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Steering Simulation readouts

The right-hand column of the Steering Simulation tab is a real-time dashboard of key performance indicators from the running simulation. Its values update while the simulation runs and hold their last value while it is paused or suspended.

Overall Performance Metrics​

This top section displays key values for the catheter as a whole.

  • X/Y Pullwire Displacement: The commanded displacement value for the pullwires along each primary axis.

  • Tip Angle (Theta): The total integrated bend angle of the catheter tip relative to its base, reported in degrees.

  • Tip Angle (Phi): The azimuthal angle, representing the rotational direction of the bend. A value of 0° indicates a bend purely in the +Y direction, while 90° indicates a bend purely in the +X direction.

  • X/Y Wire Tension: The simulated tension in each individual pullwire. Turns red when the tension reaches the wire's tensile capacity (tensile strength × wire cross-section): the physical wire would yield or break, so simulated articulation past that point is unreachable in reality. Requires the pullwire size and material to be specified.

  • X/Y Wire Stretch: The elastic elongation of each individual pullwire under its current tension, from the wire's physical stiffness k = E·A/L (cross-section and material set in Pullwire Settings). Shown while pullwire stretch is enabled (the default); wires without a specified size and material use the legacy rigid tendon and report only its tiny elastic give.

  • Total Strain Energy: The total potential energy stored in the catheter due to bending and twisting.

  • Total Shaft Shortening: The EA-based axial compression of the shaft under pullwire tension, summed over all sections: the "lost motion" absorbed by the shaft instead of articulating the tip. Shown while axial compression is enabled (the default).

  • Tip Position (X,Y,Z): The spatial coordinates of the distal tip of the catheter in the 3D world with the proximal end of the catheter serving as the origin.

  • Tip Quat (W,X,Y,Z): The orientation of the catheter tip expressed as a quaternion.

Per-Section Analysis​

This area provides calculated metrics for each individual flexible section defined in the catheter setup. Rigid sections are excluded from these calculations.

  • Bend Radius: The simulated radius of curvature of each flexible section’s centerline. A very large number or "--" indicates the section is currently straight. For the bend at which this section collapses or kinks (with its bend direction, pull-wire lumens and every layer's strain), use the Kink Radius tab.
  • Bending Moment: The internal moment within each section resulting from deflection forces. For the moment and bend radius at which the section collapses, use the Kink Radius tab.
  • Shaft Axial Compression: The EA-based axial compression of this section under the current pullwire tension, measured from the axial slide-joint displacements (independent of bending). Sections distal to the pullwire attachment always read 0.0: there is no pullwire load path past the anchor. Shown while axial compression is enabled (the default). Its static counterpart is the Axial Compliance KPI, which gives the same behaviour per unit of load.

Kink warnings​

The steering result on this tab is complete on its own: deflection, forces and the per-section readouts do not depend on anything else having been run. What it does not include, until you ask for it, is whether the catheter is being bent past what it can take.

A quiet note above the readouts says so while any section is still unmeasured, with a link that runs the Kink Radius analysis for every section. Once a section has been measured, warnings for it appear here.

The warning is live, and it clears. Steer a section past a measured limit and a banner names the section, what it passed, and the radius it reached; straighten out and the banner goes away. That is deliberate: this tab is an instrument for exploring the steering envelope, so you can find which pull-wire positions get you into trouble by scrubbing rather than by reading a log. It follows that the wording is present tense: "is bent past permanent set", never "has yielded", because a message that disappears must not read as a permanent record.

Nothing on this tab is kept for you. The warnings are live only, and the steering readouts are not a section of the report: a snapshot of whichever pose the sliders were left in is not a run with a stated scenario, so it is not offered in the report dialog. To keep a record of a steering run, use the tab's Export button, which writes the readouts step by step as a run-log CSV, alongside the viewport image and the deflected STL.

Warnings escalate permanent set → lumen closure → self-intersection → collapse. Kink Radius explains what each means and why they are ordered that way.

note

Kinking is not simulated here. The catheter's stiffness in this model does not change when a section passes its limit: nothing softens, buckles or folds on screen. The warning tells you a limit has been passed; the motion carries on as though it had not.

  • Catheter Analysis: static stiffness and failure-mode KPIs that complement the runtime metrics shown here.
  • Steering Simulation: the controls and 3D viewer these readouts sit beside.
  • 3D Viewer: visual companion for inspecting the deflected catheter shape that produces these metrics.
  • Model Accuracy: calculator and steering-simulator accuracy characterization, including downloadable verification reports for the underlying physics engine.