hi all,
I have been browsing the forum for a little while now and have started a project i believe to be over my head at the current moment. i have a brushless motor im trying to control via a brushless esc, arduino duemilanove, and a 100k pot. i would like to be able mimic the pots movement to the brushless motor, as of right now using the servo library i can make the motor move. the problem is that when it does move it raises in speed the more positive value it sees from the pot, same for nuetral, and reverse. what i would like for it to do is when the pot is at home "0" the motor is nuetral and when the pot is at max (1023) the motor would have made lets say 4 complete revolutions (just throwing a number out there) at a constant speed and when brought back to home from max it does the same in reverse. if the pot is stopped half way through the sweep that where the motor stops, here are the specs of what i have and how i have it wired...
brushless esc
pot
here is how i have the brushless motor wired, it has three poles.
As the motor has no form of feedback to tell the arduino how many revolutions it has turned I don't think you can do what you want with it in it's present state. And adding such hardware and software needed is not exactly a begineers project.
Not sure what to recommend to go forward with. Possibly you tell us what the motor is going attached to and what the end result you are trying to accomplish.
thanks for the quick response, the motor in question will be attached to a holset he351 turbo cartridge and it controls the exhaust housing vanes. i have the mechanical abilities to tackle this project, im just very lacking in the coding department. if its the feedback that's the problem, i can handle that. i can drive a pot off one of the gears in the housing that the brushless motor is located in, there is a total of three. where would i go from there??
here is a picture of the pot placement...
what would i need to know to go on to the next step? would i be better off buying some 1/4 scale servos and use the arduino to control them?
Well you will have to come up with some gearing or belt ratio as a pot is a 270 degree or so device and four turns either direction is 8 x 360. Assuming you can get that solved, then reading the pot is simply wiring it as a voltage divider and reading the analog value. Command motor forward, keep reading pot in a loop, stop loop when value reached, do same for opposite direction. You might have to consider end of travel safety stop switches for the motor circuit as it look like it has a lot of torque capacity.
as far as driving the pot i will do it off the gear on the far right (green dot)
the brushless motor gear is roughly 3/16 in diameter and the fits in the hole on the far left. the gear with the green dot is the final drive gear that drives the vvt arm through the housing in this picture:
the total range of motion we are talking about is roughly 2" on the vvt arm. If i cant use the full 2" of travel that would be fine as when the housing is full open my truck wont spool it so if we are stuck via the pot only going 270deg that will work.
yeah i'm basically trying to make a huge servo that i can control off a pot. i can take care of the mechanical side, i just need help with the coding. lefty you have been an awesome help so far and i really appreciate it! i need to know what information i need to gather as far as spec's on the gears (dia, teeth count, ect) to go to the next step. id be willing to compensate someone for their time...it may not be much but would be something to show I am thankful.
I would help further if I could, I just don't know what else to tell you specifically that might help. You are taking on a pretty unique challenge of converting a geared motor to become a servo, under arduino control.
There are extra large extra heavy duty high torque R/C servos avalible that you might consider using instead of a roll your own solution.
