The estimation and embedded sytems group is responsible for low-level interface with sensors and actuators. These systems provide the vehicle with information about its attitude and environment and the ability to move and interact with the surroundings.
The current vehicle is equipped with a three axis rate gyro, three axis accelerometer, and a pressure sensor for attitude and depth information. A microcontroller fuses the accelerometer and gyroscope data using an Unscented Kalman Filter to determine attitude. The sensor readings are then reported to the autopilot.
In the next vehicle, the microcontroller will be used to sample the sensors at high rate and report readings to a Linux computer which will run the attitude and depth estimator.
A sonar is also under development to enable the vehicle to navigate relative to a beacon on the bottom. High speed analog-digital converters will sample two pairs of two sonar transducers arranged in a cross pattern. The signals will be processed using a Linux computer and azimuth and bearing reported on the vehicle network.
Thrusters, torpedo firing, and marker dropping will all be managed using ethernet connected microcontrollers. These form the bridge between the control and decision-making which happens on computers, and the hardware which gathers data and carries out actions.
For the competition vehicle, all critical systems will be connected via
ethernet. This provides a common, high-speed data link throughout the vehicle.
Linux computers will manage processing and decision-making and communicate
using the Robot Operating System (ROS). Low-level interfaces take place using
Arduino microcontrollers equipped with ethernet shields.