A new derivation of the equations of motion for robot arms and other dynamical chains is presented using the methodology of Kane's equations. This approach combines the ease and intuition of Newtonian analysis with the capability to eliminate all non-working forces of constraint. The 'monotony' of the system's configuration is used to define the generalized coordinates and generalized speeds such that a universal and compact equation of motion was found which applies to any chain or robot arm configuration. This general, explicit closed-form eliminates much of the 'overhead' of Kane's methodology. A two-link manipulator example shows the implementation.
