嵌入式系统导论-实验课-Simulink Lab 2_system nodelling.pdfVIP

SIMULINK Lab 2 Dynamical System Modeling Important: Save your models and simulation data of each main step of the simulation in “.m” and “.slx” files and use the saved files to demonstrate your simulation results to the Lab Supervisor. You lab performance will be assessed based on your demonstrations, which is 20% of your overall course assessment. DC Motor Speed Physical setup A common actuator in control systems is the DC motor. It directly provides rotary motion and, coupled with wheels or drums and cables, can provide translational motion. The electric equivalent circuit of the armature and the free-body diagram of the rotor are shown in the following figure. For this example, we will assume that the input of the system is the voltage source (V) applied to the motors armature, while the output is the rotational speed of the shaft d(theta)/dt. The rotor and shaft are assumed to be rigid. We further assume a viscous friction model, that is, the friction torque is proportional to shaft angular velocity. The physical parameters for our example are: (J) moment of inertia of the rotor 0.01 kg.m^2 (b) motor viscous friction constant 0.1 N.m.s (Ke) electromotive force constant 0.01 V/rad/sec (Kt) motor torque constant 0.01 N.m/Amp (R) electric resistance 1 Ohm (L) electric inductance 0.5 H System equations In general, the torque generated by a DC motor is proportional to the armature current and the strength of the magnetic field. In this example we will assume that the magnetic field is constant and, therefore, that the motor torque is proportional to only the armature current i by a constant factor Kt as shown in the equation below. This is referred to as an armature-controlled motor. The back emf, e, is proportional to the angular velocity of the shaft by a constant factor Ke. In SI units, the motor torque and back emf constants are equal, that is, Kt =