Tutorial: Oxford Foot Model

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This tutorial describes C-Motion's interpretation (or "best guess") of the Oxford Foot Model. In it's current form, the segment's definitions (coordinate systems) are exactly those of the Oxford Foot Model. It is however not possible to obtain the exact same results as those generated using Vicon's Nexus software due to the use of different pose estimation methods in Visual3D.

Please contact C-Motion's support (support@c-motion.com) if you find any discrepancy or to suggest a method that replicates Nexus' results

This page is currently under construction. Make sure to read all instructions and comments before attempting to build the Oxford Foot Model as we cannot guaranty that the results generated from the model detailed on this page will be the same as those generated through the Oxford Foot Model Plug-in in Vicon's Nexus. An updated version of the model should be added in the next couple of weeks.

The Oxford Foot Model has gone through many iterations since its first publication, and there are many other multi-segment foot models in the literature.

Visual3D is a general tool capable of modeling all of the different foot models.


The Oxford Foot Model is a good choice for analyzing data from Children with Cerebral Palsy. If this is not your patient population, other options and other multi-segment foot models may be more suitable.

There are 2 different options when creating the Oxford Foot Model. The first one involves optimizing the thigh rotation offsets so that the dynamic range of knee varus/valgusis minimized. The thigh and shank's coordinate systems are them modified accordingly. The second option is to force the hindfoot and/or forefoot to be parallel to the floor.

The model you build in Visual3D will be dependent on the above options.

Constructing a multi-segment foot model consistent with the Oxford Foot Model

Carson2001.png

Stebbins2006.png

While we would recommend that users go through the tutorial to better understand how each segment is defined, the complete model template is available for download here. Please note that the same exact marker naming convention has to be used when labeling the markers in order for the model template to work. Also make sure to update all relevant subject metrics: Height, Mass, Left and Right Leg Length, Knee and Ankle Width.

While the Oxford Foot Model is a multi-segment foot model, it is often combined with a lower body model. When used within Nexus, the pelvis, thighs, shanks and single foot segments are copied from Vicon's Plug-in Gait lowerlimb model. The hindfoot and forefoot are added to create the multi-segment foot model. Because the Oxford Foot Model was intended to be independent of other models, and because of the way the Plug-in Gait model relies on the proximal segment to created the distal joint centre (used by the distal segment), a second shank definition had to be added to allow independent outputs.


Please note: If you have collected data for this tutorial using a Vicon system, do not apply the Oxford Foot Model plug-in in Nexus before importing the .c3d files in Visual3D. Running it prior to importing the .c3d files in Visual3D will make it more difficult to follow the tutorial since some marker names are modified by the Nexus processing.

Marker Set

OFM Markerset.png

L/RTIB = Lateral shank
L/RTUB = Tibial tuberosity
L/RSHN = Anterior aspect of the shin(in line with the L/RTUB and "anatomical ankle joint centre"
L/RHFB = Head of fibula
L/RANK = Lateral malleolus
L/RMMA = Medial malleolus
L/RHEE = Inferior heel
L/RPCA = Superior heel
L/RCPG = Posterior calcaneus wand marker
L/RSTL = Sustentaculum tali (should be placed same distance from the heel marker with the L/RCA marker)
L/RLCA = Lateral calcaneus (should be placed same distance from the heel marker with the L/RSTL marker)
L/RP1M = Base of the 1st metatarsal
L/RD1M = Head of the 1st metatarsal
L/RP5M = Base of the 5th metatarsal
L/RD5M = Head of the 5th metatarsal
L/RHLX = Base of hallux

Download and open the c3d files in Visual3D

Download the zip file containing the Oxford Foot Model Sample .c3d files

Unzip this file in a location of your choice.

From the File menu select Open.

caption

From the "Open the movement trial" dialog navigate to the files you downloaded and select the files labeled OFM_Walk1 to OFM_Walk6. Click Open.

Note: If you would like to perform your own motion capture for this model, make sure to use the same marker naming convention as listed above to avoid confusion.

OFM FileOpen.png

Create a hybrid model - From the Model menu open Create (Add Static Calibration File) and select Visual3D Hybrid Model.

Load the standing trial - From the "Select the calibration file for the new model" dialog box select the file labeled OFM_Static and click Open.

OFM FileStatic.png

Assign the model to the movement trial - When the "Assign Models to Motion Data" window opens select the model labeled OFM_Static from the drop down list, and check the box associated with all OFM_Walk trials, then click OK.

OFM ModelAssign.png

Visual3D will automatically open the Model Builder mode and your screen should look like the image below.

modelBuilderMode.jpg

As previously mentioned, the following markers should exist in the dynamic trials for the Oxford Foot Model:

RHFB/LHFB
RTUB/LTUB
RTIB/LTIB*
RSHN/LSHN
RANK/LANK*
RPCA/LPCA
RCPG/LCPG
RHEE/LHEE*
RSTL/LSTL
RP1M/LP1M
RHLX/LHLX
RTOE/LTOE*
RD5M/LD5M
P5M/LP5M
RLCA/LLCA

Markers identified with an * are also used by Vicon's Plug-in gait model.


The following is a list of markers only used in the static trail:

RMMA/LMMA
RPCA/LPCA
RD1M/LD1M

The targets only used in the static are anatomic only targets and used to define the orientation of the segment, but not used to track the segment. These targets may be left on during the dynamic trials, or removed.

Creating the Lowerlimb Plug-in Gait model

As mentioned above, the Oxford Foot Model makes use of the Lowerlimb Plug-in Gait model. It is therefore useful to created this model before creating the multi-segment foot model. However, this multi-segment foot model can be combined with any lowerlimb model in Visual3D. It is thus recommended to use a more robust lowerlimb markerset/model if and when possible. Please note that doing so will generate slightly different results when compared to the standard Oxford Foot Model outputs.

Because the Oxford Foot Model was designed to be a stand-alone model, it is not necessary to combine this model with a lowerlimb model.

Creating Subject Data / Metrics

To build the model, some Subject Data / Metrics should be created.
In the Model tab, click on the Subject Data / Metrics button.
Click on the Add New Item to create each of the following metrics:

Marker_Radius:

  1. Click on Subject Data/Metrics tab
  2. Click Add New Item
  3. Type in Marker_Radius in Name
  4. Type in 0.007 in Value or Expression
  5. Click on OK

RP1P5dist:

  1. Click on Subject Data/Metrics tab
  2. Click Add New Item
  3. Type in RP1P5dist in Name
  4. Type in DISTANCE(RP1M,RP5M) in Value or Expression
  5. Click on OK

LP1P5dist:

  1. Click on Subject Data/Metrics tab
  2. Click Add New Item
  3. Type in LP1P5dist in Name
  4. Type in DISTANCE(LP1M,LP5M) in Value or Expression
  5. Click on OK

RProxFFscale:

  1. Click on Subject Data/Metrics tab
  2. Click Add New Item
  3. Type in RProxFFscale in Name
  4. Type in (RP1P5dist - Marker_Radius)/(2*RP1P5dist) in Value or Expression
  5. Click on OK

LProxFFscale:

  1. Click on Subject Data/Metrics tab
  2. Click Add New Item
  3. Type in LProxFFscale in Name
  4. Type in (LP1P5dist - Marker_Radius)/(2*LP1P5dist) in Value or Expression
  5. Click on OK

SubjectDataMetricsOFM.png



NOTE: The Subject Data/Metrics rely on landmarks that will be created later in this tutorial. Until the landmarks are created these metrics will have "No Data" listed as the value, once the landmarks have been created "No Data" will be replaced with a numerical value.

Creating the Oxford Foot Model's Tibia segment

In addition to the Plug-in Gait shank segments, the Oxford Foot Model has its own shank segments. This multi-segment foot model was designed to be self-contained allowing its use without the need to have a thigh nor a pelvis segment. Contrary to the many conventional gait models where the distal segment relies on the proximal segment to create the joint centre, each of the Oxford Foot Model's segments are therefore completely independent on each other.

In reality, it is our understanding that the Oxford Foot Model's shank segments share the exact same coordinate system as that of the Plug-In gait. However, different markers are used for its tracking. This particular segment is only used when computing the shank's orientation relative to the lab.

Shank Landmarks

Before defining the Shank segments, Landmarks have to be created.

Create the (R/L)PROT landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RPROT
Starting Point: RHFB
Ending Point: RANK
Lateral object: RMMA
Project From: RTUB

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LPROT
Starting Point: LHFB
Ending Point: LANK
Lateral object: LMMA
Project From: LTUB

RPROT OFM.png


Create the (R/L)AJC_SK landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RAJC_SK
Starting Point: RANK
Ending Point: RMMA
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=0.5
Check the Offset By Percent option

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LAJC_SK
Starting Point: LANK
Ending Point: LMMA
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=0.5
Check the Offset By Percent option

RAJC SK OFM.png

Defining the Shank

1. Create Right Shank OFM:

1. In the Segment Name combo box type Right Shank OFM
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Right Shank OFM tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: RPROT     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: RAJC_SK     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     RANK
   Select Tracking Targets:
      Check: RANK, RHFB, RSHN, RTIB, RTUB
5. Click on Build Model.
6. Click on Close Tab before proceeding.

2. Create Left Shank OFM:

1. In the Segment Name combo box type Left Shank OFM
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Left Shank OFM tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: LPROT     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: LAJC_SK     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     LANK
   Select Tracking Targets:
      Check: LANK, LHFB, LSHN, LTIB, LTUB
5. Click on Build Model.
6. Click on Close Tab before proceeding.

RSK OFM.png

Creating the Hindfoot

Hindfoot Landmarks

Before defining the Hindfoot segments, Landmarks have to be created.

Create the (R/L)MidHeel landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RMidHeel
Starting Point: RLCA
Ending Point: RSTL
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=0.5
Check the Offset By Percent option


Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LMidHeel
Starting Point: LLCA
Ending Point: LSTL
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=0.5
Check the Offset By Percent option

RMidHeel OFM.png

Create the (R/L)P5Mproj landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RP5Mproj
Starting Point: RHEE
Ending Point: RMidHeel
Lateral object: RPCA
Project From: RP5M

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LP5Mproj
Starting Point: LHEE
Ending Point: LMidHeel
Lateral object: LPCA
Project From: LP5M

RP5Mproj OFM.png

Creating the Hindfoot

1. Create Right Hindfoot:

1. In the Segment Name combo box type Right Hindfoot
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Right Hindfoot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: RHEE     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: RP5Mproj     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Anterior     RPCA
   Select Tracking Targets:
      Check: RCPG, RHEE, RLCA, RSTL
5. Click on Build Model.
6. Click on Close Tab before proceeding.

2. Create Left Hindfoot:

1. In the Segment Name combo box type Left Hindfoot
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Left Hindfoot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: LHEE     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: LP5Mproj     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Anterior     LPCA
   Select Tracking Targets:
      Check: LCPG, LHEE, LLCA, LSTL
5. Click on Build Model.
6. Click on Close Tab before proceeding.

Hindfoot OFM.png

NOTE: After the segment has been created, the orientation of the segment coordinate system will need to be modified so the A/P axis is defined by +Z and the distal/proximal axis is defined by -Y. This may be done now or at the end of the tutorial when it is explained.

Creating the Forefoot

Forefoot Landmarks

Before defining the Forefoot segments, Landmarks have to be created.

Create the (R/L)P1M_FF landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RP1M_FF
Starting Point: RD1M
Ending Point: RP5M
Lateral object: RD5M
Project From: RP1M

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LP1M_FF
Starting Point: LD1M
Ending Point: LP5M
Lateral object: LD5M
Project From: LP1M

RP1M FF OFM.png

Create the (R/L)FF_O landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RFF_O
Starting Point: RP1M_FF
Ending Point: RP5M
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=RProxFFscale
Check the Offset By Percent option

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LFF_O
Starting Point: LP1M_FF
Ending Point: LP5M
Landmark Offset from Start Point or Segment Origin
Offset Using the Following ML/AP/AXIAL Offsets
AXIAL=LProxFFscale
Check the Offset By Percent option

RFF O OFM.png

Create the (R/L)TOE_FF landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RTOE_FF
Starting Point: RD1M
Ending Point: RD5M
Lateral object: RP5M
Project From: RTOE

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LTOE_FF
Starting Point: LD1M
Ending Point: LD5M
Lateral object: LP5M
Project From: LTOE

RTOE FF OFM.png

Defining the Forefoot

1. Create Right Forefoot:

1. In the Segment Name combo box type Right Forefoot
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Right Forefoot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: RFF_O     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: RTOE_FF     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     RD5M
   Select Tracking Targets:
      Check: RD5M, RP1M, RP5M, RTOE
5. Click on Build Model.
6. Click on Close Tab before proceeding.

2. Create Left Forefoot:

1. In the Segment Name combo box type Left Forefoot
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Left Forefoot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: LFF_O     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: LTOE_FF     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     LD5M
   Select Tracking Targets:
      Check: LD5M, LP1M, LP5M, LTOE
5. Click on Build Model.
6. Click on Close Tab before proceeding.

Forefoot OFM.png

NOTE: After the segment has been created, the orientation of the segment coordinate system will need to be modified so the A/P axis is defined by +Z and the distal/proximal axis is defined by -Y. This may be done now or at the end of the tutorial when it is explained.

Creating the Hallux

Hallux Landmarks

Because there is only one marker on the Hallux, additional markers are still required to track the segment in the motion trials.

Create the (R/L)D1M_HLX landmarks -

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: RD1M_HLX
Existing Segment: Right Forefoot
Landmark Offset from Start Point or Segment Origin
Offset to Existing Calibration Target or Landmark: RD1M

Go to the Landmarks tab, and click on Add New Landmark:

Landmark Name: LD1M_HLX
Existing Segment: Left Forefoot
Landmark Offset from Start Point or Segment Origin
Offset to Existing Calibration Target or Landmark: LD1M

RD1M HLX OFM.png

Defining the Hallux

While the Hallux is represented as a segment, only one marker is placed on the hallux. The Hallux segment therefore "shares" the medio-lateral axis of the Forefoot segment so that a coordinate system can be created for the Hallux.


1. Create Right Hallux:

1. In the Segment Name combo box type Right Hallux
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Right Hallux tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: RHLX     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: RD1M     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     RD5M
   Select Tracking Targets:
      Check: RD1M_HLX, RD5M, RHLX
5. Click on Build Model.
6. Click on Close Tab before proceeding.

2. Create Left Hallux:

1. In the Segment Name combo box type Left Hallux
2. Check the Kinematic Only Check Box
3. Select the Create button
4. In the Left Hallux tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: LHLX     Medial: None     
   Radius: 0.1
   Define Distal Joint and Radius
   Lateral: None     Joint: LD1M     Medial: None     
   Radius: 0.1
   Extra Target to define Orientation
   Select: Lateral     LD5M
   Select Tracking Targets:
      Check: LD1M_HLX, LD5M, LHLX
5. Click on Build Model.
6. Click on Close Tab before proceeding.

Hallux OFM.png

NOTE: After the segment has been created, the orientation of the segment coordinate system will need to be modified so the A/P axis is defined by -Z and the distal/proximal axis is defined by +Y. This may be done now or at the end of the tutorial when it is explained.

Rotate Segment Coordinate System

The final orientation of the segment coordinate systems should follow the same convention as the proximal segment. The orientation of the Hindfoot, Forefoot, and Hallux segments will need to be rotated.

For this tutorial, the correct orientation is X (red) mediolateral, Y (green) A/P, and Z (blue) up. This can be seen in the image below.

To modify the segment coordinate system:
1. Go to the Segment Properties tab
2. Set the Segment Name to the appropriate segment
3. Click Modify Segment Coordinate System

caption

For the Hindfoot and Forefoot, the segment coordinate system should be modified so that the A/P Axis is set to +Z and the Distal to Proximal set to -Y:

Original:

caption

Modified:

caption

For the Hallux, the segment coordinate system should be modified so that the A/P Axis is set to -Z and the Distal to Proximal set to +Y.


Overview of the Segment Coordinate Systems


Shown below is the correct orientation of the segment coordinate systems (the coordinate systems must be modified prior to this).

NOTE: The bones will not appear because the model file is not specified. To specify the model file, go to Segment Properties and browse for the model file (right: rshank.v3g, left: lshank.v3g). The kinetic foot segment will be created later in this tutorial.

OFM Final SCS.png


Computing Joint Angles

Computing the Oxford Foot Model joint angles uses Grood and Suntay's Joint Coordinate system, with a Cardan sequence of XYZ. If you are unsure as to how to do this processing in Visual3D, please consult the Model Based Computations tutorial.
The following details the joint angle output by the Oxford Foot Model:

Right Joint Angles:

Left Joint Angles:

RHFTBA:

Data Name= RHFTBA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Right Hindfoot
Reference Segment= Right Shank OFM
Cardan Sequence= X-Y-Z

LHFTBA:

Data Name= LHFTBA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= Y and Z checked
Normalization= Normalization Off
Segment= Left Hindfoot
Reference Segment= Left Shank OFM
Cardan Sequence= X-Y-Z

RFFTBA:

Data Name= RFFTBA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Right Forefoot
Reference Segment= Right Shank OFM
Cardan Sequence= X-Y-Z

LFFTBA:

Data Name= LFFTBA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= Y and Z checked
Normalization= Normalization Off
Segment= Left Forefoot
Reference Segment= Left Shank OFM
Cardan Sequence= X-Y-Z

RFFHFA:

Data Name= RFFHFA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Right Forefoot
Reference Segment= Right Hindfoot
Cardan Sequence= X-Y-Z

LFFHFA:

Data Name= LFFHFA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Left Forefoot
Reference Segment= Left Hindfoot
Cardan Sequence= X-Y-Z

RHXFFA:

Data Name= RHXFFA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Right Hallux
Reference Segment= Right Forefoot
Cardan Sequence= X-Y-Z

Only the X component should be used

LHXFFA:

Data Name= LHXFFA
Folder= ORIGINAL
Model Based Item Properties= JOINT_ANGLE
Negate X, Y, Z= All Unchecked
Normalization= Normalization Off
Segment= Left Hallux
Reference Segment= Left Forefoot
Cardan Sequence= X-Y-Z

Only the X component should be used

Generating a Report

The joint angles computed above, will be plotted as a percent of the gait cycle between events. To do this gait events must be identified in the dynamic trials.

The Automatic Gait Events pipeline command may be used to identify gait events once force assignments have been created. Force assignments will be automatically created once a kinetic foot segment has been defined. If a kinetic foot segment has already been defined, skip ahead to Automatic Gait Events section.

Create Kinetic Foot Segment

Before V3D can automatically create force assignments, it's necessary to create a kinetic foot segment. The foot segment may be defined using the typical Plugin Gait definition, or using the modified version described below.

1. Create Right Kinetic Foot Segment:

1. In the Segment Name combo box type Right Foot
2. Do NOT check the "Kinematic Only" Check Box
3. Select the Create button
4. In the Right Foot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: RAJC_SK     Medial: None     
   Radius: 0.5*DISTANCE(RANK,RMMA)
   Define Distal Joint and Radius
   Lateral: None     Joint: RTOE     Medial: None     
   Radius: 0.5*DISTANCE(RANK,RMMA)
   Extra Target to define Orientation
   Select: Posterior     RHEE
   Select Tracking Targets:
     RD5M, RHEE, RTOE
5. Click on Build Model.
6. Click on Close Tab before proceeding.

2. Create Left Kinetic Foot Segment:

1. In the Segment Name combo box type Left Foot
2. Do NOT check the "Kinematic Only" Check Box
3. Select the Create button
4. In the Left Foot tab, enter these values:
   Define Proximal Joint and Radius
   Lateral: None     Joint: LAJC_SK     Medial: None     
   Radius: 0.5*DISTANCE(LANK,LMMA)
   Define Distal Joint and Radius
   Lateral: None     Joint: LTOE     Medial: None     
   Radius: 0.5*DISTANCE(LANK,LMMA)
   Extra Target to define Orientation
   Select: Posterior     LHEE
   Select Tracking Targets:
     LD5M, LHEE, LTOE
5. Click on Build Model.
6. Click on Close Tab before proceeding.

KineticFoot.png

Create Automatic Gait Events

Once the Right/Left Foot segments have been created, Visual3D should have created automatic force assignments. The blue force vector shown in the 3D viewer of the Signals and Events tab indicates that a force has been assigned to a segment and will be used for kinetic calculations (unassigned force vectors are shown in red). Force assignments may be modified by going to Force -> View/Edit Segment to Force Assignments.

To create Automatic Gait Events using the pipeline:

1. Set the active file to "Active_Files"
2. Open the Pipeline Workshop

caption

3. Expand Event Creation
4. Double click Automatic_Gait_Events

The Automatic Gait Events command should move into the Main Pipeline

5. Double click the Automatic_Gait_Events command in the Main Pipeline and the dialog should open:

Check Use Pattern Recognition to Create (L/R)HS and (L/R)TO labels
Set the Frame Window for Pattern Recognition to 8
Set the FP Gravity Direction to Z
Click Done

6. Click Execute Pipeline

caption

Events should then be manually checked to ensure the correct events were identified. More information about Event Processing can be found here.

Plotting Signals

Once the joint angles have been computed using the Compute Model Based Data function, these can then be graphed in a report. For details on how to create a report, please consult the Creating a Report Tutorial

There is no predefined format for the Oxford Foot Model, and it is up to the user to choose how to present the joint angles. For the purpose of this tutorial, a report template was created to plot the joint angles. The report template can be downloaded here.

OFM HFTBA.pngOFM FFTBA.pngOFM FFHFA.pngOFM HXFFA.pngOFM HFTFL.png

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