Just wanted to see some of your thoughts on having a turret mechanism and swerve drive on a robot? I personally think it isn’t necessary due to the extra weight it may bring considering that swerve drive can orient the robot so that the shooter is aligned with the power port. Does having both provide and benefits or added flexibility on the field?
Depending on your application, it CAN provide benefits. Quite a few years back, 118 ran a turreted elevator on top of a crab drive.
They are two completely different design choices in my opinion. It is a lot easier to make small and fine adjustments (less than 2-3°) in the angle of a turreted shooter than it is to adjust the robot’s angle.
While I don’t have personal experience with this, looking at some of the robots this year it does seem to be helpful, though it may not be worth it for the added complexity. If you look at 2910 this year, they had an amazing bot that competed extremely well. Looking at the finals matches, you can see that defense significantly hurt them, to the point where they decided to go right up to the goal to score. While this isn’t an exact analogy, if you look at 148, they had another incredible bot with a turret on a swerve drive and it worked incredibly well for them. Obviously this is due to a number of factors, including their drivers, their resources and experience helped them, but you can see that even when they were swamped with defense some matches they still managed to score well. Another advantage is if you have a fast turret, it can aim a lot quicker than the when you have to rotate the entire robot. Of course, this is just a small list, and doing both might be overkill. Personally, I think it would be helpful but would also add a lot of issues with pdp slot allocation and a lot of added complexity.
Even 2767 did well at their regional running their Third Coast swerve with a turreted shooter. I suppose it comes down to how precise your turret is and how light you can make your swerve modules
148 did a turret and swerve drive this year and they did pretty well. If I remember correctly, their swerve allowed them to move around the field pretty fast and their turret would, most of the time, be facing the goal with the limelight
Personally we (1323) love doing swerve with turret. It allows you the freedom of some pretty cool moves not otherwise doable with either or. Our 2021 robot will have both
A sneak peak
Does “cool moves” include spinning the robot while keeping stuff above the turret steady? (for the record, I am aware this would
probably definitely rip out the wires)
Could I interest you in some slip rings perchance?
You’ve definitely got my attention here! I stumbled across that post about a week ago but it never hit me
+1 to this. Swerve is decent for shot alignment, but turret is definitely more accurate. Swerve is more for mobility reasons than shooting reasons.
Out of curiosity, do you run your limelight off of a pdb slot or do you use another method? Our team is looking at swerve but our motor slots are quickly adding up.
You have to run the limelight off of PDP as it’s counted as a custom circuit
Well, with swerve you don’t have to change just the robot angle. What we did this year is we start out by rotating and then close out the last few cm in the x direction(those inaccurate last 2-3°) by just moving sideways.
Of course before making the decision to forgo a turret, we tested this method with our summer swerve drive and a laser pointer, to make sure that we can stay within 1cm of our target from 6m away.
We used a turret with our swerve this year. During the design process, we debated whether or not to do this. Ultimately the turret won for 4 basic reasons:
The turret gives us the ability to continue to aim and shoot while being defended. A defender would not be able to simply push a corner of the robot to mis-align our shot. Specifically, it would allow us to park our robot against the wall in several locations on the field (using the wall to stabilize the position and orientation of the drive base against a defender) and aim using the turret from those positions.
The turret allowed less motion (less turning) of the robot between collecting and shooting. For the cycles where we collect from the loading station, the intake can remain pointed toward the driver station while the turret remains pointed toward the goal and the robot can focus on translating between the loading and shooting location. When the positive feedback gets going and we are collecting balls at the other end of the field, we can turn the shooter to stay aligned with the goal while having the robot facing various directions for collecting, and so on. In theory it also could allow shooting while hanging although we have not tried this yet.
It decouples the driving from the shooting in terms of control systems. The driver can focus on positioning the robot relative to other robots (defenders and alliance partners) and the game pieces while the operator can focus on aiming the shot. In practice, they are not completely decoupled, but the motions are decoupled enough that it significantly improves cycle time if the driver does not need to spend a lot of time re-orienting the robot to aim before shooting.
We have not done a turret before and we really wanted to do it. Our 2017 bot started off with a shooter that could rotate +/- 15 degrees, but the speed of the actuator was so slow that that we ended up locking it in one position by the end of the season. So this year we wanted to try doing a full turret that could rotate nearly 360 degrees. It was a nice engineering challenge and turned out pretty good.
We disabled our vision based turret control due to reports we heard from week 1 that it was not behaving well with the FMS. And we did not have the hood adjustment tuned prior to our week 2 event either, so we were aiming manually (using a camera feed back to the drivers’ station) and only adjusting the shooter speed for different range shots. This worked fine, but the full capabilities of the shooter relative to the 4 items above were not fully realized. Once we get the automation fully implemented, it will be a lot more effective.
We were very happy with the result and don’t plan to remove the turret for 2021. We will definitely look at improving the rotational speed, optimizing the driver interface controls and sorting out the issues that the vision aiming system is having with FMS so that we can turn that back on. I’m sure we will love it even more after we get the full capabilities operational.
Sometimes I do like to get slippy with it.
I agree with one of the posters above who said they’re mostly separate decisions. FWIW I don’t think swerve is especially useful in this game relative to other games, since the field is relatively open. If I had to pick one or the other, it would be turret for sure.
Also, 2767/148/1323/similar doing swerve+turret is not a great reason for you to do swerve+turret. Consider your resources.
Weight is not the only consideration: Complexity is (IMHO) a bigger factor to consider.
I am completely against a turret: A driver who practiced a lot can aim better. That being said, 832’s 2020 robot has a turret.
Is that with a turret that a driver would have to aim manually, or versus a turret with automatic targeting (or continuous targeting)?
We’ve gotten better with our vision processing (thanks to a bunch of resources posted here and elsewhere), but we’ve never tried a turret. I’d like to know more why you think a practiced driver (also something we need to work on more!) can aim better, if nothing else for knowledge of tradeoffs in the future.