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I compared the saturated optimal input to a new CMC results which was acquired with after assigning 4000N to maximum actuation force and bounded bounding control input between 0 and .1. The
In other word, 

 

According to the formula, the new CMC results also has maximum force of 400N
as the control input is bounded
, and it gives better
input force
result in terms of metabolic cost reduction than a result of CMC which was acquired with an actuator with 400N actuation and conventional control input.

 

 

In these graphs, you You can see a similaritly similarity between the saturated optimal input and a results of new CMC procedure.

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Loaded walkingUnloaded walking
•Loaded walking•MC Reduction(from baseline)
1.optimal: 10.35% reduction
2.ScaledSaturated: 1.34% 84% reduction
3.SaturatedNew CMC: 12.84% 68% reduction
•Unloaded walking•MC Reduction(from baseline)
1.optimal: 10.62% reduction
2.ScaledSaturated: 3.02% 46% reduction
3.SaturatedNew CMC: 3.46% reduction82%
•Saturated input is better than scaled input for MC reduction.
•Realistic force input can help unloaded walking better than loaded walking.

Discussion

 

•The input force resulted from new CMC works best for metabolic cost reduction
•New CMC result gives a force profile similar to saturated input force.
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If we take a look at what happens to metabolic cost, we can see that the result from new CMC procedure reduces metabolic cost more efficiently. However, the reduction is not significant, and it is much lower than the optimal case. The interesting thing is that the realistic actuation input force works better in unloaded walking case than loaded walking case. It makes sense because we requires lower force to assist unloaded walking.ModelBiarticular actuator

Now that we know both ankle actuator hip actuator works well to reduce metabolic cost during loaded walking, the natural progress is to create biarticular actuator which can affect both ankle plantar flexion and hip extension. In order to reduce the number of actuator, I created biarticular actuator with 1 DOF, and see how much it reduces metabolic cost, and what it’s optimal input force is.

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