Multirotor Operation – Multirotor Applications

Multirotor Operation – Multirotor Applications

Multirotor Characteristics &  Performance

Benefits and drawbacks:

  • Vertical Take-Off and Landing (V-TOL)
  • Ease of flight
  • Visibility
  • Endurance
  • Airspeed/Groundspeed
Recall the law of diminishing returns!

Performance

  • Expected performance:
    • Performance is highly reliant on weight and size
    • Typically, larger multirotor RPA have higher stability, but lower agility
  • Typical Endurance:
    • Most multirotor RPA have flight times of 20 minutes to 40 minutes
    • Some large multirotor RPA can achieve ~60 minutes
    • Payload weight has a large effect on endurance
Example Flight Manual Excerpt
Additional Devices – Altimeters

Altimeter Devices:

  • Barometer (air pressure):
    • Accuracy: <5m
    • Range: Within whole atmosphere!
    • Barometers work well over a large range, but can fluctuate with air pressure and wind
  • Sonar (sound)
    • Accuracy: <1cm
    • Range: <5m
    • Sonar work well at short range, but need areas to reflect off (e.g. flying over a pole may not register)
  • Radar (radio)
    • Accuracy: <1-5m
    • Range: <500,000m (depends on antennas!)
    • Radar work well over long ranges, but need big antennas (at least on one end) to get good range. Further the maximum range, the worse the accuracy
  • Lidar (light)
    • Accuracy: <0.005m
    • Range: <200m
    • Lidar work well on medium ranges, but act as a point-sample (like a laser dot), so may give false readings over vegetation, etc.
  • GPS (radio)
    • Accuracy: <2m
    • Range: 20,200km (orbit distance)
    • GPS are just a specific form of radar sensors!

Ground measuring altimeters let you:

  • Avoid obstacles like hills
  • Maintain a constant survey height
  • Have precise landings
Additional Devices – Gimbal & Camera Systems

Uses for a cameras and gimbals:

  • Cameras let us perform surveys
  • Gimbals let us make sure we’re surveying the right thing!
  • Gimbals are usually made for a specific camera (weight and size)

Gimbals can stabilise in:

  • Roll
  • Pitch
  • Yaw
  • Or all of the above!
Without a gimbal, the camera will nearly never be pointed straight down!
Additional Devices – Collision Avoidance Systems

Collision avoidance Systems can help the pilot avoid collisions! There are many different types which all work in different ways:

  • Based on cameras:
    • Computer vision systems
  • Based on Sonar/Radar/Lidar:
    • Like the altimeters, but looking in other directions!
  • Based on Radio Beacons:
    • ACAS – allows aircraft to “talk” to each-other
    • ADS-B – allows aircraft to “talk” to the ground station (the remote pilot would make a decision)

Most devices will still work similar regardless of the technology:

  • Inform the pilot/autopilot -> act in safest manner
  • “Safest manner” does not mean perfectly safe!