RESNA 28th Annual Conference - Atlanta, Georgia
Matrix M times the double differentiation of vector q plus matrix M times vector g equals matrix G of vector q times vector F. This equation is a matrix-vector representation for the equations of motion of rigid human body on rigid, fixed seat chair during the extension motion due to the extensor thrust. Here, matrix M is a diagonal inertia matrix, vectors q and F are the coordinate and force vectors. Vector g consists of zeros and gravity acceleration only at the y-directional coordinates. Matrix G of vector q is a system matrix varying with the dimensions and posture of human body and seat. The left hand side of the equation has the inertial effect term and the gravitational effect term. The right hand side contains a matrix and vector multiplication between a vector of internal and external forces of human body segments and the system matrix.