CSIR optronics researchers have spent many hours outside flying a kite in the name of science as part of field experimentation into crisp, smart and silent surveillance system options.
The aim is to test the effectiveness of the system for stealth surveillance in covert missions or in cases where land access is problematic, for example, deployment in rough terrain, to combat piracy and illegal crossings or dangerous unrest situations. The challenge centres on how to capture stable sensor data despite operating from a free-floating and moving platform.
“As an aerial platform, the Helikite provides a significant engineering and research challenge to achieve effective stabilisation and optical tracking using narrow field-of-view sensors.
“In essence, it is a large helium balloon floating on a string. Using CSIR-developed hardware simulation tools to optimise system controls based on actual flight data means we have the information to more rapidly come up with solutions and build our knowledge base in control systems,” said Mark Holloway, a senior engineer in optronics sensor systems at the CSIR.
The Helikite is an attractive option for surveillance as it floats silently, it has no running motors, and has a minimal running cost of R1 000 a week – mainly for helium.
These advantages make it a cost-effective alternative to helicopters and unmanned aerial vehicles (UAVs). From arrival on location to receiving the first images on screen takes only four hours. The complete system can be shut down and ready for extraction within two hours.
The Helikite can provide an elevated vantage point of two kilometres or higher, extending the area of surveillance. The elevation allows surveillance of areas where tall buildings or high trees obscure the view from the ground and where surveillance is done of areas beyond hills.
All the mounting and processing hardware, as well as the software the system runs on, have been developed by the CSIR.
The Skyphos system encompasses the complete aerial surveillance platform chain. It consists of a 64 cubic metre Helikite; an inflatable docking pontoon and anchor system; a portable winch; stabilised optical surveillance platforms; a data transmission system and a base station where image processing tools are housed. The main support logistics for the Helikite are the docking pontoon and the winch used to deploy and recover the Helikite from various altitudes during testing.
Also on the Helikite is the CSIR-developed surveillance system, the TULA, a full-colour, 20X zoom high definition HD block camera alongside a Xenics Gobi long wave infrared thermal imaging camera with a 75mm fixed focal length lens. This combination of multi-spectral sensors is typically used in optical detection and tracking and can be left overnight, with the thermal camera feeding information in total darkness. The TULA is a stabilised platform, using an Inertial Measurement Unit (IMU) based on micro-electro mechanical system technology. Optical sight line correction is inferred based on the processing of the signals from the TULA IMU.
A fibre-optic cable is used to send and receive data from Helikite to the base station, ensuring no electromagnetic interference. By not using Wi-Fi, the system is also more secure. It is safe to use it close to a communications tower as the signal cannot be interrupted by radio frequencies. The fibre-optic cable allows for high bandwidth data transfer of high-definition or higher resolution images and enables base station initiated real-time surveillance system stabilisation using feature-based tracking.
A vital element of the experimentation was to research interaction between the Helikite as a platform and the output of the surveillance system. From this, it is possible to design and optimise the control system for image stabilisation. The platform dynamics were measured using a six-degree-of-freedom IMU placed on the coupling between the Helikite and payload. Data gathered from this IMU will be compared to the surveillance system on-board IMU and the analysis used for control system optimisation. These data will also be used as input to the Target Motion Simulator (TMS) robotic arm, which is part of the flight motion simulation facility at the CSIR. The TULA surveillance system will be mounted to the TMS, which will simulate the Helikite dynamics and allow further development of the image stabilisation and tracking algorithms under controlled conditions.
Being able to stabilise a narrow field of vision image received from an unstable platform, advances the distributed surveillance concept, as a clearer image will give accurate information when optically tracking a target of interest, positively impacting, for example, on border security where long stretches of land must be monitored.
Holloway said work is ongoing. “We will continue to deploy the Helikite to evaluate the effectiveness of the laboratory optimisation in the ‘real world’. Technology cannot grow in laboratories alone. It must be tested and optimised for deployment in the field.”