|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
|
|
Thread Tools | Rate Thread | Display Modes |
|
|
|
#1
|
||||
|
||||
|
Re: FP 2011 (00801-0673) versus 9015 power
Quote:
20770.....0673 motor free rpmWhy did you gear it so fast? |
|
#2
|
|||
|
|||
|
Re: FP 2011 (00801-0673) versus 9015 power
Because that was the only remotely appropriate gearbox we had in inventory ! We hoped we could get away with a single FP or 550 size motor to minimize high up weight. We had hoped to reduce chain related losses (and sprocket & chain weights) by direct driving (through the AM). We also had no idea what sort of drop in RPM a largely unloaded motor would incur trying to shoot the ball (drop in RPM means drop in exit velocity of the ball relative to the no-load rpm). Heh I'm not in mechanical
But then we found the recover time slower than we would like. Shooting distance was limited to 14 ft which some team members wanted more so we put on a more powerful motor. Unfortunately its KV was higher. |
|
#3
|
||||
|
||||
|
Re: FP 2011 (00801-0673) versus 9015 power
The way to get fast recovery time for a shooter wheel is to use a reasonable gear ratio and control the motor closed-loop at an operating point where it has sufficient headroom to rapidly accelerate the wheel back to that operating point after being disturbed. Some design guidelines were suggested here. |
|
#4
|
|||
|
|||
|
Re: FP 2011 (00801-0673) versus 9015 power
Great points you make. We actually do have an encoder and PID on it to set and manage target speeds based on shooting distances. When shooting from any distance that has a reasonable probability of actually scoring (5-12ft), the wheels are not spinning anywhere near full power and the PID code does attempt to aggressively recover the target RPM. So I think we ended up close to what you recommend.
Last edited by de_ : 05-03-2012 at 12:16. |
|
#5
|
||||
|
||||
|
Re: FP 2011 (00801-0673) versus 9015 power
Quote:
1) how fast are the wheels spinning under those conditions? and 2) under those conditions, what voltage is being supplied to the motor (or how many amps is the motor pulling) ? |
|
#6
|
|||
|
|||
|
Re: FP 2011 (00801-0673) versus 9015 power
You may ask... It may take me a day or so to get the data. I need to know it for future reference as well. I'm also going to try to get the RPM of the wheels for the 7', 12' and max power off our encoder data, maybe even how much the wheel slows down shooting a ball at the various distances. Did a lot of shooting this afternoon at 7 and 12 feet. Motors completely cool (with fans), recover was 2 seconds or less.
|
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|