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OpenSim Documentation > Modeling, Evaluation, and Control Optimization of Exosuit with OpenSim > DARPA.png

There has a been a lot of research into exoskeletons over the years to alleviate heavy loads that soldiers should burden, but strapping a person into a robotic outfit just isn't practical in a combat zone yet.
DARPA's Warrior Web program aims to build a lightweight suit that improves a soldier's endurance and overall effectiveness, while preventing injuries.
The main goals by developing the warrior web are

1. To prevent and reduce musculoskeletal injuries.
2. To augment positive work done by the muscles and reduce the physical burden

Harvard Exosuit

In order to develop an under-suit that doesn’t interrupt wearer’s free movement, researchers are trying to make it soft and deformable, but still capable of applying force to body joints.
Harvard Biodesign group, one of a project groups in this program, is trying to make their warrior web suit soft and light, and they call their suit harvard exosuit.
Experimental data proved that it can help loaded walking by reducing metabolic costs.

it is difficult to analyze the effectivness of exosuit

It is difficult to find the optimal input force for actuators to reduce the metabolic cost

It is difficult to identify the effect of change of design parameters

The main reason

It is difficult to analyze the effectiveness of the exosuit. The under-suit may be soft and deformable

Hard to identify how external actuation assists loaded gait.

Experimental metabolic cost data is inconsistent

OpenSim Documentation > Modeling, Evaluation, and Control Optimization of Exosuit with OpenSim > LoadedModelSample.png

Cost function of optimization process in CMC (Slow target)

J = \sum_{i=1}^{n_x} x_i^2 + \sum_{j=1}^{n_q} w_j \left( \ddot{q}_j\,^* - \ddot{q}_j \right)^2

When there is active actuators on OpenSim Model, the activation term in cost function becomes

x = \begin{bmatrix} x_{muscle} \\ x_{actuator} \end{bmatrix}

F_{actuator} = F_{actuator}^{max} \times x_{actuator}

Assign large value of maximum force to each actuator to reduce the size of xactuator, so that the influence of actuator to J is diminished.