A Passive Variable Impedance Control Strategy with Viscoelastic Parameters Estimation of Soft Tissues for Safe Ultrasonography

TL;DR

This paper presents a novel passive variable impedance control strategy with viscoelastic parameter estimation for safe and effective robotic ultrasonography, optimizing compliance in real-time to ensure patient safety and high-quality imaging.

Contribution

It introduces a new control approach combining real-time parameter estimation with safety constraints for robotic ultrasonography, enhancing safety and performance.

Findings

Demonstrated safe interaction with a dummy torso during ultrasound

Achieved accurate force control even with contact loss

Validated the method's potential for clinical applications

Abstract

In the context of telehealth, robotic approaches have proven a valuable solution to in-person visits in remote areas, with decreased costs for patients and infection risks. In particular, in ultrasonography, robots have the potential to reproduce the skills required to acquire high-quality images while reducing the sonographer's physical efforts. In this paper, we address the control of the interaction of the probe with the patient's body, a critical aspect of ensuring safe and effective ultrasonography. We introduce a novel approach based on variable impedance control, allowing real-time optimisation of a compliant controller parameters during ultrasound procedures. This optimisation is formulated as a quadratic programming problem and incorporates physical constraints derived from viscoelastic parameter estimations. Safety and passivity constraints, including an energy tank, are also integrated to minimise potential risks during human-robot interaction. The proposed method's efficacy is demonstrated through experiments on a patient dummy torso, highlighting its potential for achieving safe behaviour and accurate force control during ultrasound procedures, even in cases of contact loss.