Jump to content
Sign in to follow this  
Guest kdfossum

Servos HELP!

Recommended Posts

Guest MikePowell

Hi Roger,Qualified yes. You would have to use some sort of power buffer between the servo electronics and the larger motor. The servo electronics is designed for a particular electrical power demand that a larger motor would quite likely exceed.There could well be dynamic issues. Imagine a powerful motor which spins too far and overshoots relative to where the servo control electronics is trying to position the output shaft. The motor then overcorrects and undershoots. The servo electronics is "tuned" to a particular set of parameters that include motor torque, inertia and power gain. Changing motors will upset this. Since all these paameters interact, it is hard to predict offhand just how well or poorly a motor substitution will work.Mikewww.mikesflightdeckbooks.com

Share this post


Link to post
Share on other sites
Guest MikePowell

Kevin,I don't use FSBUS and haven't kept up with its cuurent capabilities, so can't really say.Mikewww.mikesflightdeck.com

Share this post


Link to post
Share on other sites
Guest SHORT360

Hello Mike,Thanks a lot for the explanation. Your answer takes me to an other question:There must be someboby ( who knows probably you)out there able to design the electronic and the pcb of such a circuit. Greetings from France,Roger

Share this post


Link to post
Share on other sites
Guest mbessler

>Hello Mike,>>Thanks a lot for the explanation. Your answer takes me to an>other question:>>There must be someboby ( who knows probably you)out there able>to design the electronic and the pcb of such a circuit. How about that:http://www.bobblick.com/techref/projects/sv2hb/sv2hb.htmlIt takes a Servo PWM signal (as FSBus, Opencockpits, PHCC, ... can generate them) and uses it to control a motor (two actually).All you need to add are the feedback pots and some code for the microcontroller to use it.Still not a beginner circuit as motors generally draw lots of current and thus there's the potential of lots of smoke :)Manuel

Share this post


Link to post
Share on other sites
Guest SHORT360

Manuel,I am absolutely unable to write ever any codes for a chip like the PIC or any other kind of microchips. I have a very superficial understanding of what I am doing. I have an creative approach on such issues, not the knowledged technician one.But as far as I understand, the circuit of basic RC servos motors seems not to be that complicated. There must be somebody able to design such a servo circuit for high torque motors.I think that the servo approach for a feedback on the controls is more appropriate since they move in an small angle:about 60

Share this post


Link to post
Share on other sites
Guest mbessler

>Manuel,>>I am absolutely unable to write ever any codes for a chip like>the PIC or any other kind of microchips. >I have a very superficial understanding of what I am doing. I>have an creative approach on such issues, not the knowledged>technician one.>>But as far as I understand, the circuit of basic RC servos>motors seems not to be that complicated. >There must be somebody able to design such a servo circuit for>high torque motors.Hi torque motor means hi amperage drivers... and thats where things get a little more complicated and more expensive.It probably would be better to buy a industrial type servo complete with controller circuit. Ebay might be a source for this.I don't know if those servos can be controlled with RC-type PWM servo signals.>I think that the servo approach for a feedback on the controls>is more appropriate since they move in an small angle:>about 60

Share this post


Link to post
Share on other sites
Guest MikePowell

Roger,It looks promising, but Oatley has posted very little documentation. It appears they have added power transistors to buffer the output from the standard RC servo control chip. Without Oatley specs and information about the motor it is expected to drive, it's hard to say. Mikewww.mikesflightdeckbooks.com

Share this post


Link to post
Share on other sites
Guest mbessler

Roger,>Did you take a look here ???>http://www.oatleyelectronics.com/kits/k165b.htmlYes, I did.I just tried the chip name they mention on google, and it returned a data sheet:http://www.oatleyelectronics.com/pdf/m51660e.pdffrom the same site.500mA is what this chip can drive. Hardly enough. And this would still be a DC motor, but you mentioned that you'd like to use AC motors.When I looked at the site earlier, I saw the circuit picture. If you could drive high loads with it, then there'd be a big transistor, probably with heatsink. Not seeing this, and as the text seemed to indicate that the target audience are RC models and such, I concluded it would not suffice.Manuel

Share this post


Link to post
Share on other sites
Guest MikePowell

Manuel,It's difficult to see in the little picture, but I think there are the tops of 4 TO-220 power transistors on the right end of the kit PC board. The chip by itself cannot drive a large motor, but if there are indeed power transistors, the kit may be capable of much more.Mikewww.mikesflightdeck.com

Share this post


Link to post
Share on other sites
Guest SHORT360

Mike, ManuelI have send a mail to Oakley with all your questions.Will keep you informed a soon as I get an answer.CheersRoger

Share this post


Link to post
Share on other sites
Guest SHORT360

That's the answer I got from "We reccomend the use of a 12V car windscreen wiper motor for use with the giant servo kit for . Graeme MatthewsonOATLEY ELECTRONICS PTY. LTD.PO BOX 89, OATLEY, NSW 2223, AUSTRALIAPhone: 02 9584 3563 Fax: 02 9584 3561Int. Phone: 61 2 9584 3563 Int. Fax: 61 2 9584 3561Web Site: http://www.oatleyelectronics.comEmail Address: graeme@oatleyelectronics.com"Is a 12V wiper motor brusless ?? Would burn I guess if maintain on idle, would'nt it ??Cheers,Roger

Share this post


Link to post
Share on other sites
Guest mbessler

>That's the answer I got from >>"We reccomend the use of a 12V car windscreen wiper motor for>use with the giant servo kit for . >Is a 12V wiper motor brusless ?? Would burn I guess if>maintain on idle, would'nt it ??I don't think windscreen wiper motors are brushless.From what I understand, brushless motors need a special driver because commutation (energizing the motor coils) needs to be controlled since the motor doesn't do it 'automatically' like a brushed motor.The question is, will a windscreen wiper motor be powerful enough for your control feedback system for yoke, column, and rudder ?Manuel

Share this post


Link to post
Share on other sites
Guest SHORT360

Manuel,Windscreen Wiper motor taken from trucks for instance should be powerfull enough. I have tried to counteract by hand on the one of my Audi A4 and it is pretty hard. My only concern is how such motors behaves when stalled for an extented amount of time.May does Mike have the answer.regardsRoger

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...