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 ...
- 4,386
11
votes
Accepted
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 ...
- 15.9k
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 ...
- 1,843
7
votes
Accepted
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 ...
- 450
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 ...
- 1,909
7
votes
Accepted
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 ...
- 1,355
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 \\
...
- 15.9k
5
votes
Accepted
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. ...
- 331
5
votes
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What's wrong in controlling Roll+Roll rate in a quad-copter instead of using 2 separate loops for each?
That only works when the desire roll angle is 0. What happens if you are trying to turn and have a desired roll angle of 1deg? Even changing your sum to match the angle error, $w_1 (\theta - \theta_d) ...
- 2,794
5
votes
Accepted
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 ...
- 1,811
4
votes
Trying to calculate the Thrust of my quadcopter motors
Thrust is a force. You probably have a device in your house to measure force: a scale, so why not determine the thrust empirically?
Build a little mount to place the prop on a scale securely.
Tare ...
- 1,425
4
votes
What exactly are PPM controlled ESCs? Are most ESCs available to build quadcopters PPM Controlled?
I believe there is confusion about these terms. Strictly speaking, the ESC is PWM controlled. Although the signal usually gets there from a transmitter and receiver signal that is PPM encoded.
It ...
- 1,047
4
votes
How to have a 'Auto Go Home' feature, like the DJI Phantom 3, on a project built quadcopter?
I would go with one of two-ish methods to do this, but both methods require the craft to know its own position. You could do this with GPS, or an IMU, or any other means or combination of position ...
- 15.9k
4
votes
Accepted
Will a 5200mAh 30C 22.2V 6S Lipo battery work with
Your motors are rated for 466W max, which with a 6S battery gives about 20A max current draw per motor (This also tells you your ESC are a good choice, provided that they can handle the 6S voltage).
...
- 550
4
votes
Accepted
PID Control: Integral error does not converge to zero
I don't think this is related to integral windup at all.
I noticed that the I-error does not converge to zero
That's a good thing, because it means your integral term is not useless.
The integral ...
- 1,425
4
votes
Accepted
Quadrocopter PID
Technically, you can do it either way, but consider the following scenario: You are flying with a heavy load, and there is a wind gust. Each rotor is operating at almost 100% capacity due to the heavy ...
- 15.9k
4
votes
How to compensate the brushless DC motor for voltage drop?
STOP USING YOUR BATTERY IMMEDIATELY!
First of all you shouldn't let the voltage of a lipo battery drop below 3V per cell which in your case comes to 12V. Lipo Batteries are extremely dangerous and ...
4
votes
Accepted
Holonomic and Non-holonomic UAV's: Gliders vs Quadcopters
The glider definitely is a nonholomonic system, but not (only) because it has no propulsion.
As Wikipedia defines it:
A nonholonomic system in physics and mathematics is a system whose state depends ...
- 6,632
4
votes
Accepted
Paradox: I can't use accelerometer measurements to obtain information about my states in a quadcopter?
I encountered the same puzzle. I had a clue at the beginning that the gravity information is contained within accelerometer measurements due to aerodynamic drag. Then I found a paper The True Role of ...
- 56
4
votes
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Detection of linear acceleration vs rotational velocity/acceleration
The IMU itself cannot distinguish between "true" linear acceleration and "fictitious" (Coriolis) linear acceleration induced by rotation of the IMU coordinate frame with respect to ...
- 245
4
votes
Accepted
What is the consquence of Gimbal lock?
I made a clip for you (https://i.stack.imgur.com/Z0q5Y.jpg) using Unity, which internally represents rotations as quaternions, but uses Euler angles for display and positioning.
You can see that, at ...
- 15.9k
3
votes
Accepted
thrust measurement
Okay I thought I'd move this to an answer because I think this will help clear up some confusion you have.
First, if you are trying to plot RPM vs Thrust, then your battery, ESC, power, etc. have ...
- 15.9k
3
votes
Orthogonal projection of laserscanner data
Use the location and attitude measurements of your craft to develop a 4x4 transform matrix, then take the inverse of that matrix to put the points you measure back in terms of world coordinates. Then, ...
- 15.9k
3
votes
How Should I tie My quadcopter to some thing, to adjust pid on one axis
Since you're trying to adjust the stability, you should make sure that your method of restraint isn't restricting the motion along that axis.
So, the preferred way to restrain a quadcopter is by ...
- 11k
3
votes
How to use quaternions to feed a PID quadcopter stabilization loop?
This paper, Full Quaternion Based Attitude Control for a Quadrotor by
Emil Fresk and George Nikolakopoulos, demonstrates what you are trying to achieve.
Abstract— The aim of this article is to ...
- 31
3
votes
Accepted
Deciding length of quadcopter arms
For the most part, it will increase the gain of the controller.
doesn't affect lift capabilities.
Adding weight to something that flies always decreases lift capabilities. However, this influence ...
- 1,425
3
votes
Displacement with accelerometer
This will depend on what you mean by "displacement" and for how long you want to do this. Can you supply more details on what your trying to accomplish and why?
As Bending Unit 22 mentioned, you ...
- 106
3
votes
Quad Copter flight module can replace with smart phone?
A project like this was already thought and working.
It was proposed from Vijay Kumar, one of the gurus of quarotor helicopers (that is the name he thinks it is the most appropriate for these ...
- 211
3
votes
For a quadcopter: Premade flight controller or custom made?
It all depends on your experience and comfort in coding and understanding the navigation algorithms needed to allow the drone to fly autonomously. Most flight controllers on the market come with ...
- 69
3
votes
Filtering angular velocity spikes of a cheap Gyroscope
You gave the part number and protocol, but
Can you provide a schematic for how this is installed in a circuit?
Are you using the module or an individual chip?
Is this all soldered together or is it ...
- 15.9k
Only top scored, non community-wiki answers of a minimum length are eligible