db7976467c
- L1: ~14.4 ft/s, L3: ~12.8 ft/s (NEO Vortex) - Field-swappable based on game strategy - Gear ratio diagram image added
3.2 KiB
title, tags, type, owner, status, sources
| title | tags | type | owner | status | sources | ||||
|---|---|---|---|---|---|---|---|---|---|
| Team 2890 Swerve Modules — SDS MK4i |
|
hardware-spec | 2890 | active |
SDS MK4i Swerve Module — Team 2890 Standard
Overview
Team 2890 uses the Swerve Drive Specialties MK4i swerve module. This is the core drivetrain component — each robot has four modules, one per corner.
Key Features
- On-axis steering encoder — zero backlash, module can be disassembled/reassembled without resetting encoder offset
- Corner bias — compact 4" × 4" internal frame width (MK4i has same corner bias as MK4n, different from MK4)
- Full steering ratio: 150/7:1 (passes through one gear pair, then a 64T belt pulley pair)
- Mounting hardware: Updated June 2023 — changed from 8-32 to 10-32 screws
- Wheel options: Standard 4" wheel (can be replaced with 3" for weight savings)
Drive Ratios
| Ratio | Best For | Notes |
|---|---|---|
| L1 | Standard full-weight competition robots | Most popular |
| L2 | Standard full-weight competition robots | Most popular |
| L3 | Lightweight robots | More aggressive, higher speed |
L1 and L2 are recommended for standard FRC robots. L3 is for lightweight builds only.
Team 2890 — L1 and L3 (Field-Swappable)
Chris's team runs L1 and L3 gear sets, both driven by NEO Vortex motors. Gears swap in the field to change the drive ratio per event or strategy.
| Ratio | Stage 1 | Stage 2 | Stage 3 | Free Speed (Vortex) |
|---|---|---|---|---|
| L1 | 15T/22T | 20T/26T | 26T/36T | ~14.4 ft/s |
| L3 | 15T/22T | 20T/26T | 26T/36T | ~12.8 ft/s |
L1 = faster, less torque. L3 = more torque, slightly slower. Swap based on game demands — L1 for high-speed defense, L3 for climbing/pushing.
(Gear ratio diagram: mk4i-gear-ratios.png)
Connection to Training
For students learning swerve: This module uses a 1/2" hex output shaft. Understanding hex shafts and how they transfer torque is fundamental mechanical knowledge. Students should also understand:
- Why steering ratio matters (fast steering vs. precision)
- What "corner bias" means for turning radius
- How the belt drive multiplies torque from motor to wheel
Related training modules:
- motor-basics — understanding Kv, torque, current relationships
- frc-drivetrain-training — swerve kinematics and control
- 2890-codebase-index — how the code configures these modules
Source Links
- Product page: https://www.swervedrivespecialties.com/products/mk4i-swerve-module
- Assembly guide (PDF): https://www.scribd.com/document/690437836/SDS-MK4i-Swerve-Modules-Assembly-Guide
- AndyMark: https://andymark.com/products/sds-mk4i-swerve-modules
Notes for MrC
Chris uses these modules with NEO Vortex motors and SPARK Flex controllers. The full stack is: MK4i + NEO Vortex + SPARK Flex + YAGSL. The YAGSL library (Yet Another Gyro Library) handles the swerve math and motor control in code.