Quadcopter cannot balance!

Question

I am bulding a quadcopter using these compenents:

Microcontroller: Tiva C Lanchpad (ARM Cortex M4 - 80 MHz), but running at 40MHz in my code
MPU 9150 - Sensorhub TI
ESC - Hobbywing Skywalker 40A

I use the sample project comp_dcm from Tivaware and use that angles for my PID which running at 100Hz

I test PID Control on 2 motors, but the motors oscillate as in the video i found on youtube from one guy!

I'll start with the obvious question: Have you tuned the PID? — Rocketmagnet, Commented Sep 4, 2014 at 20:55
we tune the PID so many times, and the same problems. Even though that the P Term is very small — Earthgod, Commented Sep 5, 2014 at 12:50
Also the I term can make it unstable... just use a P term and rest to zero for first try — TobiasK, Commented Sep 5, 2014 at 18:21
I tune the quadcopter with just P component, and the way i did is starting with very small kP to larger kP. But the same problem occurs, with very small kP, but the quadcopter cannot balance, and actually it oscillates as shown in the video! I think about many solutions such as: the angle updates too slow, or the MCU computation is too slow... — Earthgod, Commented Sep 6, 2014 at 2:47

Mark Omo · Accepted Answer · 2014-09-10 02:39:40Z

4

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 oscillates and turn it down again to just below that point
Your code is running too slowly (this can cause all kinds of odd errors)

answered Sep 10, 2014 at 2:39

Mark Omo

1,91413 silver badges23 bronze badges

Add a comment |

Ian · Accepted Answer · 2014-09-16 18:54:32Z

0

It looks like your I term is turned up too high. This can cause the system to overcompensate before it has even started to return to equilibrium.

answered Sep 16, 2014 at 18:54

Ian

11k3 gold badges24 silver badges65 bronze badges

Add a comment |

2 Answers 2