Editing Generalized coordinates (section)

===Non-holonomic constraints===

A mechanical system can involve constraints on both the generalized coordinates and their derivatives. Constraints of this type are known as non-holonomic. First-order non-holonomic constraints have the form

:<math>g(\mathbf{q}, \dot{\mathbf{q}}, t) = 0\,,</math>

An example of such a constraint is a rolling wheel or knife-edge that constrains the direction of the velocity vector. Non-holonomic constraints can also involve next-order derivatives such as generalized accelerations.