Desensitizing Joysticks

[Mr. Lim]

Originally Posted by bob1million

My fellow programmers and I have tried many different ways to desensitize our joysticks, but none of ways work very well. Does anyone know a good way to desensitize them?

It seems the problem is big enough to cause some serious thread resurrection.

Here was Team 188's solution to sensitive joysticks for 2004 courtesy Carol, Honson, Tristan and myself:

temp_p1_long = (signed long)p1_y - 128;
pwm01 = (unsigned char)(((temp_p1_long * temp_p1_long * temp_p1_long)  >> 14) + 128);

temp_p2_long = (signed long)p2_y - 128;
pwm02 = (unsigned char)(((temp_p2_long * temp_p2_long * temp_p2_long)  >> 14) + 128);

make sure you declare temp_p1_long and temp_p2_long as signed long beforehand.

In a nutshell, it's a cubic transfer function that makes the robot accelerate exponentially when you push the joystick. There's a nice wide area to operate slowly, yet full speed is still there when you push it all the way.

We spent a few days testing different transfer functions, and this one worked out the best.

It's pretty CPU intensive (multiplying long integers), and a look-up table would be faster, but try it for a quick and dirty way to get things working smoothly. You can generate a look-up based on the code later on.

Cheers!

-SlimBoJones...

[tribotec_ca88]

Absolutely...our team also realized the joysticks provided by FIRST proportionalize poor handling...Don't know if you'd had a look at the white papers on this website yet but team 1382's written one about the advantages of converting the linear curve of the joystick into an exponential one (and includes source code). I guarantee it'll give you some ideas...
Link:
http://www.chiefdelphi.com/forums/pa...le&paperid=280