The main objective is to generate kinematic models for the head and neck mo
vements, The motivation comes from our study of individuals with, quadriple
gia and the need to design rehabilitation aiding devices such as robots and
teletheses that can be controlled by head-neck movements, It is then neces
sary to develop mathematical models for the head and neck movements, Two id
entification methods have been applied to study the kinematics of head-neck
movements of able-body as well as neck-injured subjects, In particular, sa
gittal plane movements are well modeled by a planar two-revolute-joint link
age. In fact, the motion in joint space seems to indicate that sagittal pla
ne movements may be classified as a single DOF motion. Finally, a spatial t
hree-revolute-joint system has peen employed to model three-dimensional hea
d-neck movements.