Customizable Recorder of Animal Kinesis (CRoAK): A Multi-axis Instrumented Enclosure for Measuring Animal Movements
We designed a novel device, called CRoAK, to quantify the movements of small animals in response to acoustic stimulation. We built our setup in a mini acoustically insulated chamber in which we suspended a small acoustically transparent animal enclosure. On the bottom of the enclosure, we attached an Arduino controlled 9 Degrees of Freedom (9DoF) Inertial Measurement Unit (IMU) that combines three different 3-axis sensors, an accelerometer (linear acceleration), a gyroscope (angular velocity), and a magnetometer (direction of the magnetic field). In our implementation of CRoAK, we relied solely on the gyroscope to quantify the motion of the enclosure in response to the movements made in response to a stimulus. We did not use the accelerometer in this implementation because we anchored the suspended enclosure to minimize oscillations in the system after perturbation by an animal’s movement. This means that, by design, we eliminated the possibility of linear translation such that movements would result in angular displacement of the enclosure that could be captured by the gyroscope. Other users may find the accelerometer more useful in customized implementations of CRoAK more suitable to their purpose. We also did not use the magnetometer in our single-speaker setup, but it could be used in multi-speaker implementations of CRoAK to measure perturbations of the local magnetic field that occur when different speakers are being driven, for example, to coordinate movements with sounds broadcast from different directions. Here we provide CAD figures of the device along with the Arduino code that was used to collect data from the sensor.