INAV for tracked rovers

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INAV 2.5 introduced rover and boat support. However, INAV setup on tracked vehicles like tanks or with differential steering was never really working like expected. Turning was possible but only in forward or backward movement – throttle had to be not-idle. And that meant that turning in place was not an option.

Luckily, the INAV Programming framework can be used to build a fully functional tracked vehicle/differential steering mixer. Here is a short tutorial on how to do it.

You will need:

  • INAV compatible flight controller
  • INAV 2.5.2 or newer
  • tracked or other differential steering vehicle with two bi-directional ESC

Outputs Tab

Enable Reversible Motors Mode

INAV on tracked vehicles - Outputs

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Fat Shark was sold to Red Cat Holdings

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Have you heard the news of the month? Apparently, Red Cat Holdings bought Fat Shark. Ha! Yes, the Red Cat that in 2018 wanted to buy your blackbox log and pay for them with their own cryptocurrency and in January 2020 bought Rotor Riot. The question remains if it is good for the hobby or not. Personally, I'm kind of worried…

The full news about the event is available here

My commentary with some extra context is here

FlySky FRM302 and FTR16S AFHDS3 receiver = 2.4GHz Long-Range radio system

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ImmersionRC Ghost is the new long-range 2.4GHz radio system that is getting the most traction in the media in the last few days. However, IRC Ghost is not the first 2.4GHz SX1280/SX1281 LoRa based radio system that has hit the market. FlySky FRM302 TX module and FlySky FTR16S AFHDS3 receiver are available since May 2020, and underneath, they are the same technology as Ghost.

FlySky FRM302 2.4GHz long-range module and FTR16S AFHDS3 receiver

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ImmersionRC Ghost – what do we know about it?

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If you ever wondered what is ImmersionRC Ghost and how it differs from the Team BlackSheep Crossfire or FrSky R9* long-range radio systems, this video is for you. In around 15 minutes I get through all the main features of IRC Ghost like:

  • frequency
  • LoRa modulation
  • protocols
  • update rates
  • hardware
  • antennas
  • transmitter module diversity
  • receivers

If you would like to read more on the topic, instead of watching, you can go to this link and consume the knowledge anytime you want: ImmersionRC Ghost 2.4GHz long-range radio system

Jumper T18 Review

Jumper T18 radio transmitter and FrSky R9 receivers

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One of the advantages of the Jumper T18 over its competition is the JP5in1 Multiprotocol Module compatibility not only with 2.4GHz FrSky and FlySky receivers but also with Long-Range FrSky 868/915MHz R9 system. At least in theory, because when I got the radio, I could not bind and use any of my R9MM or R9 Mini with the Jumper T18. However, to make it work, all that is required is to update the firmware of Jumper T18, JP5in1 Multiprotocol Module and, in some cases, in R9 receivers.

Jumper T18 Multiprotocol Radio

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ImmersionRC Ghost 2.4GHz long-range radio system

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ImmersionRC made a surprise and showed a new RC radio link called Ghost. And trust me, this thing, if it will get adopted, will revolutionize the FPV we know today. Why? Because it's a combination of two worlds: 2.4GHz band and LoRa technology known from TBS Crossfire and FrSky R9 systems. All the details of Ghost are not public yet, but based on the manual, specification, and other external sources, I've been able to compile a list of essential things about IRC Ghost.

ImmersionRC Ghost radio system

It is a LoRa system

ImmersionRC Ghost works in 2.4GHz band, but it's into the same technology as existing 2.4GHz radios from FrSky, Spectrum or FlySky. Instead of "traditional" FSK only RF chipsets like Texas Instruments CC2500, it uses Semtech SX1280/SX1281 (I have no solid proof which one exactly but I suspect it's a SX1281) that support both FSK modulation and LoRa. Yes, the same LoRa technology that stands behind TBS Crossfire and FrSky R9.

I will not go in details what LoRa is, but it's super clever Chirp Spread Spectrum modulation that has high sensitivity and can pick up signals that are below Noise Floor. So yes, it can do Long Range for dozens of miles, and you will sooner lose FPV feed than 2.4GHz LoRa signal!

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inav flight controller

INAV 2.5.2 – what is new, and should you upgrade?

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The patch release of INAV, version 2.5.2 was released just today. Below you will find the list of the most critical changes and advice if to update from 2.5.0 and 2.5.1 to 2.5.2.

Bug fixes:

  • Fixed a bug that affected INAV OSD menu for editing servo mixer weights. It was not possible to have negative weights. Right now it is possible to edit both positive and negative servo mixer rules
  • Fixed buffer overflow in OSD code
  • Fixed RPM Filter center frequency computation bug that was introduced in INAV 2.5.0. INAV 2.5.2 correctly handles RPM Filter and sets dynamic notch filters in on correct frequencies

New targets:

  • Flywoo Goku F411 micro flight controller suitable for all 2 and 3-inch builds with 16x16mm mounting holes
  • Flywoo Goku F7 Dual and Flywoo Goku F7 Mini flight controllers
  • Foxeer F722 V2 and Foxeer F722 Mini
  • HGLRC Zeus F722
  • SpeedyBee F7 STM32F722 flight controller with integrated BLE Bluetooth module for SpeedyBee app

Should you upgrade to INAV 2.5.2

You should upgrade all drones and airplanes if you are using INAV older than 2.5.0. Older versions of INAV are no longer supported and INAV 2.5 family has many bugfixes and improvements.

If you are using INAV 2.5.0 or INAV 2.5.1 then upgrade is highly recommended for multirotor users as it fixes issues with ESC Telemetry and RPM Filtering. It is also a very simple process since when updating from INAV 2.5.x there were no settings related changes.

Is Bidirectional DSHOT required for RPM Filter?

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There is a group of people who think that the RPM Filter is the best thing to happen to flight controllers and quadcopters since the sliced bread. Perhaps. I’m more inclined to believe that RPM Filter is just an example of good functionality. But it will not be about that, so let’s go back to the topic.

motor RPM telemetry data

Joshua Bardwell asked me a question if INAV uses ESC telemetry for the RPM filter. The answer was, of course: yes, INAV has no Bidir-DSHOT support, and 4th wire is required for RPM filter in INAV.

But the latency and jitter makes it unusable. Isn’t that the whole reason for bidirectional dshot development

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ZOHD Drift

ZOHD Drift Review – a smart FPV glider

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Airplanes are fun, and I like to fly them. Unfortunately, most RC airplanes have a severe flaw: they are big, bulky, and traveling with an FPV airplane can be a pain in a posterior. Sure, some can be disassembled into a few smaller parts, but usually, those parts are not small, and assembling the airplane is time-consuming. On top of that, the 250g weight limit hangs like a sword of Damocles over the RC hobby’s head. Everything gets so bloody complicated. And here comes the Drift!

ZOHD Drift FPV Glider Continue reading “ZOHD Drift Review – a smart FPV glider” »

inav flight controller

How popular INAV actually is?

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Let’s be honest. INAV is not the most popular flight controller software in the world. Both Ardupilot and Betaflight are more popular, and no one can deny that. Still, the question is: how popular INAV actually is and how many people use it on how many builds?

I can not answer most of those questions. First of all, there is no way to know how many drones or airplanes out there use INAV. We have some statistics, but they can not answer this particular question. However, thanks to the way INAV is distributed, it is possible to extract some statistics from GitHub itself. I put up a short script that parses GitHub API and here are the results!

In total, all INAV firmware files since the first release (that was January 2016, 1639 days ago) were downloaded around 1.1 million times! That gives 707 downloads a day!

Is that a lot? Hard to tell, but it’s much more than I expected—around 5 times more than my guestimate. Kudos for us!

While we are here, would you like to know how many times INAV 1.0 was downloaded? 3056 times. Not very impressive number 🙂