Abstract
Kinematic and kinetic measurement have been performed in rehabilitation and orthopaedic field. However, the most important feasibility of engineering in those fields may be to provid any method by which invisible physical conditions related with disabilities or diseases can be revealed. From the clinical point of view, the conditions can be magnitude of forces exerted on the joints and the muscles, stress value of bones and so on. A mathematical and mechanical model must be constructed to calculatethose values because they cannot be measured directly. And these days, there are several reports about such models. We also made a Neutonian mechanical model in which a human body was modified into five links and each joint moment and joint force was calculated from it. Different from the existing human body, muscle contraction necessary to provide powers was assumed to work so as only to output the moment in the model. A part of the model equations is as follows (see text about definitions); about leg force equilibrium [numerical formula](horizontal)[numerical formula](vertical) and about moment [numerical formula] We analysed level walking('W'), ascending('AS') and descending('DS') stairs (16cm height) and going-up('GU') and -down('GD') platform (42cm height) on a 33-year-old healthy male. Several parameters such as location of segments' mass centers and weights were derived from Dempster's method. Acceleration of the mass centers and angular acceleration of joints were calculated from Selspot data. On the other hand, floor-reaction-force ('FRF') and so-called zero moment point were measured by using handmade instrumented shoes in which commercially available gym shoes with eight miniature load cells in their soles were used. And to get reliable results, each waveform of 10 to 20 movement cycles was normalized in its time scale and averaged. After that procedure, the normalized data were input into the mathematical model. Results about the 'FRF': patterns of 'W' and 'AS' and 'DS' were similar and had two peaks. And maximum peak values were 120, 123 and 142 (% of weight), respectively. Maximum values of 'GU' and 'GD' were 112 and 138 (% of weight) each. About the joint force: patterns of joint forces in each movement were almost identical with each 'FRF' pattern and their maximum values decreased compared with the 'FRF' joint by joint. This may have occured because muscle forces were assumed to play no role on the joint forces. About the moment: different from the force patterns, moment patterns were unique in each movement and each joint. For example, peak value of knee moment in 'W' were +100 and 0(Nm), those in 'AS' and 'DS' were 40 and -10(Nm) and 50 and -25(Nm).
