robotics
The Tendons Cannot Locate a Touch by Themselves
A proof exposes a seven-dimensional ambiguity, while obstacle constraints recover contact location in a continuum-robot benchmark.
Summary
A proof exposes a seven-dimensional ambiguity, while obstacle constraints recover contact location in a continuum-robot benchmark.
Motor-side tendon measurements do not uniquely reveal where a flexible continuum robot touches its surroundings. The paper proves that the unconstrained mapping from contact forces to tendon readings has a null space of dimension at least seven. When obstacle geometry is known, non-penetration and complementarity constraints make local identification possible. A constrained moving-horizon estimator then located contact to 0.9 millimeters and force to 0.22 newtons in a finite-element wall benchmark, versus 65 millimeters and 0.72 newtons for a tuned projected extended Kalman filter. The evidence is simulated and assumes known geometry, but it distinguishes an observability limit from an estimator-tuning problem.
Why it matters
A proof exposes a seven-dimensional ambiguity, while obstacle constraints recover contact location in a continuum-robot benchmark.
Limits and context
- Motor-side tendon measurements do not uniquely reveal where a flexible continuum robot touches its surroundings.
Key claims
A proof exposes a seven-dimensional ambiguity, while obstacle constraints recover contact location in a continuum-robot benchmark.
Qualification: Motor-side tendon measurements do not uniquely reveal where a flexible continuum robot touches its surroundings.
Evidence: source-2026-11-09-007
Sources
- arXiv preprint 2611.09877, original v1arXiv · primary research
Corrections
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