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Joystick conroller

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Bach On

New Member
This may sound like a crazy idea. But it is something I'd like to try. It falls in the area of brainstorming.

I have a joystick. It has four poles of contacts. I can provide more specifics if needed. But this will tell you the general basics of the unit.

I want to use it to control a boat motor. I want to put the boat motor at the rear of a canoe. I'm thinking some sort of actuator with a 6-8 inch lateral movement . This would control the left and right direction of the motor. Then I'd need some sort of control for the speed. Some sort of actuator would be needed with a relatively short lateral movement. Forward would increase the motor speed., Backwards would decrease the motor speed. This motor doesn't have a reverse.

I'm wondering what kinds of electronics would be required to pull this off? I'm thinking of a 12 volt system with marine batteries.

Bach On
 

alec_t

Well-Known Member
Most Helpful Member
This motor doesn't have a reverse.
What sort is it? If it's a 12V DC motor it would normally be reversible. Can you post a pic or link?
 

Bach On

New Member
I have an electric trolling motor. It can be reversed. But I also have an outboard gas engine. It has no reverse.

BO
 

alec_t

Well-Known Member
Most Helpful Member
Ok, so it's the gas engine you want to control. I guess you'd need a strong linear actuator for steering and a less powerful one (or even a modeller's servo) for the throttle. Both would require some form of positional feedback. Any idea of the force they must provide?
 

dougy83

Well-Known Member
I guess you don't need any real electronics. You could just wire each of the joystick switches to a SPDT relay; the relays feed the appropriate polarity DC voltage to the linear actuator.
 

alec_t

Well-Known Member
Most Helpful Member
.....and providing the actuators are relatively slow moving you could manage without the positional feedback.
 

Bach On

New Member
The motor is a flyweight job. I think it is like 1.5 horsepower. I was wanting to sit in the middle of the 17.5 foot canoe. The motor would be at the rear.

I'm GUESSING that one linear actuator with a 8 inch movement could be used for steering. Since this process is normally done by my left arm, I'm guessing we're looking at no more than 15-20 pounds of thrust.

As for the throttle, this engine doesn't have a twist grip throttle like some outboards. Instead there is a lever. I'm GUESSING a two to four inch movement linear actuator could do that. I'd guess 10 pounds of thrust would be plenty.

If I'm reading you correctly - I could simply use the left or right poles of the joystick to run a relay. Left would turn ON the relay and move the actuator in one direction. Right would turn off that Relay. But would turn ON another relay that would move the actuator in the opposite direction.

As for the throttle - forward would turn ON a relay to advance the actuator to move the throttle. Back would turn on a relay to reduce the throttle.

Hmmm. The actuator movement would have to stop at the end of the motor's maximum allowable rotation. If it went too far it could damage the mounting mechanism. That would be tricky. Same issue for the throttle.

Since center position on the joystick is not connecting any of the relays. I'm guessing one wouldn't need to have their hand on the joystick at all times.

What's involved in feedback control for a hairbrained project like this?:)

BO
 

dougy83

Well-Known Member
If I'm reading you correctly - I could simply use the left or right poles of the joystick to run a relay. Left would turn ON the relay and move the actuator in one direction. Right would turn off that Relay. But would turn ON another relay that would move the actuator in the opposite direction.
The relays would be off unless you move the joystick. When you move left, one relay activates to move the motor to the left. When you move the joystick right, another relay causes the opposite to occur.

As for the throttle - forward would turn ON a relay to advance the actuator to move the throttle. Back would turn on a relay to reduce the throttle.
Yep, same idea.

Hmmm. The actuator movement would have to stop at the end of the motor's maximum allowable rotation. If it went too far it could damage the mounting mechanism. That would be tricky. Same issue for the throttle.
You can just put a limit switch at each end of the range to disconnect power to the relay when the limit is reached.

Since center position on the joystick is not connecting any of the relays. I'm guessing one wouldn't need to have their hand on the joystick at all times.
Yes, the actuators will hold their position when you have your hands away from the joystick.

What's involved in feedback control for a hairbrained project like this?:)
What do you mean by "feedback control"? You don't really need a control system, because you are in the control loop compensating for the error in direction or speed of the canoe. You may want a visual readout of the rotation/direction of the rudder/motor, which would likely use either the pot in the actuator (if it has one), or a pot that you mount yourself (or an array of switches).
 

alec_t

Well-Known Member
Most Helpful Member
What's involved in feedback control for a hairbrained project like this?
Suppose you want to steer your motor 10° to left of centre. If the actuator is sluggish and takes, say, 1 sec to move that amount then you, as controller, have enough time to return the joystick to its central position to stop the actuator before it moves too far. If, on the other hand, the actuator zips through 10° in 50ms then it will overshoot before you can stop it, so it would be advantageous instead to feed back a measurement (from a potentiometer or other sensor) of the motor position to control electronics which can respond more quickly than you and so prevent the overshoot.
 

Bach On

New Member
Hmmm. The actuator movement would have to stop at the end of the motor's maximum allowable rotation. If it went too far it could damage the mounting mechanism. That would be tricky. Same issue for the throttle.

You can just put a limit switch at each end of the range to disconnect power to the relay when the limit is reached.

OK. So the limit switch at each end will take the actuator off-line for only one direction. When steering is needed in the other direction, the movement would cause the limit switch to reconnect the circuit. Is that what you mean?

I can see that the speed of the actuator is going to be crucial. It needs to be responsive enough to react in time for steering around obstacles. But it can't be so fast as to be too sensitive.

Hmmm. Didn't they have paired synchronous motors for showing direction back in WWII? When one turned 55 degrees, the other turned that much too. Seems they used them in things like tanks and for big guns on ships. I wonder if something like that could be used as an visual indicator of the motor's position? Does that sound too off-the-wall?

I appreciate the brainstorming assistance. I commend you for how many times you help lost souls like me think through projects. I suspect your parents would be proud!:D

BO
 

shokjok

Member
It sounds like you want the same joystick control circuit found in overhead cranes or power pallet jacks. You would need a team of hobbyists from the local technology college to realize this ambition.
 

Bach On

New Member
Thanks. It is looking more and more that this may not be a practical solution with my limited degree of electronics knowledge.

BachOn
 
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