User Guide MTD-3. Motion Lab Systems, Inc.

Transcription

1 User Guide MTD-3 Motion Lab Systems, Inc.

2 This manual was written by Motion Lab Systems using ComponentOne Doc-To-Help. Updated Tuesday, June 07, 2016 Intended Audience This manual is written to provide a general description and usage guidelines for anyone using this application it does not provide any clinical interpretation of the data that you may collect and analyze and no clinical interpretations should be assumed. Trademarks All trademarks and registered trademarks are the property of their respective owners. Printed in the United States of America Motion Lab Systems, Inc Motion Lab Systems, Inc Old Hammond Highway Baton Rouge, LA Phone (225) Fax (225) [email protected]

3 Contents The MTD-3 1 Description... 1 Use in Force Plate Testing... 1 C-Motion Software... 3 Load Cell Option... 4 MTD-3LC... 4 Assembly... 5 Packing List... 6 Spare Parts... 6 User Guide MTD-3 Contents iii

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5 The MTD-3 Description The MDT-3 (Mechanical Testing Device V3) is the current version of our precisionmachined tool that can be assembled in less than a minute to create a force plate test object suitable for a number of 3D biomechanics laboratory tests. It allows the user to apply a pure force vector to a force plate within the Motion Capture environment and determine the alignment of the force plate within the calibrated 3D measurement space. The MTD-3 is comprised of the following items supplied in a plastic storage case: Five wands Five retro reflective markers (for passive systems). Five mounting disks (for active marker systems). Calibration testing rod. Upper and Lower conical rod tips. Dummy (non-functional) Load Cell. Test plate with dual bearing points and stand mount. Handle with recessed bearing surface All items, except the main rod, are mechanically compatible with the MTD-2 design from Motion Lab Systems. The only difference is that the center MTD-3 calibration rod is shorter than the MTD-2 to accommodate the dummy load cell and has a lower threaded mount that is compatible with standard load cell mountings. The Caltester software that automates the measurements described above is available for purchase from C-Motion corporation. C-Motion was created in 1997 to facilitate a technology transfer of the Move3D motion analysis tool from the Physical Disabilities Branch of the National Institutes of Health into the commercial market. Use in Force Plate Testing Laboratory Force Plate tests are conducted in order to ensure the accuracy and reliability of kinematic and kinetic data this is essential to the appropriate application of movement analysis data for clinical and research purposes. Thorough User Guide MTD-3 The MTD-3 1

6 movement laboratory calibration includes the accurate determination of the physical locations of the force platform(s) and cameras within the laboratory coordinate system. In addition, it is essential that the correct setting of force platform data parameters such as analog scale factors and origin offsets are known in order to accurately measure the forces and moments recorded within the data collection environment. Any errors in the parameter settings or calibration measurements can lead to incorrect values of kinematic and/or kinetic variables calculated during a movement analysis. The laboratory calibration test incorporates data derived from the force platform and data generated from the camera measurement system. The degree of spatial and temporal agreement between these two sets of data provides an assessment of the joint working status of the kinetic and kinematic systems. A small number of variables are calculated and presented for inspection these enable the user to detect the presence of errors from a large number of potential sources. Figure 1 - The MTD mechanical testing device with the five-target configuration. 2 The MTD-3 User Guide MTD-3

7 Please note that the MTD and associated software is only designed to allow assessment of the force plate and motion capture environment this is not a calibration device. The design of the mechanical testing device allows a force to be applied to the surface of the force platform without any applied moment. 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. Four or five tracking targets are attached to the testing rod using rigid posts. Data are sampled simultaneously from the force platform and the cameras, as forces are applied through the rod to the force platform. If the measurement systems are configured and functioning properly, the rod tip location (determined from the target locations measured by the camera system) should coincide with the Center of Pressure location (measured by the force platform and transformed into the laboratory coordinate system). In addition, the Force Plate measured line of action of the operator-applied force (ground reaction force minus the testing device weight) should align with the kinematic-based estimate of the rod shaft orientation. The coincidence of all of these measurements is indicated by four variables: the difference in the force vector orientation (expressed as an angle), and the differences in the three coordinates of the Center of Pressure location. C-Motion Software CalTesterPlus is a standalone program available from C-Motion Inc., which combines features of the CalTester mode in the C-Motion Visual3D program together with options for gait and biomechanics laboratory Quality Assurance. The application 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 any standard MTD device. This simple test takes only a few minutes, and can be performed prior to any 3D and force/moment data collection to provide assurance that the data collection is sound. CalTesterPlus is an essential tool for laboratories that move cameras and/or move force platforms regularly, have force plate amplifier switches that can be easily changed, settings that are regularly changed, or have students or unsupervised visitors in the laboratory. The CalTesterPlus program allows the user to apply and record a moment-free force to the surface of the force platform with the MTD device while simultaneously recording the physical application of the force via the MTD markers - the design of the MTD allows the force to be applied without any applied moment. The MTD physical position to recorded via five tracking targets are attached to the testing rod using rigid posts these can be either retroreflective markers or active markers using the supplied mounting surface disks. Data are sampled simultaneously from the force platform (FP) and the cameras, as forces are applied through the rod to the force platform. 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 platforms and cameras in the laboratory coordinate system, as well as correct setting of force platform parameters such as analog scale factors and origin offsets. Any errors in the parameter settings or calibration measurements can lead to incorrect values of kinematics and/or kinetic variables calculated during a movement analysis. User Guide MTD-3 The MTD-3 3

8 Load Cell Option Previous versions of the MTD (MTD-1 and MTD-2) do not support the use of the devices with Load Cells this has changed with the introduction of the MTD-3 which supports Load Cell operation as an option for advanced users. The MTD-3 is supplied with a dummy (non-functional) component that is mechanically identical to a FUTEK LCM200 load cell. The MTD-3 load cell mount uses standard US 3/8-24 threaded stud mounts, allowing the MTD-3 to be used with other compatible threaded load cells if desired. Please note that the MTD-3 supports, but does not include a load cell. The 3/8-24 threaded, stud mount, dummy component supplied with the MTD-3 attaches to the bottom of the MTD-3 between the lower end of the rod and the tip. The overall length of the modified MTD-3 is unchanged when used with the either the recommended FUTEK load cell device or the dummy component. When used with a FUTEK load cell or the supplied dummy component, the MTD-3 is virtually identical in all respects to the older MTD-2 devices. MTD-3LC The MTD-3LC is sold as a separate package, mechanically identical to the MTD-3, the MTD-3LC force platform quality assessment package includes an MTD-3 device with a 250lb, single axis, NIST traceable load cell and visual digital display option. This allows the user to visually and electronically monitor the force applied to the force place via an analog output for direct digital measurement. The MTD-3LC includes the following FUTEK options in addition to the MTD-3 device: LCM200 a 250lbs single axis load cell, RoHS compliant with standard US 3/8-24 thread, and a 10 foot cable. IHH500 Pro a handheld display with digital display of the applied force plus analog output (BNC cable included). The FUTEK load cell supplied with the MTD- 3LC device includes NIST traceable, 5-point compression calibration and certification of the load cell sensor. 4 The MTD-3 User Guide MTD-3

9 Assembly All MTD-3 devices shipped after August 2006 include five additional disks for use with Motion Capture Systems that use discrete LED emitters instead of retro-reflective markers. Each MTD-3 is supplied with the central mounting rod, assembled with a conical point at each end you will need to attach a number of the wands to the central rod to ensure that the wands are located in their calibrated positions. The wands are supplied with five retro-reflective markers and five disks. Screw the retro-reflective markers to the wands if your Motion Capture System is a passive system using this kind of marker. If you are using the MTD-3 with a measurement system that uses discrete LED emitters (i.e. systems similar to Codamotion, Northern Digital etc.) you will need to replace the retro-reflective marker balls with the disks supplied with the MTD-3. Attach one of your system emitters at the center of each of the disks as shown in Figure 2. The MTD-3 device does not include active markers for your system these must be supplied by the end-user. Figure 2 - Wand with active marker and disk attached. To use the MTD-3 with calibration testing software from C-Motion or other vendors please refer to the software instructions supplied with the vendor software for MTD- 3 assembly details and usage. User Guide MTD-3 The MTD-3 5

10 Packing List The MTD-1, MTD-2, and MTD-3 devices use a number of common components. Part Number Description MTD1 MDT2 MDT3 MTD-05 Base with bearing surface MTD-10 Central mounting rod - lower limb MTD Central mounting rod - standard calibration MTD Central mounting rod load cell mount MTD-DLC Dummy load cell component MTD-35 Handle Bar (with recessed bearing surface) Six inch trunk handle MTD-30 Conical point (3/8-16 thread) MTD-30LC Conical point (3/8-24 thread) MTD mm wand - Thigh, Shank, and Foot MTD-50 50mm wand - Hip, Knee and Ankle MTD mm wand - opposite ASIS wand Retro-reflective markers (passive systems) Disks for emitter markers (active systems) MTD-00 Transportation Case MTD documentation Spare Parts Please contact Motion Lab Systems using the address at the front of this manual if your MTD device should be damaged, or require repair. Spare parts for MTD-1, MTD-2, and MTD-3 devices are available from Motion Lab Systems at a nominal charge. 6 The MTD-3 User Guide MTD-3