Rotary Electrodynamics of a DC Motor

The system shown in Figure 1 is a linear model of the Quanser SRV-02 DC motor with a static inertial load. In the model, • Rs is the resistance of the cable leading to the motor. Realistically, it should also include the output impedance of the amplifier driving the cable. Because the motor is a part of the process being controlled, the amplifier and cable together make up the actuator of the plant (i.e., this system). Here, Rs ≈ 0Ω. • Rm is the equivalent input resistance of the motor (e.g., the wire in the coils of the motor’s armature). Here, Rm ≈ 2.6Ω. • La is the inductance of the motor armature coils. Here, La ≈ 0.1mH (i.e., largely overdamped system). • im is the current through the motor. Because the motor is in series with all other electrical components, this current is shared among all components.