![]() |
Re: Velocity Control - Battery Compensation Term
Quote:
(2) 775pros through 4:1 VersaPlanetary gearboxes driving a set of shooter wheels via 24T HTD pulleys (1:1) and belts. The shaft is nicely supported running on Thunderhex bearings. CTR Mag encoder on the VP. A vbus command of 1.0 yielded roughly 4400-4500 RPM. The battery checked in around 13V before we started the test but I didn't record the exact voltage while it was running. 775pro free speed is 18730, so a perfectly efficient 4:1 gearbox would give 18730/4 = 4683 RPM. The efficiency factor for this free running system is 4400/4683 = 0.94 to 4500/4683 = 0.96 I forgot to check the motor currents but IIRC from the previous night it was on the order of 3-6 amps per motor. With the motor is running at 17600-18000 RPM this roughly matches the motor curve of 6-8.5 amps. 0.95 factor seems like a better number for a free running system. However, in the case of a shooter or intake, using a 0.8 factor may get you closer to your desired vbus because of slippage at the wheel/ball interface. For the prototype mentioned above, we calculated the theoretical RPM required to achieve our desired exit velocity based on a trajectory simulation. We wanted gear ratio to run the motors around 60-65% vbus. The closest fit just under the target was a 4:1 gearbox that put it at 50% vbus. In testing, the motors ran at 60-65% vbus. So 0.5/0.625 = 0.8 magic. A bit sketchy, based on a theoretical trajectory simulation, but my guess is that using a 0.8 factor for shooter/intakes will get you close. |
Re: Velocity Control - Battery Compensation Term
Quote:
Quote:
And yet... we just added a form of battery compensation in the last CTRE installer. Check out section 10.8 in the latest Talon SRX Software Reference Manual. When enabled, the output of PIDF represents a portion of a specified voltage, which is compared against the measured battery voltage, yielding a voltage-compensated duty cycle. |
| All times are GMT -5. The time now is 03:18. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi