Design and Validation of a Novel Quadruple-Disk CYcloidal Compact-Cam Reducer for Robotic Applications: Q-CYC
Riccardo Bezzini, Giulia Bassani, Carlo Alberto Avizzano, Alessandro Filippeschi
AI summary
Problem
Conventional compact-cam cycloidal reducers suffer from low output smoothness, high vibration, irregular torque profiles, and poor backdrivability, which degrade precision motion control in robotics.
Approach
The authors propose a novel quadruple-disk architecture that applies a 180-degree phase-offset principle to two rigidly coupled compact-cam disk pairs, distributing loads more evenly and stabilizing output motion.
Key results
- Reduced gear play by 85% (from 0.361° to 0.056°)
- Increased unloaded and loaded speed regularity by ~6% and ~10% respectively
- Achieved backdrivability at ~2.45 Nm torque versus non-backdrivable conventional design
- Provided open-source CAD models, BOMs, and a geometric design tool
Why it matters
Enables more precise, smooth, and safe robotic actuation for applications like humanoid robots and exoskeletons where compliance and regularity are critical.
Abstract
Reduction gearboxes play a key role in robotics actuation. Among the existing designs, cycloidal gears are gaining popularity for their efficiency, torque density, and robustness. The compact-cam architecture is a variant of the classical cycloidal drive that employs two rigidly coupled cycloidal disks to achieve high reduction ratios within a minimized radial profile. However, this design tends to suffer from low regularity, which can degrade performance in robotics applications. Building on the concept of the double disks with a phase offset to increase regularity, in this work, we present a novel Quadruple-disk CYcloidal Compact-cam (Q- CYC) reducer that applies the phase-offset principle to the compact-cam architecture. By incorporating two additional coupled disks, the proposed design enhances load distribution and motion regularity. Two open-source, 3D-printed prototypes (one implementing the conventional compact-cam transmission and one featuring the presented quadruple-disk architecture) are designed and experimentally evaluated. The analysis focuses on friction, gear play, backdriveability, and speed regularity, demonstrating that the quadruple-disk design offers significant improvements. Therefore, the results validate the effectiveness of the proposed approach in addressing known performance limitations of cycloidal compact-cam reducers, reducing gear play and improving both speed regularity and backdrivability.