Impact processes is modeling at FRUND by system impact method. It determine the instant velocity jump from apply or free some constraints. Method is effective for define initial conditions differential equations too.

Schematized docking of spacecraft, instant applying 6 constraints

Animation trace after conservative impact.

Body velocity after impact, 1 - system impact method, 2, 3 - elastic constraints.

Determine initial condition 12 pistons diesel by system impact method.