Dynamic force analysis of planar mechanisms

A computer-oriented procedure for solving the dynamic force analysis problem for general planar mechanisms is presented. The procedure is based upon writing three equations of equilibrium for each link in the mechanism from free body diagrams. Inertia forces are included using d'Alembert's principle. A technique is shown for automatically reformulating these equations into matrix form so the joint constraint forces and the driving input force or torque can be readily solved for using Gaussian elimination. This computer-oriented technique operates directly on the equations written from body diagrams. The force analysis procedure discussed in this paper has been implemented in a computer program called KADAM, which also has a kinematic analysis capability. Because of the ease of problem formulation and since the technique is based upon first principles, it appears to have value as an educational tool. It is useful for the solution of practical industrial problems. Two illustrative examples are included.