwide, there are many technological challenges to be overcome before substantial induction into the military. Some of the major challenges include ergonomics, human-machine interaction, kinematic compatibility, architectural design of structure and mechanisms. The exoskeleton architecture should be conformal to the anatomical joints and move synchronously without impeding the motion during the biomechanical activity.
The primary objective of this work has been to design and develop an exoskeleton to transfer a backpack load carried by an individual to the ground during walking. The aim is to reduce the compressive loads in the spine and lumbo-sacral joints during walking. Such a design will in turn reduce the risk of musculoskeletal injury, increase the payload capacity, and improve the endurance. This talk will focus on the design, development, and evaluation of a load transfer mechanism for an exoskeleton to transfer the backpack load to the ground during walking.
A prerequisite for such a design is to configure an optimal kinematic configuration of the exoskeleton system, which was covered in Seminar 1. A load transfer mechanism was developed and integrated with the optimal kinematic configuration of the exoskeleton structure. Kinematic data of an individual during walking was recorded using a field deployable kinematic measurement system and processed to drive the human model in a musculoskeletal simulation platform. Further, the exoskeleton was integrated with the human model and coupled inverse dynamics were performed to simulate the backpack load transfer through the parallel exoskeleton structure during standing and walking in a musculoskeletal modelling and simulation platform.
Simultaneously a 2D multi-body dynamics analysis was performed in a simulation platform. The output of the simulations were used as boundary conditions to design the structure of the exoskeleton and study the effect of the loads and moments on the human model. Endurance testing through simulation were performed to study the life of individual components. Structural analysis of the various components was completed, and 5 prototypes were realised and evaluated on volunteers in lab and field conditions. Evaluation of the exoskeleton design was performed using an experimental methodology involving motion capture systems, load cells, EMG, and metabolic analyser. Experimental results have shown a significant reduction in erector spinae muscle activation indicating successful load transfer through the exoskeleton to the ground. Comparison of the experimental and simulation results have helped further improve the design.