Development of a General 6-DOF Parallel Robotic System: Load-Control Methodology for Spine Biomechanics Testing

Parallel robots have gained popularity for applications requiring large payloads and accurate multi-degree-of-freedom (DOF) motion. This project focused on the development of a parallel robotic system to examine the injury mechanics of the structures of the lumbar intervertebral joint. Six-DOF position- and load-control algorithms were programmed for machine operation. The positional accuracy of the machine was considered substandard. The kinematic errors were attributed to problems in machine deformation, manufacturing, and assembly. These errors led to poor loadcontrol in porcine lumbar spine tests. A 3-DOF approach improved load-control tests since the other 3-DOF loads were not explicitly controlled. Forces and the principal bending moment were satisfied within ±25N and 1Nm in 6-DOF, and ± 10N and 0.25Nm in 3-DOF. The developed methods are specific to 6-DOF joint testing with parallel robots. The incorporation of these methods into a 6-DOF parallel robot with submillimetre accuracy is warranted for improved multidimensional joint testing

Year	Entry
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1996	Rudy TW, Livesay GA, Woo SL-Y, Fu FH. A combined robotic/universal force sensor approach to determine in situ forces of knee ligaments. J Biomech. October 1996;29(10):1357-1360.
2000	Cripton PA, Bruehlmann SB, Orr TE, Oxland TR, Nolte L-P. In vitro axial preload application during spine flexibility testing: towards reduced apparatus-related artefacts. J Biomech. December 2000;33(12):1559-1568.
2002	Gillespie KA. Biomechanical Role of Lumbar Spine Ligaments in Flexion and Extension Using a Parallel Linkage Robot: A Porcine Model [Master's thesis]. University of Guelph; April 2002.
1984	Yang KH, King AI. Mechanism of facet load transmission as a hypothesis for low-back pain. Spine. September 1984;9(6):557-565.
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Year

Entry

1980

Adams MA, Stott JRR. The resistance to flexion of the lumbar intervertebral joint. Spine. May–June 1980;5(3):245-253.

1996

Rudy TW, Livesay GA, Woo SL-Y, Fu FH. A combined robotic/universal force sensor approach to determine in situ forces of knee ligaments. J Biomech. October 1996;29(10):1357-1360.

2000

Cripton PA, Bruehlmann SB, Orr TE, Oxland TR, Nolte L-P. In vitro axial preload application during spine flexibility testing: towards reduced apparatus-related artefacts. J Biomech. December 2000;33(12):1559-1568.

2002

Gillespie KA. Biomechanical Role of Lumbar Spine Ligaments in Flexion and Extension Using a Parallel Linkage Robot: A Porcine Model [Master's thesis]. University of Guelph; April 2002.

1984

Yang KH, King AI. Mechanism of facet load transmission as a hypothesis for low-back pain. Spine. September 1984;9(6):557-565.