Abstract
A novel definition of singular points of mechanisms is proposed in this paper. The linear equation of infinitesimal motion of a mechanism is derived by differentiating the equations of displacement in loops of a mechanism. Three matrices are determined as the coefficients of three vectors of infinitesimal displacements of input-, output-, and passive-joints. Singular points are classified in accord with the ranks of the matrices and the relation of inclusion of the linear spaces determined by the matrices.
