DEWBOT XVIII Drive-Train
From DEW Robotics
Revision as of 03:32, 28 February 2023 by MaiKangWei (talk | contribs)
1640's Swerve history dates back to 2009 and all of our Robots from 2010 up to now (excluding 2016 - Stronghold_ have been swerve robots. We've always made our own kit and originally our swerve focus made us unique. But the world has changed. A number of excellent COTS swerve drive systems are now available to FRC teams and swerve has become a common feature.
So this year, for the first time ever, team Sab-BOT-age had to go through a make-versus-buy analysis. Using a COTS swerve module provides some very compelling benefits:
- COTS may be purchased ahead of the start of Build Season; and
- COTS may be reused.
Balanced against this:
- Some teams using COTS swerves in 2022 experienced supply-chain delays with spare parts (we can manufacture our spare parts);
- Designing & building the swerve modules provide a great education for our students;
- 1640's swerve is very light-weight (4.8 lb); and
- We are very comfortable with our swerve's performance.
The result of our make-versus-buy analysis was the decision to build our own modules again in 2023. But we'll go through this analysis again next fall.
Sab-BOT-age's 2023 swerve design was developed from the post- Hatboro 2022 design. Improvements focused on ease-of-manufacture, ease-of-service, and survivability.
Key 2023 changes were:
- 4" VexPro Traction Wheels (217-2588) replaced the 4" 80A durometer AndyMary HiGrip wheels (am-2256) we had used since 2013. The HiGrips perform well, are economical and they're light, but they wear out and replacements require a lot of machining before they can be used. The VexPro Traction wheels are used as-is and we employ a replaceable tread (which 1640 prints to a HiGrip tread pattern using Priline Assure 95A Urethane). The new wheels and treads were tested at Ramp Riot and found reliable with acceptable wear rates.
- Replaced the BI Technologies Magnepot Hall Effect Potentiometer Part # 6127V1A360L.5FS with Calt encoder. The Calt encoder is a Hall Effect device with double ball bearings (the BI has a bushing) and 12 bit resolution (vs the BI's 10 bit). Equal cost. 1640 had used the BI Potentiometer since 2012 DEWBOT VIII.
- Replaced COTS 1st stage drive reduction gears (15T & 29T steel 20DP spur gears) with gears cut from gear stock and broached in-house. This change allowed more rational and better-fitting bores in these gears and represents a significant time and cost savings.
- polycarbonate top plate - We changed supplier to obtain a full .250 thk polycarbonate for better stiffness.
- Replaced a COTS 11T HTD5 timing belt pulley with 1-piece printed Pulley & Gear. The old pulley had been prone to failure and was no longer readily available. had purchased from si/sdp - prone to cracking during broaching. eliminated a stage of reduction. htd5. 6t-48t stage 1 - hard sure 75d Ninjateck armadillo PU very tough filiment. Changed to 1 piece gear pulley.2 stage with nEO 550. 1100 rpm. 6:48 * 11:60 .ack of commercially available 11t pulley was the motivation.
- G10 bottom plate