For a while I have been wanting to make new differential swerve as my last (HERE) had some room for improvement. I had some free time over the past couple days to design a new module, so I would like to share my Differential Swerve MK2.
There were 3 key areas I wanted to improve in this model over the previous model;
- Increased ground clearance, comparable to a traditional swerve (around 1.5in-2.5in target)
- Reduced weight (Sub 3lbs target)
- Reduced used space inside of frame length/width (Sub 3in in X and Y target)
Alone with those requirements a few other things I wanted in the design where;
- Easily replaceable in case of mechanical failure.
- Integration with frame
- Wheel pivot point as close to corner as posable for wider wheelbase.
- High use of 3D printing technologies
Some major differences in between the MK1 and the MK2 are;
- New style of Differential mechanism (inspired by 4341’s)
- Use of 2x Neo 550s instead of 2x Neos
- Instead of being nested into the frame it acts as a structural member (inspired by Bryce’s Design HERE)
- Use of custom bearing set up instead of COT bearings to save weight
I went with a new style of differential mainly because a setup like this if far easier to change the ground clearance depending upon the requirements. The new style also lent itself to my custom bearing set up more easily then the differential I used on my MK1. My original plan was to use two 775 pros instead of two Neos due to the smaller diameter however I ended up choosing to use two of revs new Neo 550’s as they are shorter than a 775 and sport an integrated encoder, however this design could easily be modified to use 775 pros.
The MK1 module was nesting into the frame to reduce its footprint inside the frame. Instead of nesting MK2 into the frame I decided to integrate it as a structural member for two main reasons. First to again reduce the inner frame footprint. Second to allow the module to be able to side out diagonally from the frame if/when it needs to be replaced.
While this module has a lot going for it however there are a few things I will improve in the MK3 when/If I design it;
- Reduce modules total height (sub 4.5in)
- Reduce the need for ultra-high precision machining.
- Reduce number of heavily modified/custom COTS parts (mainly in terms of the gears).
- Reduce part count.
- Allow for easy servicing of module for repairs while installed (currently if anything breaks or you want to replace a motor you would need to replace the whole module)
Critics, comments and, questions are, as always, more than welcome!
If you would like you can check out the CAD for the module HERE
-Trevor Glasheen, Alumni