This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: EECS 314 Fall 2008 Homework set 2 Student’s name ___________________________ Discussion section # _______ (Last, First, write legibly, use ink) (use ink) Instructor is not responsible for grading and entering scores for HW papers lacking clear information in the required fields above © 2008 Alexander Ganago Page 1 of 2 Scores for the HW set: Problem 1 2 3 4 5 6 7 Total Score Problem 1 Potentiometer as an angular position sensor The circuit shown on this diagram shows a potentiometer used as a sensor for the angular position (angle α ) of a robotic arm. At α = 0, the potentiometer’s tap is in its middle position so that R X = R = R P /2 At an arbitrary, nonzero angle α (in degrees) the resistance equals R X = R P /2 + K ⋅ α where K is constant measured in k Ω /degrees. As shown in lectures, the output voltage is a linear function of the angle: V OUT = a + b ⋅ α The coefficients a and b depend on the source voltage and the potentiometer. Part 1 (10 points) Assume R P = 560 k Ω , K = 2.5 k Ω /degree, V S = 12 V Calculate a in volts and b in volts/degree a = ______________ volts b = _______________ volts/degree Continued on the next page. Part 1 2 3 4 Total EECS 314 Fall 2008 Homework set 2 Student’s name ___________________________ Discussion section # _______ (Last, First, write legibly, use ink) (use ink) Instructor is not responsible for grading and entering scores for HW papers lacking clear information in the required fields above © 2008 Alexander Ganago Page 2 of 2 Problem 1, continued Part 2 (10 points) Make a computergenerated plot of V OUT vs. the angle α over the interval from – 100 degrees to +100 degrees; attach your computer code or show your work in handwritten form. Part 3 (10 points) Determine the angles in degrees: α 4 corresponding to V OUT = 4 V and α 7 corresponding to V OUT = 7 V α 4 = ____________˚ α 7 = ____________˚ Assume that the error of readout of V OUT is 10 mV and calculate the error Δα of readout of the angle α . Δα = ____________˚ Briefly discuss how to reduce the error of readout of the angle α : increase/decrease R P ; increase/decrease K; increase/decrease V S , etc. Part 4 (10 points) Suppose you have to monitor the angular position of a robotic arm from negative 120˚ to positive 120˚, with a readout device that accepts voltages from 0 to +5 V, with +2.5 V readout at the middle position of the potentiometer’s tap. Can you use the device discussed above (Parts 1 – 3)? Yes / No If Yes , explain/prove with calculations. If No , determine the necessary changes. Consider increase/decrease of R P , K, and V S If you change any of these parameters, briefly explain whether the other parameters should be increased, decreased, or kept the same....
View
Full
Document
This note was uploaded on 10/25/2008 for the course EECS 314 taught by Professor Ganago during the Fall '07 term at University of Michigan.
 Fall '07
 Ganago

Click to edit the document details