OpenMarine
Adjustable end-of-travel switches for tiller actuator - Printable Version

+- OpenMarine (https://forum.openmarine.net)
+-- Forum: Pypilot (https://forum.openmarine.net/forumdisplay.php?fid=17)
+--- Forum: General discussion (https://forum.openmarine.net/forumdisplay.php?fid=18)
+--- Thread: Adjustable end-of-travel switches for tiller actuator (/showthread.php?tid=2000)



Adjustable end-of-travel switches for tiller actuator - ironman - 2019-09-20

Has anybody put end-of-travel switches in their tiller pilot? I got some microswitches now, but I am not sure yet how to put them in in such a way that I can adjust them. These switches have this long metal strip that I can bend a few times, but rather I'd have some adjustment screw for that. It all has to be tiny. If you have any (adjustable) implementation of end-of-travel switches, please share or describe for inspirational purposes.

Already off-topic, but a rudder angle indicator seems quite difficult to devise inside tiller pilot's lineair actuators. The traditional potentiometer is not practical here. Better would be some magnetic / optical mechanism that counts revolutions of the screw, possibly in combination with the end-of-travel switches. Any experience here?

EDIT
I cannot get my head around how it is possible to make a PID control without knowing the exact position of the rudder. Without knowing it, you have to guess. But humans do that as well. With one of those big steering wheels, quite often you don't know either, unless someone marked the middle with a piece of tape. But to me that's not optimal, especially for a 'deaf, dumb and blind' autopilot.


RE: Adjustable end-of-travel switches for tiller actuator - seandepagnier - 2019-09-21

It might be easier to use magnetic reed switches for end of travel.

A magnetic sensor is better for rudder feedback because it won't wear out.

Counting revolutions won't work at power up without traveling to one end and back which is not desirable. Brushless controllers can already do this without an extra sensor, but still won't know the absolute position at startup. Having a relative measurement like this could be a useful feedback. It is also possible to measure the motor current draw to correct for the actual speed the motor is moving and compensate for weather helm.

As far as working without knowledge of the absolute rudder position, it is working on relative rudder position and this already works well. It's possible to try with absolute commands, and also by just using this as an additional input to the autopilot logic to hopefully improve the steering in the future.


RE: Adjustable end-of-travel switches for tiller actuator - ironman - 2019-11-20

Finally installed end-of-travel switches. Decided to go for the good old sturdy microswitches because I'm unfamiliar with magnetism really, can't see it nor feel it. Looked into hall effect sensors, but it merely complicates my adjustment problem. Did not want to drag it on forever so just got on with switches. The adjustment of these is quite intuitive: just bend until right. I got the maximum out of my travel now, and at full travel speed it stops without current peaks, so now I can now safely increase max_current a bit and not run the risk of getting stuck in an involuntary 360 again (see this post). The mounts are epoxied resp. screwed, but the bottom switch is hot glued so I can heat it up and move it if necessary, although I don't expect that will be needed.

Fingers crossed for the next trip.

[Image: attachment.php?aid=628]

[Image: attachment.php?aid=629]

[Image: attachment.php?aid=630]