Back in 2008, the Autonomous Intelligence Systems Section at Defence Research Canada, the Canadian Forces, and Meggitt were all interested in developing an unmanned rotary wing platform. While they all had their individual reasons for developing this type of system, they decided to come together to make it happen.
After researching the subject, the group determined it was best to model the new platform off an existing manned helicopter. This is something Meggitt has excelled at in the past, and the team knew that working with an existing system would enable them to develop the system much faster.
They found their inspiration in the form of the Mosquito XE helicopter from Innovator Technologies. Not only did this lightweight platform have the features and the capabilities they were looking for, Innovator Technologies is also based in Alberta—making it easy for Meggitt engineers to study the system first-hand while also giving Meggitt the opportunity to work with another Canadian company.
The first iteration of this unmanned helicopter essentially featured everything one would expect to find in a manned helicopter. Controls were removed and replaced with Meggitt’s proprietary kit as new iterations were developed. During the process, engineers were faced with plenty of challenging questions, such as what changes did they need to make in the manned version to optimize control. They had to think about how to control the throttle and the choke, as well as how to interface with the cyclic and collective to control things such as pitch and roll.
Meggitt’s relationship with NovAtel expanded during this development process, Godbolt said. The engineers needed a flight sensor with more capabilities than any system they’d used previously, and knew NovAtel was a trusted Canadian company with a wealth of experience in this area.
Using NovAtel’s SPAN system, Meggitt collaborated with Defence Research and Development Canada and the NRC Flight Research lab to perform helicopter system identification as they developed the Mosquito. Through the project, the team worked to establish a dynamic helicopter model of the vehicle and to determine the relationship between control services.
“Changes in control surfaces have different effects over an entire flight envelope. The model relates this control surface motion to changes in altitude, roll, pitch and yaw.” Godbolt said. “That type of modeling work is important for developing simulation capability and for developing a flight control system. For that type of work you want to have the best quality data you can afford.”
The detailed computer model allowed the UHV-T to control itself in virtual simulations and provided the simulation baseline for hardware-in-the-loop autopilot development, Malley said.
Meggitt also uses NovAtel’s ALIGN® firmware as part of the helicopter’s flight control system, Godbolt said. The dual receiver’s heading solution provides information that’s critical for an unmanned helicopter. Unlike a fixed wing aircraft, a helicopter can move sideways, hover, or rotate. Because of that movement, it’s important to be able to measure its heading directly. This is difficult to do reliably through other means, making this a very important technology for Meggitt’s system development work.
“ALIGN gives us a sophisticated ability to get the heading measurement. It’s not about the accuracy in this case. It’s about the enabling technology that gives us a stable heading measurement in all phases of operation—static and dynamic. They’re not the only company out there that does it, but they certainly do it very well, and it has worked very reliably for us. It (heading) is actually critical for flight control because the course is independent of heading. The vehicle could be facing north and traveling east. We need to know the vehicle’s heading and direction of travel in order to fly it.”