electro-mechanical linkage help?

[drozovs]

I am working on a flight control system that is electro-mechanically driven. I want to linear displaced levers together so that when you move one the other one moves as well. If both levers are moved the one being displaced with the higher force will move the other. Its similair to a mechanical linkage but it will be done via a motor. Does anyone know if this has been done or where I can find more information on it? I know BAE has flight sticks that can do this and they are not "hard" linked. Thanks in advance!

 

[jraef]

Someone in this forum do that a few years ago. Posted pictures and everything.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[drozovs]

Do you (or anyone else) know where ? Ive been trying to do this for a year now.

thanks!

 

[jraef]

thread237-85683


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[drozovs]

I think I need to clarify. I have an airplane with an engine, in the flight deck there are accommodations for two pilots, each pilot has a throttle, the throttle needs to mimic the other throttle (i.e. if one throttle gets pushed forward the other throttle mirrors it).

I do not have the ability to link them through "hard" linkages. I do have the ability to place a device (i.e. motor with another sensor perhaps) on each lever that would "couple" them together so they would "feel" like they are linked mechanically through a "hard" linkage.

I was debating on using a stepper motor with a position sensor and torque transducer but I think there are faster methods then this.

I have heard of synchros but I have been relatively unsuccessful in finding out if this would work.

I want it so that if both pilots try to move the throttle, only the stronger pilot will succeed.

 

[itsmoked]

Dominant piloting thru gym training... Had no idea!




Joking aside:

Aircraft have needed the system you mention for years.

"Electrical sychro" systems. Lots on google.

Here's a company that has a lot of that:

http://www.allaboutcircuits.com/vol_2/chpt_13/11.html

Here's; A historical troubleshooting lesson.

http://www.tpub.com/neets/book15/61o.htm

Keith Cress
kcress -

http://www.flaminsystems.com

 

[drozovs]

Thanks Keith! I will read up on those materials and Ill report back here

Best,

David

 

[fangas]

Might consider a small hydraulic cylinder on each throttle, couple them with a with a small line. Simple, cheap, robust

Ed

 

[fangas]

opps, missed the "Mirrors it" part.

Ed

 

[cswilson]

Synchros are, like, SO 1970s! ;-)

Seriously, synchros were the main method for performing this type of "electronic gearing" in the pre-digital era. But I really can't imagine doing it that way now. Software-based digital techniques will give you so much more flexibility -- you're changing a few lines of code to tweak the performance, rather than changing component values or rewiring.

Many "remote operated" systems, including fly-by-wire and drive-by-wire (plus robotic surgery) provide digitally generated feedback to the operator -- yours would just be an extension of these techniques.

Curt Wilson
Delta Tau Data Systems

 

[Compositepro]

Hydraulics will still work. You simply have to mount the cylinders so the levers move in the same direction when one cylinder extends while the other retracts. The advantage would be that the levers always stay synchronized and large forces can be applied. This would be the closest to mechanical linkage in reliability and not needing a power supply.

I've played with sychros and they are fascinating devices, but I don't know how much force they can apply without using a lot of power. They won't stay in sych without power.

Digital would certainly work but require position and force sensors. This could help to integrate the levers with other flight controls. But this would be very complex for such a simple function if it is a stand-alone system.

 

[drozovs]

Thank you guys for the additional info! I should clarify further too.

The package dimension requirements limit me to using a small motor 4x4x4 inches max in the assembly. My thoughts were to hook the throttles using a "looped" cable so that the motor receives the position in a rotary form. I can live with a nominal "break away" force in which the throttles would not be mirrored if high counteracting force was placed on them. I figure I wont get a huge power density in such a small motor.

I looked at synchros but it appears that only one company (

http://www.windings.com)

manufactures them still and it was for GE (and they are not small !).

I dont mind using hydraulics but it cant be a linear actuator. The assembly is 8 inches in length and the throttle slides 6 inches along that with 1 inch on each end. I can increase the package size to accommodate a rotary motor but not by much.

I would ideally like to use two stepper motors but I dont have the foggiest in how to implement the control method or system. :-/

 

[drozovs]

So one idea I have had is using a master/slave servo motor configuration with torque transducers on the shaft heads. Then tying the torque transducers into to the control loop and making the system bi-directional by using the higher loaded motor to be the master. The concern I have is if there will be too much latency. Has anyone tried this before?