Assessing the Feasibility of Using Spherical Contact Pairs to Model the Contact Regions in the Joints of the Index Finger

The index finger is a complex structure in the human body, which contains multiple joints. It is used for precise interaction with the environment. In the available studies, the joints of the finger are usually replaced with simple constraints, such as revolute or spherical joints. The main aim of this research was to assess whether the contact areas in the three joints of the finger could be replaced with simple spherical contact pairs. This was motivated by the fact that such contact pairs would allow for more accurate contact analysis than the simplified constraints, while still being computationally inexpensive. The research was performed using two computer tomography datasets, which were transformed into surface meshes of the bones. Parts of the bones, which corresponded to the contact areas in the joints, were selected and imported into Python. Then, sphere fitting was performed in a custom script, which also allowed for visualization of the obtained contact pairs – obtained from the fitted spheres. The pairs were then analyzed. The results showed that it might be possible to replace the contact areas in the joints of the index finger with simple spherical contact pairs. Moreover, in two of the joints, better results were obtained when using two contact pairs – medial and lateral – instead of one for the whole area.