# Coupled Design and Analysis of a Nonlinear Parallel Mechanism for Dynamic Humanoid Legs

- Source: arXiv cs.RO
- Published: 2026-10-26T04:00:00.000Z
- RoboHot: https://robohot.news/en/items/u2yp4x1zn4s8txrsbchllqnqn
- Original: https://arxiv.org/abs/2610.16604

## Summary

The paper proposes a series-parallel humanoid leg design that combines a knee parallel mechanism, an ankle parallel mechanism, and a nonlinear knee-ankle coupling, with all actuators placed near the hip. The authors derive coupled nonlinear transmission models and validate them in simulation and on hardware. The 6 kg leg achieves an effective reflected mass of 0.37 kg at the foot end; the coupling passively assists ankle dorsiflexion to lift the foot when the knee flexes, and assists plantarflexion for push-off when the knee extends.