47a8b40fdb
TREE(74): training modules, entity profiles, 2890 references, keyword indices SPROUT(42): knowledge pages, project docs, curated source material SEED(164): daily notes, raw session logs, unprocessed material Updated AUDIT_MANIFEST.json with growth classifications.
76 lines
3.2 KiB
Markdown
76 lines
3.2 KiB
Markdown
---
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title: "Team 2890 Swerve Modules — SDS MK4i"
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tags:
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- hardware
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- drivetrain
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- swerve
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- 2890
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type: hardware-spec
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owner: 2890
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status: active
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sources:
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- "https://www.swervedrivespecialties.com/products/mk4i-swerve-module"
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- "https://andymark.com/products/sds-mk4i-swerve-modules"
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- "https://www.scribd.com/document/690437836/SDS-MK4i-Swerve-Modules-Assembly-Guide"
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growth: tree
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---
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# SDS MK4i Swerve Module — Team 2890 Standard
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## Overview
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Team 2890 uses the **Swerve Drive Specialties MK4i** swerve module. This is the core drivetrain component — each robot has four modules, one per corner.
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## Key Features
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- **On-axis steering encoder** — zero backlash, module can be disassembled/reassembled without resetting encoder offset
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- **Corner bias** — compact 4" × 4" internal frame width (MK4i has same corner bias as MK4n, different from MK4)
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- **Full steering ratio:** 150/7:1 (passes through one gear pair, then a 64T belt pulley pair)
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- **Mounting hardware:** Updated June 2023 — changed from 8-32 to **10-32 screws**
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- **Wheel options:** Standard 4" wheel (can be replaced with 3" for weight savings)
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## Drive Ratios
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| Ratio | Best For | Notes |
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|-------|----------|-------|
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| **L1** | Standard full-weight competition robots | Most popular |
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| **L2** | Standard full-weight competition robots | Most popular |
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| **L3** | Lightweight robots | More aggressive, higher speed |
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L1 and L2 are recommended for standard FRC robots. L3 is for lightweight builds only.
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### Team 2890 — L1 and L3 (Field-Swappable)
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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.
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| Ratio | Stage 1 | Stage 2 | Stage 3 | Free Speed (Vortex) |
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|-------|---------|---------|---------|---------------------|
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| **L1** | 15T/22T | 20T/26T | 26T/36T | ~14.4 ft/s |
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| **L3** | 15T/22T | 20T/26T | 26T/36T | ~12.8 ft/s |
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**L1 = faster, less torque.** **L3 = more torque, slightly slower.** Swap based on game demands — L1 for high-speed defense, L3 for climbing/pushing.
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*(Gear ratio diagram: `mk4i-gear-ratios.png`)*
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## Connection to Training
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**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:
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- Why steering ratio matters (fast steering vs. precision)
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- What "corner bias" means for turning radius
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- How the belt drive multiplies torque from motor to wheel
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**Related training modules:**
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- [[motor-basics]] — understanding Kv, torque, current relationships
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- [[frc-drivetrain-training]] — swerve kinematics and control
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- [[2890-codebase-index]] — how the code configures these modules
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## Source Links
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- Product page: https://www.swervedrivespecialties.com/products/mk4i-swerve-module
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- Assembly guide (PDF): https://www.scribd.com/document/690437836/SDS-MK4i-Swerve-Modules-Assembly-Guide
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- AndyMark: https://andymark.com/products/sds-mk4i-swerve-modules
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## Notes for MrC
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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.
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