Force Feedback Motors - Can you recommend?

[Boeing 747 Flyer]

Hi everyone,

I am looking for suitable motors for a FFB system in a Saitek Yoke.

Firstly, it must be a simple (but powerful) DC motor that is compatible with the Opencockpits DCMotors Card. I can build myself a PA amplifer so the specifications are not all important; provided it is powerful enough.

The motor, however, must be fairly small; having to fit within a 7x7 cm area. I have other motors that fit perfectly; but they just aren't powerful enough.

The motors must be able to be "turned back" on. For example, if the motor is turning left, I must be able to override it manually and force it right, without damaging it.

These are obviously the fundamental aspects of a FFB system; I just need a motor that will fit and is powerful enough.

Kindest regards,

Jack

[fordgt40]

Jack

There is some useful info re motors for force feedback in these links

http://www.mycockpit.org/forums/showthread.php/22654-737NG-control-forces?p=119216&highlight=#post119216

I think you will be fortunate to find a motor that can have enough power to provide solid "feedback" without significant gearing, ie can be "turned back", within the constraints of the OC DCMotors card which has a max current capacity of 1 amp - not 1 amp per motor

Regards

David

[Boeing 747 Flyer]

Hi David,

The specifications of the motor do not matter to me. It could be 0.000001 Amperes or 5000000 Amperes (don't that that literally obviously, you get the point!); I have the equipment available to adapt the OC signal into whatever I want.

I think I should rephrase my question slightly. What sort of specifications will I need for acceptable force feedback? What torque? That link is good, but it doesn't give readings such as torque.

His design, however, is very interesting. I might have to borrow it!

Regards,

Jack

[fordgt40]

Jack

To establish the likely torque, I suggest that you find a way with perhaps a fulcrum lever weighted down at one end and try to establish an acceptable resistance (your likely force feedback) when you try to move the other end. If you then multiply the lever arm by the weight you will get a figure in ft/lbs (sorry for the old units). There are many conversion progs on the web that can then reproduce the torque in newtons/cm etc etc - this will then give you the torque requirements for the motor. I did it this way for my motors for the throttle levers!

I am interested in "I have the equipment available to adapt the OC signal into whatever I want." as I fear that my OC DCmotors card may not have enough current capacity, care to share more info :).

Regards

David

[Boeing 747 Flyer]

Hi David,

I used a set of old fashioned scales for the calulcation.

Feedback Load = 2.5 KG. Distance from pivot to load = 8.5cm.

So that's 25 (because Newton = KG x 10) X 8.5 = 212.5 = round up to 213 to be sure I get more than I need

So I'm looking for a motor with 212.5 NewtonCentimeter of Torque?

Please correct if I'm wrong.

Jack

[fordgt40]

Jack

Looks ok to me. Now the fun bit starts to find a motor that matches :) Your challenge will be to find a motor that can output that torque without relying on significant gearing that can be reverse driven

David

[Boeing 747 Flyer]

Hi David,

A bit out of my price range, but I think this is a good start:

http://www.active-robots.com/products/motorsandwheels/ampflow-motors.shtml

Using converters, that's 303 Newton-Centimeter of Torque. More than I need, but the more the better. It's also fairly small considering its strength. Also, the motor is non-geared.

Regards,

Jack

[fordgt40]

Jack

Thanks for the link, I have bookmarked it for future reference :)
As you say, the price is steep

Regards

David

[Boeing 747 Flyer]

Hi David,

I have just located an 8 Ampere, 12 Volt DC Motor and testing it in my house using a simple makeshift yoke.

The feedback was excellent. Although it probably wasn't as powerful as some set-ups, I certainly felt it.

I'm planning on OD the motor to 15V; it can handle it. This would bring the power to 120 Watts.

Regards,

Jack

[fordgt40]

Jack

That was lucky
How are you going to control it via OC cards - I am very interested because I will have the same problem soon :)

David

[Boeing 747 Flyer]

Hi David,

Yes of course! I forgot about your question.

The Opencockpits PWM output connects to a power amplifier circuit, containing a MOSFET Transistor.

EG; I can use a signal from the OC card "0.1A 12V", and can amplify to "24V 10A".

Once I have progressed, remind me and I shall provide you with a circuit diagram.

Regards,

Jack

[fordgt40]

Jack

OK, I basically understand that, many thanks.

Regards

David

[speedbird1]

hi David i have just come across your thread, i live in braintree and i am building a 747-400 tq i was wondering if you know were i can get the knobs for the thrust reverse and the thrust levers ,or something simular.
best regards Steve.

[fordgt40]

Hi neighbour :)

Sorry, but I do not have an answer other than try this link which has a tutorial on making 737 knobs andd also links to simparts.de who sell 737 knobs

http://www.mycockpit.org/forums/showthread.php/15230-Throttle-Knobs-NOT-Paidrigs

Regards

David