Greetings great gurus of Chief Delphi,
Here is another question from a rookie Mentor. I was wondering if most programmers/drivers let their shooter’s flywheel run continuously during an entire match or do they program it so that it only speeds when the driver is ready to shoot? For the ones who might ask, our shooting mechanism is fairly basic. It consists of two Colson wheels spun by a mini-Cim directly connected to the hex shaft. We have also included a through-the-bore CTRE mag encoder to get the RPM but nothing has been programmed yet. The system does not include a separate inertia wheel. So far, we have made some shooting tests where we would shoot just outside the tarmac and it takes about 3 to 4 secs for the motor to rev up to speed so we can hit the high goal. So, my concern is should we just let the motor spin constantly in order to prevent from having to wait for it to get up to the desired speed between cycles. Moreover, if we do let the motor spin continuously ( we would obviously slow it down) wouldn’t it drain the battery quite substantially?
Any advice or recommendation would be appreciated
I don’t believe I have ever seen a team run the Flywheel the entire match.
I understand your a rookie so a closed loop velocity control maybe a bit frightening, but your adding the right parts (encoder). So do try and watch the output and when it reaches a preset window value let the feeder send cargo.
I would worry about battery drain.
We ran the shooter for the previous year at 3000 RPM consistently through the match then went up to 3000-4500 depending on the distance, however we had 2 6inch steel flywheels to maintain speed so we wouldn’t be draining the power. i don’t recommend this because it takes a while to get up to speed for auto, especially if you only have 1 mini-cim but that only applies to the weight on the shaft. you should probably double up the motors to the shooter or gear it up
I would add some motor powere to get the speed up quicker, if it really is taking 3-4 seconds to spin up. For reference, ours is powered with two Falcon’s and spins up in a fraction of a second.
We run our twin wheel shooter continuously at reduced speed during the match and run it up to shooting speed only when needed. This improves the response time when going for a shot. Running shooter wheels that have very low friction does not consume much power at steady state - your only load is friction and windage (air resistance) both of which are minimal.
We have two Colsons driven by two Falcon motors and did a basic test: Simply letting them run at ~50 res/sec for 4 minute leaves the motors cold. On the other hand, starting and stopping the motors resulted in them getting quite warm. So we added a timer to leave the spinner runnig for a few seconds after the last shot in case another shot follows soon. Next was ramping them up to speed slowly (~3 seconds) to reduce the current spikes and heatup, which then meant we needed a button for the driver to “pre-spinup” ahead of a shot to reduce the time for shooting. Bottom line, simply leaving them running all the time, maybe at a slightly reduced speed, seems simplest and most gentle on the motors and battery.
Our driver has had the shooter on almost the entire time during match testing, he is able to use A to turn it on and B to turn it off. Because we are also using a turret and the limelight to achieve pose estimation our shooter stays ready to shoot almost constantly (uses swerve odometry to fill in gaps without vision solution, and constantly adjusts RPMs and hood angle) so this helps save time, and reduce the number of button presses (which takes his thumbs off the analog sticks) to just RB to feed. On a good battery he is able to go through over 6 minutes of constant runtime with the shooter, drivetrain, and constant intaking and indexing going on.
Edit: I should’ve mentioned we are using 2 NEOs in a 1:1 configuration with our average shot being around 2750rpms.
Thanks to everyone who have replied. Your advice is gold and I would certainly consider implementing some of them ( ex: doubling up the motors or even swapping them for some brushless types) . Cheers everyone and I wish you well with your respective teams.
I have seen some teams spin their flywheel throughout the entire match however it is unnecessary this year.
Shooter wheels this year don’t need to spin that fast (ours don’t even reach 3000 rpm for most shots) and you can put a lot of motor power into them. Running 2 falcons which a slight belt reduction (we are running 21:15) will allow the shooter wheels to spin up to speed in fractions of a second. Do make sure to correctly tune your velocity PIDs as an incorrectly tuned one can either spin up slowly or behave erratically.
I know from talking to some of their students that Orbit 1690 runs their flywheel through the whole match so that they can be constantly shooting without waiting for anything to spin up.
For just about any other team though, that’s pretty unnecessary. As you’re driving to your shooting position, your driver can press the button to start spinning up your shooter. It should be ready within a few seconds, right as you’re done aligning with the target. This will save on battery charge and keep the motor from overheating.
Can confirm, in our case there aren’t many motors that aren’t running just about all the time - the turret and hood keep moving to their desired position, the collector keeps spinning whenever it’s deployed unless we have 2 cargos in hand, the drivetrain is always on the move and the flywheel as well, the conveyor doesn’t have much down time as well.
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