Inertial stabilization and visual servoing for aerial surveilance

Since 2006 our group has been involved in an R&D activity funded by Ministry of Industry and Trade of the Czech Republic and aimed at development of an inertially stabilized camera platform for aerial surveilance. The coordinator of the project is Czech Air Force and Air Defense Technological Institute (VTÚLaPVO) (a branch of LOM Praha). Other partners are computer vision specialists from Center of Machine Perception (CMP) FEE CTU and a small mechanical engineering company ESSA located in Prague.

The goal of the platform is to stabilize the line of sight of the optoelectrical payload (day vision camera, infrared camera, laser range finder and laser beamer) in presence of disturbing rotational motions of the carrier (helicopter, unmanned aircraft). On top of the inercial stabilization, automatic image tracking of the ground target is implemented, which compensates for the translational motion of the aircraft and/or the ground target.

The early prototype finalized in 2008 was based on the classical double-gimbal mechanical configuration, two direct drive DC motors and a three-axis MEMS-based gyro. The prototype was tested extensively in the lab, and also outdoor, carried by a car and a helicopter. Functional system was demonstrated at several large international fairs such as IDET and MSV in Brno.

The practical lessons learnt with the first prototype were used to design the second version aiming for a production. It features four gimbals: two outer gimbals are driven by regular DC motors with a belt gear and the two inner gimbals are driven by DC voice-coil motors with a limited angle. MEMS gyros are used to detect inertial angular rate, but replacement by fiber optics gyros is planned. MEMS accelerometers are used to compensate for fhe disturbing torque induced by combined effect of vibrations and static unbalance of the optoelectrical payload. Again, extensive testing has been conducted both in the lab and outdoor, some snapshots below.

The development of the prototype system was finalized and the system is now (as of spring 2012) being commercialized by LOM Praha.

 

Project leader: 
Zdeněk Hurák
Participating: 
Jan Salášek, Jaromír Dvořák
Publications: 
Hurák, Z., and M. Řezáč, "Image-based pointing and tracking for inertially stabilized airborne camera platform", IEEE Transactions on Control Systems Technology, vol. 20, issue 5, pp. 1146 - 1159 , September, 2012. Abstract
Řezáč, M., and Z. Hurák, "Structured MIMO H-Infinity Design for Dual-Stage Inertial Stabilization: Case Study for HIFOO", 18th World Congress of the International Federation of Automatic Control (IFAC), Milano, Italy, September, 2011. Abstract
Řezáč, M., and Z. Hurák, "Low-cost inertial estimation unit based on extended Kalman filtering", Proc. SPIE Automatic Target Recognition XX; Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIV; and Optical Pattern Recognition XXI, vol. 7696, Orlando, Florida, USA , SPIE, April, 2010.
Hurák, Z., and M. Řezáč, "Control design for image tracking with an inertially stabilized airborne camera platform", Proc. SPIE Automatic Target Recognition XX; Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIV; and Optical Pattern Recognition XXI, vol. 7696, Orlando, Florida, USA, SPIE, April, 2010. Abstract
Hurák, Z., and M. Řezáč, "Combined line-of-sight inertial stabilization and visual tracking: application to an airborne camera platform", Proceedings of the 2009 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference, Shanghai, China, IEEE, pp. 8458 - 8463, December, 2009.
Video: Demonstration of an inertial stabilization with one of the early prototypes of the inertially stabilized platform.
Video: Inertial estimation unit based on MEMS inertial sensors.
Video: Experimental automatic visual tracking of a castle from the air
Video: Experimental automatic visual tracking of cars on a highway
Video: Experimental automatic visual tracking from a hovering and yawing helicopter
Video: Tracking demo with gyro stabilized camera gimbal
Video: Single-axis dual-stage inertial stabilization benchmarking setup
Image: Inertially stabilized camera platform S250
Image: Inertially stabilized camera platform S120
Image: Inertially stabilized camera platform S120 carried by Manta UAV
Image: The stabilized platform S250 underneath a Mi-17 helicopter
Image: Mi-17 helicopter carrying the inertially stabilized camera platform S250
Image: Inertially stabilized camera platform underneath a military helicopter Mi-17
Image: Loading the inertially stabilized platform onboard the Mi-17 helicopter
Image: Flight experiments with an inertially stabilized camera platform