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Drone use in COVID-19 mitigation and how to prevent collisions

With the COVID-19 purge expected to run for months ahead there is an increasing interest in the use of drones for both containment and vital deliveries. However, there is still the need to solve the problem of collisions and accidents in dense urban environments – a topic of immense interest for Smart Cities technologists.

In Spain, drones are being used by the police to warn people to stay at home and China has used them for similar purposes, including warning its citizens to wear masks. In addition, the world’s most populous nation, has been using the technology for medical deliveries, spraying disinfectant over large areas with retrofitted agricultural drones and using attached thermal cameras to take people’s temperatures.

Terra Drone’s Antwork has been conducting medical deliveries from Xinchang County’s disease control centre to its People’s Hospital to help reduce exposure to the virus and medical drone deliveries have also been made from the hospital to the Chinese Centre for Disease Control and Prevention. In the USA, in North Carolina, Zipline has been asked by Novant Health to begin such deliveries.

Then literally ‘waiting in the wings’ are also Amazon’s Prime Air and Aquiline Drones. Both companies are rumored to be close to holding Part 135 certifications, which could lead to the expedited rollout of new delivery programmes to help curb the crisis.

Drone delivery has obvious benefits at a time like this, when both expediency and minimal human contact are incredibly important as well as their ability to save time, particularly in dense urban environments. So how can we maximise their benefits at this crucial time?

It’s the regulation, stupid

It still remains that the main barrier is not drone technology per se but the regulation which surrounds their use. 

Drones have to be piloted, or at least have human pilot back-up and flown within the line of sight of that pilot. Regulation also limits the use of drones in built up and uncontrolled areas and prevents operation where visibility is degraded (e.g. due to adverse weather). The consequences of non-regulation in the flying of drones can be deadly serious. Drones can and do fall out of the sky, GPS systems aren’t as robust as we’d like to believe and no-one wants one to crash in a densely populated environment. To address these, they will need to be equipped with technology which will mitigate the risk of accidents to an acceptably low rate. 

One such technology will be collision avoidance sensing to detect all kinds of obstacles including, but not limited to, power lines, streetlights, trees, children, pets and vehicles. Finding the right sensor technology is important because optical cameras are no good at night or in low visibility whereas infrared can alleviate some of the issues and enable operation at night. However, their resolution is likely to be too poor to spot fine obstacles such as powerlines or wire fences at enough range to plan an avoiding route. 

Lidar, a detection technology system which uses pulses of coherent light, has its attractions but can struggle to detect very dark objects or smooth ones at specular angles, including puddles of water or large glass panes. It is also usually adversely affected by rain or snow precipitation, as well as fog and smoke. In addition, its performance usually depends on the amount of ambient light, usually performing better at night than in the day. 

Wavelength dimensions count 

There is a good alternative which we are exploring at Plextek and that is radar operating in the 60 GHz band. At this frequency, a very compact design of radar can offer detection ranges of many tens of metres and be able to detect and resolve very small targets such as power lines, regardless of the time of day. 60 GHz radar is also generally less affected by adverse weather in comparison to the aforementioned technologies. 

The 60 GHz band is beneficial in comparison to other radio frequency bands as it is very wide.  This means that radar solutions can offer a resolution down to a few centimetres. This resolution is crucial to be able to detect and resolve weak returns from small objects such as a low walls or even a child, which may come between the drone and an object with a much stronger return like the ground or a wall. 

At 60 GHz, the wavelength is only 5 mm, which means that an appreciable return can be achieved from fine objects including powerlines or wire fences, which may be invisible at lower frequencies. Also due to the small wavelength, a radar with very high angular resolution can be realised in a very small and lightweight form, so can be integrated onto a drone of limited payload capacity. 

Trials of a prototype radar, developed by Plextek, mounted on a drone have shown that there is the genuine ability to detect thin powerlines as well as trees, vehicles and small boxes against a strong ground return at a range of tens of metres – more than enough to aid navigation, route planning and avoidance of obstacles in cluttered environments. Crucially, these detections will also not be affected by the time of day or meaningfully reduced by poor weather. 

There are a number of prototype miniature 60 GHz radar systems, which we are already supplying to drone operators to support this safe use in highly cluttered environments or in poor visibility. This enables them to manoeuvre drones very close to dangerous and expensive infrastructure in order to get detailed measurements or deliver goods, even in poor visibility, which otherwise would be almost impossible.

With this unfolding emergency, these developments can’t be realised soon enough.

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