Drake
Collaboration diagram for Variable definitions:


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• nb The number of bilateral constraint equations (nb ≥ 0)
• nk The number of edges in a polygonal approximation to a friction cone (nk ≥ 4 for contacts between three-dimensional bodies, nk = 2 for contacts between two-dimensional bodies). Note that nk = 2nr (where nr is defined immediately below).
• nr Half the number of edges in a polygonal approximation to a friction cone. (nr ≥ 2 for contacts between three-dimensional bodies, nr = 1 for contacts between two-dimensional bodies).
• nc The number of contact surface constraint equations.
• nck The total number of edges in the polygonal approximations to the nc friction cones corresponding to the nc point contacts. Note that nck = 2ncr (where ncr is defined immediately below).
• ncr Half the total number of edges in the polygonal approximations to the nc friction cones corresponding to the nc point contacts.
• nv The dimension of the system generalized velocity / force.
• nq The dimension of the system generalized coordinates.
• v The system's generalized velocity vector (of dimension nv), which is a linear transformation of the time derivative of the system's generalized coordinates.
• q The generalized coordinate vector of the system (of dimension nq).
• t The system time variable (a non-negative real number).
• nu The number of "generic" (non-contact related) unilateral constraint equations.
• α A non-negative, real valued scalar used to correct the time derivative of position constraint errors (i.e., "stabilize" the constraints) via an error feedback process (Baumgarte Stabilization).
• β A non-negative, real valued scalar used to correct position constraint errors via the same error feedback process (Baumgarte Stabilization) that uses α.
• γ Non-negative, real valued scalar used to regularize constraints.