Assessing transferred energy in drone impacts using rigid impactor tests

Area of Science:

• Biomechanics and Accident Reconstruction
• Robotics and Unmanned Systems Safety

Background:

• Unmanned aerial systems (UAS) are rapidly advancing, increasing the need to understand collision safety.
• Assessing health consequences of drone-human impacts requires robust testing methodologies.

Purpose of the Study:

• To determine anthropomorphic test device (ATD) response to vertical head impacts from unmanned aerial systems (UAS).
• To generate a validated dataset for comparing UAS impacts with rigid impactor tests.
• To analyze energy transfer dynamics across a range of impact kinetic energies (KE).

Main Methods:

• Conducted 30 tests using an ATD with a rigid impactor, varying kinetic energy from 5 to 180 J.
• Assumed most impact kinetic energy was absorbed by the ATD head for scalable analysis.
• Compared ATD test results with actual UAS impact data, focusing on vertical, top-of-head impacts.

Main Results:

• Transferred energy to the ATD decreased as UAS impact kinetic energy increased, deviating from linear trends seen with rigid impactors.
• Deformation of UAS structures, like the DJI Phantom, significantly reduced energy transmission to the head.
• Biomechanical criteria (Peak Head Acceleration, Head Injury Criterion 15ms [HIC15], Neck Injury Criterion [Nij]) confirmed reduced energy transfer.
• HIC15 demonstrated a more accurate relationship with KE than peak head acceleration when critical impact speeds are unattainable.

Conclusions:

• Current UAS safety criteria based on linear energy transfer assumptions may overestimate injury risks due to UAS deformability.
• The study provides a validated dataset for vertical, top-of-head impacts, crucial for refining safety standards.
• HIC15 is a potentially more reliable metric than peak head acceleration for assessing injury risk in limited testing scenarios.