Wireless Center of Pressure Feedback System for Humanoid Robot Balance Control using ESP32-C3

TL;DR

This paper introduces a wireless CoP feedback system using ESP32-C3 for humanoid robot balance control, enabling stable single-leg support on uneven surfaces with high sensor accuracy and successful experimental validation.

Contribution

It presents a novel wireless embedded balance system with real-time CoP estimation and control for humanoid robots, reducing wiring complexity and improving stability.

Findings

High sensor accuracy with 14.8 g error

Achieved 100% balance success in single-leg tasks

Effective PID control for stability on uneven surfaces

Abstract

Maintaining stability during the single-support phase is a fundamental challenge in humanoid robotics, particularly in dance robots that require complex maneuvers and high mechanical freedom. Traditional tethered sensor configurations often restrict joint movement and introduce mechanical noises. This study proposes a wireless embedded balance system designed to maintain stability on uneven surfaces. The system utilizes a custom-designed foot unit integrated with four load cells and an ESP32-C3 microcontroller to estimate the Center of Pressure (CoP) in real time. The CoP data were transmitted wirelessly to the main controller to minimize the wiring complexity of the 29-DoF VI-ROSE humanoid robot. A PID control strategy is implemented to adjust the torso, hip, and ankle roll joints based on CoP feedback. Experimental characterization demonstrated high sensor precision with an average measurement error of 14.8 g. Furthermore, the proposed control system achieved a 100% success rate in maintaining balance during single-leg lifting tasks at a 3-degree inclination with optimized PID parameters (Kp=0.10, Kd=0.005). These results validate the efficacy of wireless CoP feedback in enhancing the postural stability of humanoid robots, without compromising their mechanical flexibility.