I am looking in to design and manufacture the perfect swerve drive. What would be the best features if you had unlimited resources. Would you use field centric control robot centric or some type of hybrid? 2 speed shifters or a static gearing? What speeds? 4 wheel’s or 3 wheel’s? Do you care about the weight more then shifting? What wheel size? Any cool layouts that save weight or make it stronger?
Opinions are welcome.
hmm… an interesting question. Personally, I think that this is my favorite. It’s really small, really light, and really cool. It’s also nice because you don’t have the drive axle after the supports on the module. Having the drive axle higher up than the module rotation bearing will really decrease the loads that part will see.
If you want two speed, I’ve seen a team 111/team 16 style swerve that has both the motor and the shifting mechanism in the rotating part. another cool idea would be to use a vex pro ball shifter, but then have the output shaft go directly into the module, so you’re “direct driving” the swerve.
973’s Emperor Swerve is the closest to a “Unicorn”-class swerve out there.
The “Unicorn” class, as I recall, is 2-speed, unlimited turning, non-coaxial (AKA, the motor is in the module), and each side (or is it each wheel) can be rotated independently of the other (minimum of 2 steering motors). It’s not easy to do, but the benefits can be worth it.
OTOH, then there’s 118’s V6 designs…
Possibly a suspension like this: http://www.chiefdelphi.com/forums/showthread.php?t=92393
Our team also has some cool top-secret ideas on swerve, I must have speaks with my superiors. 
Each module needs a CVT to transmit power to the drive wheel, and must not be limited by module rotation (similar to a coaxial module or a module with slip rings to power the motor).
Must be controlled by a plug directly into the driver’s brain.
1717 has the best I’ve seen so far, and it improves every year. They do not have the restriction of unlimited resources, but do a good job of hiding it!
Technically, I don’t think Unicorn drives can shift. The 973 implementation went above and beyond theoretical magical constraints.
Quoted for truth. I hear they actually cut all their own gears, because it’s cheaper and faster for them to make it out of round stock, in house than it is for them to buy and wait a few days for shipping.
I’d also check out 368’s swerve, especially their driver setup. They played really well at SVR, and were the first swerve I’ve ever seen where the swerving actually improved their gameplay, rather than just being a cool way to move around the field.
The perfect swerve for each team is the design that a team can implement in the build season constraints and with their resources.
The perfect swerve drive is the one that your team can design, build, and implement with the greatest degree of success. There is no magical gearing, wheel size, or control scheme that makes one swerve drive inherently better than another. There are several examples of very well-done swerves, but I’m sure each team who has done swerve drive can pick out something to improve.
Some witty comment about pursuing perfection and catching excellence instead…
Personally, I think you are missing the point of the thread. The hypothetical is with no limits on resources of any kind, so some designs are certainly going to be better than others.
Mechanically, a good swerve design is a good design. Teams that have gone through numerous iterations probably have it figured out better than most. Personally, I would love to see a 3 wheel swerve design with two cims driving each wheel, I’m not convinced the swerves we have seen so far are as fast as some of the tank bots. Additionally, I doubt a shifter gives much of an advantage to a swerve unless you are playing overdrive. 67 did an awesome 3 wheel swerve in 05, and I think that was the most dominant robot they have built to date.
I believe, the best swerve probably take their advantages from the controls that are engineered into the design. It goes above just having the right sensors, but having the correct algorithms to make driving intuitive and easy. Field oriented drive, with the ability to make the robot do what you want when you want is the hallmark of a well controlled swerve. Anyone have suggestions of teams that did this well? I know 16 and 111 did a lot of controls development to allow their drive teams to get the results they wanted, but I can’t really comment on specifics.
I think we are just touching the tip of the iceberg with what can be done with the controls, the revised CAN system will really open up possibilities with finer control, and even make an auto shifting 2 speed shifter simple to implement.
I think using a high end gaming mouse in the future to track the robot on the field will be something to watch out for in the future. I know i have been looking in to when it was mentioned in another thread.
If we attempt a swerve this offseason, this is going to be something we will try. It will be much more accurate for a field centric control scheme than what is currently being used (to my knowledge)
If we attempt a swerve this offseason, this is going to be something we will try. It will be much more accurate for a field centric control scheme than what is currently being used (to my knowledge)[/quote]
Field-centric is about robot angular orientation. How are you planning to measure robot angular orientation with a single mouse? Won’t you need two?
Yeah you would need 2 mice to have the rotation control. As far as i know my mouse can track on the fields carpet extremely well. I wonder if they would loss calibration over time.
I was thinking the same thing. I suppose a team could create a device using a laser and receiver from a gaming mouse and something like a scroll wheel mounted sideways and controlled by the thumb with the purpose of changing angle relative to the field. The programming would be complex but the results could be good.
I wonder what their dynamic response capability is. Like if you take a hit.
In 2013 looked at high end gaming mice. With swerve and the chassis orientation decoupled, there are 2 solutions of the x and y counts coming from the mouse. On competition carpet and no changes to the optics we found the accuracy to be less than needed. The optic flow algorithm is not tuned for this use. With a usb port on the roborio in 2015, A usb camera highly filtered and a more robust optic flow algorithm may yield better results. A gyro at minimum would need to be fused with the optic flow. This is all for field centric control. There are 2 paths 2 look at. Sensing from the robot reference frame (gyro accelerometer fusion). Adding a world reference frame with a magnetometer or some other sensor to reference out side the robot frame of reference. GPS is out. Constellation navigation has grabbed my curiosity. It’s hard. In 2013 we could have reset the gyro every time we went up against the feeder station wall to correct for drift. This year we considered IMU field centric control not doable because of the constant impacts and never having time for a reset. The last thing our drivers need this year is for the field centric control to suddenly shift several degrees while being smash defended and trying to roll out. With our low designs the last several years a magnetometer location and calibration issues ruled out that solution. Fortunately for the future of swerve field centric a couple of companies have released affordable IMUs based on gyro, accelerometer and magnetometer sensors coupled with highly tuned extended state kalman filters that should handle the rough First environment. The key is constant hard and soft iron calibrations on the magnetometer sensor. I’m hoping to make this an off season project if I can get some programming students on board. I think soon a plug and play Field centric IMU solution will be available for FIRST.
It’s not clear what you mean by 2 solutions. With a single mouse, an XY displacement could correspond to a multitude of possible robot motions.
With 2 mice, you could in theory derive all three degrees of freedom of the robot motion, if the XY readings are accurate.