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I'm trying to implement an 737 motorized throttle.

For those not familiar, it's something that's on a motor shaft and needs to move about 80-90 degrees. Max. load is about 2-3 lbs. I also need the user to be able to move it manually by moving the arm, i.e. the motor shaft should be manually rotatable i.e. cannot be rigid.

I also need to know the current position of the arm, but I think I can add a potentiometer to do that.

So what's recommended, a DC motor, a stepper motor, or a servo?

The key is that the user needs to be able to move the motor shaft - the force will be about max. 5 lbs with an arm length of about a foot, not that much, but the shaft cannot be rigid.

I know you can do this with a stepper motor as long as the current is shut off. I can turn the current on to move the arm to a position and then shut it off and have the user optionally move it also, then have the potentiometer read the current position.

Maybe that requirement will help.

It's for a homebuilt project. It seems that most people are using a stepper motor.

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  • \$\begingroup\$ "... max. load is about 2-3 lbs." Motors are rated in torque (force x distance), not weight or mass. You'll need to calculate or measure this first. \$\endgroup\$
    – Transistor
    Dec 29, 2022 at 22:56
  • \$\begingroup\$ Based on the limited information it is difficult to give a recommendation. All of your choices could work. I’d suggest you research how it is implemented in the actual plane to give you guidance. How did Boeing have it so the pilot could move the levers as well as the automated system? \$\endgroup\$
    – Kartman
    Dec 29, 2022 at 23:00
  • \$\begingroup\$ for clarification - this is for a home-built simulator, not actual aircraft flight equipment right? \$\endgroup\$ Dec 30, 2022 at 0:42

2 Answers 2

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Motorised Potentiometer as an off-the-shelf part.

Or a gearmotor driving the lever through a friction clutch if you need something stronger.

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I'm assuming this lever doesn't actually do anything except get read by the potentiometer?

If that's the case, you can simplify the design immensely by having the friction coupling between the lever and a beefy gear motor, instead of between the lever and the console. Pick a gear motor with more backdrive resistance than the friction coupling, and you're done. You hook the pot up to the lever directly, and when you want to move the lever you drive the motor. If the user moves the lever the friction coupling slips, so it will feel exactly like it would if there was no motor at all.

When I say friction coupling, I mean whatever keeps the lever in place so that it doesn't just flop around in the breeze.

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