Hi yachtie 2k4
I have been watching this post with interest, but been to busy at work 12-14 hr days 7 day weeks for the last 3 weeks.
I will cut and paste some sections of emails from earlier this year discusing the same situation that you are in regarding an automatic canting system.
<font color=“blue”>I am looking at automating the control of the canting keel, do you know of anyone (like yourself) with electronic skill to design a simple control system. My idea would be to use a pendulum weight swinging off a potentiometer, which would than control the 380d winch. The winch would be setup with a two 3:1 purchase systems either side of the keel control lever this allows for 600 mm of travel of the winch. Would limit the rotation of the pot to 25 to 30 degrees of rotation either side (equals angle of heel), and the keel swing of 50 to 55 degrees swing either side.</font id=“blue”>
This was before I designed the gear quardant and pinion drive.
<font color=“blue”>Sounds interesting. If I understand correctly, you want to position the canting keel winch with an on board controller which has a pot that is positioned by a pendulum. Mechanically, I see some possible problems with the action of the pendulum. I think it would want to be dampened so that it does not swing freely with the motion of the boat. The dampening would want to be stiff enough so that the winch would not be continually correcting itself. If it did it would chew up batteries very quickly.</font id=“blue”>
<font color=“red”>Electronically however, it’s very simple. It would only need a small circuit to produce the signal pulse to control the winch. This circuit would have a three wire connection to the winch. This is simply the winch servo lead that is normally plugged into the receiver. It would also have another 3 wire lead connected to the pendulum pot. Possibly a trim pot might be used to adjust the throw of the controller.</font id=“red”>
<font color=“blue”>Thanks, you did understand it correctly, yes the pendulum would need to be dampened. I have found several sites with servo driver plans, just a case of building one and try it out.</font id=“blue”>
<font color=“red”>There are some servo driver kits available from some of the Electronics chains such as DSE, Altronics etc. However, I did a bit more thinking about how simple a circuit could be for your application. I have recently changed my winch circuit to be based on a new range of micro controllers. The one in the winch is a more complex one than needed for this job, but this range of micros includes a tiny surface mount 8 pin ic that could be mounted on small pcb about 1 cm x 1cm. The pcb could mount direct to the pendulum pot. The only connection needed is the servo lead from the winch. Thinking about the trim pot option, it would not be necessary since the winch itself can store the trim settings of the pendulum pot. But another option is that a spare channel in the receiver could be used to trim the system while on the water or even override the system when desired and drive the keel direct from the transmitter.</font id=“red”>
<font color=“blue”>I have been thinking of ways to dampen the pot.
A. a mechanical brake system working on the pot shaft,
B. a liquid dampened pendulum could be messy
C. electronically dampen the pot signal with a resistor / capacitor setup D. simplified endcoder say 60 or 72 steps per rev</font id=“blue”>
<font color=“red”>Dampening would be a real suck it and see job. A simple solution may be simply be to match the pendulum moment with the operating torque of the potentiometer. All pots have a certain amount of resistance (pardon the pun) to rotation due to the lubrication in the bush. The pendulum moment is the combined mass of the pendulum and the radius of that mass to the pivot. So the experimenting you might do would be to play with various weights placed at various distances from the pivot to see how fast it will rotate and to pick an ideal maximum rate of rotation to suit the boat.
You could theoretically add a function into the controller which adds in damping. But since maximum speed would be needed for tacking, this damping might need an override perhaps triggered by the rudder servo being deflected a certain degree. The rudder servo lead would have to go through the controller to get that signal. Software wise this damping would be complicated and time consuming to develop so hopefully it would not be needed.
For the driver circuit, I’ve drawn up a PCB which contains only a small microcontroller on a printed circuit board which will fit on the back of a pot. The pot/circuit combo will have a servo lead with a connector for the winch servo lead to plug into. That’s it, nothing more needed. The winch will be controlled by the rotation of that pot. The pot circuit gets its power from the winch.</font id=“red”>
<font color=“blue”>Things progressing slowly on the F100, unfortunately there’s work to be done. At this stage I will go with the direct control of the keel and look at the automatic control as a future development. I have finalised the design of the canting keel, its going to be a segment of a 150t module spur gear fixed to the inside of the hull. The servo motor is mounted on the keel control lever driving a 15 t pinion meshing with the quadrant gear. By my calculations the torque of the servo motor needs to be 15 kg/cm (includes 1.5 safety factor). Guess it would be a 380D unit, I will be using 6 x 1.5v batteries. Is the stall torque proportional to voltage? </font id=“blue”>
I hope this has helped or has it put you into a tailspin sorry a chinese gybe