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visual3d:documentation:kinematics_and_kinetics:induced_acceleration [2024/06/18 13:28] – sgrangervisual3d:documentation:kinematics_and_kinetics:induced_acceleration [2024/12/31 22:55] (current) – wikisysop
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 +====== Induced Acceleration ======
 +
 \\ \\
-//NOTE: This feature it is no longer supported.//+//NOTE: This feature is no longer supported.//
  
 \\ \\
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 **Edit --> Preferences** --> Plugin Folder in the Default Folders tab **Edit --> Preferences** --> Plugin Folder in the Default Folders tab
  
-===== PowerPoint Lecture Notes =====+==== PowerPoint Lecture Notes ====
  
 Lecture notes used by Tom Kepple for a class at the University of Delaware. Lecture notes used by Tom Kepple for a class at the University of Delaware.
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 Note: The classroom materials are not for the current version of Visual3D, and were produced years ago, outside of C-Motion using different plug-in libraries. Note: The classroom materials are not for the current version of Visual3D, and were produced years ago, outside of C-Motion using different plug-in libraries.
  
-===== Running an Induced Acceleration =====+==== Running an Induced Acceleration ====
  
 To run the sample IAA for left stance phase you run the Visual3D script Mambo_IAA.v3s. (Note: in the script the user can chose to set the frames in which the feet are fixed relative to the ground. This is usually done during the foot-flat interval of stance. The parameters right_start, right_end, left_start and left_end are used to do this. ) **It is also critical that you select the trial you want run the IAA on in the file selection box and then check the "EVENT_LABEL" folder in the data tree.** To run the sample IAA for left stance phase you run the Visual3D script Mambo_IAA.v3s. (Note: in the script the user can chose to set the frames in which the feet are fixed relative to the ground. This is usually done during the foot-flat interval of stance. The parameters right_start, right_end, left_start and left_end are used to do this. ) **It is also critical that you select the trial you want run the IAA on in the file selection box and then check the "EVENT_LABEL" folder in the data tree.**
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 **LKNEEX_PW_LSK** - This is the segmental power produced by the X component (plantar/dorsi flexion) of the left knee moment (LSKX) at the left shank (LSK). **LKNEEX_PW_LSK** - This is the segmental power produced by the X component (plantar/dorsi flexion) of the left knee moment (LSKX) at the left shank (LSK).
  
-===== Running an Induced Acceleration – Simulation Mode =====+==== Running an Induced Acceleration – Simulation Mode ====
  
 //Note: IAA works without the Simulations tab. That tab is only for visualizing the effects of a subset of the results and is not required. The tab is enabled via a special license key in the Visual3D license file. Contact C-Motion if you need a new license file created with the simulations tab enabled.// //Note: IAA works without the Simulations tab. That tab is only for visualizing the effects of a subset of the results and is not required. The tab is enabled via a special license key in the Visual3D license file. Contact C-Motion if you need a new license file created with the simulations tab enabled.//
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 For example if "Right Fixed" is checked. "Frame" is 80. "Steps" is 100. "Time" is 0.1. And RKNEEX is selected. The simulation would should what would happen if the model, starting at the position in frame 80 and with the right foot fixed to the ground, was driven by the knee flexion/extension torque for a period 0.1 seconds. (Since we have 100 steps each step size in the Simulation would 0.001.) For example if "Right Fixed" is checked. "Frame" is 80. "Steps" is 100. "Time" is 0.1. And RKNEEX is selected. The simulation would should what would happen if the model, starting at the position in frame 80 and with the right foot fixed to the ground, was driven by the knee flexion/extension torque for a period 0.1 seconds. (Since we have 100 steps each step size in the Simulation would 0.001.)
  
-===== IAA with IK or 6 DOF Pose Estimation =====+==== IAA with IK or 6 DOF Pose Estimation ====
  
 The IAA will work whether the data is run through Visual3D IK or not. However you will get slightly different results with and without the Visual3D IK. Here is what happens in the two cases: The IAA will work whether the data is run through Visual3D IK or not. However you will get slightly different results with and without the Visual3D IK. Here is what happens in the two cases:
  
-==== IAA without Visual3D IK ====+=== IAA without Visual3D IK ===
  
 In this case the segments’ positions and orientations are computed with the traditional Visual3D 6 dof method and exported to the IAA plug-in. For the pelvis (the IAA model root) all position and orientation information are used by the IAA model. However, at the joints all the joint translation computed by Visual3D are ignored. Also at all joints three Euler angles are computed; however at the knees the ab/aduction and axial rotation components get set to zero, and at the ankles the toe-in/toe-out angles get set to zero. After the joint translations are removed and the knee and ankle rotations are constrained the IAA is computed for the model. Note that although the IAA has all joint translations and some ankle and knee rotations removed this is done by setting the values to zero and not through an optimization process (like used in Visual3D IK). In this case the segments’ positions and orientations are computed with the traditional Visual3D 6 dof method and exported to the IAA plug-in. For the pelvis (the IAA model root) all position and orientation information are used by the IAA model. However, at the joints all the joint translation computed by Visual3D are ignored. Also at all joints three Euler angles are computed; however at the knees the ab/aduction and axial rotation components get set to zero, and at the ankles the toe-in/toe-out angles get set to zero. After the joint translations are removed and the knee and ankle rotations are constrained the IAA is computed for the model. Note that although the IAA has all joint translations and some ankle and knee rotations removed this is done by setting the values to zero and not through an optimization process (like used in Visual3D IK).
  
-==== IAA with Visual3D IK ====+=== IAA with Visual3D IK ===
  
 The IK was actually first added to the Visual3d so that the data exported out of Visual3D to the IAA would match the IAA model. To make this work you would first run an IK model that starts with the pelvis as the root (6 dof) but allows no translations at the hips, knees and ankles. All three rotations at the hip are allowed while at the knee only flexion/extension is allowed and at the ankle plantar- and dorsi-flexion and inversion/eversion are allowed. Using this IK model matches the Visual3D output to the IAA model. The IK was actually first added to the Visual3d so that the data exported out of Visual3D to the IAA would match the IAA model. To make this work you would first run an IK model that starts with the pelvis as the root (6 dof) but allows no translations at the hips, knees and ankles. All three rotations at the hip are allowed while at the knee only flexion/extension is allowed and at the ankle plantar- and dorsi-flexion and inversion/eversion are allowed. Using this IK model matches the Visual3D output to the IAA model.
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 Now here the advantages of each approach: Now here the advantages of each approach:
  
-==== Advantage of IAA with Visual3D IK ====+=== Advantage of IAA with Visual3D IK ===
  
 The model used to generate the position and orientation data coming out of Visual3D exactly matches the IAA model. In forward dynamics and IAA this generally a good thing to do. The model used to generate the position and orientation data coming out of Visual3D exactly matches the IAA model. In forward dynamics and IAA this generally a good thing to do.
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-==== Advantage of IAA without Visual3D IK ====+=== Advantage of IAA without Visual3D IK ===
  
 If you have really noisy target data (particular in the proximal segments) the Visual3D IK can cause the entire model to shift away from the center of pressure which would change the value of the joint moments used to drive the IAA. Thus if you suspect your target data at the proximal segments are bad you may either want to skip the Visual3D IK. If you have really noisy target data (particular in the proximal segments) the Visual3D IK can cause the entire model to shift away from the center of pressure which would change the value of the joint moments used to drive the IAA. Thus if you suspect your target data at the proximal segments are bad you may either want to skip the Visual3D IK.
visual3d/documentation/kinematics_and_kinetics/induced_acceleration.1718717280.txt.gz · Last modified: 2024/06/18 13:28 by sgranger