Large wooden BiCopter

You just know a great project when you see one. Like, for example, large BiCopter made from wood and running INAV and flight controller software that kermets has built.
BiCopters might look strange, but the idea is quite simple. Instead of 4 motors, we have 2 motors and 2 servos tilting the motors. Like a one step further from a tricopter.

Similar idea (not the same, only similar) is used on large helicopters like Boeing CH-47 Chinook

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INAV jumped over the bench

Let's say I have almost a good news about sonar support in INAV: yesterday I flew terrain following mode with experimental INAV code. And did not crashed when shooting video below. I did crashed next code version, but that is only a minor detail, right?

  1. When shooting that video I did not touched throttle stick. Altitude control was 100% automatic
  2. It is US-100, not HC-SR04 ultrasonic rangefinder!
  3. US-100 was connected to Omnibus F4 Pro using experimental I2C interface with ATtiny85
  4. If you want to try it, here is the code. But be prepared to crash 🙂

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Chasing airplanes is cool

Chasing airplanes with drones is cool. Do not try to argue 🙂 But airplanes are cool too. So here is a short video my friend shoot some time ago:

Drone pilot: Krystian

Flying wing pilot: me (I had no idea I was chased)

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GPS Racer: worklog #7 – flying at night

Like promised, I took GPS Racer equipped with night vision camera RunCam Night Eagle and IR projectors for a night flight. And it worked. Not as good as I expected, but worked.

  1. RunCam Night Eagle is sensitive enough to fly at night. Just like that. As long as there is at least some light, you can fly. In my case, full moon and some residual light was fully enough
  2. IR projectors (3W in total) are underpowered. They help, but up to 3-4 meters. Not any further
  3. Propellers flooded with IR are no bright… I will have to look for some black props…
  4. OSD started to flicker out of the blue. I suspect new BEC for IR projectors introduces some noise. I will have to fix it somehow…

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Gyroscope and filtering video tutorial – Episode 1

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 🙂

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INAV 1.8: Automated landing for fixed wings

It's official: next release of INAV (1.8 or maybe 1.7.2) will incorporate an automated landing procedure for fixed wings. I was already writing about it 2 weeks ago, but now new code has been merged back and will be released.

Bear in mind, that this is not "state of the art" landing yet. It's rather a simple solution that can be used in emergency situations that will not crash an airplane, but rather put it on the ground without crashing. Procedure is quite simple:

  1. When Return-To-Home or Failsafe with RTH is engaged, go to Home position
  2. When Home is reached, start to loiter with defined radius and descend. Descent speed is limited to nav_landing_speed when altitude is above nav_land_slowdown_maxalt. When altitude is below nav_land_slowdown_maxalt, vertical speed is scaled down to one fourth of nav_landing_speed at nav_land_slowdown_minalt. So, on using default values, vertical speed is between 2m/s and 0.5m/s
  3. During descend, airplane is not allowed to raise throttle above nav_fw_cruise_thr when nose is up. This is to prevent airplane from gaining horizontal speed
  4. When nav_land_slowdown_minalt is reached, ROLL axis is locked to 0 degrees, PITCH axis is locked to nav_fw_land_dive_angle (default is 2 degrees) and motor is stopped when MOTOR_STOP is used or put to IDLE when MOTOR_STOP is not used. This puts airplane into a shallow dive to the ground

fixed wing landing in inav

That is all. Airplane should glide last few meters to the ground. Most designs should be able to do it without a problem. My testing platform did it like that:

Since there is no auto-disarm procedure yet, MOTOR_STOP is recommended to prevent propeller from breaking and motors/ESC from burning.

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FS1000A and XY-MK-5V range test

Very often, where you go cheap, there is a price to pay. Exactly like with cheap 433MHz transmitter-receiver pair of FS1000A and XY-MK-5V. You rather do not expect much for $1, right?

When playing with them in a middle of a big city (Berlin), few meters of range was all those modules were able to archive. Too much interferences form other devices. But what about open space in a middle of nowhere? I’ve decided to test that, and this is what I came up with:

If video was too long: 315m apart, no direct line of sight between transmitter and receiver and still stable data flow! It would be more, but nature was against me and I just was not able to go further. I did not expected that much range from those two…

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