me375_sp04_final

me375_sp04_final - Division Meckl 10:30 / King 1:30 (circle...

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Unformatted text preview: Division Meckl 10:30 / King 1:30 (circle one) ME 375 FINAL EXAM Monday, May 3, 2004 Name_§_DjA£9_r\_ M (1) This is a closed book examination, but you are allowed three 8.5x11 crib sheets. (2) You have two hours to work all the problems on the exam. (3) Use the solution procedure we have discussed: what are you given, what are you asked to find, what are your assumptions, what is your solution, does your solution make sense. You must show all of your work to receive any credit. (4) You must write neatly and should use a logical format to solve the problems. You are encouraged to really “think” about the problems before you start to solve them. Please write your name in the top right-hand corner of each page. (5) A table of Laplace transform pairs and properties of Laplace transforms is attached at the end of this exam set. Section A Section B Problems Score Problems Score l.(lO) 2.(8) 3.(5) 4.(5) 5.(6) 6.(10) 7.(12) 8.(6) 9.(10) 10.(8) ll.(6) 12.(14) Total (A) / 100 Total (B) / 100 May 3, 2004 Name ._____... 2 ALL (10%) Using Laplace transforms, find the total response y(t) of a system with equation of motion given by: ji+6y+13y=13u when the input u(t) is a unit step, y(0) = 0, and j) (0) : 0. (51+ és+l3>V($) = /3 (Am = 13- S BSi—Q Yo) = ___’_§___~_ : A + I . 3<St+es+‘3) s s «f—(gS'f‘lS 2 ,A-sz-l— 6245+/3/4 + 352+ C3 s (s'LJ- 654-13) May 3, 2004 Name 3 A._2 (8%) A two—degree-of—freedom mechanical system is described by the following two differential equations: Assuming that the state variables are given by q1 = x1, q2 = 221, q3 = x2 , q4 2 X2 , the input is F, and the output is x2, write down the state and output equations for this system. ét :67?- p 7"?» ’2 “5.71 “372 +§73+ 2’74 73: 7+ _ 3; 5“ 3 1 -s‘ ._, _,_ __ 7+ iqt+4ll 4?? +7+++F 31:73 A; (5%) The motion of a system is governed by 33 + 4y = 3_u , where y is the output of the system, and u is the input of the system. Get the transfer function from input to output. Find the poles of the transfer function. Determine the stability of this system with a brief explanation. (5+ 4) rcs) : 2 (Ms) May 3, 2004 Name 4 M (5%) A second order system is described by j} + 3y + 36y = 3611, where y is the output of the system, and u is the input of the system. Find the natural frequency, damping ratio, and static gain of this system. M (6%) You have been given the following parameters for a dc motor: RA 2 0.38 ohm KT = 0.05 Nm/amp K b = 0.05 V/(rad/sec) B = 2.9x104 Nm/(rad/sec) The steady-state torque-speed relationship is given by the following formula: where e,- represents the nominal input voltage. (a) Compute the stall torque (where speed is zero) when the nominal input voltage is 15 volts. T :: NM. L. (b) Compute the no-load speed when the nominal input voltage is 15 volts. ec‘ : 1F. 3 . May 3, 2004 Name 5 t M»- sow->126 : Kl (9001’ K! CI Qour+ 0°01. :‘ Q IA) _A_._6_ (10%) Consider the flow control system shown below: _—>‘ Qm :a 1 im The tank serves to smooth out the outlet flow rate and provides back-up flow in case the inlet flow is interrupted. However, because of the tank dynamics, the inlet flow must be properly controlled to maintain desired outlet flow. Thus, a flow sensor is used to measure the outlet flow rate QOUT. This value is compared with the desired flow rate QDES and the difference is used in a proportional controller to set the proper valve opening to regulate the inlet flow QIN. Generate a block diagram that describes this flow control system. @ouT‘ A.7 (12%) Consider the fluid system shown below. Derive the differential equation relating the gage pressure at the bottom of the tank pmnk to the pump gage pressure [95. F‘l‘hk = lac—P" =Pcr May 3, 2004 Name 7 Y A35 (6%) Obtain the transfer function GCL (S) = (S) for the system described by the following block diagram. Express it as function of K. = p , 5K (5+2) 6;" (S) 1&2)— : 0'5 CS+~OCS+§ e“) /+ o i r/c (3+2) . (S+I)(5+§) M (10%) The performance requirements 0 a c ennc process require that its output have a two— percent settling time less than 1 second and an overshoot less than 5 percent. Sketch the region on the real—imagi ary plane that satisfies these performance requirements. ‘3 -1. 70$:(00ar (3‘45‘2 f5 giw < "Tl c. ”‘ ,— 3 o. as Jz-o‘ 713‘ = (Azo'°f(lgfz) I -Ja___ _I____ I I I I I | I I I I I I I I | May 3, 2004 Name 8 A.10 (8%) Find the steady—state response yss(t) of a system with transfer function G(s)= 11(3) zTL when the input is u(t)=28in(6t). Make sure you compute all U(s) s +3s+36 ‘ 3Q required terms. g “a :7 fl—t—f— ZQ‘ou +J3°° L15: Cf) = 2 / ago] 5,; (Cf 4— LGCJ'GD G _ _____.?‘ : /C(J°°)’ = 3 z =3 [Cgai‘ xe 2‘ A.11 (6%) Given the following two transfer functions: (1) —3—3——— (2) 46 s2+6s+13 : 32+15s+50 (a) Determine damping ratio for each system. Which system has more overshoot for a step res onse? P w, : J7; 2 3.4, .4, col =JT—cT = 1.07 H: 2551‘“ ‘ (D a j! 2 0'33 / 252‘“ z [5. =7 ‘___—_.. 3754*». U) Ans haw-a OVfr'Slxbfi'é'. (b) Determine static gain for each system. Which system has the higher gain? 6,0) = 1/ 63(0) =_—;E—§- = 0.92. 37344:.» C A00 tub LL;- j‘au‘n . May 3, 2004 Name 9 Q (14%) The cooling system in your automobile engine serves to remove excess heat from the engine block. We will model this system as follows. The combustion process is assumed to provide a heat flow rate Qi(t) to the engine block, which has total mass m, specific heat cp, and temperature Tb. Coolant flows through the block and removes heat via convection, with convection coefficient hi and total interface area Ai. Coolant at temperature Tc flows to the radiator, where it exchanges heat with ambient air at temperature T ,1 via convection, with convection coefficient ho and total interface area A0. Neglect thermal capacitance of the coolant. Derive a differential equation that describes how the engine block temperature Tb reacts to the heat flow rate Qi(t). p. i élock Cééié—A May 3, 2004 Name 10 a; (20%) The following schematic shows a rack and pinion system: In the above schematic, F is the force acting at the center of the disk, which has moment of inertia l J = Emsz and mass mg. The disk has radius R and makes an angle 6with the vertical. Note that :9: 0 when x: = 0; 31131 (10%) Draw free body diagrams of all the elements and write down the elemental equations. Use the positive directions given in the above schematic. Be sure that the motions and forces are indicated as necessary. x. x MI W" r”! V5)“ F3” lax \. F v—EEwee—j, ‘ W5 1: we {a IC May 3, 2004 Name 11 B.1§b[ (10%) With F being the input and x1 being the output, derive the input-output model. You may use the Laplace transform in the process of derivation. However, be sure that the final result is a differential equation. May 3, 2004 Name 12 Q (20%) Draw a straight—line approximation bode magnitude plot for the system with transfer 20003 function: G(s) = -2——-—-—— S +1001s+1000 . Clearly show the break frequencies. GO) 2 23 (5+ 0(5/m0 -i- 1) am = 2 6,0) = s can): —i— go): d?..PlOF%Mag9éF94¢ {. l ’1 It “i w r Magnitude (dB) 0.01 0.1 1 10 100 1-10 Frequency (rad/s) May 3, 2004 13 Name 3.; (30%) Given the following system: (a) Design PD controller gains Kay and KP such that the closed—loop system has poles at Sz—7ij7. €16): Vb) : 5Q: +519 [6(5) (desa—S“) +§Qs+Sl<P WW 51+ C(+S"<4)s + (Si—SK?) .2. (j chick-.41 Jar. 2,7: CS+¥+J ?)(3+1 j?) =- 52}. [45+ 98 efiu—ait W‘C’RC‘afl—J‘s: («pkg/<4 = (4- e 5“+5I§0'= C98 ==> [KP—ewe (b) What is the steady-state error for a unit step reference? J. QLC“): __5:_EE_ :1 S % €552 /“ A : "5“ - ‘j 5 {+519 stay/go §+ C) - A— C” “ /+ Isa (c) If the error is nonzero, suggest a different controller that will eliminate the error. FIZZ or F3: :9 14 Name May 3, 2004 5+6 (s+2)(s—2) 1+K B.4 (30%) Sketch the root locus for the following characteristic equation: Be sure to calculate (and clearly label) any asymptotes, break-infbreakaway points, and imaginary axis crossings (if any). _____l_____ ____ __-_—|———.._.L._____J_-_—__ J—_--_. m r. m m 0.0 Am A.» m. 0 \/.. V» a m . 1 3 G? .,.T o m c a. 4. \./% . a Q .5 + [w .1.» s 1‘ L2 ( u 2 .r. G C H ¢1 41 H O 85 c. s + {a . . ~ & 2. S _ r2 : (k 4.. R 2 a 2 z + S S K K’s h .. lac“ . s 3/ -14 -16 Provide the range of gain K for which this system is stable. 2. s+~l< H—A LC (SAL—C.) 7- 4- : O ‘ i 3-20 3:. 3 =>x<=~ 6K=4 $47M 42.. lz<>1§— ...
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This note was uploaded on 12/22/2011 for the course ME 375 taught by Professor Meckle during the Fall '10 term at Purdue.

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me375_sp04_final - Division Meckl 10:30 / King 1:30 (circle...

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