dual engine control system

Discussion in 'OnBoard Electronics & Controls' started by rifraf, Jun 7, 2010.

  1. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    have 2 motors on the back of me boat. need to control the throttle via standard wire control. have a basic central wire control system worked out that could rev both motors at the same time but am thinkin maybe there is a way to steer the craft by in addition to moving both both cables being able to adjust the amount each cable was being pulled to allow a differing rpm on each engine.

    any ideas to get me goin would be appreciated, maybe just use 2 levers? btw these are not real huge engines so a small lightweight setup would be the best
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Normally each engine has its own throttle control
     
  3. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Lots of hi-tec options are possible, but I guess you want simplicity.
    So use two levers!
     
  4. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    thanks for the ideas, after trying to work on a manual mixing system for a few days have decided to go electronic controlling the 2 throttle cables with 2 servos. the idea is to have 2 levers hooked up to 2 servo controllers, the output going to a v tail mixer then the servos and throttle cables. this should allow using one lever to adjust both throttle cables at the same time while having second lever to act as steering by adjusting the amount each motor is revved.

    as both motors spin the props in the same direction would a rudder be a big help as well?
     
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  5. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    A beautiful albeit complex solution.

    For full steering capability with engines you should include actuators to shift gear as well. In that case you could use a single joystick for all functions.

    Keep us informed about the progress!
     
  6. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    have to get the second prop tomorrow, was thinking to get a 3 fin prop and put it on the side of the boat that receives the least power to compensate for both props going the same direction. so there would be a 3 fin and a 2 fin with the same diameter and pitch. does this sound reasonable?

    the dual servo controller is coming along well, still waiting on the v-tail mixer to finish it.
     
  7. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    prototype

    have made up a unit to test. some bike brake handles came in handy chopped down, will epoxy to the servo horn when is right. will make the servos bigger if need be but current ones seem to be able to pull the cable ok. have a breadboarded circuit that moves the servos only about 45 degrees for full rotation of the pot so should be ok, might have to put the cables closer to the center of servo as they do not need to travel much and closer will make it easier on the servos. am waiting on the v tail mixer before i solder parts to the board to get the values worked out best.

    also picked up a 3 fin prop today the same pitch and diameter of the current 2 fin one. will be handy for testing with a single motor as well. in case you are wondering what i am trying to do its make 2 motors accelerate with the left knob and then with the right knob be able to steer by in effect slowing down one motor or varying the amount each motor is revving. can waterproof it with some epoxy around the servos later, the case itself is waterproof, could also add an extension cable going to 2 pots to allow steering from the front of the boat or any comfortable position.

    am planning to mount the unit on a 1 inch tube running between the 2 motors clamping onto each one, in effect locking the props at a set angle, to be worked out durin testing. this means the current cables are a usable length and there will be no twisting of cables because nothing is moving, just the props speeds being varied.

    edit: ok the first servos were not strong enough, added a pic of the new setup that is accelerating the motor as planned, need to get 2nd motor hooked up next
     

    Attached Files:

  8. Pandoras box
    Joined: Jul 2010
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    Location: Pensacola, Fl.

    Pandoras box Junior Member

    Couple of thoughts. First one not mount the servos to the engines and 11 eight to drag of the cables. Throttles themselves are very easy to move. Second you may need bigger batteries to run the servos looks like you're using AA batteries. You might try a voltmeter when you're activating the servos.
    I do not know what kind of boat you are running this on that I think I would definitely put on some sort of rather system.
    Mike
     
  9. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    mounting directly was a thought, though the vibration and heat of motor so close to servo and control put me off the idea. Also am getting a fair amount of interference in the circiuts when having them very close to motors, about 12 inches away seems to be ok now.

    Have updated to stronger servos, a 4.5V sla for the servos and separate small supply for electronics, this has removed almost all the interference, you are correct that the 4 x aa were not handling current spikes well, leading to uncontrollable servos when mixed with the interference from the weed eater.

    a recent update, am making new pcb at moment that should eliminate jitter completely, worked when tested with breadboard.

    the boat is a 8 foot long inflatable :), a half decent one though. is designed to have a small motor on the back but have made my own brackets for it, on the weekend with move he motors further apart than in this video to keep the props more separate. am using this for river fishing and trips down the rivers lasting a few days, so the lightweight boat and motor make it easy to get around log jams and stuff which have to be dealt with.

    the motors need a tuneup and a carby kit still, got em for $5 each at the dump a few weeks ago, both have had river testing of at least a 2 hours by themselves and start so easy http://www.youtube.com/watch?v=_yVGg1eaUvo
     

  10. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    Attached Files:

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