When you are flying your drone there are few scarier incidents than an uncontrollable toilet bowl movement from your drone. This movement is when the drone moves from side to side in a slight curve whilst also, potentially, moving forward and backward too. There is no doubt that this is incredibly scary. The amplitude of the movement can become very large. This means that any overhanging branches or obstructions could easily come into contact with your drone as it uncontrollably oscillates from side to side. In this article, we are going over all of the reasons why drones toilet bowl and exactly what you can do about it to make sure it never happens to you.
Why does my drone toilet bowl? Drones toilet bowl when there is a significant discrepancy between what the compass is telling the drone and the GPS or IMU data. Once a drone sees a discrepancy it starts to ignore the GPS data and can switch to ATTI mode or it can start oscillating from side to side uncontrollably.
Sometimes, the toilet bowl effect is caused by a combination of issues and so you need to calibrate a series of the drone’s electronic components to make sure that one, or a combination, of these sensors are not sending conflicting data to the inertial measurement unit and flight controller.
What causes toilet bowling
Toilet bowling on a drone is caused by a discrepancy between the compass sensor and the inertial measurement unit. Also, the GPS data can also cause a discrepancy between the direction the compass thinks it is pointing and the direction the drone ends up moving.
Quite often, DJI drones turn into ATTI mode when they experience significant discrepancies in GPS data or if the satellite quality or numbers decreases significantly.
Typically there are two numbers which can help you:
- gpsHealth – this is the health of the GPS signal from 0 to 5. And it is a measure of the vertical and horizontal precision of your drone. It often correlates with the number of satellites that the drone has been able to get location data from.
- numSats – this is the number of satellites that the drone can get data from throughout the flight. Typically a drone will not let you take off in GPS mode until there are more than eight satellites connected.
When the GPS health number drops below 3 the drone will turn off the GPS location module and enter ATTI mode – will talk about this in more detail later in the article but if you want more details about it check out my other article – what is drone ATTI mode [the ultimate guide] – click here to be taken to article.
Here are some examples of toilet bowling from YouTube:
Examples of toilet bowling
Tt can be hard to visualise exactly what toilet bowling looks like with different types of drones. Here are some of the examples which you can use to compare your own experience.
The first example is from a popular YouTube channel TheRcSaylors.
In all of these examples you can see that the size of the toilet bowl varies significantly. However, no matter what the size of the oscillations they are always very hard to control.
There are a few things that you can do before your flight to make sure that toilet bowling does not happen but what can you do in the heat of the moment to stop your drone from crashing?
What to do it if happens
Imagine this, you are out flying your drone and you’re having a wonderful time but you start noticing oscillations occurring while your drone is flying. It doesn’t matter whether this is a cheap, inexpensive drone or a top-of-the-line consumer drone from a respected manufacturer like DJI, it can happen to every type of drone.
Here are the simple actions that you can take to stop your drone from crashing.
Try the pause button
If you have a DJI drone you will notice that the remote controller has a big red pause button on the front near the left joystick.
Not only can it save your drone from return to home malfunctions or other automated flight features where you are getting too close to trees or other obstacles – it can also, in some circumstances stop your drone from toilet bowling.
If the pause button doesn’t work for you here are a few more options.
Try sports mode
If you have a DJI drone some people say that flicking the drone into sports mode and then back again can save you from the dreaded toilet bowling action of your drone.
This is very simple to do as a lot of drones have a physical button right in the centre of the drone controller which you can flick backwards and forwards.
It is right next to the pause button so it makes sense that you will be able to quickly implement these two interventions simultaneously while the drone is flying.
Manually fly back with ATTI mode
When the drone senses a significant decrease in GPS data health or number of satellites it may turn itself into ATTI mode. ATTI stands for attitude mode. In this mode the GPS sensors are disabled as are the global navigation satellite systems (which will mean the drone will drift with the wind) and object avoidance sensors. The aircraft uses an on-board barometer to maintain altitude and to keep it level. This mode is used for capturing smoother footage, flying indoors, or preventing flyaways in the event of GPS signal failure or compass errors.
That is why it is recommended that you get used to flying your drone without GPS data so that you can return it safely to the takeoff spot should you lose GPS connection.
Practice flying manually
If you want to learn how to practice flying a drone check out my other article – how to practice flying a drone [get better faster] – click here to be taken to article.
I also have another article which will go through all of the drone flying practice drills that you need to make yourself completely comfortable while flying whether or not you are a complete beginner or a professional drone pilot – click here to be taken to that article.
Learning to fly manually really can help you feel confident in a variety of different flying conditions and give you the boost of confidence that no matter what the flight mission throws at you that you will be able to handle anything.
These are the things that you can do immediately to stop your drone from toilet bowling but when you land safely and you are make sure that it doesn’t happen again you have to go through these steps.
How to stop your drone toilet bowling
You just returned home from a flight and you want to make sure that your drone will never toilet bowl again. Here are all of the steps that you need to go through to make sure that your drone flies safely and securely without the wild oscillations caused by toilet bowling.
Check that the compass is showing the right direction
The first thing you should do is check that your compass is showing the right direction. This is a very simple cheque to do and all you have to do is turn on your drone and head outside. Once you are comfortable that the GPS has been locked and the compass is showing an arrow on the software you just have to check that the drone is facing the direction that the software thinks it is.
If it doesn’t point the same direction that the drone is pointing you should calibrate your compass.
Calibrate the compass
The compass on a drone is very important. It is the one thing that drone software asked you to calibrate often. This is because the drone compass is the failsafe for your drone returning to home if something goes wrong during the flight. If your compass is miscalibrated your drone can very easily go off in the wrong direction and you may never see it again.
In the DJI GO4 app you can see the interference by going to settings> advanced> compass and look at the interference indicator. You will be able to do your own seeing the interference indicator increase as you bring your drone to magnetically charged objects.
You may be surprised at how little it really does change but there are some things that will cause it to move a lot. In my experience the biggest issue is reinforced concrete. I like to take off on flat surfaces and I often find flat concrete surfaces to take off from however the iron reinforcement on the inside of the concrete causes significant Compass interference.
As a rule of thumb you should stay away from:
- power lines
- huge metal deposits like junkyards
- any large metallic structure such as sheds
- any large speakers – they have magnets on the inside
A Mavic owner tried to create compass interference by bringing his belt buckle, keys, and other personal effects close to the drone. It was only when the phone is a speaker was on top of the drone that there was significant interference. They note that the only consistent way to produce interference was to place a pocketknife on top of the battery compartment. So you don’t need to be too worried about having any metallic objects in your pocket or near the drone during takeoff.
To check that your calibration is good all you have to do is take off and do some yawing at an altitude of about 10 m. Check your screen and see if the movements correspond with the direction that the drone is being yawed. This simple check is something that will save you a lot of headaches if you are worried about compass miscalibration.
Calibrate the IMU
The inertial measurement unit is a device that is built into your drone and contains a load of different sensors to keep the drone running properly. Specifically, it measures the force, altitude, and angular velocity of the drone during its flight. These are measured through a series of different sensors that combine for a very powerful unit.
The sensors that it includes are the accelerometer, gyroscope, barometer, and thermometer. The gyroscope is a sensor that will detect the drone’s movements relative to the horizon level and it will be responsible for retaining the stability so that you can get some awesomely smooth shots that will not come out blurry. The barometer is used for detecting the changes in the height of the drone. And I think everyone knows what a thermometer is – it measures the temperature of the drone to make sure that the batteries do not overheat and start a fire.
All you need is an area that is sitting level and is stationary while you are calibrating the IMU.
This is what you need to do for a DJI manufactured drone:
- lay the drone down on a completely flat surface.
- Allowing the drone to cool down if it has recently been flown.
- Use a battery that is more than 50% charged.
- Open up the GO4 app.
- Turn on the controller for the drone
- navigate towards the advanced settings in the GO4 app and follow the calibration instructions.
The process for calibrating a mid range consumer drone varies from a mini drone. This is because a mini drone does not contain the same level of hardware to keep it stable during flight. Instead, it relies on something called “trimming” to keep it flying stable.
Calibrate the accelerometer
Accelerometer’s are present in every drone and they play a very important part in determining the stability of the drones flight.
Each drone is calibrated slightly differently due to the software differences as well as the hardware that each drone contains but all of them follow the simple basic steps whilst calibrating the accelerometer.
- Make sure the drone is held in the same orientation as indicated by the software that you are using to calibrate the accelerometer.
- Place the drone on a flat and stable surface and it is not moving.
- Initiate the software calibration procedure for your drone.
- Some require the drone to be powered off and on again. Follow all instructions on the software.
Here are some common drone models with a link to the best calibration methods that I have found.
|Drone Model||Link to the calibration method|
|DJI Mavic Mini||Youtube Link|
|DJI Mavic Air||Youtube Link|
|Parrot Anafi||Youtube Link|
|Syma X20 Mini Drone||Official YouTube|
|DJI Phantom 4 Pro+||Official Youtube|
There are also many scientific research groups which are looking at making drone accelerometer calibration more accurate. One such study published in 2018, shows that they are able to increase the accuracy of the accelerometer simply by running the calibration data through a different series of mathematical filters.
Update the firmware
Next, you should make sure that your drone is operating on the most up-to-date firmware available from the manufacturer. The firmware not only contains things like security updates and fixes to bugs and new features – it also contains fixes to common issues reported by drone customers.
Also, make sure that the remote controller is also up-to-date in terms of the firmware and that the DJI Go4 app or whatever app you decide to use to fly your drone is also the newest for your model of smart phone.
Never fly with less than 8 locked GPS satellites
Sometimes, it can be tempting to quickly take off without proper GPS satellite location lock. In DJI drones you cannot get GPS mode without at least eight satellites connected. If you don’t want your toilet bowling to happen again you should make sure that you have much more than eight GPS satellite locks before taking off. This will stop the drone going into ATTI mode unexpectedly during your flight.
Use an external GPS
If you have built your own drone you can decide to use an external GPS instead of the one which comes integrated with some other circuit boards. The GPS unit should be mounted far away from any electronic or magnetic interference. You can mount the GPS unit on a stand which makes it much less likely to encounter any significant interference from any other electronic components.
Twist ground wires
When you build a drone there are many wires running throughout the frame and body. You can reduce the amount of magnetic interference generated by these wires by twisting the wires together so that they cancel each other out.
This is a common tactic when building electronic devices which are sensitive to magnetic pulses or signals.
Looking at the .DAT files can help
Lastly, getting the flight data files off of the drone (you have to get off the drone not the controller] and analysing the data can help you understand exactly what is causing your toilet bowling. Sometimes there is nothing you can do other than send the drone back to the manufacturer and as for a replacement.
People on a number of different forums have also said that getting a replacement drone has help them overcome a range of other issues – this could be one of them.
Your drone toilet bowls because of conflicting information from a range of electronic components. One of the simplest solutions to this is to calibrate your compass and also update any firmware for your drone.
Learning to fly manually will be one of the best skills that you can learn to make sure that you are super comfortable while flying your drone even when it is toilet bowling.