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DroneStock University: GPS Mode versus ATTI Mode or Positioning Mode versus Attitude Mode

DroneStock University: GPS Mode versus ATTI Mode or Positioning Mode versus Attitude Mode
By DroneStock.com 4 years ago 7515 Views 1 comment

Controller Positions

Most drone pilots these days fly their copter in GPS Mode (or Positioning Mode), and nothing else. This makes sense because drone manufacturers like DJI have tried to make it very easy to fly their drones using low-cost advanced sensors and electronics, so that anyone can fly their copters, and for the most part they have succeeded. However for professional pilots (or those who would like to be able to get more professional shots), using other modes than just GPS Mode is a big advantage.

Here are the common modes using in current DJI drones:

  • Positioning Mode, also know as GPS Mode
  • Attitude Mode (Attitude), also know as ATTI Mode. Attitude just means the angle (or tilt) of the copter, relative to the ground.
  • Function Mode (Function)

Positioning Mode also has some sub-categories:

  • P-GPS: GPS and Vision Positinioning available
  • P-OPTI: Only Vision Positioning is available (GPS is not)
  • P-ATTI: Neither GPS or Vision Positioning is available

These latter modes happen when you are flying around in Positioning Mode, but if you fly into a tunnel, or near some tall buildings, or you’re flying inside, then the GPS signal is not available. GPS done NOT work indoors!

For a good understanding of which mode to use when flying, and getting the perfect shot, it is good to have a basic understanding of how the sensors in the copter work. Here is the short version:

Basic Sensors:

  • Gyros: These allow the drone to know how fast it is tilting (or changing angle) in any direction.
  • Accelerometers (or accels): These tell the drone when it is moving vertically or sideways, the acceleration in each direction.
  • Barometer: This tells the drone when it is moving up and down in altitude.

GPS doesn't work indoors or in amongst tall buildings, because your GPS
sensor needs direct line-of-sight to the GPS satillites orbiting the Earth.

Advanced Sensors:

  • GPS: Global Positioning System: The drone is receiving signals broadcast by satellites circling the globe, and it is figuring out is 3D position in the air based on those signals. (Within a few feet).
  • Vision Positioning System: Or camera with vision processing. There one or more cameras pointed at the ground, and a dedicated processor is analyzing the pixels from the camera to determine how the drone is moving in 3D space.
  • Vision Obstacle Detection System: There is a pair of cameras pointed out the front of the drone, and it is comparing pixels in the camera to determine the range to obstacles that the drone might hit!

In all flight modes you drone is using it’s Basic Sensors to keep the copter level, or direct it to a particular angle based on how much you push that right stick around. It is maintaining an angle.

In GPS Mode (or Positioning Mode) the copter is using one or more 3D position sensors, like the GPS, to try to keep the copter at a certain position is 3D space. When you move the stick on your controller you are moving that 3D point around, and it is trying to follow it. It is maintaining level flight, while trying to get to that 3D point.

Now, if you LOSE your 3D position sensor while in flight, for example if you fly under an overpass and lose your GPS, or you fly too high and lose your Vision Positioning system, then all your copter is left with are its Basic Sensors, and it will automatically switch to Attitude Mode; you thought you were flying in GPS mode, but you are now automatically flying in Attitude Mode (ATTI mode)!

Vision Positioning doesn’t work when going 8 m/s at 2 meters, or 4 m/s at 1 meter.

So, it is very valuable to learn how to fly in Attitude Mode, so that you can handle the copter when those Advanced Sensors are not available. For example if you need to do an indoor shoot in a large room or stadium, you won’t have GPS and your Vision Positioning system won’t work under most circumstances (above 3 meters high, or if you are over reflective surfaces, or going faster than 8 m/s, or, or, or).

That being said though, the MAIN reason you want to be familiar with flying in Attitude Mode is that in general can get a smoother, cleaner, or faster shot than with GPS Mode, and you can do things that you can’t do at all in GPS mode, like land or take off from a moving boat. More on that below.

We’re going to focus here on the main differences between Positioning Mode, and Attitude Mode; those are the two main modes we fly in to get professional shots. We’ll cover Function Mode with Point-Of-Interest, Follow Mode, and other fancy modes in other posts.

The things to remember when trying to pick which mode to fly in, is what are the sensors doing. GPS Mode is trying to move the copter to a certain point in 3D space using the GPS or Camera Sensors, so if that point is fixed (you aren’t pressing on the sticks). Attitude Mode is simple trying to maintain a copter angle – if you aren’t touching the sticks, that angle is the copter just being perfectly level. However it is not paying attention to 3D space at all, so if there is a wind, the copter will drift by itself, still being perfectly level.

If you are just flying along straight with some wind hitting you from a certain direction, in GPS mode the copter will make quick (and sometime very twitchy) changes, to keep going towards that 3D point. In Attitude Hold mode the copter will just maintain that angle, regardless of where the wind is pushing it. So if you need an exact path being followed, GPS mode wins. If you need a smooth flight in a certain direction in general (or to fly as fast as possible), Attitude Hold mode wins.

When you’re doing professional shoots, you’ll find that it is best to be able to easily and quickly switch between GPS Mode and Attitude Mode, depending on what is needed for the next shot. You might even switch between modes during a shot.

Alright, so here is a rack-up of situations you might encounter, and which mode to fly in:

Hope this helps. Fly smart!

joseph malka 7 months ago at 3:36 PM
just execellent.
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