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Wireless sensor network control Drones?

Posted by Kostas Alexis on May 11, 2010 at 2:43am
Hello to community!

It is a great fact that UAVs tend to miniaturization. Despite the high technology advances on microprocessors and embedded systems it is clear that only simple control laws can be implemented into Miniature Autonomous Vehicles. Note that i am not talking for rf manned control but for fully autonomous solutions. So what about Wireless Sensor Network control for Drones? It is an idea implemented widely in ground robots. The main approach is to implement on-board only the main control functions (for example stabilization with simple PID loops for safety mainly when the wirelless network is not availible for some reasons) and let advanced control laws send commands from the ground station. Obvioysly the drone will also send its state vector through the network. What's your opinion?


|------------------------|........................|-------------|
| Ground Station | <---- WSN ----> | DRONE |
|------------------------|........................|-------------|
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Comments

  • Kostas Alexis May 11, 2010 at 12:45pm
    So we can conclude that there is a meaning on this approach. Let's go a step ahead. What type of MAV do you think is the most appropriate? What type of rotorcraft? With what sensors and based on what MCU?
  • Overwatch May 11, 2010 at 11:06am
    Yeah, many big-budget military MAVs implement some kind of flocking/swarming behavior.
  • DrJeseuss May 11, 2010 at 10:48am
    I like the concept of "distributed computing" but had another concept in mind at first read. How about a "control" UAV that does all the waypoints, etc. Then each additional UAV would communicate with it for direction. This way the "swarm" UAVs could use the free space onboard for other gadgets like atmospheric monitoring, distress signal triangulation, video monitoring, etc. Additionally, with the "control" UAV doing the the big-picture work, the others don't have to, making them more affordable.
  • Overwatch May 11, 2010 at 9:14am
    Yes, 50 g is what I ment by MAV, those little suckers sure could use an external coordinator. This way one operator could control a swarm of cheap and simplistic MAVs.

    It's my opinion, however, that even a small, minimal UAV should, if possible, implement at least some kind of autonomy (I call them fallback behaviors in my design) - e.g. if signal is lost, the vehicle would backtrack and return to base, land, or do something else instead of just flying straight on until it hits something. Reading your post again, I think we're talking about the same thing :-)
  • Kostas Alexis May 11, 2010 at 8:45am
    I agree with you Martin. This is almost what i have in mind but let me be a little more clear. Image UAVs of 50g or less. You can not put something with high power consuming parameters on such a small UAV! But yes you have to add sufficient controls for failures. To my point of view those are simple PD loops and some extra safety procedures (example a very small parachute!). But you can use Wireless Sensor Networks to guide those units using advanced control laws, to send navigation commands (waypoints), enforce cooperation among them etc. etc. It is an approach don't you think? You can also use the current infrastructure in areas like forests, borders etc.
  • Overwatch May 11, 2010 at 5:06am
    I can see this being useful for MAVs, which are obviously constrained for processing power (end everything else).

    However, it introduces several additional layers of complexity and with them single points of failure. Especially the radio link. A normal-sized UAV (think Easystar or Quad) has enough lifting power to lift a couple hundred MIPS with it, so it doesn't actually need to offload everything except stabilization to the ground (or a larger vehicle). If it can lift it, use it. The idea works in ground vehicles because usually, if the UGV loses connection with the WSN, it just stops operating. If a UAV loses connection with the WSN, it gets destroyed.

    I'm currently in the development phase of a control system that shares some points with your concept: it has one onboard computer doing only the most basic of control - stabilization, orientation, throttle control. Then there's a second computer doing higher-level brain functions like waypoints, telemetry and video. And the third segment is the groundstation which constantly streams elevation data, waypoints and other commands to the UAV. The key difference is that it can handle a total failure of just about any component and still continue its mission, RTB or at least attempt a landing using fallback behaviors, waypoint plans or, in the worst case, parachutes.
  • Nima K May 11, 2010 at 4:24am
    Hmm. There are a couple of factors at play here, latency, bandwidth, mathematical stability. The question is why opt to do such a thing and not increase the onboard power? At the moment MCUs with embedded Flash and SRAM are running up to 200 MIPS. For external memory you can try the 600MIPS blackfin series. Why not use these solutions?
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