Motor Costs Comparison (more pro-electric)

[Dean Pappas]

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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