Iteration Process:

The following segment lists several of the distinguishable features concerning each iteration of the Adaptive Calf-muscle Exoskeleton. Please refer to the Design and Development Video Series tab for a closer look at this project's development process. 

Revision I:

• Carbon fiber stores depleted

• Chaffing in the lower knee and the medial malleolus 

• Clashing between upper-posterior exoskeleton edge and semitendinosus tendon lead to a restricted range of motion - could not bend the knee

• Inadequate fit between peg caps and body - lead to repeated disjointing of spring chambers from foot flexion lever

• Insufficient arch support led to pronation that snapped the foot flexion lever

• Only the spring chambers functioned correctly

• Snapping of foot flexion lever Velcro straps due to insufficient supporting material

• Upper exoskeleton fracture due to insufficient supporting material 

• Velcro strap extrusions are too tight to allow straps to enter freely

Revision II:

• Added extrusion in the upper-posterior exoskeletal shell to improve range of motion - partially successful in improving motion   

• Added reinforcement to foot flexion lever to prevent snapping

• Adopted High-strength, High-temperature fiberglass to reinforce major exoskeleton parts

• Adopted Kevlar to reinforce foot flexion lever

• Improved peg-cover fit enabled exoskeleton use

• Incorporated lips to minimize shifting of spring chambers and degradation of threaded holes

• Increased height of arch support to mitigate foot pronation

• Increased range of motion

• Revision printed out halfway due to user error in 3D printing

• Upper exoskeleton continues to fracture in spite of incremented width and reinforcement with HSHT fiberglass

Revision III:

• Normal-force foot flexion lever snapped by the force-setting-peg interface extrusions after extraneous use 

• Optimal range of motion by increasing size of the posterior extrusion

• Plantar flexion resistance successfully induced 

• Promotes running 

• Velcro straps improved to allow ease of adjustment

Final Revision:

• Normal-force foot flexion lever redesigned to incorporate ergonomic features to reducing chaffing of the medial malleolus

• Occasional shifting of exoskeleton during use - leads to chaffing in the lower knee or posterior lower thigh

• Replacement of defective peg cap - decreased frequency of spring-chamber disjointing

• Shoe-adaptor foot flexion lever constructed - employs replaceable parts in case breakage occurs

• Upper exoskeleton shows incipient signs of fracturing after extraneous use

Conclusions:

In short, the Adaptive Calf-muscle Exoskeleton certainly functions as expected, yet whether such functionality succeeds in achieving its purpose – mitigating microgravity-induced calf muscle loss – remains unclear. Further testing with dynamometers, a stratified experimental design, a more extensive subject pool, and reduced variability by removing the subjectivity of unmediated exercise in the future could certainly establish this project’s efficacy. Nevertheless, in the face of many setbacks such as pandemic restrictions, premature testing termination, and a lack of a proper testing environment, the Adaptive Calf-muscle Exoskeleton succeeded in promoting plantar flexor resistance and surviving repeated use without suffering from significant failures, meeting eight of its eleven executable design criteria. Indubitably, this solution is a small step towards preserving the safety of spaceflight and a giant leap towards countless possibilities in the future of aerospace medicine.   

Note: For more in-depth conclusions and statistical analyses, refer to Statistical Analyses and Conclusions paper at the end of this segment