[PSUBS-MAILIST] Joystick

Mon Feb 26 18:30:42 EST 2018

If you have the PLC then I would definitely take advantage of buttons on the stick as follows:

Have a thumb switch to jog depth, but as soon as you release the switch, the system uses the instantaneous current depth as the depth setpoint, and implement PID control on the PLC to operate the vertical thrusters as necessary to maintain depth at that setpoint.

Similarly, use the Z axis of a three axis stick to turn (yaw) the vessel, but as soon as you release that axis back to the neutral position (spring return), the system uses the instantaneous azimuth as a heading setpoint, and automatically operates thrusters as necessary to maintain heading. This will be particularly useful if you're operating a manipulator when not bottomed, as all you need to do in that case is control the vessel's movement in a 2D plane.

Surge and sway motions should have thruster output proportional to stick displacement, but you might consider a switch function to enable cruise control. I would definitely use spring return to neutral on all axes though (safety). Allow the stick to go neutral after engaging cruise once, but any subsequent stick movement drops it back to manual.

Reading stick inputs through the PLC also permits you to have a configurable deadband around the neutral position, which is useful to avoid creep if your hand is resting on the stick at all.

Sean

Sent from ProtonMail mobile

-------- Original Message --------
On Feb 26, 2018, 16:00, Alan via Personal_Submersibles wrote:

> Thanks Sean,
> sounds like I got my X & Y mixed up.
> I don't think I need a yaw motion from the rotation of the joystick as
> I get this with a combination of X & Y. The tractor steering on my ambient
> works well, & this just has an X & Y axis on the horizontal thrusters. I could
> however feed the control through the PLC & put in some logic so that when
> I go nearly full left on the joy stick, the right hand thruster goes in reverse to
> turn the sub on it's axis.
> On my ambient sub I have a separate joy stick for the horizontal thrusters ( PS2 controller ). This is reasonably intuitive but takes two hands, & I want a hand
> free for a camera, HMI or manipulator.
> If I can't find anything off the shelf it may come down to putting a small finger
> operated joystick horizontally off the main joystick shaft.
> Cheers Alan
>
> Sent from my iPad
>
> On 27/02/2018, at 11:15 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> I would stick with an intuitive control scheme, and find a joystick with three axes. Forward / back Y axis corresponds to ahead / astern propulsion (surge), left / right X axis corresponds to straight lateral motion (sway), and rotating the stick clockwise or counterclockwise around the Z axis corresponds to turning (yaw) motion. Three axis sticks are pretty common industrial controls, although I don't know about meeting your budget. For depth control (heave), you could use a stick with an additional thumb wheel or accessory axis, or make use of a simple switch, but ramp the output in proportion to how long you hold the digital state changed. You could also have a button which toggles e.g. your stick's Y axis between surge and heave control modes. Wanting single stick control limits your options a bit, unless you're also using a PLC / PAC, in which case you could use joystick buttons just to jog your depth setpoint, and rely on other code to actually implement an associated control algorithm.
>>
>> Sean
>>
>> Sent from ProtonMail mobile
>>
>> -------- Original Message --------
>> On Feb 26, 2018, 14:48, Alan via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
>>
>>> Should mention that the buttons or whatever for the vertical
>>> thrusters will have to be analogue to give me speed control,
>>> & not on & off.
>>> Cheers Alan
>>>
>>> Sent from my iPad
>>>
>>>> On 27/02/2018, at 10:36 AM, Alan via Personal_Submersibles  wrote:
>>>>
>>>> Am looking for a semi industrial or industrial joystick for controlling
>>>> 4 thrusters; two vertical, two horizontal.
>>>> I want to operate it with one hand. The X axis will be the horizontal thrusters
>>>> throttle forward & reverse, the Y axis is the horizontal thrusters proportional
>>>> speed for turning ( pretty standard ). The vertical thruster control is what I
>>>> am having trouble with; I want it to be as intuitive as possible & have seen
>>>> buttons on joystick shafts that could be used for up & down. In the attached
>>>> picture the buttons are on the top of the shaft in the left hand example.
>>>> I am also wanting the unit pretty small, so small intuitive, one handed operation.
>>>> It doesn't matter if there is a few extra buttons as I could use these for lights
>>>> or display control etc.
>>>> If anyone knows of anything, or has a better solution, I would be interested
>>>> thanks. Oh yeah, & not really expensive!
>>>> Alan
>>>>
>>>>
>>>>
>>>>
>>>> Sent from my iPad
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