Nonholonomic system

A nonholonomic system in classical mechanics is a physical system with some constraints and mostly more than two constraints that are impossible to be cast into the form of holonomic constraints. That is, a nonholonomic system is a system that is not a holonomic system. Intuitively stated, they are mechanical systems with constraints on their velocity that are not derivable from position constraints. They are contrasted with classical Lagrangian and Hamiltonian systems, in which there are only constraints on position.