# Design of a flexible probe-holder arm for robot assisted echography

Samar Jridi, Manel Abbes, Hassen Mekki, Pierre Vieyres, G. Poisson

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Samar Jridi, Manel Abbes, Hassen Mekki, Pierre Vieyres, G. Poisson. Design of a flexible probe-holder arm for robot assisted echography. Conférence en TéléSANté et Dispositifs Médicaux (JETSAN), Jun 2025, TROYES, France. hal-05428940

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Submitted on 22 Dec 2025

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# Design of a flexible probe-holder arm for robot assisted echography

Samar JRIDI¹,², Manel ABBES¹, Hassen MEKKI², Pierre VIEYRES¹ and Gérard POISSON¹

(1) Université d'Orléans, INSA CVL, PRISME UR4229, Orléans, France

(2) NOCCS Laboratory, University of Sousse, Sousse, Tunisia

samar.jridi@etu.univ-orleans.fr

## MOTIVATION

Soft robotics is rapidly advancing in medical applications, such as ultrasound imaging, where manual and rigid systems limit precision and patient comfort.

Soft robotics can address these limitations by enabling safe, **compliant**, flexible, and controlled movements.

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Addressing the gap in the literature on **intermediate deformation** in soft robots to advance robotic assistance for ultrasound applications.

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Achieve the optimal **compromise** between **flexibility** and **rigidity** for precise, controlled movements.

## OBJECTIVES

Design and optimize a flexible arm guided by 6 DoF rigid robot to achieve precise positioning through a closed-loop control.

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Ensure accuracy and reliability through the optimization of arm design and materials, together with a real-time deformation compensation control strategy.

## ADVANCED APPLICATIONS

### Infiltration into the carpal tunnel

Robotic assistance for ultrasound probe positioning:

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Improves accuracy

→ Enhances precision in probe positioning.

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Simplifies clinical procedure and reduces clinician workload

→ The robot provides a third hand, supporting the clinician.

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Reduces procedure time

→ Optimizes workflow and increases efficiency.

### Image fusion between Ultrafast Ultrasound Imaging (UUI) and Positron Emission Tomography (TEP) Scan

<figure><img src="image_11.png" /></figure>

Enable precise, and reliable interpretation of cancerous tumors evolution by generating 3D representations using two complementary imagery modalities.

## STATE OF THE ART

The concept of soft robotics is defined in various ways, from material-based criteria to broader approaches emphasizing adaptability and safe interaction. Some definitions even include robots with rigid parts if they offer sufficient compliance.

The table below summarizes key differences between robot types.

<table><thead><tr><th></th><th>Rigid Robots</th><th>Mixed Soft Robots</th><th>Soft Robots</th></tr></thead><tbody><tr><th scope="row">Characteristics</th><td>n &le; 6<br>E = 10<sup>4</sup>.. 10<sup>5</sup><br>No</td><td>n = &infin;<br>E = 10<sup>-2</sup>.. 10<sup>4</sup><br>Limited</td><td>n = &infin;<br>E = 10<sup>-2</sup>.. 10<sup>2</sup><br>Infinite</td></tr><tr><th scope="row">Capabilities</th><td></td><td></td><td></td></tr><tr><th scope="row">Precision</th><td>● ● ● ●</td><td>● ● ● ●</td><td>● ● ● ●</td></tr><tr><th scope="row">Speed</th><td>● ● ● ●</td><td>● ● ● ●</td><td>● ● ● ●</td></tr><tr><th scope="row">Loading Capacity</th><td>● ● ● ●</td><td>● ● ● ●</td><td>● ● ● ●</td></tr><tr><th scope="row">Adaptability</th><td>● ● ● ●</td><td>● ● ● ●</td><td>● ● ● ●</td></tr><tr><th scope="row">Safe Interaction</th><td>● ● ● ●</td><td>● ● ● ●</td><td>● ● ● ●</td></tr><tr><th scope="row">Realization</th><td></td><td></td><td></td></tr><tr><th scope="row">Design</th><td>Easy</td><td>Complex</td><td>Complex</td></tr><tr><th scope="row">Modeling</th><td>Easy</td><td>Complex</td><td>Complex</td></tr><tr><th scope="row">Control</th><td>Easy</td><td>Complex</td><td>Complex</td></tr></tbody></table>

Terrile, S. (2022). Soft robotics: applications, design and control (Doctoral dissertation, Industriales).

Our challenges

## METHODOLOGY

This research focuses on developing an optimized soft robotic arm by integrating modeling, simulations, sensor-based state estimation, advanced control strategies, and experimentations.

A rigid 6 degree-of-freedom robotic arm provides a stable and accurate ultrasound probe positioning and a contact force control, acting as the main support structure for guiding the flexible interface arm despite the patient's movements.

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The passive flexible arm enables safe interaction with delicate areas, such as the human body. Its shape will be optimized, prototyped and experimentally validated.

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### Deformation modeling

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A patient biomechanical model and then an interaction one will be established. They will permit the control parametrization and to meet the needs in terms of positioning accuracy and interaction forces.

A deformation model (Bernoulli, Timoshenko, Cosserat...) will be chosen, it will bring efficiency and real-time compatibility.

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The control architecture integrates the robot's inverse kinematics and the arm's deformation model, continuously correcting positioning errors and safe contact.

## EXPECTED OUTCOMES

The system will be validated through simulations and experiments in lab.

Its use in clinical environment, with patients, will be planned in a second time through RIPH protocol.

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