Implement closed-loop system (servo) instead of stepper motor
AlexAsplund opened this issue · comments
A stepper motor can be pretty loud, especially in an aluminium boat. A servo should be quieter and the feedback loop should remove the need of an error-prone hall sensor calibration
This would be great. Found this project after i looked online for some similar solutions. I'm planning to buy the (relatively cheap) remote controlled bow mounted trolling motor from Biltema. I think this has a servo/dc motor based system, and might or might not have feedback. I'll let you know when I have bought the motor and opened it up for reverse engineering
This would be great. Found this project after i looked online for some similar solutions. I'm planning to buy the (relatively cheap) remote controlled bow mounted trolling motor from Biltema. I think this has a servo/dc motor based system, and might or might not have feedback. I'll let you know when I have bought the motor and opened it up for reverse engineering
Interesting! I looked at using the bow mounted Biltema motor, but I'm not sure if it has any positioning feedback.
But I'm sure it could be added with an AS5600 (A magnetic positioning sensor that I bought and is planning to use for the trolling motor servo).
I bought one, so we'll see. I'll try to have a look at it during the weekend
So i had a look at the Biltema motor, and as expected there is no positioning feedback. At first eyesight, it seems like it's possible to open the positioning gearbox and add some sort of angular positioning sensor like the one you suggested, see image below for the die-cast metal gearbox.
However, the screws holding the gearbox together are all glued in, probably with epoxy. No matter how hard i try, they are completely fixed.
I could cut it open, but I want to try it on my boat and see if the trolling motor is strong enough to even move the boat first. I could also try with some heat, but i'm afraid i'll damage any plastic gears inside.
What could be a possibility, is to 3d print some parts that can attach as a split ring on the outside of the gearbox and get an angular reading that way.
As i see it there are three alternatives to splitting the gearbox open:
1: Use a split collar with magnets and read the angle of the shaft by counting pulses, similar to this:
2: 3D-print a split gear that can clamp around the shaft in a way, and then use that to drive a mechanism to use an AS5600 with
3: Make use of the fact that the rotational speed of the positioning motor is (relatively) constant and just use software timers to estimate the angle. It is relatively easy to attach one or two microswitches on top of the gearbox that can serve as timing marks to calibrate the software angle estimation every time it passes the microswitch.