| Description |
Modeling the human hand's tendon system can bring better understanding to roboticists trying to create tendon based robotic hands and clinicians trying to identify new surgical solutions to hand tendon injuries. Accurate modeling of the hand's tendon system is complex due to the intricate nature of how tendons route and attach to each other and the skeleton system. These tendon complexities have restricted previous tendon models to single finger models with limited anatomical accuracy and no ability to depict fingertip contact force with external surfaces. This dissertation outlines the use of bond graph modeling to create and improve upon previous tendon models of the single finger. This bond graph tendon model of the single finger is the first model to incorporate many anatomical features, including tendon interconnections and anatomical stiffness, of the tendon system. A graphical user interface is presented to visually explore the relationship between tendon input and finger posture. The bond graph tendon model is validated using cadaver and in vivo experiments, along with the Anatomically Correct Testbed (ACT) Hand, which is a biologically inspired robotic hand that accurately mimics the bone structure, joints, and tendons of the human hand. Comparisons of the bond graph tendon model to in vivo data on finger joint coupling and fingertip pinch force, and cadaver data on the tendon system showed strong correlation in trends and magnitudes. A motion experiment, comparing the joint angle results of tendon excursions of the bond graph tendon model and the ACT Hand, and a force experiment, comparing the fingertip force generation of the two systems, were devised to validate the bond graph tendon model. The results of the motion experiments showed close agreement between the two systems (< 8 joint angle error), while the results of the force experiments showed a larger range correlation between the two systems (8-42% difference). The result of the validation experiments showed that the bond graph tendon model is able to accurately represent the tendon system of the finger. The model is also the first tendon model to allow for exploration of the effects of fingertip contact on the tendon system. |
