Contents
Mechanical Testing of Musculoskeletal Joints
The BioRobotics Core at the Cleveland Clinic has several robotic systems considered musculoskeletal simulators. Mechanical testing of knee joints will be performed using a simVitro System. This system includes:
- A 6 DOF robot (Rotopod R2000) with a rotary stage mounted to the top to yeild a 7th DOF for increased range of motion.
- An Optotrak motion tracking system to digitize the robotic system hardware, specimen anatomy, and to create and control motions and loads in a Grood and Suntay knee joint coordinate system specific to the specimen.
- A universal force sensor (UFS) to measure the tibia loads.
Robot Specifications
Rotopod R2000; Parallel Robotic Systems Corp., Hampton, NH, USA
- Translation Range (maximum in robot coordinate system)
- x = ± 100 mm
- y = ± 100 mm
- z = ± 100 mm
- Rotation Range (maximum in robot coordinate system)
- roll = ± 13°
- pitch = ± 13°
- yaw = ± 720°
- Load Capacity 2000 N
- Torque Capacity 1000 Nm
- Translational Velocity 0.1 m/s
- Angular Velocity 120°/s
- Accuracy = 50-300 μm (depending on speed and position within range of motion)
- Repeatability 25 μm
Load Cell Specifications
Tibiofemoral Testing: Theta, ATI Industries Corp., Apex, NC, USA
- Load Rating (in load cell coordinate system)
- Fx 1500 N
- Fy 1500 N
- Fz 3750 N
- Mx 240 Nm
- My 240 Nm
- Mz 240 Nm
- Resolution (in load cell coordinate system)
- Fx 0.5 N
- Fy 0.5 N
- Fz 0.5 N
- Mx 0.05 Nm
- My 0.05 Nm
- Mz 0.025 Nm
- Accuracy (in load cell coordinate system)
- Fx 1.50 % FS
- Fy 1.25 % FS
- Fz 0.75 % FS
- Mx 1.25 % FS
- My 1.00 % FS
- Mz 1.50 % FS
Patellofemoral Testing: Omega85, ATI Industries Corp., Apex, NC, USA
- Load Rating (in load cell coordinate system)
- Fx 1900 N
- Fy 1900 N
- Fz 3800 N
- Mx 80 Nm
- My 80 Nm
- Mz 80 Nm
- Resolution (in load cell coordinate system)
- Fx 0.3 N
- Fy 0.3 N
- Fz 0.5 N
- Mx 0.014 Nm
- My 0.014 Nm
- Mz 0.009 Nm
- Accuracy (in load cell coordinate system)
- Fx 1.50 % FS
- Fy 1.50 % FS
- Fz 1.00 % FS
- Mx 1.25 % FS
- My 1.75 % FS
- Mz 1.25 % FS
Digitizer and Motion Capture Specifications
Optotrak Certus, Northern Digital Inc., Waterloo, Ontario, CA
- Accuracy 100 μm
- Resolution 10 μm
Data Collection and Control Software
simVITRO, Cleveland Clinic BioRobotics Lab, Cleveland, Ohio, USA
- Default Analog Sample Rate (Analog based sensor data) 100 Hz
- Default Digitized Sample Rate (Digitized based sensor data) 5-100 Hz
Sample rates, channel names, channel units, and other experiment and setup specific parameters are recorded for each experiment run in the experiment run folder.
This system allows the robot to operate in real-time force feedback control, as well as position control, so that loading trajectories can be applied to determine joint kinetic and kinematic responses.
- Websites
http://mds.clevelandclinic.org/Services/BioRobotics/Portfolio.aspx?n=248
- Documentation
2013RB-001-002.A simVITRO Data File Structure Quick Reference Guide.pdf
simVITRO File Organization, Contents, and Conventions Specification_Rev01.pdf
Peripheral_Soft_Tissue_Effects.pdf (WCB 2014 abstract)
- Key publication
Noble LD, Jr., Colbrunn RW, Lee DG, van den Bogert AJ, Davis BL. Design and validation of a general purpose robotic testing system for musculoskeletal applications. J Biomech Eng. 2010;132(2):025001.Abstract in PubMed.
Patella Registration
- Registration of the patella between the image and experiment will be accomplished with the following MRI opaque geometry:
PatellaRegistration_SphereCenterNumbers.PDF Using SVD, the mean error between CAD based and Optotrak probed divot locations was found to bet 0.23 +/- 0.19 mm. Related, MRI based sphere centers were found to agree with CAD based to within 0.5 mm or approximately 1% of the distance between points.
Pressure Measurement
- Pressure sensor L Tekscan 5051/P1/16813DT1/1,200
Characterization of Tissue Mechanical Properties
Specimen Cutting
Dumbell shaped tensile sample die cutter and arbor press
- Cartilage sample area - TBD x TBD (~200 micron thick)
Ligament sample area - 10mm x 2mm (< 1mm thick)
Meniscus sample area - 5mm x 1mm (< 1mm thick)
Circular shaped compression sample die cutter and arbor press
- Cartilage sample size - 5mm diameter x full and uniform thickness (created with vibratome)
- Meniscus sample area - 5mm diameter x full and uniform thickness (created with vibratome)
Vibratome
- Leica VT1200S
- Cutting frequency (±10%): 85 Hz (±10%)
- Amplitude: from 0-3mm,in 0.05mm/s increments
- Cutting speed (±10%): 0.01 - 1.5mm/s
- Cutting range: 45mm
- Cutting window: 0.5mm - 45mm
- Maximum specimen size:
- With standard blade holder:33*50mm
- Specimen orientation,rotating: 360˚
- Specimen plate, swiveling: 0-10˚
- Section thickness adjustment: manual 1 micron increment or automatic max. 1000 microns.
Sample Grips and Indentors
Tensile Grips with alignment fixture
Indentor
Sample Thickness Measurement System
Custom optical thickness measurement system.
- Resolution: TBD
- Accuracy: TBD
Uniaxial Mechanical Testing System
Biomomentum Mach-1 Mechanical Tester
- Mach-1 V500c: Vertical Stage (100 mm Travel; 0.5 um Res.)
- Multiple-Axis Load Cell (70 N)
- Single-Axis Load Cell (100 N)
- Manual X Positioner (50 mm)
- Manual Angular Positioner (Tilt: ±25°, Rotation: 360°)
Sample Enviroment
Saline bath
- Room temperature