Partial preview of the text
Download Second Order System Parameters - Laboratory 9 Report | ECE 207 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity!
ECE 207 Lab 9—Second-order system parameters Purpose This lab continues the use of the cantilever beam, this time to make measurements that will yield the parameters of a second-order system. Deliverables * Dynamic data needed for parameter extraction Calculation of the parameters of the second-order system (after a lecture on the method) Procedure 1. Build the same setup you had for the strain-gauge bar in Lab 8 by following that lab’s procedure through step 7, in which you rezero the bridge. When you have a good display, record it for print- ing: a. Puta floppy disk into the scope. b. Press Save/Recatt, then Formats, then tie, then Quick PRINT. c. Take the floppy to the computer in the lab. d. Open Worp, drag the file onto a blank page, and print it for your records. Put a weight on the bar and repeat the “boinging’ process to get another second-order response. Re- cord data about the weight on the hand-in page. Print the display to hand in. After a lecture on the method of calculation, extract the parameters of the second-order system from 2. Disconnect the pum and connect Channel 1 of the your data. Show your complete analysis on the scape to Vo. hand-in page: 3. Press “Single,” thereby arming the scope to display a. Use the pair of measurements to extract two val- a single trace. ues of the natural frequency. This gives a set of two pit . equations in w, k, m, and Am, where » and Am are 4. Boing” the bar (not violently} to produce response known. Solve these for k and m. that should trigger the scope. a. Pressing down on the end of the bar and letting your fingers slide off quickly seems to produce a good “boing.” b. Continue to do this until you get a good second- order damped sinusoid displayed on the scope. You will probably have to make the horizontal scan rate very low to get a goad display. c. When you finally learn haw to make and record a good “hoing,” have someone sit on the bench right b. Calculate the logarithmic decrement 6 from both responses. Then compute the damping ratio © for each. c. Use both sets of values af € and of w to get two values of b. d. Average the two values of 6 for the final result. e. Record the results on the hand-in page. beside the clamp—the bench top tends to become Finishing too much a part of the second-order system. “ pare secon ysie! The hand-in page, with the scope display attached, is due at the beginning of the first class follawing the lecture on parameter extraction. 5. Now make a good “boing” display for your recard. Fall 2007 33 
