嵌入式系统导论-实验课-Simulink Lab 3_Time domain analysis.pdfVIP

SIMULINK Lab 3 Time Domain Analysis of Systems 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: System Analysis From the system modelling Lab, the dynamic equations in the Laplace domain and the open-loop transfer function of the DC Motor are the following. Open-loop response First create an m-file or recall your saved file containing the following commands J = 0.01; b = 0.1; K = 0.01; R = 1; L = 0.5; s = tf(s); P_motor = K/((J*s+b)*(L*s+R)+K^2); We now see how the original open-loop system performs. Add the following ltiview command onto the end of the m-file and run it in the MATLAB command window. The string step passed to the function specifies to generate a unit step response plot for the system P_motor. The range of numbers 0:0.1:5 specify that the step response plot should include data points for times from 0 to 5 seconds in steps of 0.1 seconds. The resulting plot is shown in the figure below, where you can view some of the systems characteristics by right clicking on the figure and choosing from the Characteristics menu such performance aspects as Settling Time and Steady State. ltiview(step, P_motor, 0:0.1:5); From the plot we see that when 1 Volt is applied to the system the motor can only achieve a maximum speed of 0.1 rad/sec, ten times smaller than our desired speed. Also, it takes the motor 2.07 seconds to reach its steady-state speed. If the desirable settling time is 2 seconds, the open loop system is 2 seconds, the open loop system does not meet this criterion. LTI model characteristics Since our open-loop transfer function has the form of a canonical second-order system, we should be able to accurately predict the