The objectives of the work reported in this article were to develop a novel 6-degree-of-freedom (DOF) robotic system for knee joint biomechanics, to complete a hybrid force-position control scheme, to evaluate the system performance, and to demonstrate a combined loading test. The manipulator of the system utilizes two mechanisms; the upper mechanism has two translational axes and three rotational axes while the lower mechanism has only a single translational axis. All axes were driven with AC servo-motors. This unique configuration results in a simple kinematic description of manipulator motion. Jacobian transformation was used to calculate both the displacement and force/moment, which allowed for a hybrid control of the displacement of, and force/moment applied to, the human knee joint. The control and data acquisition were performed on a personal computer in the C-language programming environment with a multi-tasking operating system. Preliminary tests revealed that the clamp-to-clamp compliance of the system was smaller in the vertical (Z) and longitudinal (Y) directions (0.001 mm/N) than in lateral (X) direction (0.003 mm/N). The displacement error under the application of 500 N of load was smallest in the vertical direction (0.001±0.003 mm (mean±SD), and largest in the lateral direction (0.084±0.027 mm). Using this test system, it was possible to simulate multiple loading conditions in a human knee joint in which a cyclic anterior force was applied together with a coupled, joint compressive force, while allowing natural knee motion. The developed system seems to be a useful tool for studies of knee joint biomechanics.
A Novel Robotic System for Joint Biomechanical Tests: Application to the Human Knee Joint
Contributed by the Bioengineering Division for publication in the JOURNAL OF BIOMECHANICAL ENGINEERING. Manuscript received by the Bioengineering Division November 18, 1999; revision received August 11, 2003. Associate Editor: M. L. Hull.
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Fujie, H., Sekito, T., and Orita, A. (March 9, 2004). "A Novel Robotic System for Joint Biomechanical Tests: Application to the Human Knee Joint ." ASME. J Biomech Eng. February 2004; 126(1): 54–61. https://doi.org/10.1115/1.1644567
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