# Can a Robotic Arm Use a Single Actuator to Achieve Both Extension and Joint Rotation? A Discussion of Cycloidal Gear Solutions

- Source: Reddit r/robotics
- Published: 2026-10-26T20:18:42.000Z
- RoboHot: https://robohot.news/en/items/upysau1apbhqylg1g8k4pue09
- Original: https://www.reddit.com/r/robotics/comments/1xg7z4o/extendable_mechanism_incorporating_into_a_robotic/

## Summary

A developer asked whether anyone has seen a single actuator achieve both extension and rotation of a robotic arm joint at the same time, and considered using cycloidal gears to compensate for the extra weight and joint torque requirements introduced by the extension section. The post is only a request for ideas; it gives no specific model, experiment, or validation results.