Description
Return inertia about a shifted parallel axis.
Mechanical inertia, torque and muscle-force projections require compatible axes, origins and geometric assumptions. A parallel-axis contribution, planar moment or ideal pennation factor is one local model term rather than a full anatomical load or muscle-activation calculation.
Return inertia about a shifted parallel axis.
When to use this tool
Use Segment Inertia Parallelaxis Reference Offset when evaluating the stated segment, moment, inertia or ideal muscle-geometry term.
How to use the tool and how it works
- Enter centerInertia, mass, distance. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read parallelAxisTerm, shiftedInertia. Use the output convention below.
Return inertia about a shifted parallel axis. Require nonnegative centerInertia, mass and distance; parallelAxisTerm = mass*distance², shiftedInertia adds centerInertia.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| centerInertia | Center Inertia | Required. Finite number; minimum 0. |
| mass | Mass | Required. Finite number; minimum 0. |
| distance | Distance | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| parallelAxisTerm | Parallel Axis Term | Required. Finite number. |
| shiftedInertia | Shifted Inertia | Required. Finite number. |
{
"input": {
"centerInertia": 2,
"mass": 3,
"distance": 4
},
"output": {
"parallelAxisTerm": 48,
"shiftedInertia": 50
}
}Limitations and assumptions
- Distance must be perpendicular between parallel axes; this is not a general rotation or complete body-segment model.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use verified anatomy and calibration, a consistent coordinate frame and a complete appropriate mechanical model for actual loading or clinical interpretation.
References
Similar or alternative tools
- Segment Inertia Unit Factor
Convert moment of inertia with supplied unit factors.
- Segment Mass Moment Contribution
Return a parallel-axis inertia contribution.