MAE 318 Lab 1

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Arizona State University, Tempe *

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318

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Mechanical Engineering

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Apr 3, 2024

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Fabian Ameen Lab station #: 2 Mohammad Alduhayman Date: 2/12/24 Vibbhav 4 Post-lab deliverable: Results and Evaluation Please complete the tables and write the answers to these questions and submit them on canvas as a pdf file. Post-labs are to be submitted one per team. On the submission document, only write the names of members who actually participated. Table-1: Experiment 1 Data NOTE: Find the instances t 0 and t 1 to get a clean ramp down phase chunk of data . Make sure the initial angular velocity around t 0 is around 9-15 rad/s Test # B J (s -1 ) B 0 J (rad/s) 1 0.5021 6.1693 2 0.93573 4.9471 3 0.73399 5.4403 4 0.6866 5.4361 5 0.84529 4.943 6 0.65647 5.4726 Average: B J = ¿ 0.7267 Average: B 0 J = ¿ 5.4014 (6 points) Table-2: Experiment 2 Data NOTE: Make sure to choose DAC number so that the steady state angular velocity is around 9-15 rad/s. You don’t have to stick to the DAC numbers in the tables below for that. Test # DAC voltage (number) V p (mV) i (steady) = V p / R p (A) ω (steady) (rad/s) K t J = Bω + B 0 Ji (rad/As 2 ) 1 2000 1.9 .19 5.3159 48.76 2 2100 2.1 .21 6.4957 48.199 3 2200 2.2 .22 7.3883 48.956 4 2300 2.3 .23 8.6641 50.86 5 2400 2.5 .25 10.0873 50.927 6 2500 2.8 .28 10.35 46.1526 (Be careful of unit conversions from mA to A)

Average: K t J = ¿ 48.9759 (4 points)

4.1 Post Lab Questions for Submission 1. Question: Propose a different experiment to measure the value of K t that doesn’t involve measuring the speed of the disk! Explain in a few sentences with a diagram. (2 points, EM@FSE(b)) 2. Question: You may have noticed that numerical differentiation can get very noisy. Even though angular data looks quite smooth or minimally noisy, the angular speed data obtained by differentiation is significantly noisier. What may be the reason for it? Research on your own. Hint: Think about what you are dividing by what, and the numerical size of the denominator. (2 points) This happens because the differentiation is taken by dividing by the change in time, and because each time step is so small the denominator is a small decimal which causes the noise to be amplified 3. Question: Research about the ‘smooth’ command used in the MATLAB code. Explain in a few sentences what does it do quantitatively . What does 5 in the smooth(x, 5) mean? (1 point) Smooth 4. Question: It takes a certain minimum amount of current to overcome the dry friction and make the motor move. Calculate this current for your setup using the motor parameters you have calculated. (2 points) 5. Question: Assume there was no dry friction ( B 0 = 0 ) and there was only the linear viscous friction. How the graph in figure 3 will look like, after the disc is given some initial speed ω 0 and let go? Paste it below. Do the same if there was no viscous friction ( B = 0 ) but just the dry friction. (2 points) 6. Question : Continuing with the theme of one of the pre-lab questions: A few types of motors available these days are: brushed DC motors (you are using this in the labs), brushless DC motors, AC induction motors, AC synchronous motors etc. In the pre-lab you researched on their use in the electric cars. Now look up some journal papers (e.g. on google scholar) or patents and comment on which direction the motor technology is evolving for their use in the electric cars. (1 point, EM@FSE(e)) Note: If you have time, research about methods of operation of the motors mentioned above and how they are controlled.

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