This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
linear actuator recomendations
#1
I would like some ideas on specs or recommendations i should look for in an linear actuator.
I currently have a Marine pilot 1600.
My boat is a Tanzer 26.
stroke is about 10"
stroke speed is slow i could use faster as i have a modified rudder.
I plan to set up the autopilot with my old Autopilot but I would really like to replace it.
ThanksSmile
Reply
#2
I would start off using what you have and then you can find out what you need. The 1600 is a very small motor, not really suitable for ocean unless it were driving a pendulum oar or trim tab instead of the main rudder.

I would look for wiper motors. Motors that draw 1-2 amps unloaded, and stall at 6-10 amps are about the right side for your boat if they are geared properly.

I am working on using cordless drill motors (already right size motor and gear box) attached to lead screw for 3d printer. This is very inexpensive, but requires an enclosure.

I also just got a 3d printer working on my boat. I am limited to print 1-2 hours a day this time of year until I get more solar panels, but it looks promising for printing the pieces to mount an electric motor with belt drive to a lead screw. I also printed anemometer wind cups yesterday.
Reply
#3
I have been carrying out a search for a linear actuator. After closely looking at the Pelagic autopilot actuator I found this chinese product that looks identical: https://wxhongba.en.made-in-china.com/pr...J806-.html. It appears to be waterproof, powerful enough and quick. It also comes in various stroke lengths. I also found this controller which I think has been mentioned on another forum for a higher price: https://www.cytron.io/p-md10c. If they could work together with a Pi Zero W then a robust tiller pilot for $50 sounds good.
Reply
#4
For a tiller autopilot the "at rest position" is mid stroke i.e. 125mm on a 250mm stroke linear actuator. Does the Pypilot software cater for this neutral dead ahead position?
Reply
#5
I read somewhere the pelagic actuator is actually bought from china, and upgraded to make it more corrosion resistant, and brackets added to make it easy to mount. I found similar looking actuators on aliexpress, but none had the speed needed, and were not designed for continuous duty. Where did you find the actuator you mention?

I am hopefully going to release 3d printing files to build your own actuator soon using lead screw (from 3d printer is cheap) electric motor and belt. The $50 figure is achievable, and even using a brushless motor would be possible. Further, it would be possible to scale the design and produce whatever size needed.

The motor controller you linked has been mentioned before. It has virtually no protection built into it. I don't mind you try it, I encourage this, but if it burns the raspberry or the motor, I made my warning a lot of times about this. You might be able to isolate the pwm and direction signals, but there would still be no feedback of motor currents and voltages etc... Please make a thread about your experiments and progress if you try.

I intend to release a controller kit in 1-2 months which will be the latest version of my existing controller so have all of the protection, and other features, but it will require soldering (not surface mount though) and it's going to cost a lot less, but more than $7

Currently rudder feedback is only used to prevent end of travel, and report nmea0183 rudder angle. The error in integrating the rudder error is above the normal errors corrected for, but it would be very interesting to implement a pilot that uses absolute rudder position (nested PID filters) and compare it.

Another nice feature would to have it be able to auto-center, but there is also weather helm to consider.
Reply
#6
Sean thank you for the above. I've just noticed Cytron have a new version of their controller:https://www.cytron.io/p-md13s Not sure if this is any improvement for use with Pypilot. Re the linked actuator, I am pretty sure it is from the same manufacturer as Pelagic's. https://cdn.shopify.com/s/files/1/1826/1...1495424622 I did a google image search on Pelagic and the branding appears to be the same "HB", the actuators appearance is the same and the quoted speed of 56 mm/s is the same.
Reply
#7
(2018-12-02, 11:14 PM)hartswood Wrote: Sean thank you for the above. I've just noticed Cytron have a new version of their controller:https://www.cytron.io/p-md13s  Not sure if this is any improvement for use with Pypilot.  Re the linked actuator, I am pretty sure it is from the same manufacturer as Pelagic's. https://cdn.shopify.com/s/files/1/1826/1...1495424622 I did a google image search on Pelagic and the branding appears to be the same  "HB", the actuators appearance is the same and the quoted speed of 56 mm/s is the same.

Input Voltage 12V/24V/36V/48VDC   --  ok
Load Capacity   1000N   --   This is 100kg, should be ok
Speed  5~60mm/s   -   At 56 or 60mm/s it's ok but not enough for storms even on a small boat, I have the same problem with all tiller pilots, 50mm/s is the normal speed.
Stroke 20~300mm (Optional)   ---    300mm is short.  Most tiller pilots are more like 450mm

"We can customized the actuator for you. "

I think maybe that is what he did.  Probably got a longer stroke, but maybe some other differences.  Maybe you can contact them and ask for the same customizations!  If this is indeed the same actuator I'm confused why the price on pelagic is so high.


It seems they also have a version with a potentiometer built in.   This would be perfect for rudder feedback.
Reply
#8
I've sent a couple of Alibaba linear actuator suppliers messages. I Will ask about potentiometers. It looks like the Pelagic actuator is 250mm stroke and 56mm/s. You can see it on label of the Pelagic actuator on their home page: https://pelagicautopilot.com/collections...ller-drive. I guess it's priced relative to other marine autopilots.
Reply
#9
specs 100kg= 220lbs is that static..
I wonder what i really need 100kg seems like a lot? I have noodle arms with Popeye forearms. Assuming i hold the tiller at the end. I doubt i am sweating usually looking cool with a couple fingers all relaxed unless sail trim is bad .
speed for power? what would a change in gears ratio would do? correct me if the ratio is 20 to if i change it to 10 to1 the 100KG would be 50kg and the speed would be 100mm/s given a length of 400mm/2 assume the rudder is centered. it would take about 2 sec to go to the end?
or better yet
https://auto.howstuffworks.com/cvt2.htm
how much friction does a ball screw have when disengaged? Could i hand steer with autopilot off but autopilot connected?
A wheel would make this easier but i dont have a wheel and i get all F@#$ upped with a wheel, over steer, cant find center it is real sad when i have a wheel in my hand.. every thing is backwards with the Devil wheel.... Ya Ya laugh it up...
Reply
#10
(2018-12-02, 03:28 PM)seandepagnier Wrote: .../...  The 1600 is a very small motor, not really suitable for ocean unless it were driving a pendulum oar or trim tab instead of the main rudder./...

Hello seandepagnier,

I am using an Aries wind-vane. What would be your recommendation to drive it with PiPylot. Actually I use a shortened dummy air vane with my tiller pylot...
Cordialement
Didier B
Pi4, SSD USB3, OP 2.6.2, OC  5.2.4




Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)