Swerve drives

[bbradf44]

Heres a couple images of our inventor creation. Its still missing the gears, chain, axles, and belts but this is the basic design. This is only a rough and dirty concept. Below the piece of wood is the lazy suzan bearing. about 1/2 inch above the wood is a sprocket for the turning

[Bryce2471]

Originally Posted by Gdeaver

I like the 6127's. We did have problems losing calibration. We used plastic beam couplers from Automation Direct. They would some times slip requiring calibration. This year we took advantage of the good AL beam couplers that were on First Choice and they do not slip.

Ours were really easy to set up compared to the USD encoders we were using. We thankfully decided to get the fattened shaft version. This means that the setscrew we use to pin them down will not slip, and we don't have to find the junction between 0v and 5v on each one individually. We know that when the flat of the shaft is facing towards the BI symbol of the encoder, it is at "zero". We then mount them to the drive so that when the encoder is at zero the set screw is accessible. We then turn the module to a 45 degree angle,(witch is where we used to put the index) and slide on the plastic encoder gear.

We haven't done extensive testing, but the process seams promising.

PS. How do you interface with the output pins on the 6127's? We just solder PWM cables to them.

[ekapalka]

I'm not sure if this is true or not, but I've been told that a good thing to use for swerve drives are ten-turn potentiometers. The benefit being that you can easily plug it into the following

angle=(potentiometer_voltage-inherent_zero)*voltage_to_degrees

to get to the angle, whereas with other potentiometers you need to account for some sort of wraparound

[Orion.DeYoe]

Swerve is something I've wanted to build in the offseason for a while. I understand the mechanical and control concept of it and I know how it's driven and mostly how the modules need to be constructed.
The point that I have a really hard time understanding is how the pivot is set up. Does it just ride metal on metal? Or is there some sort of bearings, rollers, or slip pads/blocks? How do you contain the rotating module (the yoke) up and down and side-to-side while still being able to disassemble it? No one seems to have any good cross section views of the modules in an assembled state.

[Tyler2517]

Originally Posted by Orion.DeYoe

Swerve is something I've wanted to build in the offseason for a while. I understand the mechanical and control concept of it and I know how it's driven and mostly how the modules need to be constructed.
The point that I have a really hard time understanding is how the pivot is set up. Does it just ride metal on metal? Or is there some sort of bearings, rollers, or slip pads/blocks? How do you contain the rotating module (the yoke) up and down and side-to-side while still being able to disassemble it? No one seems to have any good cross section views of the modules in an assembled state.

We use thrust bearings in the top of the yoke so that it can carry weight but still rotate freely.
What do you mean by contain the rotating module? We have a retaining ring at the top of the pivot shaft that keeps it from falling out the bottom. The sides of our yoke have 3 bolts that have threads on the top of the yoke to connect. On ours at least it takes about 2 hours to get every thing to go together, to take it apart it can take up to 6 after a little use(with the help of a hammer). Our pivot shaft is thermal press fit in to the top of the yoke. We can not get it out even if we wanted to.

[The Doctor]

Originally Posted by ekapalka

I'm not sure if this is true or not, but I've been told that a good thing to use for swerve drives are ten-turn potentiometers. The benefit being that you can easily plug it into the following

angle=(potentiometer_voltage-inherent_zero)*voltage_to_degrees

to get to the angle, whereas with other potentiometers you need to account for some sort of wraparound

Team PWNage was using a $60 Absolute value encoder to figure out the angle.

[Jefferson]

Originally Posted by ekapalka

I'm not sure if this is true or not, but I've been told that a good thing to use for swerve drives are ten-turn potentiometers. The benefit being that you can easily plug it into the following

angle=(potentiometer_voltage-inherent_zero)*voltage_to_degrees

to get to the angle, whereas with other potentiometers you need to account for some sort of wraparound

If you are using the WPILib PIDController, it's as simple as setting the PIDController to continuous when using a continuous rotation encoder/potentiometer.

You have to keep up with turns and unwind if you get close to the limit on a 10 turn pot.

[ekapalka]

Originally Posted by The Doctor

Team PWNage was using a $60 Absolute value encoder to figure out the angle.

Believe it or not, our team (your team) is quite familiar with those. We have them on more than one of our older robots.

[mman1506]

Originally Posted by ekapalka

Believe it or not, our team (your team) is quite familiar with those. We have them on more than one of our older robots.

Any tips for preventing the tiny wire on the connectors breaking?

[ekapalka]

Originally Posted by mman1506

Any tips for preventing the tiny wire on the connectors breaking?

We connected ours by simply removing one wire (and 1/4 of the connector itself) from one of the 4 wire connectors that we had acquired for our OEM encoders (because we bought the 3 pin analogue versions). We've never had any problems with this setup, but we probably would have been better off with one designed for this task. We also cut the top off of a Mountain Dew bottle and used it to shield the sensor because it was located a bit precariously