User Guide MTD-2. Motion Lab Systems, Inc.

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1 User Guide MTD-2 Motion Lab Systems, Inc.

2 This manual was written by Motion Lab Systems using ComponentOne Doc-To-Help. Updated Thursday, April 12, 2012 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)

3 Contents The MTD-2 1 Description...1 Use in Calibration Tests...1 MTD-2LC Option...3 Assembly...3 Packing List...4 Damage...4 User Guide MTD-2 Contents i

The MTD-2 Description The MDT-2 (Mechanical Testing Device) is a precision-machined tool that can be assembled in less than a minute to create a force plate test object suitable for a number of 3D

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.

5 The MTD-2 Description The MDT-2 (Mechanical Testing Device) is a precision-machined 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-2 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 with two conical tips 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 original MTD- 1 design from Motion Lab Systems. The only difference is that the center MTD-2 calibration rod is shorter than the MTD-1 and does not offer alternative marker wand mounting points that allow the MTD-1 to simulate a standard lower limb gait model. 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 Calibration Tests Laboratory calibration tests are conducted in order to ensure the accuracy and reliability of kinematic and kinetic data which are essential to the appropriate application of movement analysis data for clinical and research purposes. Thorough 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 force platform parameters such as analog scale factors and origin offsets. Any errors in the parameter settings or calibration measurements can lead to User Guide MTD-2 The MTD-2 1

6 incorrect values of kinematic and/or kinetic variables calculated during a movement analysis. The 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-2 mechanical testing device with the five-target configuration. 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 (FP) and the cameras, as forces are applied through the rod to the FP. 2 The MTD-2 User Guide MTD-2

7 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 (CoP) location (measured by the force platform and transformed into the laboratory coordinate system). In addition, the FP-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 CoP location. MTD-2LC Option The MTD-2LC option can be added to any MTD-2 device and adapts a standard MTD-2 for use with a Futek LCM200 load cell, or any load cell using standard US 3/8-24 threaded stud mounts. The option consists of a modified rod and tip with standard US 3/8-24 threaded mounts at the lower end of the rod while retaining the standard 3/8-16 threaded mount for the tip at the other end. To avoid confusion, the rod and tip supplied with the MTD-2LC are anodized red instead of the standard black coloring used by the standard MTD-2 components. The 3/8-24 threaded, stud mount, load cell attaches to the bottom of the MTD-2 between the new rod and tip. The overall length of the modified MTD-2 is unchanged when used with the suggested Futek device. The MTD-2 with the MTD- 2LC option is virtually identical in all respects to a standard MTD-2 with virtually the same mass and identical dimensions. This option does not include the load cell or amplifier these must be purchased separately by the user to produce the desired output signals. Assembly All MTD-2 devices shipped after August include five additional disks for use with Motion Capture Systems that use discrete LED emitters instead of retro-reflective markers. To use the MTD-2 with calibration testing software from C-Motion or other vendors please refer to the software instructions supplied with the vendor software for MTD- 2 assembly details and usage. Each MTD-2 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-2 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-2. Attach one of your system emitters at the center of each of the disks as shown in Figure 2. The MTD-2 device does not include active markers for your system these must be supplied by the end-user. User Guide MTD-2 The MTD-2 3

recessed bearing surface) 1 1 Six inch trunk handle 1 0 MTD-20 Conical point (3/8-16 NC thread) 2 2 MTD-150 150mm wand - Thigh, Shank, and Foot (1/4-20 NC).

8 Figure 2 - Wand with active marker and disk attached. Packing List The MTD-1 and MTD-2 devices use a number of common components. Part Number Description MTD-1 MDT-2 MTD-05 Base with bearing surface 1 1 MTD-10 Central mounting rod - lower limb 1 0 MTD Central mounting rod - standard calibration 0 1 MTD-25 Handle Bar (with recessed bearing surface) 1 1 Six inch trunk handle 1 0 MTD-20 Conical point (3/8-16 NC thread) 2 2 MTD mm wand - Thigh, Shank, and Foot (1/4-20 NC). 5 5 MTD-50 50mm wand - Hip, Knee and Ankle (1/4-20 NC). 5 0 MTD mm wand - opposite ASIS wand (1/4-20 NC). 1 0 Retro-reflective markers (passive systems) 11 5 Disks for emitter markers (active systems) 0 5 MTD-00 Transportation Case 1 1 MTD documentation 1 1 Damage Please contact Motion Lab Systems using the address at the front of this manual if your MTD-2 device should be damaged, or require repair. Spare parts for both MTD-1 and MTD-2 devices are available from Motion Lab Systems at a nominal charge. 4 The MTD-2 User Guide MTD-2

9 The MTD-2 5

The objective of this tutorial is to present Model Based Calculations. These are calculations that only make sense relative to rigid segments.

C-Motion Online Documentation Visual3D : Model Based Computations Objectives (# 1388) The objective of this tutorial is to present Model Based Calculations. These are calculations that only make sense