Dead Zones

[CronosPrime1]

Greetings,

Can anyone tell me how to change the dead zone that exists by default? That is, I know any input between pretty much 120 and 140 is read as neutral. I don't necessarily want to remove that, but if I did, how would I do so? Also, is anyone else changing their dead zone?

[Alan Anderson]

The Victor's dead zone can be compensated for in code if you want. Just add 7 or so to the value you're sending to if if it's more than 127, and subtract 7 or so from the value if it's less than 127.

[Cuog]

it may be better to expontially map the joysticks so that there is no dead zone but it is less sensitive at lower values

We use a lookup table to "curve" our drive outputs...
I don't remember the syntax for defining tables offhand; if you need it let me know and I'll look it up tomorrow.
if you put this in your code...

pwm01 = lookuptable[p1_y];

Say you've moved the joystick slightly, and p1_y = 132. This line will define pwm01 as the 133rd value in your lookup table (since lookuptable[0] is the first number in the list).
You could make that 133rd value anything you want... indeed, you could make all table values from 90 to 170 equal to 127, making a freaking huge dead zone.

Hope that helps

[mogunus]

Yeah, we do the same thing as the guy in the above post. "Smoothed" lookup table makes the robot move nicer.

[CronosPrime1]

What is the victor's dead zone?

[Alan Anderson]

Originally Posted by CronosPrime1

What is the victor's dead zone?

It's the range of PWM values that result in the Victor staying in "neutral". I think it's about 8 or 9 counts either side of 127. I saw it defined on the IFI web site somewhere, but I'm not sure where to find it right now.

[aaeamdar]

Originally Posted by Alan Anderson

It's the range of PWM values that result in the Victor staying in "neutral". I think it's about 8 or 9 counts either side of 127. I saw it defined on the IFI web site somewhere, but I'm not sure where to find it right now.

I don't know about that. Our initial tests (just playing around with it) seemed to indicate that there was effectively no dead zone. We set ours to 15. We also used the look table, but as seen in the camera code thread, make sure that it's

rom const unsigned char lookTable[XXX] = {x, y, z};

and not this:

 unsigned char lookTable[255];

Ooops. That story didn't end well.

Paul Dennis

[Alan Anderson]

The main Victor page describes the deadband:

The Victor 884 has a deadband with respect to the PWM signal, which is approximately 117 to 137 (127 center). Any PWM signal within the deadband results in no output (neutral).

A little more detail is given in the IFI Tech Support forum.