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--- visual3d:documentation:definitions:adjusted_zatsiorsky-seluyanov_s_segment_inertia_parameters [2024/07/03 17:27] – removed sgranger
+++ visual3d:documentation:definitions:adjusted_zatsiorsky-seluyanov_s_segment_inertia_parameters [2026/06/12 17:11] (current) – Added cross-reference and links to Visual3D's default parameters from Dempster 1955. wikisysop
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+====== Adjusted Zatsiorsky-Seluyanov's segment inertia parameters ======
+While the original Zatsiorsky-Seluyanov segment inertia parameters (1983) used bony landmarks as reference points, [[https://doi.org/10.1016/0021-9290(95)00178-6|de Leva (1996)]] adjusted these parameters using joints centres instead, more commonly used in biomechanics. This page lists these adjusted parameters and describes how to used them in Visual3D.
+===== The Adjusted Parameters =====
+^ Segment Mass (Relative to total body mass)^ ^ ^
+^Segment  ^Female^Male  ^
+|Head     |0.0668|0.0694|
+|Trunk    |0.4257|0.4346|
+|Upper arm|0.0255|0.0271|
+|Forearm  |0.0138|0.0162|
+|Hand     |0.0056|0.0061|
+|Thigh    |0.1478|0.1416|
+|Shank    |0.0481|0.0433|
+|Foot     |0.0129|0.0137|
+^ Segment centre of mass location (relative to the segment's proximal endpoint) ^ ^ ^
+^Segment  ^Female^Male  ^
+|Head     |0.4841|0.5002|
+|Trunk    |0.4964|0.5138|
+|Upper arm|0.5754|0.5772|
+|Forearm  |0.4559|0.4574|
+|Hand     |0.7474|0.7900|
+|Thigh    |0.3612|0.4095|
+|Shank    |0.4352|0.4395|
+|Foot     |0.4014|0.4415|
+^ Segment radii of gyration ^ ^ ^ ^ ^ ^ ^
+^         ^Female^     ^     ^Male ^     ^     ^
+^Segment  ^IXX   ^IYY  ^IZZ  ^IXX  ^IYY  ^IZZ  ^
+|Head     |0.271 |0.295|0.261|0.303|0.315|0.261|
+|Trunk    |0.307 |0.292|0.147|0.328|0.306|0.169|
+|Upper arm|0.278 |0.260|0.148|0.285|0.269|0.158|
+|Forearm  |0.261 |0.257|0.094|0.276|0.265|0.121|
+|Hand     |0.631 |0.454|0.335|0.628|0.513|0.401|
+|Thigh    |0.369 |0.364|0.162|0.329|0.329|0.149|
+|Shank    |0.267 |0.263|0.092|0.251|0.246|0.102|
+|Foot     |0.299 |0.279|0.139|0.257|0.245|0.124|
+===== Modifying Inertial Values within Visual3D =====
+The images below show the default segment properties on the left and the modified segment properties on the right. The modified segment properties reflect Zatsiorsky's adjusted segment properties for a female's right thigh.
+|  __**ORIGINAL**__\\ This is an example of the **original** properties using Hanavan's geometric model.\\ {{:HanavanInertialProperties.png}}  |  __**MODIFIED**__\\ This is an example of the **modified** properties using De Leva's values.\\ {{:deLevaInertialProperties.png}}  |
+**1.** Change the **segment geometry** to CUSTOM_SEG
+**2.** To modify the **Mass**, replace the mass factor from the current equation (0.1* Mass) to Zatsiorsky-Seluyanov mass value(For example: "0.1478 * Mass" for a female thigh segment).\\
+**3.** To modify the **Inertia Values**, the expression has to be entered as: "m*r^2"\\
+Where m is the segment's mass parameter, and r is the IXX, IYY or IZZ radius of gyration parameter. The radius of gyration in De Lava's paper is presented as a percent of segment length, so this value must be multiplied by the length of the segment.
+ For example, to use the Zatsiorsky-Seluyanov's Inertia Values for the right thigh for a female subject, the following expressions would have to be entered in the IXX, IYY and IZZ fields.
+  IXX = ( 0.1478*Mass ) *((RTH_SEG_LENGTH * 0.369 )^2)
+  IYY = ( 0.1478*Mass ) *((RTH_SEG_LENGTH * 0.364 )^2)
+  IZZ = ( 0.1478*Mass ) *((RTH_SEG_LENGTH * 0.162 )^2)
+**4.** To modify the location of the **center of mass** according to Zatsiorsky-Seluyanov's parameters, replace the factor from the current equation (0.444004 * RTH_Seg_Length in the above image) with the corresponding Centre of Mass location parameter (for example: "0.3612 * RTH_Seg_Length" for a female thigh segment).
+ The segment length (RTH_SEG_LENGTH) is listed under the Subject Data / Metrics tabs. This value is automatically created when a segment is created.
+===== See Also =====
+Visual3D's default segment parameters are derived from [[visual3d:documentation:modeling:segments:segment_mass#default_segment_mass|Dempster's 1955 equations]].
+===== Reference =====
+  * de Leva (1996) Adjustments to Zatsiorsky-Seluyanov's segment Inertia Parameters. **Journal of Biomechanics** Vol.29 No. 9. pp.1223-1230. [[https://doi.org/10.1016/0021-9290(95)00178-6|DOI]]
+  * Dempster, W. T. (1955). Space requirements of the seated operator, geometrical, kinematic, and mechanical aspects of the body with special reference to the limbs (No. WADCTR55159) [[https://hdl.handle.net/2027.42/4540|link]]
+  * Zatsiorsky, V. M., & Seluyanov, V. (1983). The mass and inertial characteristics of the main segments of the human body. In H. Matsui & K. Kobayashi (Eds.), Biomechanics VIII-B (pp. 1152-1159). Baltimore: University Park Press.