CODEWITHSUNDEEP
javaheightballoonaltitude
Magic Rune
Magic Rune

Reputation: 11

Algorithm to make balloon fly to specified altitude/height

I'm looking for a way/algorithm to make a robot balloon fly to a certain altitude. The robot is controlled by a Raspberry Pi and has a propeller. Propeller speed can be set to several values (it uses PWM so technically 1024 different power outputs). The balloon has a distance sensor pointing down, so it's possible to get the current height several times per second. Only idea I had so far was to measure the height constantly and set to max speed based on the height left to travel. This doesn't seem like the best option though, but can't figure out how to fit all power outputs in.

Any ideas would be welcome. I'm using Java to code the project but any high-level algorithm/description would be great!

Thx,

Magic

Upvotes: 1

Views: 713

Answers (2)

MadConan
MadConan

Reputation: 3767

Pseudo code. 

  while(true){
    val height = getHeight(); // from sensor

    // Get the difference between the current height and
    // the TARGET height.  Positive values mean too low
    // while negative values mean too high
    val offset = TARGET_VALUE - height;

    // Set the power to some direct ratio of the offset
    // When the baloon is at 0 height, the offset should 
    // be relatively high, so the power will be set 
    // high.  If the offset is negative, the power will be 
    // set negative from the current power.
    setPower(offset);// I'll leave it up to you to figure out the ratio
}

Upvotes: 1

TwoThe
TwoThe

Reputation: 14289

There is a great "game" available that lets you try and play around with exactly that problem: Colobot (seems to be open source now). Create a Winged-Grabber (or shooter if you are more the FPS type of person) and try to get it to fly to a specific destination using only the altitude and motor controls.

in general the Pseudo-Code by MadConan is the way to go, however the main task lies in writing a smart setPower function. In the end you need some smoothing function that reduces the power in relation to how close you are to your desired altitude, however the exact values of that function completely depend on your hardware and the weight of your final system.

Depending on how valuable and/or fragile your setup will be in the end, you might want to develop a learning system, that takes the under-/overshot as a basis to adjust the smoothing function while it runs. Make sure to take factors like up-/down-wind into your calculation.

Upvotes: 2

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