DIY strain gauge sensor for a Winwing Viper Grip

[DracuOrc]

Hi there,

As per the title, I am (re)searching, building and testing a solution to make a strain gauge sensor Pitch/Roll/Yaw that can fit to a Winwing Viper Grip.

In real life, F-16 stick does not move like a normal stick, it only measures pressure applied by pilot hand. OK, there's a Netherlands F-16 variant where the stick moves +/-3 deg if I am not mistaken.

I started some time ago with these tests. Two beams 10x2mm ( Alu 6063 T6 alloy ) that are narrowed at the strain gauge position. They are assembled using 3D printed parts: a central part that keeps the cross and fixes on the grip and another 2 Rings that are fixing the crosses ends then on a base (table).

 

Below my test variants ( in a picture). They all supposed to have advantages and one should have stand ahead with the most.

In above picture no. 5 is actually simplified no. 2 or no. 3 where I removed Yaw so only the cross beams are used.

No. 5 before the Viper grip is assembled. Inside there are visible - the two cross beams and strain gauges installed. 

null

As electronics I use a STM32F411 MCU running at 100MHz and that has libraries for USB HID devices, so it can make a Joystick with 3 axes and 64 buttons for Windows on it's onboard USB. Also a half-duplex serial UART connection is used to read all buttons of the the Viper grip then sent to Windows by the same HID USB.

For each axis 2 strain gauges are connected in a half Wheatstone bridge in pairs ( 2x for Pitch and 2x for Roll ) then connected to a HX711 board that converts and sends values to MCU. 

The sensor as it is now is really sensitive, it reads from the HX711 ( calibration on MCU startup ) +/- 4.000.000 ( max range of HX711 is +/- 8mills ) with an offset up to 50.000 .  Below values during tests - pulled the grip by hand ...

And some graphs with values on Pitch (Trace-1) and Roll (Trace-2) ... 

I also done some bending simulation in  a 3D CAD and results are quite consistent with the measurements. Actually the simulation helped to determine the best location on the beams for the strain gauges.

I have a question - if did anyone build/tested recently something similar ?

My only issue now is that I still could not find a solution to embed the Yaw sensor using simple tools and materials ( or without complicating the solution too much ... )

If there's any one interested, I can share more information or code ...

 

 

 

Edited Tuesday at 12:17 PM by DracuOrc

[Vinc_Vega]

I like your design!

But isn't in reality the yaw axis controlled by the rudder pedals?

If you really mean the grip's yaw, you should measure the applied torque. That's not easy but may be a calibrated and combined signal of all four strain gauges. It will be even harder to get the direction of the torque moment.

 

Regards, Vinc

Edited Tuesday at 05:20 PM by Vinc_Vega

[DracuOrc]

Reality is rudder pedals but I'm still on a desk and trying to avoid having pedals under ...

But you are not the only one working with me - so one day I get convinced .
I may keep this design and fine tune it as it is - and just add a set of rudder pedals ...

Thanks