Contributions to Books:
I. Reichl, W. Auzinger, H. Schmiedmayer, E. Weinmüller:
"Reconstruting the knee joint mechnism from kinematic data";
in: "ASC Report48/2009",
issued by: Institute for Analysis and Scientific Computing;
Vienna University of Technology,
The interpretation of joint kinematics data in terms of displacements is a product of the type of
movement, the measurement technique, and the underlying model of the joint implemented in
optimization procedures. Kinematic constraints reducing the number of degrees of freedom are
expected to compensate for measurement errors and noise, thus, increasing the reproducibil-
ity of joint angles. One approach already successfully applied by several groups approximates
the healthy human knee joint as a compound hinge joint with minimal varus/valgus rotation.
Most of these optimizations involve an orthogonality constraint. This contribution compares
the eŽect of a model with and without orthogonality constraint on the obtained joint rotation
angles. For this purpose kinematic data is simulated without noise and with normally dis-
tributed noise of varying size. For small noise the unconstrained model provides more accurate
results while for larger noise this is the case for the constrained model. This can be attributed
to the shape of the objective function of the unconstrained model near its minimum.
tibiofemoral joint; kinematics; optimization; compound hinge joint; model
Electronic version of the publication:
Created from the Publication Database of the Vienna University of Technology.