Local Linearized Cosserat Rod Model for Contact Force Estimation in Flexible Medical Instruments and Continuum Robots
Christoph Eyberg, Johannes Horsch, Thomas Bauernhansl, Jens Langejürgen
AI summary
Problem
Existing model-based force estimation for flexible medical instruments relies on computationally expensive nonlinear optimization that struggles with convergence, while sensor-based methods increase cost and complicate procedures.
Approach
The method linearizes the nonlinear Cosserat rod force-deflection relationship around the instrument's measured pose, transforming contact force estimation into a solvable linear system with physically motivated constraints.
Key results
- 14% average relative force estimation error in endovascular tests
- ~190 ms computation time via constrained linear inversion
- Accurate localization and magnitude estimation for single and simultaneous forces
- Competitive accuracy versus FBG and image-based methods without extra sensors
Why it matters
Enables safer, sensor-free haptic feedback and model-based control for flexible medical robots and catheters in minimally invasive surgeries.
Abstract
Knowledge of instrument contact forces can lead to safer medical interventions. We present a formulation of the frequently used Cosserat rod model that is linearized around the measured shape for efficient model-based contact force estimation in flexible instruments and robots. Validation on instruments’ deflection in an endovascular intervention use case resulted in an average force estimation error of only 14 %.