ME4543: Mechatronics, Finals-Part 1, December 8, 2015. Time: 6 - 7 PMUseful information: (1) There are 15 questions in all. However, the finals will have 20 questionsin all. (2) Each question is worth 2 points. So in the finals, the total will be 40 points. (3) Darkenthe appropriate bubble in bubble sheet given to you. Completely darken the bubble that you thinkmatches the correct answer. Hand back the questions and the bubble sheet back. (5) There isonly 1 correct answer. There is no negative points. Please read (6) and (7) carefully as wewill enforce them during the exam. (6) No electronic device (phone, smart watch, camera,electronic glasses, computer, unapproved calculator) on student body (in pockets, boots, clothing,etc) or within reach (under seat, on adjacent seat) during exam. Only approved calculators allowedand are listed on the course syllabus. It is considered cheating to have a phone, computer, or otherelectronic device accessible during an exam and will lead to a zero for the entire test. (7) You willnot be allowed to leave the classroom during the entire duration of the test. There is no exceptionto this rule. Bathroom break may be provided if students provides a medical note.

1. A 1MΩ resistor and a 0.1 µ F are connected to form a low pass filter. The cutoff frequency inrad (not Hz) is(A) 0.1 (B) 1 (C) 10 (D) 100

2. Which of the following is FALSE for a npn transistor(A) IE = IC + IB(B) IC = βIB(C) The emitter is more heavily doped than the collector.(D) The base is denoted by p.

3. The equation describing a motor is 2T + 0.05ω = 2 where T is the torque in Nm and ω is thespeed in rad/s. The starting torque for the motor in Nm is(A) 0 (B) 1 (C) 2 (D) 4

4. The simplest H-bridge used to control the magnitude and direction of a brushed DC motoruses how many switches?(A) 1 (B) 2 (C) 3 (D) 4

5. For a strain gauge operating in the linear strain region, if the strain is doubled then the changein resistance will (A) get halved (B) not change (C) get doubled (D) get quadrupled

6. Which of the following is a proximity sensor based on physical contact(A) hall-effect sensor. (B) eddy current sensor. (C) infra red sensor. (D) limit switch.

7. A signal’s values have a range of ±10V and you wish to make measurements with an analogquantization size no more than 10 mV. What minimum resolution A/D converted is requiredto perform this task?(A) 8 bit (B) 10 bit (C) 12 bit (D) 16 bit

8. For the given input signal compute the Nyquist Frequency. y = sin(πt) sin(2πt) sin(4πt).NOTE: If f is the frequency of a sinusoid then the signal is given by sin(2πft)(A) 1 Hz (B) 2 Hz (C) 4 Hz (D) 8 Hz

9. The unit vectors along x-, y-, and z-direction are; ı, , and k. If the external magnetic field ona wire carrying current ~I = ı is given by ~B = . Then the force, ~F , experienced by the wire is(A) ~F = 0 (B) ~F = ı (C) ~F = −k (D) ~F = k

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10. Which of the following brushed motors need to be carrying a load to prevent run-away, i.e.speed reaching high values at low loads.(A) Permanent Magnet DC motor (B) Shunt DC motor (C) Series DC motor(D) Compound DC motor

11. A permanent DC magnet motor has no load speed of 100 rad/s and stall torque of 5 Nm. Themaximum power that can be obtained from this motor is(A) 125 W (B) 250 W (C) 500 W (D) 1000 W

12. Which of the following motor provides position control without the use of a position sensor(A) brushed DC motor (B) brushless DC motor (C) stepper motor (D) servo motor

13. A strain gauge has a resistance of 120 Ω. When loaded, the resistance changes by 0.012 Ω.Assuming a gauge factor of 2, find the strain.(A) 0.5 × 10−4 (B) 1 × 10−4 (C) 2 × 10−4 (D) 4 × 10−4

14. A and B are binary number. A · (A+B) =(A) A (B) B (C) A+B (D) A ·B

15. For a positive edge trigged T flip-flop let Q0 be the current output. When the clock goesthrough a positive edge, the output Q will turn(A) 0 (B) 1 (C) Q0 (D) Q0

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ME4543: Mechatronics, Finals-Part 2, Dec 9, 2015. Time: 7 - 8:30 PMUseful information: (1) Answer all five questions. (2) Box your final answers. (3) Show interme-diate steps to get partial credit. (4) The points for the questions are indicated near the questions.(5) Maximum points is 60. Please read (6) and (7) carefully as we will enforce them duringthe exam. (6) No electronic device (phone, smart watch, camera, electronic glasses, computer,unapproved calculator) on student body (in pockets, boots, clothing, etc) or within reach (underseat, on adjacent seat) during exam. Only approved calculators allowed and are listed on the coursesyllabus. It is considered cheating to have a phone, computer, or other electronic device accessibleduring an exam and will lead to a zero for the entire test. (7) You will not be allowed to leavethe classroom during the entire duration of the test. There is no exception to this rule. Bathroombreak may be provided if students provides a medical note.

1. For binary variables A and B, show that the following expression is true.

(A + B) · (A + B) = A

2. Complete the timing diagram for the following circuit.

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3. A J type thermocouple is used in standard 2 junction thermocouple configuration with a 250Creference configuration. What measured temperature will correspond to a measured voltageof 20 mV? Use a truncated expression for the relation between temperature, T in degreesCelsius, and voltage VT/0, in volts as shown below

T = −0.04886 + 19873.1VT/0 − 218615V 2T/0

4. The torque-speed curve for a motor can be approximated by two straight lines as shownbelow. The motor is attached to the pulley of radius r = 0.2 m and is used to move a massof 4 kg upwards against gravity g = 10 m/s2.

(a) Find the steady state speed of the mass.

(b) Find the mechanical power of the motor when the mass is moving at steady speed.

(c) How will the speed of the motor change if the mass is doubled.

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5. A digital ultrasonic sensor has to be hooked to an Arduino. Wire the Arduino to the sensor.Just connect the pin outs of the sensor to appropriate pins. You do not have to re-draw thecircuit. (5 points)

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