Differential Swerve Drives are on the cutting edge of FRC drivetrains. Designs like 971s have inspired many to think about the potential. If you can handle the increased complexity, having two motors driving each wheel instead of one seems like an obvious improvement right?
Well, I’m not so sure anymore with the release of the Neo and Falcon500 brushless motors. With the incredible power these motors provide, I’m wondering if using only one puts you in a situation where you are traction limited, and therefore, unable to utilize the added power of an extra motor.
Assume a 140lb swerve robot with 4" wheels and a 10:1 reduction.
The force each wheel can produce with a Falcon500 at stall is:
(4.69N*m * 10 / 0.0508m) = 923N
The normal force on each wheel (assuming equal weight distribution) is:
140lb / 4 = 622.75N / 4 = 155.6875N
To avoid slipping, we would need a coefficient of friction of
923 / 155.6875 ~= 6. Based on the thread CoF ranges, no common FRC wheels come close to this.
- Is this the right analysis to do to calculate if the configuration is traction limited?
- If a single motor is traction limited, are there any benefits to doing a Differential Swerve over a traditional one? (I suppose it may allow the use of lighter motors)