Toward A Method for Scaling Human Body Models in an IMU-Based Workflow

- Scaled biomechanical models can more accurately inform crew health decisions when tailored to the wide range of astronaut sizes.
One component to improve scaling of existing models to better represent each unique astronaut’s size is the individual length scaling
of limbs. Traditionally, limb lengths are determined by motion capture or manual measurement.
- A new method is herein proposed for length scaling which can be done by measuring linear and angular accelerations at a desired
point during isolated motion around a point of rotation, then calculating the distance between the desired point and point of rotation.
- When an Inertial Measurement Unit (IMU) device is placed at the distal point of a limb, the isolated motion is about that limb’s
proximal joint. This method of scaling limb segments can be used for any limb that has an easily defined proximal joint for the limb to
rotate around including hands, arms, legs, feet.
- Calculated limb lengths are then used to scale models to each unique astronaut’s size, thereby improving the applicability of the
model.
- This method was investigated as a possible away to obtain scaling information in data collections where IMUs are worn, but optical
motion capture may not always be available, such as inside spacesuits or during crew exercise on the International Space Station.