by Altix » Mon Mar 16, 2015 9:43 am
Hi Axel,
actually, I’m working on a similar project. Its one of these popular 250 sized Mini H quads, which are not perfecty square. Electronics are the M4, a Get em expansion board, 18A KISS, MN1806 clones, 6*4,5 HQ props and a 3S 1.800 mAh Nanotech LiPo. I have another Mini H with the same electronics, but a Naze32 with baseflight instead the M4, and additionally, I have a Mini Hexa with the same motors, ESCs and props, but a NanoWii as FC. The latter two ones are flying very well and flying with speed is a lot of fun. That means, the motor, ESC and prop combo is nothing exotic and is proven to be a good combination of components.
My experience so far is, that the default PID are far too high for these little devils. I first came down to similar values as you did, and it were the same parameters as those you mentioned, that had the highest impact on the flying behaviour (Tilt Rate D, Tilt Angle D, and Tilt Angle P). The result was not exiting, but at least the quad was flying on an acceptable level. The problem I had at that stage was, that the motor values in the logfiles were still too high and the graphs showed „clipping“. That’s why I further reduced those three parameters roughly to one third, if I remember correctly (I’m sitting in the office right now with no access to my data). Now, the clipping almost disappeared and the quad is still flying fairly stable. But now, I have a new problem: the agility is very poor and the reaction on stick commands is so slow, that flying is no fun (flying with the values before was not much better and very poor compared to the performance of my Naze32 or NanoWii). I could solve the problem on yaw by increasing the deg/s parameter to around 180, but pitch and roll is still a mess.
I don’t want to hitchhike your thread here, and because I have similar problems with a much larger X8, I will open a new thread on that. But I can confirm, that the default PIDs are far too high for these type of small quads. May be, that Quatos will be the final solution, but for the timebeing I will continue on the PID thing, as it must be possible to get this devil flying just on PID tuning.
Regards, Michael