90 Focus | Launch & recovery damaged and need replacing for safety reasons. Hence, designing systems for manufacturability is vital as potentially tens of thousands of units are needed across the UAV world today. Naturally, as a safety-critical component, reliability is vital, across not only the various plastics and fabrics used to capture air but also the launching mechanisms and computing systems within turnkey parachute or airbag products. All of these important components must be chosen and optimised to work together as a reliable package. To start with, many launch or actuation mechanisms exist for parachutes as they must be able to deploy and rapidly fill with air, as a rotor failure at low altitude could fail to slow the UAV before impact with the ground, or worse, people. The optimal selection of a launch actuator largely hinges on the size and weight of the UAV to be ferried gently to the ground. At the lower end, springs and elastic bands can work well for parachutes weighing up to a few kilograms, although these can be heavy relative to the deployment energy they release, making their efficiency debatable. As parachutes get bigger and heavier, it becomes too cumbersome to rely on springs or bands large enough to launch them, so it is increasingly common to resort to pyrotechnic devices, which can pack in considerable force and speed of deployment relative to their weight. These are much like those used in safe, certified automotive airbags and seatbelts, and not harmful explosives. Speed of deployment is a factor not to be underestimated, particularly as UAVs increasingly perform missions at high altitude, such as surveys of mountains or skyscrapers. In such locations, faster parachute deployment using pyrotechnics can ensure sufficient air catchment – even in low-density air – to prevent impact against high surfaces, which could destroy expensive inspection sensors. Proving launch processes can be performed in various ways, such as crane tests, where the parachute is deployed from a range of heights to see how well it reduces impact force at increasingly lower dropping altitudes. Reaction speed also depends on the computer responsible for managing parachutes or airbags. Many of today’s products come with dedicated control computers to relieve the burden of managing a timing-critical parachute on autopilots or flight controllers, which must already be the right size for overseeing numerous core and auxiliary components across a professional-grade UAV. A dedicated computer will have optimised hardware and software to carry out deployment reliably and efficiently, with its own IMU for recognising movements indicative of propulsion failure. The computer needs redundancy and the capacity to recognise false positives, lest the parachute be wasted unnecessarily due to an incorrect reading. Today, modern parachute-type recovery systems are even being trained using AI systems to learn the operational envelopes of the UAVs in which they will be integrated. Rather than having strict binary rules over when a recovery system should or shouldn’t be deployed, it can be flexible and adaptive; for instance, by recognising when the UAV is not falling uncontrollably, despite multiple anomalous sensor readings seeming to suggest it is. Design and engineering of parachutetype solutions is also guided by December/January 2025 | Uncrewed Systems Technology Careful selection of materials, launch devices, control systems and more are needed for both routine and emergency parachute recoveries (Image courtesy of Manta Air) It is increasingly common to resort to pyrotechnic devices, which can pack in considerable force and speed of deployment relative to their weight
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