Motor Costs Comparison (more pro-electric)

[Earl Haury]

Dean

I agree.

Since the very nature of how servos function involves control input (from the ground) and position info (onboard) (feedback loop) it seems obvious that onboard feedback loops are not only permitted, but necessary. A good example of an expansion of this is EGT to control engine A/F. 

I have toyed with the idea of an airspeed feedback loop to the throttle, where airspeed is set by stick position and the "loop" works to maintain that speed. In discussions with folks, I find that many interpret this as violating the intent of the "no feedback" rule while careful interpretation might result in a different conclusion. Basis current rules, any communication between a motor and ESC would seem quite legal. Adding speed input, I suspect could trigger a rules change.

Earl
  ----- Original Message ----- 
  From: Dean Pappas 
  To: discussion at nsrca.org 
  Sent: Tuesday, September 21, 2004 9:20 AM
  Subject: RE: Motor Costs Comparison (more pro-electric)


  Hi John,

  As I read this, a motor speed controller is just as legal as a motor applied voltage controller.

  The following is excerpted from section 5.1.2 of the Sporting Code:



  Radio equipment shall be of the open loop type (i.e. no electronic feedback from the model aircraft to the

  ground). Auto-pilot control utilising inertia, gravity or any type of terrestrial reference is prohibited. Automatic

  control sequencing (pre-programming) or automatic control timing devices are prohibited.

  Example:Permitted:

  1. Control rate devices that are manually switched by the pilot.

  2. Any type of button or lever control that is initiated and terminated by the pilot.

  3. Manually operated switches to couple control functions.

  Not permitted:

  1. Snap buttons with automatic timing mode.

  2. Preprogramming devices to automatically perform a series of commands.

  3. Auto-pilots for automatic wing leveling.

  4. Propeller pitch change with automatic timing mode.

  5. Any type of voice recognition system.

  6. Any type of learning function involving manoeuvre to manoeuvre or flight to flight analysis.

  Thanks for jogging me to give the section a critical reading,
  Dean Pappas 
  Sr. Design Engineer 
  Kodeos Communications 
  111 Corporate Blvd. 
  South Plainfield, N.J. 07080 
  (908) 222-7817 phone 
  (908) 222-2392 fax 
  d.pappas at kodeos.com 

    -----Original Message-----
    From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of John Ferrell
    Sent: Monday, September 20, 2004 7:50 PM
    To: discussion at nsrca.org
    Subject: Re: Motor Costs Comparison (more pro-electric)


    I hate to be a party pooper, but a constant speed control loop is not permitted under the existing FAI Rules as I understand it for our wet engines. Is it allowable for the dry whiners?
    BTW, I am all for closed loop control devices...

    John Ferrell    
    http://DixieNC.US

      ----- Original Message ----- 
      From: Dean Pappas 
      To: discussion at nsrca.org 
      Sent: Monday, September 20, 2004 12:52 PM
      Subject: RE: Motor Costs Comparison (more pro-electric)


      Hi John
      No fuzzy logic! When the stick moves. something deterministic should happen!
      I suspect that the existing ESC makers already have all the hardware needed, as brushless brakes only require an intentionally retarded commutation timing, while brushed motors require the additional shorting transistors. But you can never have enough projects going at once ... eh?
      We'll talk later,
      Dean

      Dean Pappas 
      Sr. Design Engineer 
      Kodeos Communications 
      111 Corporate Blvd. 
      South Plainfield, N.J. 07080 
      (908) 222-7817 phone 
      (908) 222-2392 fax 
      d.pappas at kodeos.com 

        -----Original Message-----
        From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of John Pavlick
        Sent: Friday, September 17, 2004 9:19 PM
        To: discussion at nsrca.org
        Subject: RE: Motor Costs Comparison (more pro-electric)


        Dean & Matt,
         Yes. I forgot to mention the the "programmability" factor of an electric motor. Whereas a glow motor's characteristics come from mechanical things (bore, stroke, port timing, etc.), an electric motor and speed controller can work together to alter the torque curve. Some speed controls take advantage of this now, but most people don't realize it. The better speed controls use a non linear type of output (I'm oversimplifying here) to make the electric motor "feel" more like a glow motor. I haven't worked much with the brushless motors but I have a bit of experience with the can motors (from R/C car racing). It seems like what we need is a speed controller with a P.I.D. control loop. The currently available ones are one dimensional / open loop. The throttle stick simply increases or decreases the output of the motor. The speed controller just changes the PWM duty cycle in direct response to the stick position. We need some feedback and Fuzzy Logic to do this right. Dean: If you design the hardware, I'll work on the code...
        John Pavlick

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