Differences

This shows you the differences between two versions of the page.

--- caltester:caltester_mode_overview [2024/08/01 15:31] – [Experimental Data Collection] wikisysop
+++ caltester:caltester_mode_overview [2025/03/31 17:22] (current) – wikisysop
@@ Line 5: / Line 5: @@
 The functionality is **now available in Visual3D when a CalTester license key is provided**. There is also a stand-alone version of Visual3D that ONLY supports the CalTester, and these options now replace the older software. Users of the old software should have access to the new software automatically when they log into our web downloads page.
-**UPDATE:** The standalone CalTester-Plus software application has been discontinued and replaced with a newer CalTester stand-alone application. The new application is simply the CalTester tab in Visual3D all by itself.
+**UPDATE:** The standalone CalTester-Plus software application has been discontinued and replaced with a newer CalTester module, which is simply the CalTester tab in Visual3D.
 As a reminder, always go to the CalTester tab first, before opening any CalTester related data files.
@@ Line 13: / Line 13: @@
 Accurate and reliable kinematics and kinetics data are essential to the appropriate application of movement analysis data for clinical and research purposes. Proper laboratory calibration includes the accurate determination of the positions of the force platform(s) and cameras in the laboratory coordinate system, as well as correct setting of [[Visual3D:Documentation:Pipeline:Force_Commands:Modify_Force_Platform_Parameters|force platform parameters]]. Any errors in the parameter settings or calibration measurements will lead to incorrect values of kinetic calculations that rely on the force data.
-{{:CalTesterFigureSmall.jpg}} {{:CalTesterResults.gif}}
+{{:CalTesterFigureSmall.jpg?250px}} {{:CalTesterResults.gif?250px}}
 CalTester is an essential tool for laboratories that:
@@ Line 27: / Line 27: @@
 Functionality is based on recording the position and orientation of a standard commercially available precision mechanical testing device [[CalTester:Documentation:MTD3|MTD-2 CalTester Rod]] via the motion capture system. Implementation of the CalTester functionality was based on the following articles:
-     **The design of the [[CalTester:Documentation:MTD3|MTD2]] device allows a force to be applied to the surface of the force platform without any applied moment.**
+==== The design of the MTD2 device allows a force to be applied to the surface of the force platform without any applied moment.====
-The [[CalTester:Documentation:MTD3|MTD-2 rod]] is a rigid, machined rod with a conical (pointed) tip at each end is used together with a handle and a test plate, each with machined conical depressions. Five tracking targets are attached to the testing rod using rigid posts. Data are sampled simultaneously from the force platform (FP) and the cameras, as forces are applied through the rod to the force platform. The Mechanical Testing Device (MTD-2) is manufactured and supported by [[http://www.motion-labs.com/|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. (NOTE: There is an MTD-3 rod that supports adding a load cell on it, and the rods are the same size and work equally well. The MTD-3 may replace the MTD-2.)\\ \\ The following graphics are from the [[https://www.has-motion.com/download/CalTester/CalTesterArticle2003.pdf|CalTester Paper]] Holden JP, Selbie WS, Stanhope SJ, "A proposed test to support the clinical movement analysis laboratory".\\ \\ {{:Fig1CalTesterArticle.png}}\\ \\ {{:Fig2CalTesterArticle.png}}
+The [[CalTester:Documentation:MTD3|MTD-2 rod]] is a rigid, machined rod with a conical (pointed) tip at each end is used together with a handle and a test plate, each with machined conical depressions. Five tracking targets are attached to the testing rod using rigid posts. Data are sampled simultaneously from the force platform (FP) and the cameras, as forces are applied through the rod to the force platform. The Mechanical Testing Device (MTD-2) is manufactured and supported by [[https://mocapmarkers.myshopify.com/|Sisco Mocap]] 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. (NOTE: There is an MTD-3 rod that supports adding a load cell on it, and the rods are the same size and work equally well. The MTD-3 may replace the MTD-2.)\\ \\ The following graphics are from the [[https://www.has-motion.com/download/CalTester/CalTesterArticle2003.pdf|CalTester Paper]] Holden JP, Selbie WS, Stanhope SJ, "A proposed test to support the clinical movement analysis laboratory".\\ \\ {{:Fig1CalTesterArticle.png}}\\ \\ {{:Fig2CalTesterArticle.png}}
 Within the CalTester mode there are two classes of functionality:
-     **Estimate errors in the Center of Pressure and Orientation of the Force Vector.**
+====Estimate errors in the Center of Pressure and Orientation of the Force Vector.====
-Estimate the errors between the force platform recordings and the Motion Capture System. 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.\\ \\ The following calculations and explanations are from the [[https://www.has-motion.com/download/CalTester/CalTesterArticle2003.pdf|CalTester Paper]] Holden JP, Selbie WS, Stanhope SJ, "A proposed test to support the clinical movement analysis laboratory".\\ \\ **Section I : Calculating the rod orientation variable under the assumed condition of static equilibrium**\\ \\ Free-body diagram of testing device: Fp, ground reaction force; Fg, gravitational force (weight); Fa, applied force; r, position vector between tips (p to a) of testing device rod:\\ {{:Calc1CalTesterPlusArticle.png}}\\ Thus, r and A are parallel and the test device rod orientation (r) is defined entirely by the vector quantity A that is derived from FP measurements (Fp) and the physical characteristics of the testing device (Fg/2, i.e.the weight of the rod and its center of mass location; in this case, half the rod length).\\ {{:CalTesterPlus_DeltaTheta.jpg}}\\\\ The rod orientation variable ( {{:DeltaTheta.jpg}}) is determined from the dot product of the unit vector along A and the unit vector aligned with the long axis of the rod (r) as determined using the motion capture components.\\ \\ **Section II : Equation for evaluating the static equilibrium assumption**\\ \\ Under 2D dynamic conditions, the following holds:\\ {{:CalTesterPlus_Eq4_v2.jpg}}\\ \\ Rewriting the left-hand side of Eq. (4)\\ {{:CalTesterPlus_Eq5_v2.jpg}}\\ \\ Rearranging Eq. (5), the magnitude of the angular displacement ( {{:Beta.jpg}} ) between vectors r and A due exclusively to the inertial terms can be isolated:\\ \\ {{:CalTesterPlus_Eq6_v2.jpg}}\\ \\ where r is the length of the testing device rod, Icg the moment of inertia of the test device rod about the center of mass location, m the mass of the testing device rod and {{:ThetaDoubleDot.jpg}} is the angular acceleration of the testing device rod relative to an inertial reference frame.\\ \\ CalTesterPlus does not calculate {{:Beta.jpg}} since it operates under the assumption that there is no angular acceleration. For this reason it is important to move the CalTester rod slowly at a constant speed.  |
+Estimate the errors between the force platform recordings and the Motion Capture System. 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.\\ \\ The following calculations and explanations are from the [[https://www.has-motion.com/download/CalTester/CalTesterArticle2003.pdf|CalTester Paper]] Holden JP, Selbie WS, Stanhope SJ, "A proposed test to support the clinical movement analysis laboratory".\\
+====Section I : Calculating the rod orientation variable under the assumed condition of static equilibrium====
+Free-body diagram of testing device: Fp, ground reaction force; Fg, gravitational force (weight); Fa, applied force; r, position vector between tips (p to a) of testing device rod:\\ {{:Calc1CalTesterPlusArticle.png}}\\ Thus, r and A are parallel and the test device rod orientation (r) is defined entirely by the vector quantity A that is derived from FP measurements (Fp) and the physical characteristics of the testing device (Fg/2, i.e.the weight of the rod and its center of mass location; in this case, half the rod length).\\ {{:CalTesterPlus_DeltaTheta.jpg}}\\ \\ The rod orientation variable ( {{:DeltaTheta.jpg}}) is determined from the dot product of the unit vector along A and the unit vector aligned with the long axis of the rod (r) as determined using the motion capture components.\\ \\ **Section II : Equation for evaluating the static equilibrium assumption**\\ \\ Under 2D dynamic conditions, the following holds:\\ {{:CalTesterPlus_Eq4_v2.jpg}}\\ \\ Rewriting the left-hand side of Eq. (4)\\ {{:20140107212337caltesterplus_eq5_v2.jpg}}\\ \\ Rearranging Eq. (5), the magnitude of the angular displacement ( {{:Beta.jpg}} ) between vectors r and A due exclusively to the inertial terms can be isolated:\\ \\ {{:CalTesterPlus_Eq6_v2.jpg}}\\ \\ where r is the length of the testing device rod, Icg the moment of inertia of the test device rod about the center of mass location, m the mass of the testing device rod and {{:ThetaDoubleDot.jpg}} is the angular acceleration of the testing device rod relative to an inertial reference frame.\\ \\ CalTesterPlus does not calculate {{:Beta.jpg}} since it operates under the assumption that there is no angular acceleration. For this reason it is important to move the CalTester rod slowly at a constant speed.  |
      **Estimate the position and orientation of a force platform, instrumented treadmill, or instrumented stair that minimizes these errors..**
@@ Line 42: / Line 46: @@
 Force Platform signals are computed in compliance with [[http://www.c3d.org|the C3D File Format]]
-     **About [[Visual3D:Documentation:Kinematics_and_Kinetics:External_Forces:Force_Overview|Force Platform Parameters]].**
+** About [[Visual3D:Documentation:Kinematics_and_Kinetics:External_Forces:Force_Overview|Force Platform Parameters]].**
 Force Platforms, Instrumented Treadmills, Instrumented Stairs are examples of external force measuring devices. Each of these devices generates signals that are recorded by the Motion Capture System.\\ \\ These signals are used in conjunction with a set of parameters to compute a [[Visual3D:Documentation:Kinematics_and_Kinetics:External_Forces:Force_Representation|force signal]] comprising a Force Vector, a Center of Pressure, and a Free Moment applied to the platform.\\ \\ The set of parameters, and how they are used in the computations are unique to each manufacturer. The user should refer to the force platform documentation to identify the correct parameters. These parameters are typically stored in the [[Visual3D:Documentation:Kinematics_and_Kinetics:External_Forces:Force_Platforms#C3D_Parameters|c3d file]] alongside the signals.\\ \\ For calculations involving the interaction of an object/person in the motion capture volume and the force platform, it is necessary to establish the location of the force platform in the laboratory, so that the [[https://www.c-motion.com/v3dwiki/index.php/Transform_from_FCS_to_LCS%7Cforces|can be transformed into the motion capture volume]].\\ \\ In most cases the errors identified in the CalTester report are a result of determining the position and orientation of the platform in the motion capture volume, and not in errors from the platform sensors directly.