Joysticks

[billbo911]

Originally Posted by Mike Soukup

No, the workaround is as Sven stated, fix the range in software. All you need to do is determine the min & max values of each joystick axis and create a function that linearly maps the smaller joystick range to the full 0-254 range. Just make sure you have two mapping functions, one for below 127 and one for above. Then calibrate your speed controllers for the full 0-254 range. We've been using this method for at least 3 years.

I've often wondered how I could linearize a range of values to another range of values, such as 137-235 linearized to 137-254. But, not being a software guru, yet, I am not certain how to do this without several "if, if else, else" statements turning the output into a multi stepped scale. Something like:
if (P2y > 135 && P2Y <= 145)
PWM02 = 140
if else (P2Y > 145 && P2y <= 155)
PWM02 =150
etc. etc. etc.

As you can see, not too smooth a response. So the question is, what code would you use to linearly map one range to another?

[Alan Anderson]

Originally Posted by billbo911

I've often wondered how I could linearize a range of values to another range of values, such as 137-235 linearized to 137-254...So the question is, what code would you use to linearly map one range to another?

Use the equation for a line, y = mx + b.
Take the input value x, multiply it by a factor m, and add an offset b to yield the output value y. The factor can be a floating point value, or to save time you can multiply by an integer and divide by another integer.
To determine the m and b constants, use algebra to solve the pair of equations for the known input and output values.

[billbo911]

Originally Posted by Alan Anderson

Use the equation for a line, y = mx + b.
Take the input value x, multiply it by a factor m, and add an offset b to yield the output value y. The factor can be a floating point value, or to save time you can multiply by an integer and divide by another integer.
To determine the m and b constants, use algebra to solve the pair of equations for the known input and output values.

Thank You Alan

I knew it would be a relatively simple solution.
My years removed from Algebra are many, too many in fact, so some portions of my memory need a little refresh. This will help tremendously.