Virginia Research Day 2021

Undergraduate Student Research Biomedical

01 Proposed Injury Threshold for Drone Blade Skin Lacerations

Lauren A. Duma; Mark T. Begonia; Barry Miller; Stefan M. Duma Corresponding author: lauren@duma.us

Virginia Tech – Institute for Critical Technology and Applied Science

As the use of drones becomes increasingly popular and more widespread, the number of drone related injuries has the potential to increase. Drone accidents have caused a variety of injuries, including head injuries with loss of consciousness (LOC), open globe eye lacerations, and skin lacerations. The objective of this study was to determine the different properties of various drone propellers that cause laceration injuries, and to propose an injury threshold that can be used to reduce the risk of skin lacerations. A total of seventeen experiments were performed using nine different drones. For each drone, the blade tip thickness, blade length, and angular velocity (rpm) were recorded. A laser tachometer was used to measure the angular velocity. Blade tip velocity was calculated using the angular velocity and blade length. Each experiment had full contact with the blade at speed into the skin surrogate, second trimester fetal bovine skin. This skin surrogate was used due to its ability to accurately model drone blade laceration injuries in human skin. The observed injury caused by the drone was then assigned a level of injury severity: 0 for no injury, 1 for a minor abrasion, and 2 for a minor laceration. Minor abrasions were only observed at blade tip speeds higher than 80 ft/s, and minor lacerations were only observed at blade tip speeds higher than

200 ft/s. For example, the Air Car A380 caused a minor laceration when the drone blades at 313.1 ft/s came into contact with the fetal bovine skin (Figure 1). Overall, injury severity had the strongest correlation to tip speed (r2=0.79). However, injury severity did not correlate as strongly to angular velocity (r2=0.56), blade length (r2=0.034), and blade tip thickness (r2=0.00008). Blade tip speed proved to contribute the most to laceration injuries caused by drone blades, with speeds above 80 ft/s causing minor abrasions and speeds above 200 ft/s causing minor lacerations. In order to avoid severe injuries caused by drone propellers, maximum blade tip speed should stay below the threshold of 200 ft/s, especially for drones designed for toy use. Interestingly, all other parameters (blade tip thickness, blade length, and blade angular velocity) were not correlated to risk of skin injury.

Figure 1: Fetal bovine skin laceration (top), and injury severity vs tip speed (bottom).

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