M.Sc.2 Topic – Optimal Sensor Placement and Pressure Observation for an Inflatable Sail

M.Sc. Topic Proposal

Optimal Sensor Placement and Pressure Observation for an Inflatable Sail

Advisors:

Florent KRAVSTOFF (WISAMO)

Emmanuel WITRANT (UGA / GIPSA-lab) – emmanuel.witrant@univ-grenoble-alpes.fr

Web: http://www.gipsa-lab.grenoble-inp.fr/~e.witrant/

Motivations

Greenhouse gas emission regulations for maritime transport are becoming increasingly stringent, forcing industry stakeholders to find ways to reduce fuel consumption on ships. Among the emerging solutions are WASPs (Wind Assisted Ship Propulsion systems), which consist of adding a wind-propulsion system to existing or newly built vessels.

In this context, Michelin, through its WISAMO initiative (WIng SAil MObility, based in Nantes and Vannes), is developing an automated wing sail designed for maritime transport. This wing sail is hoisted, reefed, and operated automatically, notably based on wind measurements. Depending on the vessel, wind sensors may be located at the top of the mast, at the bow, the stern, or a combination of these positions.

This variability in measurement points, combined with the sensitivity of wind data to the ship’s superstructure, makes it difficult to characterize the incident wind on the sail. To address this, WISAMO is exploring alternatives to sail control strategies that depend solely on direct wind measurements.

At GIPSA-lab, a concept for dynamic onboard control based on the pressure field across the sail is currently under development. This internship will specifically focus on adapting this control strategy to the WISAMO wing sail.

Our previous joint work validated a proof of concept for the design of observers based on the linearized Navier–Stokes equation with transport coefficients estimated as combined Legendre polynomials. The performance of the method was evaluated on synthetic CFD data. In parallel, some progress was made on the experimental side to design WiFi cobra probes that could provide pressure measurements and wind direction at multiple sail locations.

Scientific Objectives

This project aims to develop a sail control method based on dynamic adaptation to sail performance. Performance will be inferred using a limited but optimally placed set of pressure sensors on the sail surface, combined with onboard resolution of simplified flow dynamics models.

Methodological Steps

1. Finalize the observer design with coefficients parameterized by offline optimization for calculating optimal pressure sensor placement — developed for conventional wings (constant airfoil along the span) — using CFD simulations performed at WISAMO.
2. Propose a recursive method with online parameter adaptation to design an adaptive PDE observer that adapts to varying sail angle and wind conditions.
3. Calculate the lift and drag forces resulting from the pressure field, along with the location of the center of effort, to integrate the force generated by the sail in the 3-degrees-of-freedom sailboat model developed by Centrale Nantes.
4. Finalize and test wireless Cobra pressure sensors to acquire realistic pressure field data for algorithm validation.
5. If time allows, design a feedback control strategy integrating the sail with the 3-DOF model.

Expected Outcomes

• The inference method adapted to conventional wings will have direct scientific value (publication potential) and future applicability in collaboration with WISAMO.
• A proposal for an advanced control strategy for the WISAMO wing sail based on this new inference framework.

Work Organization

The internship will be primarily based at GIPSA-lab, where methodological developments and preliminary sensor testing will take place.

Two short visits to WISAMO are planned (to be confirmed):

• the first to become familiar with the problem and available CFD datasets,
• the second for sensor testing (to be confirmed).

The intern will be supervised by Dr. Florent KRAVSTOFF (WISAMO) and Prof. Emmanuel WITRANT.

Requirements

• Enrolled in a Master 2 program in Automatic Control,
• Excellent academic record,
• Strong background in partial differential equations (PDEs) and related systems.

How to Apply

Interested applicants, please send your CV, copies of transcripts, recommandation letters, and previous publications (if any) to Prof. WITRANT using the subject line “MSc Position Application – Sail”. All qualified applicants are encouraged to apply. However, only candidates under consideration will be contacted.

References

1. European Commission. “Reducing emissions from the shipping sector.” (2022).
2. IMO, “Fourth IMO greenhouse gas study 2020: Safe, secure and efficient shipping on clean ocean,” London: International Maritime Organization (IMO), Jan. 24, 2022.
3. D. Le Pelley, D. Morris, P. Richards, and D. Motta, “Aerodynamic force deduction on yacht sails using pressure and shape measurements in real time,” The International Journal of Small Craft Technology, 157:65, 2015.
4. S.J. Ying, K.C. Wong, “Two-dimensional sail shape determined by pressure and its tension,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 19, Issues 1–3, 1985, pp. 363–376.
5. M. Ghousein, E. Witrant, V. Bhanot, and P. Petagna, “Adaptive boundary observer design for linear hyperbolic systems; application to estimation in heat exchangers,” Automatica, Vol. 114, p. 108824, 2020.
6. S. Smith, Y.-J. Pan and E. Witrant, Optimal Observer-Based Pressure Sensor Placement for Rigid Sails, Control Engineering Practice, vol. 173, 106976, 2026.