1+2/2010 - Společnost pro pojivové tkáně

, (9)where is acceleration of center of gravity, can be calculated from (6) andwhere are coordinates of point i.3.3 Two points are in contact with floorThe human body is in contact with floor at points cont1, cont2 (for example bought legends). It is supposed that and is nonzero; at point cont2 only momentM cont2,ext is non zero, on the axis connecting points cont1 and cont2 and F y,cont2,ext , F z,cont2,ext .The moment equilibrium condition for point cont1 is, (10)whereare coordinates of the points cont1, cont2. The vectoris coordinate vector of element centers of gravity, where are coordinates of elementstarts and are local coordinates of gravity centers. The unit vector at direction from thepoint cont1 to the point cont2 isrcont1,cont21 r r= ( Xcont2− Xcont1),lwhere l is distance between points cont1 and cont2. The vector equation (10) (3 scalarequations) has 4 unknowns – the vector and the scalar M cont2 , but we set F cont2,ext,x equalzero.The force can be calculated from the force equilibrium condition (11)3.4 Three points are in contact with floorThe human body is contact with floor at points, cont1, cont2, cont3. The vectorsfrom point cont1 to point cont2 and/or to point cont3 are defined (see fig. 3). Thevectors are unit vectors at the same directions. The perpendicular vectors are64LOCOMOTOR SYSTEM vol. 17, 2010, No. 1+2