11 votes

If I must fly my drone in bad weather, how can I maintain control of it in strong winds?

In controls this is known as disturbance rejection. In order to sustain your motion in the presence of high winds you need the controller to be as responsive as possible, and an accelerometer would ...
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  • 4,326
11 votes
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Quadcopter PID Algorithm

The glaring issue I see at the moment is that you are forcing polarity on the I and D terms. In general, you are using a lot of sign checks, sign assignments, and conditional programming. None of that ...
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  • 14.7k
10 votes

Need help calculating the thrust on quadcopter motors

You could probably calculate this value, but the sensible thing to do would be to just measure it directly. Just turn it upside-down and put it on a kitchen scale as shown in this video.
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  • 10.8k
10 votes
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Virtual Testing Environment for Drones

For testing simple algorithms, you might be able to get by with a 2D simulator. There are a few out there that I am aware of: Stage: http://playerstage.sourceforge.net/index.php?src=stage STDR: http:/...
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  • 298
10 votes
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How can we use the accelerometer for altitude estimation?

The barometer carried on the pixhawk has an altitude resolution of 10 cm. If that isn't enough, you could write a kalman filter that uses the accelerometer data in the prediction step and the ...
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  • 1,825
8 votes
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How do quadcopters turn left and right?

This is video is from an Edx course on Autonomous Quadcopters...It is 10 minutes and goes over the "Flying Principle" of quadrotors. But basically what you are missing is the reactions. The famous ...
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8 votes

Drones and camera streaming

It all depends on the video quality that you require. The short answer is to use a 3G or 4G transmitter, assuming that you are in an area with mobile coverage, to either a local device (Mobile phone) ...
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  • 1,284
8 votes
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How to calculate quadcopter lift capabilities?

Similar answer to this post: Choosing motor for a tricopter This depends on what you want to do with your copter. Hovering: 100-150 Watt/kg ScaleFlight: 200-300 Watt/kg Some chilling acrobatic ...
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  • 1,647
7 votes

How to estimate yaw angle from tri-axis accelerometer and gyroscope

Assuming your vehicle is roughly horizontal to the ground, you won't be able get a good estimate of yaw from the accelerometer. Consider the nominal case: when your accelerometer is pointing straight ...
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  • 2,679
7 votes
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Stabilizing a Drone

Gyro is needed to stabilize angular acceleration. Knowing only your attitude, drone doesn't know how fast on which axis is rotating, knows only where is gravity ...
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  • 440
7 votes

Explanation of Quadcopter Dynamics, Components and Control

A couple things, the first is that the controller does not really care what the "real" values are. Everything is relative, if the controller sees that it is sinking it will increase the thrust until ...
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  • 1,909
7 votes
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What is the purpose of these grey balls on the drone?

These are markers for a visual Motion Capture system. Buy some markers here Most MoCap systems work by setting up multiple cameras with strong IR-Flashes and IR-Cameras and the surface of the balls ...
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  • 1,335
6 votes

What is the minimum number of RC channels required to control a Quad Copter?

Ironic answer: you do not need any channel, but your quadcopter will just hover stationary :) Practical answer: The throttle controls translation on the vertical axis. This allows you to gain or ...
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  • 478
6 votes
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How to use quaternions to feed a PID quadcopter stabilization loop?

A quadcopter contains (among other things) two separate and independent algorithms: an attitude estimation algorithm, and a control algorithm. The attitude estimation algorithm computes information ...
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  • 478
6 votes
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Position Controller for a Quadrotor

By far, the most common solution to this problem is to use 2 separate controllers. The inner loop controller is what you already have: it tracks angle and height commands. The outer loop controller ...
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  • 2,679
6 votes
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Can a quadcopter hover while tilted?

In a normal quadcopter configuration, if you tilt you will be pointing some of the lift force to the side. The only way to hover at a tilt, then, would be to somehow apply a counter force. A standard ...
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  • 2,679
6 votes

Paradox: I can't use accelerometer measurements to obtain information about my states in a quadcopter?

If the drone is not falling (holding height in the sky), and it's not accelerating in any particular direction, then the accelerometer should be reading: $$ a = \left[ \begin{array}{} g_x \\ g_y \\ ...
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  • 14.7k
5 votes

How frequently should a PID controller update?

1) I would try find out how fast your ESCs can update and use that as the PID update rate. Your current rate is definitely too slow (need at least 50Hz for marginal performance). 2) Putting a ...
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  • 2,679
5 votes
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How to estimate yaw angle from tri-axis accelerometer and gyroscope

Gyroscopes will only give you the rate of change of the yaw angle, not the absolute yaw angle. Unless you plan to set the yaw angle initially and have it drift further and further into garbage ...
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5 votes
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How do you calculate the moment of inertia of a Quadcopter?

You can calculate the moment of inertia of a pendulum by measuring the period of oscillation for small amplitudes. Suspend the quad by one arm and give it a little push and time the period. It does ...
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  • 1,825
5 votes

Powering a multirotor with dedicated batteries for each motor

There are a few ways to read your question, but in general what you are suggesting is a bad idea. The only reason to do it would be in the extreme case where splitting a large battery into several ...
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5 votes
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How do safety cages around quadcopter rotors/blades affect lift capabilities?

To what degree are you looking to cage the fans? IP code gives some grades for fan protection, which may help you decide or even find some stock guards. Level 'A' protects against striking by the back ...
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5 votes
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Arduino or Raspberry Pi?

For interfacing with a camera, I would recommend the Pi. The reason is that the AVR in the Arduino is an ordinary processor, whereas the Broadcom SoC in the Pi was originally designed for multimedia. ...
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  • 321
5 votes
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What flight firmware stack is most common in aerial robotics research environments?

It is usually a combination of 2 different pieces software. Generally a higher level software which implements most of your autonomy, advanced navigation algorithms, and a lower level software which ...
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  • 1,571
4 votes

Quadcopter forward speed

As you said, as AlphaP increases, the amount of upward thrust decreases, and when AlphaP = Forget about speed. This idea that each propeller is capable of 100mph isn't that helpful. The problem is ...
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  • 6,337
4 votes

Quadcopter degrees of freedom

I think that it is important to recall that a rigid body in space has 6 Dof without considering quantum or relativistic effects ;). So if you use the newton equations, written in an inertial frame of ...
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4 votes

Quadcopter cannot balance!

A couple possibilities come to mind, PIDs need tuning, this is relatively simple (entire books have been written on it) Basically, set the I and D terms to 0 and slowly move up the P term till it ...
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  • 1,909
4 votes

Control a 2.4 Ghz AR Drone from the computer

The simplest way to do this, is to buy a more advanced PPM transmitter that has a trainer port, and use this PCTx device to control it from your PC through USB. They provice a simple library and some ...
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  • 193
4 votes
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DualCopter Degree Of Freedom

A dualcopter, of the form you are talking about, can control all roll, pitch, yaw and it's altitude. To do so, it employs two rotors running in opposite directions to cancel any torque. This would ...
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4 votes

How would i go about learning to code a flight controller?

Controlling a flying robot (or anything else) is a very complex subject (well, people are doing PhD on it..). I can recommend this free online course on the subject (I have taken it myself). It will ...
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