SO-ARM100 Track Axis

October 22, 2024 ยท View on GitHub

Summary

This project is related to the SO-ARM100 robot arm and LeRobot

It provides an additional axis, using the same STS3215 servo.

The carriage comes in 2 Versions:

  1. Direct Drive (best for leader with encoders or higher precision)
  2. Additional gear for twice the speed

Hardware

  • 1 x FeeTech STS3215 Servo (same as SO-ARM100)
  • 8 x 624 Bearing (ID: 4mm / OD: 13mm / H: 5mm)
  • 8 x M4 10mm or 12mm machine screws for bearings
  • 6 x M3 6mm or 8mm screws for motor bracket
  • 4 x M4 20mm bolts and hex nuts to mount arm to slide (there are also versions with 3.2mm holes for drywall screws)
  • M3 wood screws to mount rails to wooden base

The "Fast" version with additional gear additionally needs:

  • 2 x 624 Bearing (ID: 4mm / OD: 13mm / H: 5mm)
  • 1 x 4mm rod, ca. 35mm, longer is fine

Drive Gear Specs

  • Modulo: 1.5
  • Pressure Angle: 20
  • 18 Teeth
  • Height: 14mm

Code

The servo can give current feedback. This is used to home the axis and find the length of the track. A small python program demonstrates this and also shows how to keep track of multiple servo rotations.

  • Find end of track
  • Find home position
  • Move to 10% and 90% of track length
  • Move to middle

Video

https://youtu.be/PuqxYcexV3M

Images