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- Actuation is started right after the toe-off of a foot on the opposite side, and the peak force occurs 7.12% of gait cycle before toe off, and ends at the toe-off of a foot on the same side.
- This actuation scheme is valid for both loaded gait and unloaded gait.
- This force signal is clear and easy to implement in real world.
- However, the maximum actuation force is about 2500 N, which is too high
Optimal input force for Hip actuator
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Modeling
Simulation result
| Optimal input | Metabolic cost reduction |
|---|---|
 |  |
- Metabolic cost reduction when biarticular actuators are added to loaded gait is 3.12% from baseline. It is much lower than reduction rate of ankle actuator or hip actuator.
- Control input is noisy, which makes it hard to realize
- Biarticular actuator is not as effective as uni-articular actuators in terms of metabolic cost reduction.
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- If we can apply sufficient amount of force, it is better to apply force to ankle joint.
- If not, hip actuator is a good alternative, even though it is hard to control
- Exosuit offers greater assist for loaded walking than unloaded walking
- Optimal input of ankle actuator is consistent with gait cycle and muscle forces data, while that of hip actuator is not.
- The optimal input force for ankle actuator when it’s maximum force is bounded is similar to the general optimal input force saturated at maximum force
- Biarticular actuator doesn’t assist loaded walking very well and the force input is not consistent.
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Limitations
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- The experimental data was obtained from a subject without exosuit. Exosuit may change the kinematics of a subject as well as GRF.
- The simulation methodology to use CMC as an optimization tool works, but more improvement is needed.
- CMC process doesn’t minimize metabolic cost. Instead, it minimizes 2-norm of activation.
- The experimental data is only one gait cycle.
- More realistic actuator simulation is needed. (E.g. Combination of passive & active actuator.
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