GEOMETRIC ELIMINATION OF CONSTRAINT VIOLATIONS IN NUMERICAL-SIMULATION OF LAGRANGIAN EQUATIONS

Conventional holonomic or nonholonomic constraints are defined as geometric constraints. The total enregy of a dynamic system can be treated as a constrained quantity for the purpose of accurate numerical simulation. In the simulation of Lagrangian equations of motion with constraint equations the Geometric Elimination Method turns out to be more effective in controlling constraint violations than any conventional methods, including Baumgarte's Constraint Violation Stabilization Method (CVSM). At each step, this method first goes through the numerical integration process without correction to obtain updated values of the state variables. These values are then used in a gradient-based procedure to eliminate the geometric and energy errors simultaneously before processing to the next step. For small step size, this procedure is stable and very accurate.