[PSUBS-MAILIST] Speed controllers

[Jon Wallace via Personal_Submersibles]

I'm a proponent of spring return joysticks also.  I considered 
non-return ones early on but rejected them just on a perceived need 
(real or not) to have them quickly return to a dead zone instead of 
fumbling to find that dead zone if I was in a hurry to stop propulsion.  
Assuming there's no throttle feedback to indicate where center is, 
you'll need a relatively large dead band (or zone) to not overshoot the 
center position.  I've never been a fan of Z-axis though because I 
personally do not find them comfortable or user-friendly even with a 
large joystick for a computer.  There's something about twisting motion 
that is fatiguing and this would be especially true on a small diameter 
joystick.

The degrees of joystick movement is not as important as the 
potentiometer value controlling the signal to the controller.  You can 
find joysticks with different potentiometer values to get the fine 
control you need.  The more expensive joysticks use hall sensors (I 
believe) to get past this issue.  One problem I see with a mechanical 
KISS approach for components is that the UI ultimately begins to 
suffer.  Instead of one or two joysticks, extreme KISS requires four to 
accomplish tractoring and crabbing which means both hands on controls.  
I think potentiometers in this configuration are going to be less 
intuitive and more complex to operate, relatively speaking, than 
joysticks.  Think Etch-a-Sketch, and I was never good at that.  
Mechanical KISS ultimately equates to more buttons/levers/switches than 
a fly-by-wire design.  Yes, at a component level mechanical KISS has the 
benefit of being able to target a single switch for replacement but 
nothing is free and the UI becomes more complex because the user has to 
control multiple components simultaneously to perform a certain task.

Back to the Z-axis, I think if I were to use one I would give up 
crabbing and use the Z-axis simply for vertical movement.  Twist left 
for down, right for up.  I'm not sure there is a lot of use for crabbing 
in something that is not a Deep-Worker type vessel, but I do plan on 
implementing it for my sub.

Jon