Swerve designs

[asid61]

Originally Posted by MStump

Another thing to keep in mind is with swerve comes a lot of extra parts: eight motors, eight motor controllers, four sets of gears, and another stage for rotating the gearboxes.

You will also almost certainly need at least four encoders (maybe even eight depending on how you do it!). Encoders can often be difficult to work with so if you decide to use a swerve drive during the season, it would probably be a good idea to be confident with the use of these sensors.

How would you use only 4 encoders? You could probably live with 5 on a 4-wheel crab, or 4 encoders on a 3-wheel crab, but I thought you needed at least 6 for a 3-wheel swerve?

[Ether]

Originally Posted by asid61

How would you use only 4 encoders?

4 encoders for steering 4 wheels.

Voltage control of drive motors.

[Gdeaver]

For a 4 wheel drive independent swerve we use 4 0 - 360 continuous rotation absolute encoders with 10 bit analog output for stearing. We do not control individual drive wheel speed with encoders. We do have a tach on each drive wheel. We use a cheap analog IR analog reflectance sensor plugged in to a digital input. The roborio does the digital chopping. Pololu QTR-1a 's for $4.25 a pair. We use the tach's for distance measurements. This year we went with a navx-mxp board for autonomous navigation. Swerves do not like to drive straight.