torsion_stick_field — DRIVE tactorque op

• Data kinds: matrix × matrix × scalar × scalar × table × scalar → table

• Call: import fullseye as fs; fs.ledger.torsion_stick_field(X, Y, a: 'float', Mz: 'float', kern: 'dict', G: 'float') -> 'dict' (to call the implementation directly, import tactorque; tactorque.torsion_stick_field(X, Y, a: 'float', Mz: 'float', kern: 'dict', G: 'float') -> 'dict'; from the registry, opsdrive.get("torsion_stick_field"))

Usage

Surface displacement field of no-slip torsion (Reissner–Sagoci, corresponding to Johnson 1985 §3.9; equation number unconfirmed → verified numerically by convolution): ux, uy [m] obtained by convolving the traction q_θ = 3M_z r/(4πa³√(a²−r²)) with the kernel of tacslip.cerruti_kernel, plus the closed form beta = 3M_z/(16Ga³), the rigid rotation inside the circle ux_cf = −βy, uy_cf = βx (r < a), and the tractions qx, qy. Because the convolution returns a uniform u_θ/r = β inside the circle, the β formula is verified by an independent implementation (−0.5 %, uniformity 0.14 %, measured). This is the no-slip field: for a flat punch it is exact up to 8/(3π) times full slip, but Hertz contact always slips from the edge — for the partial-slip field of Hertz contact use field=True of cuttouch.torsion_partial_slip (see the module docstring). Raises ValueError: G ≤ 0, a ≤ 0, X and Y differ in shape, the kernel grid does not match.

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• poc_tactile_dipole_torque — py -3.11 examples/poc_tactile_dipole_torque.py

Ops the type connects to (they accept table as input)

course_layout · course_occupancy · course_contains · world_build · world_camera · world_move · lidar_scan · rss_longitudinal_same

Same category (tactorque)

punch_pressure · punch_surface_uz · hertz_pressure_shifted · ellipse_pressure_shifted · pressure_first_moment · boussinesq_kernel · boussinesq_surface_displacement · surface_divergence_closed_form


*Provenance: tactorque.py — DRIVE operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.