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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 ...
SteveO's user avatar
  • 4,396
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 ...
Chuck's user avatar
  • 16k
10 votes
Accepted

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 ...
holmeski's user avatar
  • 1,853
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 ...
Szczepan's user avatar
  • 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 ...
Mark Omo's user avatar
  • 1,919
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 ...
FooTheBar's user avatar
  • 1,375
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 \\ ...
Chuck's user avatar
  • 16k
6 votes
Accepted

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 ...
Adam Williams's user avatar
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. ...
Mark's user avatar
  • 331
5 votes
Accepted

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) ...
ryan0270's user avatar
  • 2,814
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 ...
edwinem's user avatar
  • 1,871
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 ...
Chuck's user avatar
  • 16k
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 ...
WizardOfRobots's user avatar
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 ...
50k4's user avatar
  • 6,682
4 votes
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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 ...
V. Yao's user avatar
  • 56
4 votes
Accepted

What is the consquence of Gimbal lock?

I made a clip for you (https://i.sstatic.net/Z0q5Y.jpg) using Unity, which internally represents rotations as quaternions, but uses Euler angles for display and positioning. You can see that, at zero ...
Chuck's user avatar
  • 16k
3 votes

Why do I need I-gain in my outer-loop?

Integral gain is how you eliminate steady state error. An integral gain in the inner loop means you'll (eventually) have no steady state error on the angular velocity. What ensures no steady state ...
Chuck's user avatar
  • 16k
3 votes
Accepted

Why do I need I-gain in my outer-loop?

In my own experience, it is not necessary Integral term in any of these loops. I got a fine PD tuning of both inner and outer loop. See for instance this paper, where I firstly tuned PD only with PSO. ...
galtor's user avatar
  • 470
3 votes

Can i use DC Brushed motors for building a drone?

I would definitely look at a brushed motor when the budget is low. They have a reputation of being less powerful, but the main problem is they have a very high RPM. This means you either have to use ...
Henning Pedersen's user avatar
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 ...
Sandesh's user avatar
  • 69
3 votes
Accepted

Real-time object classification for an indoor autonomous quad-rotor

tl;dr - SLAM is good enough for your task. The ceiling is the area where your robot will be traveling in. Few things to notice - Ceiling is fixed and not changing. Things on the ceiling are fixed as ...
Tvaṣṭā's user avatar
3 votes

How can a quadcopter be made to hover perfectly still?

Using existing resources: Very similar answer to @SteveO - I'd focus on tuning the PID control loop for each motor individually, if possible, to eliminate any instability in the power delivery which ...
Mr Karoshi's user avatar
3 votes
Accepted

Are all Flight Controllers and Remote Controls using the same protocol?

There are standard protocols, and then there are proprietary protocols. The choice of what protocol to use depends on many things. Without listing the precise set of flight controllers you are ...
Ian's user avatar
  • 11k
3 votes

Arduino or Raspberry Pi?

The only issue with having the off-board controller is that the commands to the quad-rotor might lag, because of 1. range to controller or 2. the complexity of image processing code. With that said I ...
sgk525's user avatar
  • 31
3 votes
Accepted

Can I use a 3D gimbal system as a simplistic quadcopter IMU(3 axis accelerometer)?

A gimbal system will not replace an accelerometer. I assume by gimbal system you mean something like a Gyroscope, i.e. a device that has a fixed orientation allowing you to measure your orientation ...
BarbalatsDilemma's user avatar
3 votes
Accepted

Multiple robots in ROS Gazebo SITL with separate MAVlink/MAVproxy codes

I feel like I'm having to do a lot of work to understand this question. You are trying to simulate two vehicles, and... what's the issue? You are trying to simulate them in Gazebo, right? Have you ...
Chuck's user avatar
  • 16k
3 votes
Accepted

What kinematic equations should I use for Kalman filter state propagation in IMU based quadcopter navigation?

The first form, from both the math and the webpage to which you link, is for linear motion only. Tie a string to a rock. Swing the rock around in a circle above your head at a constant speed. If you ...
Chuck's user avatar
  • 16k
3 votes

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

Accelerometers measure kinematic acceleration with the addition of gravity. So for an accel to measure 0, the vehicle would need to be accelerating downward at $g$. To get inertial acceleration out of ...
holmeski's user avatar
  • 1,853
3 votes
Accepted

Can high voltage power lines provide a super highway for drones?

Sure, a drone can land on a powerline. That's a standard task like the "peg in hole problem" for robotarms. The aim is to maneuver a UAV near to a highvoltage line and eating all the energy. The ...
Manuel Rodriguez's user avatar
3 votes

Can high voltage power lines provide a super highway for drones?

I think yes it can but how? My options are here: Static system for conventional systems It should stand or hang to line/pole/special place like birds. Please watch video for an example: https://www....
acs's user avatar
  • 1,124

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