AN INSTANTANEOUS EIGENSTRUCTURE QUASIVELOCITY FORMULATION FOR NONLINEAR MULTIBODY DYNAMICS

A novel method is presented to solve the equations of motion for a lar ge class of constrained and unconstrained dynamical systems. Given an analytic expression for the system mass matrix, quasivelocity equation s of motion are derived in a manner that generates equations analogous to the dynamics/kinematics partitioning in Eulerian rigid body dynami cs. This separation is accomplished by introducing a new quasivelocity vector eta which yields a dynamical system with an identity mass matr ix. The problem of inverting a complex mass matrix is replaced by the problem of solving two first-order differential equations for the mass matrix eigenfactors. Dynamic constraint equations are incorporated di rectly into the new eta differential equation, forgoing any need to so lve the algebraic constraint equations simultaneously with the differe ntial equations of motion.