Experimental apparatus for the investigation of human knee dynamics

This thesis details the design, construction and validation of an experimental apparatus suitable for the investigation of human knee dynamics in vivo. Current research has centred on fixed-axis joints such as the thumb, elbow and ankle, however, due to its size and varying axis of rotation, the dynamic characteristics of the experimental system include a 20 ms rise time to a 1 mm step input, and a frequency bandwidth extending to 35 Hz. Validation of the experimental system was done using inertial systems with properties similar to those expected of the leg. Preliminary human results are presented with an analytical model of the knee. The knee is modelled as a second order system with a natural frequency of approximately 5 Hz and stiffness k of 120 Nm/rad. The results demonstrate that the experimental system is capable of applying position perturbations suitable for system identification of a human knee. This apparatus represents an experimental tool for the quantitive examination of human knee dynamics in vivo