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Abstract

Evaluating sports bra comfort in an objective manner is challenging because it is difficult to reproduce experiments consistently with human subjects. Using a mannequin with ap propriate breast prostheses and a motion simulator can overcome this limitation. However, commercially available motion simulators are not optimized for reproducing the specific combination of range of movement, speed and high acceleration observed during athletic activity. Achieving this requires a purpose-built motion simulation platform with the right combination of travel range, speed, and dynamic performance. A Stewart’s platform motion simulator is particularly well suited for this task. To meet the specific demands of torso motion simulation, a custom six-degree-of-freedom (6-DOF), rotary-actuated Stewart’s platform was designed. A parametric torso motion trajectory was synthesized from motion capture and inertial measurement unit (IMU) data collected in collaboration with Lululemon and the Human Motion Biomechanics Lab (HuMBL). The system was optimized from the ground up to replicate the most demanding portions of this trajectory using impedance matching in the design phase, and the control system was tuned for maximum dynamic performance. The resulting platform enables repeatable reproduction of high intensity torso motion and provides a cost-effective, high performance solution for objective comfort testing of sports bras.