Swerve Drive
The swerve drivetrain is a drivetrain capable of omnidirectional motion. Swerve is typically composed of modules that contain a wheel assembly, a propulsion motor, a steering motor and all of the necessary mounting and gearing to propel a robot across the competition field. While swerve drive programming is inherently more complicated than alternative drivetrains used by teams in FRC, it offers the capability of fully independent component rotation and translation of the robot.
Swerve Drive History
Swerve drive has had a long history of use in the FRC environment.
The early Years
first introduced in ---- by team ----
Crab Drive
before fully independent control of each modules wheel orientation existed, there was a drive train concept called crab drive. Crab drive involved the use of modules thats wheels rotations were synchronized. the modules rotated together via chain or belt drives to a centralized propulsion motor gearbox and steering motor gearbox. Crab drive was capable of moving the robot omni-directionally while translating but was not capable of rotation of the robot through the rotation of modules. often robots that had crab drivetrain would include turrets that housed all robot mechanisms oto play the game.
Unicorn Drive
after many years we arrive at what look closer to what we currently refer to as simply swerve drive
SDS and the COTS swerve revolution
When FRC 2910 worked on an offseason project in the summer of 2017, nobody expected that the module that their team created would revolutionize the landscape of FRC drivetrains forever. After a world finalist medal was won by the team, a mentor of Jack in the Bot started the Company Swerve Drive Specialties (SDS). SDS began producing swerve modules that were drop in ready drive trains that were built to withstand the rigors of modern FRC games at a price point that enabled most teams to begin considering swerve as a primary drivetrain option.
Differential Swerve drive
while the drive train motors race was ongoing
Commercial off the shelf (COTS) Swerve
The following lines will describe the swerves sold by each vendor and show what they look like so that they may be more easily identified in the future.
Swerve Drive Specialties (SDS)
West Coast products (WCP)
REV Robotics
The Thrifty Bot
AndyMark
Module has been discontinued but may still be found on robots utalizing used components.
221 Robotics
Module not sold anymore but is a good example of what advanced early swerve drive looked like.
COTS vs Custom Swerve Modules
Most teams today have switched to the use of Commercial off the Shelf Swerve modules from common FRC Vendors. Some teams however will build custom swerve modules that are designed to fit the specific needs of the team during that years competition. There are many different unique iterations of swerve created by teams, too many to cover completely. A few unique or interesting modules will be showcased below.
FRC 2767 StrykeForce
Double wheel swerve modules with spring suspension
FRC 1640 Sabotage
CVT Shifting swerve modules allowing smooth transitions in drive speed via servo powered transmission
FRC 2451 PWNAGE
Mini Cim motor in wheel swerve modules