Page 325 - Control Theory in Biomedical Engineering

Continuum NasoXplorer manipulator with shape memory actuators 299

plugged into an iPhone to capture the temperature of the device at each time
frame. We used an Arduino program such that the circuit would turn on for
25seconds, and cool for the next 25seconds.
One drawback of the design of the NasoXplorer is that the acrylic tube
prevented cooling. Even when the circuit is off, the temperature of the
device remains at a constant, with few reductions observed. This was the
case even after we drilled holes into the working end to prevent the device
from overheating. Hence, we shifted the working end ex vivo.
None of the test results at all four voltages reported temperatures close to
80°C, the temperature for acrylic warping (Figs. 8 and 9). However, these
are the results for just one cycle of the actuation. When running the circuit
for 120seconds, temperatures stabilized around 53°C. Hence, it is con-
cluded that the acrylic tube is safe to use in the NasoXplorer. Another thing

Fig. 8 Temperature-time relationship at 80%, 90%, 100% PWM.