This note presents a recursive identification method to estimate the minimal parameters of a class of nonlinear deterministic system. The result can be applied to a manipulator with unknown torque constants. A procedure to identify the torque constants, the friction, and the gravity parameters at the same time is then proposed. This is worthwhile since the PD feedback control with the gravity and friction compensation ensures a zero steady-state response for the set-point control. A theory addresses the minimal parameters composed of the three groups of parameters. The identification procedure for the minimal parameters is conducted by moving one joint with a constant velocity at a time. The persistently exciting trajectories for the identification are also suggested. The experiment on the PUMA 560 illustrates the identification method.