Robust UAV Autopilot


Robotic and autonomous vehicles are finding wider and broader military and civilian applications, from Remotely Operated Vehicles (ROVs) for explosive ordnance disposal (EOD) to Unmanned Air Vehicles (UAVs) for remote surveillance. When the mission is dull, dirty or dangerous, it is far better to send a machine than a human.


Furthermore, the predicted spectrum of conflicts and challenges for 21st century is forcing an expansion of the technologies needed to mount an effective response. One such new technology is the Micro Vehicle (MV), an important component in the technological makeup of the future. MVs are typically Micro Air Vehicles (MAVs), but recent work on Micro Ground Vehicles (MGVs) also shows promise. These assets will be owned and operated at a more local level, and are intended to reduce the latency of current reconnaissance assets in both deployment and data retrieval strategies.


Significant technological challenges arise from the MVs small size and limited payload capabilities. Their fast dynamics make them extremely difficult to control, and feedback control systems are necessary to pilot them effectively. With vehicle lengths around 15 cm and payloads of less than 1 kg, current Guidance, Navigation, and Control (GNC) solutions are unable to provide adequate performance within the power, size and weight budgets required. Without adequate GNC capabilities, a MAV is essentially useless and will tie up a human asset simply trying to keep it flying upright.


Current designers face a dilemma: they must choose either low-power, low-weight, low-cost, and low-performance, or high-power, high-weight, high-cost, and high-performance. What is missing is a low-power, small, high-performance system that enables MV technologies to be deployed where they are needed most. In order to push MV capabilities closer to where they’re needed, they must move from the expensive, heavy and scarce resource category into the affordable, easily managed and ubiquitous category.


Paramount to this change is a dramatic improvement in power and weight of the GNC system. Such a system will not only be miniature and low-power, but also economically viable, allowing each group to have its own surveillance assets. In their current incarnation, surveillance assets such as UAVs are a scarce resource, often controlled far away from the scene of interest, and sometimes relaying their imagery to the ground location too late. Tactically, the widespread deployment of the proposed MVs will dramatically increase their utility, shorten the time required to obtain information, increase situational awareness, and reduce the inherent risk to the responders.


Attitude and positioning for a very small platform is by no means a “solved problem.” While there are several products on the market, few work well in difficult environments. As an example of current technology, the Honeywell HG-1700 Ring Laser Gyro IMU or HG-1900 MEMS-based IMU are small and high-performance, but the sensor heads alone are still much too heavy and power intensive for use on a MAV. Add on the guidance and control subsystems and the systems are completely outside of a typical 100 gram weight budget.


We are designing an integrated robust autopilot for UAV control research in conjunction with the UAV group at the Naval Postgraduate School.



multimedia


  1. • SLUGS UAV website



Publications


  1. (1)Lizarraga, M., Curry, R., Elkaim, G., “Reprogrammable UAV Autopilot System (Part 2)— Testing and Results,” Circuit Cellar Magazine, Vol. 250, May 2011, pp. 36-43. [not peer-reviewed] (pdf)

  2. (2)Lizarraga, M., Curry, R., Elkaim, G., “Reprogrammable UAV Autopilot System (Part 1)— System Hardware and Software,” Circuit Cellar Magazine, Vol. 249, April 2011, pp. 24-35. [not peer-reviewed] (pdf)

  3. (3)Vasconcelos, J., Elkaim, G., Silvestre, C., Oliveira, P., Cardeira, B., “Geometric Approach to Strapdown Magnetometer Calibration in Sensor Frame,” IEEE Transactions on Aerospace Electronic Systems, Vol. 47, No. 2, April 2011, pp. 1293-1306, doi:10.1109/TAES.2011.5751259. (pdf)

  4. (4)Elkaim, G., Lie, F. A., and Gebre-Egziabher, D., “Principles of Guidance, Navigation and Control of UAVs,” in Handbook of Unmanned Aerial Vehicles, ISBN 978-90-481-9708-8, Springer, July 2013. (pdf)

  5. (5)Lizarraga, M., Elkaim, G., Curry, R., “SLUGS UAV: A Flexible and Versatile Hardware/Software Platform for Guidance Navigation and Control Research,” Invited Tutorial Session, Airborne Experimental Test Platforms: From Theory to Flight, American Control Conference, ACC13, Washington D.C., 17-19 June 2013, submitted (pdf)

  6. (6)Lizarraga, M., Curry, R., Elkaim, G., “Flight Test Results for An Improved Line of Sight Guidance Law for UAVs” American Control Conference, ACC13, Washington D.C., 17-19 June 2013, submitted (pdf)

  7. (7)Curry, R., Lizarraga, M., Elkaim, G., Mairs, B., “L2+, an Improved Line of Sight Guidance Law for UAVs” American Control Conference, ACC13, Washington D.C., 17-19 June 2013, submitted (pdf)

  8. (8)Elkaim, G., “Misalignment Calibration Using Body Frame Measurements” American Control Conference, ACC13, Washington D.C., 17-19 June 2013, submitted (pdf)

  9. (9)Ilstrup, D., Lizarraga, M., Elkaim, G., and Davis, J., “Aerial Photography using a Nokia N95,” World Congress on Engineering and Computer Science, WCECS 2008, San Francisco, CA, Oct. 22-24, 2008 (pdf)

  10. (10)Elkaim, G. H., Foster, C., “Extension of a Non-Linear, Two-Step Calibration Methodology to Include Non-Orthogonal Sensor Axes,” IEEE Journal of Aerospace Electronic Systems, Vol. 44, No. 3, July 2008. (pdf)

  11. (11)Gebre-Egziabher, D., Elkaim, G. H., “MAV Attitude Determination from Observations of Earth's Magnetic and Gravity Field Vectors,” IEEE Journal of Aerospace Electronic Systems, Vol. 44, No. 3. July 2008. (pdf)

  12. (12)Vasconcelos, J., Elkaim, G., Silvestre, C., Oliveira, P., Cardeira, B., “A Geometric Approach to Strapdown Magnetometer Calibration in Sensor Frame,” IEEE Transactions on Aerospace Electronic Systems, submitted May 2008, pending review. (pdf)

  13. (13)Lizarraga, M., Elkaim, G., “Spatially Deconflicted Path Generation for Multiple UAVs in a Bounded Airspace,” ION/IEEE Position, Location, and Navigation Symposium, ION/IEEE PLANS 2008, Monterey, CA, May 5-8, 2008, pp. 633-640 (pdf)

  14. (14)Elkaim, G., Lizarraga, M., Pedersen, L., “Comparison of Low-Cost GPS/INS Sensors for Autonomous Vehicle Applications,” ION/IEEE Position, Location, and Navigation Symposium, ION/IEEE PLANS 2008, Monterey, CA, May 5-8, 2008, pp. 285-293 (pdf)

  15. (15)Vasconcelos, J., Elkaim, G., Silvestre, C., Oliveira, P., Cardeira, B., “A Geometric Approach to Strapdown Magnetometer Calibration in Sensor Frame,” IFAC Workshop on Navigation, Guidance, and Control of Underwater Vehicles, IFAC NGCUV 2008, Ireland, Apr. 8-10, 2008. (pdf)

  16. (16)Elkaim, G., Foster, C., “Sensor Stability of a Low-Cost Attitude Sensor Suitable for Micro Air Vehicles,”ION National Technical Meeting, ION NTM 2007, San Diego, CA, Jan. 22-24, 2007, pp. 756-770 (pdf)

  17. (17)Elkaim, G., Foster, C., “Development of the Metasensor: A Low-Cost Attitude Heading Reference System for use in Autonomous Vehicles,” ION Global Navigation Satellite Systems Conference, ION GNSS 2006, Fort Worth, TX, Sept. 22-24, 2006, pp. 1124-1135 (pdf)

  18. (18)Gebre-Egziabher, D., Elkaim, G. H., “Calibration of Strapdown Magnetometers in the Magnetic Field Domain,” ASCE Journal of Aerospace Engineering. Vol. 19. No. 2, April 2006, pp. 1-16 (pdf)

  19. (19)Gebre-Egziabher, D., Elkaim, G., Powell, J., Parkinson, B., “A Non-Linear, Two-Step Estimation Algorithm for Calibrating Solid-State Strapdown Magnetometers,” 8th International St. Petersburg Conference on Navigation Systems (IEEE/AIAA), St. Petersburg, Russia, May 27-31, 2001 (pdf)

  20. (20)Gebre-Egziabher, D., Elkaim, G., Powell, J., Parkinson, B., “A Gyro-Free Quaternion-Based Attitude Determination System Suitable for Implementation using Low-Cost Sensors,” IEEE Position Location and Navigations Symposium (IEEE PLANS 2000), San Diego, CA, Mar. 13-16, 2000. pp. 185-192 (pdf)

  21. (21)Evans, J. Elkaim, G., Lo, S., Parkinson, B., “System Identification of an Autonomous Aircraft Using GPS,” ION Global Positioning System Conference, ION GPS 1997, Kansas City, MO, Sept. 16-19, 1997, pp. 1065-1074 (pdf)


People


  1. • Gabriel Elkaim, Associate Professor, Computer Engineering, UCSC, 831.459.3054

  2. • Renwick Curry, Adjunct Professor, Computer Engineering, UCSC, 831.466.3332

  3. • Mariano Lizarraga, Ph.D. Student (graduated), CE UCSC, now Researcher at UCSC.

  4. • Robert Casey, Masters Student, Computer Engineering, UCSC, 831.459.2140

  5. • Samuel Toekpe, Masters Student, Computer Engineering, UCSC, 831.459.2140

  6. • Greg Horn, Undergraduate Student (graduated), Physics UCSC, now at KU Leuven.

Robust UAV Autopilot

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PEOPLE