The CalTester function in Visual3D estimates the optimal position and orientation of a force platform, instrumented treadmill, or instrumented stair within the 3D motion capture volume based on a set of experimental trials using a standard MTD-2 CalTester Rod.

The Mechanical Testing Device (MTD-2) is manufactured and supported by Motion Lab Systems, Inc. The MTD-2 is a precision-machined calibration-testing tool that can be assembled in less than a minute to create a calibration-testing object suitable for a number of 3D biomechanics laboratory tests.

This simple test takes only a few minutes, could be performed prior to any data collection, and provides reassurance that your data collection is sound.

CalTester is an essential tool for laboratories that:

• Move cameras and/or Move force platforms regularly
• Have amplifier switches that can be easily bumped
• Have settings that are regularly changed
• Have students or unsupervised visitors in the laboratory

The CalTester tab automatically uses the file or files that have been loaded into the Visual3D workspace. CalTester can then be controlled using the tool bar at the top of the screen or the controller at the bottom of the screen.

View CalTester Report Summary Page 1 - This button helps to control the right side of the screen. When selected, the right side of the screen displays page 1 of the CalTester report, which contains a summary of the full report.

View CalTester Report Graphs Page 2 - This button helps to control the right side of the screen. When selected, the right side of the screen displays page 2 of the CalTester report, which contains graphs for the Ground Reaction Force Magnitude, the CoP Error (X, Y & Z), and the CalTester Rod Orientation Error.

View CalTester Report Graphs Page 3 - This button helps to control the right side of the screen. When selected, the right side of the screen displays page 3 of the CalTester report, which contains graphs for the CalTester Segment Residual, and Marker Residuals (Top Left, Top Right, Middle Left, Bottom Left, and Bottom Right).

Zoom in on the report - This button allows the user to zoom in on the page of the report that is shown on the right side of the screen.

Zoom out of the report - This button allows the user to zoom out on the page of the report that is shown on the right side of the screen.

]] Modify CalTester Rod Dimensions - This button opens the Rod Dimensions dialogue box. Further details on the function of the dialogue box can be found Rod_Dimensions}}. {{V3DCalTesterPlatformParameters.png{{/images/2/29/V3DCalTesterPlatformParameters.png Modify Force Platform Parameters - This button opens the Modify Force Platform Parameters dialogue box. Further details on the function of the dialogue box can be found Modify_Force_Platform_Parameters}}. {{V3DCalTesterForceStructure.png{{/images/1/1e/V3DCalTesterForceStructure.png Modify Force Structures - This button opens the Modify Force Structure Parameters dialogue box. Further details on the function of the dialogue box can be found Tab_Force_Structure}}. {{V3DCalTesterPlatformLocator.png{{/images/5/50/V3DCalTesterPlatformLocator.png Force Platform Locator - This button opens the Force Plate Location dialogue box. Further details on the function of the dialogue box can be found In order to use the CalTesterPlus program you need a set of properly collected data for each force platform you wish to calibrate. To collect a useful static trial for CalTester follow the following process.\\ \\ - Set up your capture volume making sure that all force platforms and cameras are in the positions that they will remain in for following data collections.\\ - Place the [[CalTester:CalTesterPlus:Hardware#Base_Plate|CalTester base plate on the force platform before you begining the collecting the trial.
- Zero the force platform so that it will not record the force produced by the CalTester base.
- Begin the trial with the CalTester Rod on the CalTester base plate OFF the force platform.
- Press down firmly on the Rod with a load of at least 200 N.
- Keep the Rod aligned vertically and motionless during the trial.
- The trial needs to be at least 1 second long.
- There should be a minimum of three trial collected per force platform. Ideally there should be 8 or more, with at least one near each corner of the force platform and one near the center of the force platform. |

Collecting Dynamic Trials (click to expand)

Creating a Report (click to expand)

The report capabilities of the CalTester tab creates an error report based on collection trials. 1. Add C3D files In order to open a C3d file for use in the CalTester tab you must first navigate to the CalTester tab and leave it active. The C3D files are then opened by clicking on the open button. ]] This will open a standard file navigation window which you can use to select the files you wish to include in the report. 2. Check Report Once the files are loaded the right side of the CalTester tab will show the first page of the CalTester report. You can navigate between the three report pages by using the page buttons in the tool bar. V3DCalTester3PageButtons.png]] 3. Print Report The report that has been generated on the right side of the screen can be saved as a pdf document by using the file drop down menu and selecting Print or by using the Ctrl + P short cut. 4. Understanding the Report A detailed explanation of how to understand the report that CalTester produces can be found index.php. Note: If there appears to be errors or discrepancies in the report or the 3D-view check that the markers have been identified correctly and that the rod dimensions are correct using the Modify CalTester Rod Dimensions button. V3DCalTesterRodDimensions.png}}

Determining the Force Plate Location (click to expand)

The CalTester tab can be used to determine the location of a force plate relative to the cameras and the coordinate system if a jig is also present in the file. It will produce a written report detailing the force platform's exact location in your lab. This report can be saved as a text file and the values can be inputted into the data collection software that you use. - Load the files into Visual3D while the CalTester tab is active. - Click on the Force Platform Locator button in order to open the Force Platform Locator dialogue box. - Make sure that the FPLoc tab is selected. - In the Select Force Platform section, select the Force Plate you whish to locate using the drop down box. - In the Define Force Platform Dimension section, check that the FP Length and FP Width are correct. If they are, make sure that the Use Current Dimension radio box is selected. If they are not, select Use New Dimension radio box and change the FP Length and FP Width to the correct values. - In the file list at the bottom of the box, select the C3D files that have both the force plate and the jig in the same location. At least 3 files must be used, but it is recommended that at least 8 be used. - Click on the Compute Optimal Configuration button. - Wait for Visual3D to calculate the configuration. This may take a few seconds. - The CalTester Results window will open and present the following: the output for the force platform, the corrected location (in mm), the force platform center, the rotation matrix (into lab space), the cardan angles to rotate from lab to force platform, the cardan angles to rotate from force platform to lab space, the nexus orientation parameters, and the Visual3D command. - If you wish to save the output you can click on the Export to text button at the bottom left of the results dialogue box. A sample of the output that should be created is provided below: Output for force platform 1 : ======== Corrected Locations (in mm): ======== Corner 1: -624.8758, 685.1889, 1.5064 Corner 2: -17.5759, 687.8662, 1.6895 Corner 3: -14.8988, 80.5641, 2.1519 Corner 4: -622.1987, 77.8868, 1.9688 Force platform Center: -319.8873, 382.8765, 1.8292 =============================================== Rotation Matrix (into lab space): -0.999990 -0.004408 0.000305 -0.004408 0.999990 -0.000760 -0.000302 -0.000761 -1.000000 Cardan angles to rotate from lab to force platform Angle 1 (x): 179.956451 Angle 2 (y): 0.017473 Angle 3 (z): 179.747421 Cardan angles to rotate from force platform to lab space Angle 1 (x): 179.956375 Angle 2 (y): -0.017281 Angle 3 (z): 179.747406 Nexus orientation parameters: -0.043584 -0.017377 0.252580 Visual3D Command Modify_One_Force_Platform /FP_SELECTED= 1 /FP_CORNER1= -624.8758 + 685.1889 + 1.5064 /FP_CORNER2= -17.5759 + 687.8662 + 1.6895 /FP_CORNER3= -14.8988 + 80.5641 + 2.1519 /FP_CORNER4= -622.1987 + 77.8868 + 1.9688

Defining a Jig (click to expand)

By creating a jig the user can identify the location of a force plate without having to repeating the entire CalTesterPlus platform protocol each time. In order to use this function you need to have a set of permanent markers (i.e. a template or a jig) which have a consistent position relative to the force platform. - Load the files into Visual3D while the CalTester tab is active. - Click on the Force Platform Locator button in order to open the Force Platform Locator dialogue box. - Make sure that the Define Jig tab is selected. - In the Select Jig section, click the Add New Jig button. - In the Define Jig Targets section, use the drop down menu at the left of the section to select the targets that are included in the jig and click Add Targets. Do this until all of the targets that are in the jig are listed in the Target list to the right of the section. - In the Force Platform section, select from the FP drop down menu that you wish to locate with the Jig. - In the Define Force Platform Dimension section, check that the FP Length and FP Width are correct. If they are, make sure that the Use Current Dimension radio box is selected. If they are not, select Use New Dimension radio box and change the FP Length and FP Width to the correct values. - In the file list at the bottom of the box, select the C3D files that have both the force plate and the jig. A minimum of 3 C3D files must be used to create the Jig File. - Click on the Calculate Results button in order to produce the CalTester Results window. This window can be exported by using the Export to text button in the bottom left of the screen. A sample of the output that should be created is provided below: ==== Fixed marker locations in force platform space (MKS units) ==== /JIG_NAME = Jig_1 /FP_TESTED = 1 /USE_FP_DIMENSIONS = FALSE

Locating the Force Plate with a Jig (click to expand)

The CalTester tab can define the location of the Force Plates in lab coordinate system based on the location of the Jig (how to define the location of the Jig is described above). - Load the files into Visual3D while the CalTester tab is active. - Click on the Force Platform Locator button in order to open the Force Platform Locator dialogue box. - Make sure that the FP Loc (Jig) tab is selected. - In the Select Jig section, if the Jig you wish to use is already listed in the text box, select it, otherwise click on the Load Jig File button and select the Jig File that you created using the Defining a Jig tutorial above. - At the bottom of the dialogue box, select the C3D files that should be updated using the selected jig. - Click on the Calculate Results button.