Thrusters

The Duke AUV Charybdis uses four Tecnadyne 250 Thrusters for its main propulsion system. Each thruster provides approximately 12lbs of force in the forward direction and 6lbs of force in the reverse direction. The thrusters contain built in amplifiers and control circuitry. Each thruster is equipped with a Subconn 7-pin low profile series connector. Pins 1 and 2 provide Ground and +30V directly from two lithium polymer batteries connected in series. A 5600uf electrolytic capacitor conditions the raw power fed to the thrusters to alleviate voltage spikes. Pins 3 and 4 receive Ground and +12V of power from the DC/DC converters in the electronics tube. The 12V supply powers the control circuitry inside of the thruster. Pin 5 provides the -+5V control signal provided by the Diamond-MM-32-AT Data Acquisition Card (DAC). This card is capable of providing analog control output between -5 and +5 Volts. The PC/104 controls the DAC, allowing the thrusters to be controlled autonomously via the central computer system. Pin 6 provides a feedback mechanism that generates an analog signal that corresponds with the actual measured thrust. This feature is currently unused by the vehicle. Pin 7 exist on theSubconn connector but does not connect to the thruster.
The thrusters are arranged around the central disk with 120 degrees of separation between them. This vectored arrangement allows the thrusters to move in any direction within the x-y plane without rotating the vehicle. By using a combination of the three thrusters, precise search patterns can be conducted without the need to constantly be reorienting the vehicle.