When few months ago my older daughter (10 years old) started to express interest in FPV quadcopters, I was both happy and concerned. Happy, since I would have someone to fly with. Concerned, since she has no idea how to fly, I do not have a quadcopter for her and there is a big chance she will get bored fast. So, instead of getting her a brand new, cheap, standard off-the-shelf drone, I checked my repository of “spare” parts and drones, purchased this and that and week later “Omlette du fromage” came to life…
Is it worth to soft mount flight controller? Are gyro pads I recommended here better than rubber standoffs? I feel that they are better, but I do not have any solid data to prove it. So I can only tell, that I find them better and that is all. But, I can answer the question is it worth to soft mount flight controller at all. The answer is YES and here is a proof…
The problem of twitching motors
After I updated my 5" racer to stronger motors (EMAX RS2205S 2300KV over RS2205 2300KV) I noticed something very very irritating: twitching motors. When the throttle was in more less middle position or after rapid throttle change, twitching from motors was very audible. Quad was flyable, but performance was very low. I had to reduce yaw P gain by more than 50% not to see those twitches in FPV footage!
Blackbox log revealed the truth: from time to time, the strong vibration was getting into yaw gyro traces. I also localized the source of those twitches: stronger motors with more torque and higher radial acceleration were able to shake the whole machine when the frequency was close to the resonance frequency of the frame.
Did you ever wondered what is the most popular flight controller? Hardware I mean. I can tell you 🙂 OK, maybe it will not be a full truth, since I have data only from INAV, but assuming that distribution for Betaflight and Cleanflight is similar, we might know what is happening…
Important, this is not the number of boards flashed with INAV, but rather number of times a board was connected to Configurator!
This counts TARGET software name, not retail name. For example, all clones of Naze32 will be counted as Naze32
Data was taken in June 2017, multiple connections during single user session are stored as single entry. Continue reading And the most popular flight controller for INAV is…
I will not try to proof if you should soft mount a flight controller on a racing drone. I will only say, that few months ago I was against it, but lately I changed my mind. Stronger motors, stronger magnets, more torque, more speed and out of nowhere, incredible amount of noise can be fed into gyro signal. Sure, this is not required, but motors, ESCs and battery will thank you when you soft mount flight controller. Less, noise, less restrictive filtering required, lower signal delay, better flight performance.
In most places over internet you can find either a rubber standoff or double sided tape solution. Sure, that works, but there is something better. Dedicated, double sided adhesive, vibration dampening pads. There are many sources, and many names. I'm using Sekisui brand. Check ebay, Amazon, HobbyKing. Look for gyro pads, vibration pads, vibration dampening. I do not want to advertise any particular seller, so you are on your own here.
Because both original and Banggood clone of AnyFC F7 flight controller and missing buzzer support, its usefulness is somehow limited. There is no dedicated pin and driver. Next release of INAV (1.7.2) will finally solve this problem by reusing Motor #9 output as buzzer output.
But, some additional hardware will be required. To be precise, single n-channel signal MOSFET transistor like 2N7000. Connection diagram is shown below.
And this is how it can be soldered together.
That is all. Simple, right?
Thanks to Airbot I got my hands on a new STM32 F7 flight controller: Omnibus F7.
Before we proceed, small note.
I am a huge fan of F7 flight controllers. In a year, they will be a main line of high performance FC on the market. STM32F7 with built-in UART inverters solves so many issues STM32 F4 boards are facing. But, F7 are not there yet. Currently available boards uses STM32F745 CPU in 100 pin packages. They are just too big to comfortably fit 36x36mm format. You place CPU and most of the PCB is taken. Than means there is no space left for either connectors or OSD for example. What we are waiting are FC with STM32F722 in 64pin package!
In this episode I talk about:
- How to analyze Blackbox log for gyro noise
- How to find frequencies for gyro and Dterm notch filters in INAV, Cleanflight and Betaflight
In this episode I talk about:
- How Betaflight, Cleanflight and INAV filters gyroscope signals
- What is the difference between LPF and notch filter
- How to setup blackbox logs for precise gyro signal analysis
I’m not completely sure why, but I’ve been pushing this topic away for quite a long time now. But it’s finally time to present it in this blog too. So, here we go.
Something like 3 month ago I’ve started to record and publish a video series about basics of gyroscope data processing in modern flight controllers (Betaflight, INAV, Cleanflight). It started as a tutorial how to setup notch filters in INAV, but ended up as a much bigger thing. Series consist of 4 episodes where I use Blackbox logs to show gyroscope signal noise and how to fight with it. Over next few days I will be posting links to those videos here, but if you eager to see them sooner, just use this link.
In Episode 1 I talk about:
- Gyroscope noise sources
- How unfiltered, raw, gyroscope signal looks like
- How noise sources manifests in gyro traces
- How filtered gyroscope signal looks like
Ah yes, I’m running a YouTube channel too, feel free to subscribe 🙂
There is still very little about AnyFC F7 on the internet. Especially pinout is kept secret. Without sambas official GitHub repository for hardware projects, there would be nothing at all. I’ve decided to close that gap a little and prepared full pinout for AnyFCF7.
Yes, I know they are hand drawn and scanned, but I have a strong aversion for computer graphics software. I can move a slider left and right, but every time I have to do some creative photoshopping, my head starts to hurt. This is extremely ironic, since my major at university was computer graphics. Heh…