Latch-based control of energy output in spring actuated systems

Data from Latch Physical Model: Experiments with the latch physical model described in the associated paper were recorded with a Photron AX-200 high-speed camera (pixel resolution: 896 x 768, calibrated ruler) at 10000 fps (shutter duration: 1/60000 second) and both latch motion and projectile motion were analyzed using tracking software (Image Systems, TEMA). Take-off velocity was calculated from these images at the point when the spring and mass separated from the substrate. Measuring latch delay was more challenging. In theory, the point of maximum projectile acceleration should equate to the instant at which latch force goes to zero, but this was not the case in the physical system. Instead, latch delay was measured when physical separation was visually observed between the projectile and the latch. While this method is expected to slightly overpredict delay, it provided consistent results. Data was processed in Matlab using the scripts provided. Dracula ant data processing: Mandible tip position data captured on high speed video from two types of Dracula ants (larger major and smaller minor workers) was made available in [Larabee 2018, doi: 10.5061/dryad.4863215]. This dataset provides x-y coordinates of the mandible tips for each frame along with the camera frame rate. Four ants of each type were analyzed over 4-5 strikes per ant as available in the dataset. The first mandible to move during each strike was designated as the latch mandible, and unlatching time was defined as the time difference between the start of latch mandible and strike mandible motion. Average latch mandible velocity was calculated as the angle over which the latch mandible displaced before the strike mandible began to move, divided by the unlatching time. The maximum strike velocity was calculated using the maximum angular motion of the strike mandible between two frames and dividing by the time interval between frames. The Matlab script used to process this data is included in the dataset, but the dataset itself is available from Larabee (doi: 10.5061/dryad.4863215).