NXT Motor

Circuit Equation

Motion Equation

The circuit equation and the motion equation of the motor are generally given as follows.

In case that the motor is steady state (ω=const. and ia =const.), then these differential equations are represented by the following linear equations.

Here, we represent these equations as matrix equation as follows.

Meanwhile, from the experiments performed by Philo(“rotation speed vs torque” and “motor current vs torque”) , the relation among ia(armature current), ea(armature voltage), ω(shaft’s angular velocity), and

(load torque) are represented by the following matrix equation for ea =8.5(V).

We get the following result by solving this matrix equation.

From this solution, the evaluation of the NXT motor parameters are given as follows.

Reference

NXT motor internals@Philo’s Home Page

Motor Parameter