Parameter Optimization of Optical Six-Axis Force/Torque Sensor for Legged Robots

2025-02-11

AI Summary

To address the urgent need for compact, lightweight six-axis force/torque sensors in legged robots, this work proposes a non-contact sensing architecture based on optocouplers—overcoming key limitations of conventional strain-gauge sensors, such as mechanical fragility and significant thermal drift. A differentiable multiphysics parametric–performance mapping model is developed to enable joint global optimization of sensitivity and measurement error. The resulting sensor weighs less than 85 g and features full-scale ranges of ±150 N and ±5 N·m. Calibration and dynamic testing demonstrate a static error of ≤1.2%, with excellent agreement between theoretical predictions and empirical measurements. Integrated successfully onto a quadrupedal robot, the sensor accurately captures high-frequency ground–foot interaction forces. This work establishes a new paradigm for high-precision, robust force perception in highly dynamic legged platforms.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Humans and AI: Brain-Sensing and Analysis
• Computer Vision: Low Level & Physics-based Vision

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

This paper introduces a novel six-axis force/torque sensor tailored for compact and lightweight legged robots. Unlike traditional strain gauge-based sensors, the proposed non-contact design employs photocouplers, enhancing resistance to physical impacts and reducing damage risk. This approach simplifies manufacturing, lowers costs, and meets the demands of legged robots by combining small size, light weight, and a wide force measurement range. A methodology for optimizing sensor parameters is also presented, focusing on maximizing sensitivity and minimizing error. Precise modeling and analysis of objective functions enabled the derivation of optimal design parameters. The sensor's performance was validated through extensive testing and integration into quadruped robots, demonstrating alignment with theoretical modeling. The sensor's precise measurement capabilities make it suitable for diverse robotic environments, particularly in analyzing interactions between robot feet and the ground. This innovation addresses existing sensor limitations while contributing to advancements in robotics and sensor technology, paving the way for future applications in robotic systems.

Problem

• Optimizing six-axis force/torque sensor parameters
• Enhanced sensor design for legged robots
• Improving sensitivity and minimizing measurement error

Innovation

• Non-contact photocouplers enhance durability
• Optimized parameters maximize sensitivity and precision
• Compact design suits lightweight legged robots