Rudder failure is a common issue in autonomous transatlantic attempts, therefore the rudder control requires a special attention. If we expect a rudder movement every 3 seconds for a duration of 6 months, that makes over 2.5 million cycles! That’s more than any servo manufacturer can guarantee (besides some very special and expensive products for medical applications). To make things even worse, turbulent water flow may be kicking the rudder from side to side which shortens the servo life span. Common linear actuators have a life span of only 50 thousand cycles and we need 50 times more.
It seems hopeless, but…
I have been testing a simple worm drive connected to a magnetic encoder as seen in the video. It’s loaded with weight to simulate water resistance. Two million cycles so far and no signs of wear (!) completely exceeded all expectations. Of course, real ocean conditions may be different. Let’s give it a try in the upcoming transatlantic attempt.
As usual, it’s open source on GitHub:
https://github.com/OpenTransat/ServoEncoder
