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visual3d:tutorials:kinematics_and_kinetics:model_based_computations [2024/07/30 14:23] – wikisysopvisual3d:tutorials:kinematics_and_kinetics:model_based_computations [2025/01/15 19:51] (current) – [Preparation] wikisysop
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 ====== Model Based Computations ====== ====== Model Based Computations ======
  
-The objective of this tutorial is to present [[Visual3D:Documentation:Visual3D_Signal_Types:LINK_MODEL_BASED_Data_Type|**Model Based Calculations.**]] These are calculations that only make sense relative to rigid segments.+=====Objectives==== 
 +The objective of this tutorial is to present **[[Visual3D:Documentation:Visual3D_Signal_Types:LINK_MODEL_BASED_Data_Type|Model Based Calculations.]]** These are calculations that only make sense relative to rigid segments.
  
 If you have a Ph.D. in Kinesiology or Biomechanics, or you are an M.D. or researcher – do not skim lightly or jump completely over these sections. This tutorial is written without as much jargon as possible to address a very broad customer base. However, the interfaces and techniques described are the exactly the same approaches and techniques used for the most sophisticated analyses. If you have a Ph.D. in Kinesiology or Biomechanics, or you are an M.D. or researcher – do not skim lightly or jump completely over these sections. This tutorial is written without as much jargon as possible to address a very broad customer base. However, the interfaces and techniques described are the exactly the same approaches and techniques used for the most sophisticated analyses.
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 Part of the power of Visual3D is the ability to determine exactly what and how calculations are done – and the ability to point to the published works proving its validity. From a pure tool perspective, the power is in additional Pipeline command parameters and options. Part of the power of Visual3D is the ability to determine exactly what and how calculations are done – and the ability to point to the published works proving its validity. From a pure tool perspective, the power is in additional Pipeline command parameters and options.
  
 +If you would like to follow along with a Youtube video tutorial based on this tutorial, please select the link here: [[https://youtu.be/JAg7iNpGJJY?feature=shared|Visual3D Tutorial Video 7: Model Based Computations]]
 || ||
  
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 Some of the analysis characteristics we will examine will be positions of the pelvis and foot during gait, knee flexion and extension, and knee joint moments and powers. To do this we will define segment angles, joint angles, joint moments, and joint powers. We will also be reporting on basic attributes such as stride length and other fundamental gait characteristics. Some of the analysis characteristics we will examine will be positions of the pelvis and foot during gait, knee flexion and extension, and knee joint moments and powers. To do this we will define segment angles, joint angles, joint moments, and joint powers. We will also be reporting on basic attributes such as stride length and other fundamental gait characteristics.
  
-  - create a report with basic gait information +  - Create a report with basic gait information. 
-  - calculate joint angles to measure left and right knee flexion/extension +  - Calculate joint angles to measure left and right knee flexion/extension. 
-  - add the computed signals to a report.+  - Add the computed signals to a report.
  
 ===== Preparation ===== ===== Preparation =====
  
-  - Open the file [[https://www.has-motion.com/download/examples/Tutorial3.cmo|Tutorial3.cmo]] +  - Download the following ZIP File: [[https://has-motion.com/download/YouTubeTutorial/Visual3D Tutorial 7 Model Based Computations.zip|Visual3D Tutorial 7 Sample Data]]. It contains: 
-  - Click on the **Signal and Event Processing** Tab to visualize the animation of the model based on the movement data and the model that was applied to it. If the animation doesn’t appear in the 3D Animation viewer, check the active file combo box on the toolbar. It should read ’r;Walking Trial 1.c3d’ rather than ALL-FILES+  * **Tutorial7_MBC_Start.cmz**: Starting point of tutorial, CMZ file containing //Lower Body Static Trial.c3d// as the static/calibration file and //Walking Trial 1.c3d// as the motion file. 
 +  * **Tutorial7_MBC_End.cmz**: Final result of tutorial containing the model based computation definitions added throughout. 
 +  - Click on the **Signal and Event Processing** Tab to visualize the animation of the model based on the movement data and the model that was applied to it. If the animation doesn’t appear in the 3D Animation viewer, check the active file combo box on the toolbar. It should read 'Walking Trial 1.c3d' rather than ALL-FILES
  
 ===== Computing Joint Angles ===== ===== Computing Joint Angles =====
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 X = flexion/extension X = flexion/extension
 +
 Y = abduction/adduction Y = abduction/adduction
 +
 Z = longitudinal rotation Z = longitudinal rotation
-One of the options for joint angles is to select normalization (not generally recommended). Normalization means that when the segments in the movement trial are in the same relative posture as the same segments in the standing trial, the joint angle is considered zero. The problem with the calculation of a normalized angle (as we have done it) is that the standing posture and the movement trial should both be aligned with the laboratory axis. Getting a patient to stand oriented relative to the lab may not be possible. An alternative approach is to create Virtual Segments that define the desired angle in the standing posture. For example, See [[https://www.c-motion.com/v3dwiki/index.php?title=Normalized_Joint_Angle_-_Method_1|here,]] or [[https://www.c-motion.com/v3dwiki/index.php?title=Normalized_Joint_Angle_-_Method_2|here.]]+ 
 +One of the options for joint angles is to select normalization (not generally recommended). Normalization means that when the segments in the movement trial are in the same relative posture as the same segments in the standing trial, the joint angle is considered zero. The problem with the calculation of a normalized angle (as we have done it) is that the standing posture and the movement trial should both be aligned with the laboratory axis. Getting a patient to stand oriented relative to the lab may not be possible. An alternative approach is to create Virtual Segments that define the desired angle in the standing posture. For example, See [[visual3d:documentation:kinematics_and_kinetics:normalized_joint_angle_-_method_2|here,]] or [[visual3d:documentation:kinematics_and_kinetics:normalized_joint_angle_-_method_1|here.]]
  
 ===== Create a joint angles for the right knee ===== ===== Create a joint angles for the right knee =====
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 {{:tutorial8_6.jpg}} {{:tutorial8_6.jpg}}
  
-For this segment coordinate system (z-up, y-anterior) rotation about the x-axis represents flexion/extension. Visual3D always computes all signals based on the [[https://www.c-motion.com/support/Visual3D.php?topic=FAQ_Kinetics&title=Visual3D%20:%20Kinetics#topic-876|Right Hand Rule.]]+For this segment coordinate system (z-up, y-anterior) rotation about the x-axis represents flexion/extension. Visual3D always computes all signals based on the Right Hand Rule.
  
 For example, if you point your thumb in the direction of the x-axis of the hip (shown in Red in the animation viewer) pointing laterally to the right. Knee extension will be zero when the **thigh segment coordinate system** and the **shank segment coordinate system** are aligned. Knee flexion will be seen as a negative angle. For example, if you point your thumb in the direction of the x-axis of the hip (shown in Red in the animation viewer) pointing laterally to the right. Knee extension will be zero when the **thigh segment coordinate system** and the **shank segment coordinate system** are aligned. Knee flexion will be seen as a negative angle.
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 Normalize to local metric value\\ Normalize to local metric value\\
 For example, a metric could be created containing the Mass*Height of the subject using the following command. For example, a metric could be created containing the Mass*Height of the subject using the following command.
-**Multiply_Signals**+ 
 +<code> 
 +Multiply_Signals
 /SIGNAL_TYPES=METRIC+METRIC /SIGNAL_TYPES=METRIC+METRIC
 /SIGNAL_NAMES=MASS+HEIGHT /SIGNAL_NAMES=MASS+HEIGHT
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 /RESULT_NAME=MxH /RESULT_NAME=MxH
 ! /RESULT_FOLDER=PROCESSED ! /RESULT_FOLDER=PROCESSED
 +</code>
 In the Compute Model Based Dialog selecting this normalization will cause a combo box to appear to allow you to select the Metric. In the Compute Model Based Dialog selecting this normalization will cause a combo box to appear to allow you to select the Metric.
 Normalize to GLOBAL metric value\\ Normalize to GLOBAL metric value\\
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 If you have selected the [[Visual3D:Getting_Started:Menus#Program_Settings|settings]] option to use PROCESSED targets, the PROCESSED targets and PROCESSED FORCE, COFP, and FREEMOMENT are used for computing the model based items. If the PROCESSED signal doesn't exist, Visual3D uses the ORIGINAL folder. If you have selected the [[Visual3D:Getting_Started:Menus#Program_Settings|settings]] option to use PROCESSED targets, the PROCESSED targets and PROCESSED FORCE, COFP, and FREEMOMENT are used for computing the model based items. If the PROCESSED signal doesn't exist, Visual3D uses the ORIGINAL folder.
  
-[[Visual3D:Documentation:Visual3D_Signal_Types:LINK_MODEL_BASED_Data_Type#Using_PROCESSED_Signals|Using PROCESSED Signals]]+**[[Visual3D:Documentation:Visual3D_Signal_Types:LINK_MODEL_BASED_Data_Type#Using_PROCESSED_Signals|Using PROCESSED Signals]]**
  
 The model based signals that are computed from the PROCESSED signal are still defined as ORIGINAL model based signals. The model based signals that are computed from the PROCESSED signal are still defined as ORIGINAL model based signals.
visual3d/tutorials/kinematics_and_kinetics/model_based_computations.1722349434.txt.gz · Last modified: 2024/07/30 14:23 by wikisysop