Drone Use in SAR – Part One: Selecting the Right UAV
-Article courtesy of Mike Scott
With the cost and size of unmanned aerial vehicles (UAV’s) shrinking we are seeing more and more teams employing these amazing little machines to aid in searches and team coordination. However, like any piece of great gear, it’s only as good as the person using it. Some of you may be sitting on the fence when it comes to using a UAV or drone in your SAR operations. Some may be fully one way or the other. Over the next few posts I will try to clear up some of the misconceptions and maybe help you decide if this is something your team could benefit from.
Drones are getting a lot of attention in the media recently especially in the US. Canada is not at the point of requiring every drone to be registered, but all commercial UAV’s do fall under a certain set of rules and regulations with a few provincial rules thrown in. So, what is the difference between a drone or UAV we would us in SAR and Uncle Dave’s remote controlled helicopter or plane?
Drone is just another term for quadcopter (or multicopter), and that would most accurately describe the common usage of the word. Most consumer drones aren’t very robotic though. Most just hold position without user input. You could say a drone is a robotic aircraft, and I would not object. The professionals use UAV for this category though.
The key word here is probably ‘unmanned’ where unmanned can also refer to autonomous, and that’s where the edges get a bit fuzzy. Autonomous means a UAV can lift of, fly, navigate and return following a pre-programmed route and even extend to some independent decision making. There is no need for RC input even though it is usually available. Such UAV’s do not require the hours of practice of an operator skilled in RC flight. They can fly themselves with input from a laptop rather than a skilled operator using a remote transmitter. These are the type of UAV’s that have been developed for aerial photographers, the military, Law enforcement and search and rescue work just to name a few.
R/C UAV’s are controlled from the ground, but the lines are fuzzy here too in the past few years as more and more functions are controlled by sensors and computer programs. First we had simple Gyro’s to help stabilize flight. Now we have all kinds of help which can hold altitude, maintain attitude and heading, even fly back to home, and all within the budget of regular hobbyists. We can even fly out of line of sight using on board cameras. However Hobbyists like to maintain the physical link of a hand held transmitter, which is the real difference between RAV and UAV to me as someone with several hundreds of UAV hours of my own.
Pepijin de Vos, a designer of RC planes said it best “I would say all RC planes (especially those with a camera, gyro, autopilot, etc.) are drones, but not all drones are RC planes.”
OK, so now we know the difference. The next question is one I hear a lot, “What’s the best UAV for SAR?” My answers has always been the same, “That depends.”
The <em>best</em> UAV for any application will depend on a few things, but first and foremost is Budget. Everything else, desired flight time, payload limits, camera requirements and range should be on your list and probably in that order as they are cascading <em><u>after</u></em> how much money you are willing to spend. You are not going to be able to buy a UAV that will fly for an hour with a gyro-stabilized full size Sony camcorder for $500.
So let’s start with the cost. You can go on the Shopping Channel and buy a drone for about $200 (less if it’s on sale) that will capture video with a flight time of 10-15 minutes with a range of a few hundred feet, but it will be forced to land in winds higher than 5 knots. The video quality may less than stellar.
Conversely, for a mere $135,000, you can have a UAV with a live day/IR camera flying at 50Kph for 45 minutes in most weather conditions. This is a classic redneck dilemma; you want the biggest, badass truck with more horsepower than all of the Bar U Ranch stables for the cost of a Chevy S-10. Sorry to say mate, it’s just not going to happen.
So let’s get realistic, somewhere you are going to have to compromise, where that will be is up to you and your budget. Do you need to have full HD recordings from a Cannon 5D MkIII; well you may only get 15 minutes of flight time. You want live streaming FLIR footage: you may have to land and swap cameras to view in colour because you can’t afford a dual camera setup. All of these things will come down to cost. So, figure out what you have to spend and then start looking for the options you need. If you can cover all of your needs and have room left, upgrade in the same order of your needs if you can. But beware; adding bigger batteries may shave time off of the flight time due to increased weight.
Speaking of flight time, one of the things to consider will be the cost of replacement batteries. I have yet to see a package that comes with more than two batteries. Look back at past SAR operations and that should give you a rough idea of how much total time you might need. Having the ability to fly for three hours would be great, but maybe not if it’s going to cost an additional $1000 above your budget for batteries.
The type and size of the cameras you can use will be limited by the amount of weight the UAV can carry. On smaller platforms this will be in measured in grams, where the larger more expensive UAV’s will list the limits in Kilo’s. Most companies that sell UAV’s will have a selection of camera options that will work with their platforms though. It’s when you try to mix and match that you may run into trouble.
We will discuss the workings of infrared cameras later on in some detail, but for now, it’s worth mentioning these may cost more than the UAV itself. However, not enough can be said about the value of being able to search the ground both day and night. It is very common to see day or electro-optical (EO) cameras as the stock option when selecting a payload. Some of these will stream to a phone, a tablet or to a dedicated screen on the controller itself, which may or may not be included in the package. Whatever the option, make sure the screen you will be using in large enough to see the detail the camera is sending. If you can afford it, any form of HD is the way to go, but not at the expense of anything we have already discussed. Dual camera systems allow you to scan an area in EO and switch to IR to confirm a possible hit. Despite what you may have seen or heard, IR works great in the daytime too!
Now let’s talk about range. Several factors will dictate the operating range of a platform. Transmission/receiving strength, altitude limits and line of sight (LoS) requirements are just a few. If your team works a national park of 10,000 square kilometers, a 1k range is going to be frustrating and limiting. Some of you will have conducted searches in the same locations multiple times and know where the trouble areas are. You may be able to send a UAV ahead 5k from the staging area to spot that lost hiker or pesky backcountry skier as everyone else is gearing up. But only if you have the range available!
OK, if I haven’t scared you off by now, you already have a UAV and just wanted to see if I even had a clue about all of this or you are seriously thinking about adding this tool to your team, thanks for taking the time to read through the first part. In the following parts, I will talk about mission planning, buttonology (yep, it’s a real word), payload operation and search techniques. Read Part Two: Preparation and Operation