The unmanned system selected is the OpenROV tethered Unmanned Underwater Vehicle (UUV).  It is a low cost (approximately $900) and open-source exploration UUV that has a strong and active community of users. (OpenROV.Com, 2015) The UUV is based on the compact BeagleBone Black Linux computer board.  Power requirement for the board is 300 – 500 mA at 5V. (elinux.org, 2015)   The UUV is also equipped with three electronic speed controls (ESC) to manage the three electric motors.  The ESCs control the power going to each of the thruster motors (two horizontal and one vertical), which require 3.7A and 12Vdc.
The OpenROV has several onboard sensors that monitor the proper operation of the UUV as well as providing information on the environment.  This is critical for an electric powered system that can dive to depths up to 75 meters / 246 feet. (OpenROV, 2015).  The data monitored by sensors are as follows:
  • ·     Humidity: The UUV uses a HIH-5031 low voltage humidity sensor. It operates with 2.7 Vdc and draws only 200 microA.  The sensor generates a voltage signal directly proportional to the humidity detected.  (Honeywell, 2010)
  • ·      Temperature and depth: The UUV uses an MS5803-01BA miniature variometer to measure temperature and depth.  It operates with a supply volta e from 1.8 to 3 Vdc and draws 1 microA during operation (0.15 during standby). (measurement Specialties, 2015)
  • ·      Connectivity: It is monitored by the BeagleBoard Black computer.
  • ·      Current draw:  It is measured by an Allegro ACS711 sensor.  This sensor operates at 3.3 Vdc and draws 4 milliAmps. Its output is a slope corresponding to the current draw.  (Allegro MicroSystems LLC, 2015)
  • ·      Battery voltage:  It is monitored by the BeagleBoard Black computer.
  • ·      Pitch / Roll / Yaw / Acceleration: The UUV utilizes an MPU-9150 motion tracker 9-axis sensor.  The package includes a 3-axis gyroscope, a 3-axis accelerometer, and a digital motion processor, and an AK8975 3-axis digital compass.  The unit runs on 2.4 Vdc and 3.6 – 4.5 mA. (InvenSense, 2015)
  • ·      Camera tilt: The UUV measures camera tilt (+/- 60 deg from center) via the BeagleBoard Black computer.  It controls the servo that moves the assembly and monitors the tilt angle.
  • ·      High Definition Video: The UUV utilizes a Genius F100 HD USB webcam to capture video.  It has a field of view of 120 degrees and has a fixed focus point. (Genius,KYE Systems Corp., 2015)

All of the sensor data is routed directly to the BeagleBoard Black computer, which has an onboard storage capacity of 4GB.  All the inputs come as low voltage signals that the computer analyzes and converts them into understandable information for the operator.  This information stream is sent via Ethernet using a tether from the UUV to the ground control station.  The OpenROV Cockpit application displays all of the collected sensor data in an intuitive layout for the operator.  The HD video feed occupies the majority of the display, and includes artificial horizon pitch, roll, and yaw information.  All the other sensor data is provided above or below the video feed.  The simple and effective sensor integration and data protocols leave little room for improvement.  Future developments can be concentrated on integrating additional sensors to leverage the UUV.

References

Allegro MicroSystems LLC. (2015, February 6). ACS711 Hall Effect Linear Current Sensor with Overcurrent Fault Output for <100 V Isolation Applications. Retrieved February 8, 2015, from Allegro MicroSystems LLC: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCcQFjAB&url=http%3A%2F%2Fwww.allegromicro.com%2F~%2FMedia%2FFiles%2FDatasheets%2FACS711-Datasheet.ashx&ei=NfvXVPOZM8KfggT AmoOYCw&usg=AFQjCNHcmHe5OvyDm_WMuX_REIx8faX4Vw&sig2=VcKiImbTmgs0VyT47xjp5Q&bvm=bv.85464276,d.eXY
elinux.org. (2015). Beagleboard:BeagleBoneBlack. Retrieved February 8, 2015, from elinux.org: http://elinux.org/Beagleboard:BeagleBoneBlack#Revision_C_.28 Production_Version.29
Genius,KYE Systems Corp. (2015). Ultra wide angle Full HD webcam WideCam F100. Retrieved February 8, 2015, from Genius, KYE Systems Corp.: http://www. geniusnet.com/Genius/wSite/ct?xItem=53214&ctNode=161
Honeywell. (2010). HIH-5030/5031 Series Low Voltage Humidity Sensors. Retrieved February 7, 2015, from Honeywell: http://sensing.honeywell.com/index.php?ci_id =49692
InvenSense. (2015). MPU-9150 Nine-Axis (Gyro + Accelerometer + Compass) MEMS MotionTracking™ Device. Retrieved February 8, 2015, from InvenSense: http://www.invensense.com/mems/gyro/mpu9150.html
measurement Specialties. (2015). Pressure Sensor - MS5803-01BA. Retrieved February 8, 2015, from measurement Specialties: http://www.meas-spec.com/product/ Pressure/MS5803-01BA.aspx
OpenROV. (2015). OpenROV - Underwater Exploration Robots. Retrieved February 8, 2015, from OpenROV.Com: http://www.openrov.com

OpenROV.Com. (2015). OpenROV v2.7 Kit. Retrieved February 7, 2015, from OpenROV.Com: http://store.openrov.com/collections/frontpage/products/ openrov-v2-7-kit