ENGR 1620 Lab 1. Sensors and Detection Pre-lab

Transcription

1 Ver (Fall, 2013) ENGR 1620 Lab Sensors and Detection Pre-lab Objectives Learn how to setup and interface with several basic sensors, including an accelerometer, an infrared motion sensor, an RFID sensor, and a variety of others. Learn how to calibrate, measure, and analyze data from those sensors. Develop creative applications for sensors. Before you come to lab on the assigned day: Complete the pre-lab portion of this lab (this document). It must be handed in by the beginning of the first day of lab. Install the necessary software on your computer. Instructions will be provided separately. The pre-lab report is an individual assignment. Cite all sources used. Use whatever citation format you like just be consistent. Wikipedia should not be used as a primary source of information. Print this out, answer the questions, and turn it in at the beginning of the first day of lab.

2 Pre-lab report Name: Question 1 We encounter many different kinds of sensors in our everyday lives. For example, motion sensors in a security system are used to detect the presence of an intruder. As commercial products become more and more advanced, sensors will play an even bigger part in engineering. What are some other examples of sensors and their uses found in our everyday lives? List five Question 2 An iphone (and most smart phones) can detect its orientation and change the screen from portrait view (vertical) to landscape view (horizontal) when rotated. What type of sensor do you think is being used to sense this? Question 3 In what other ways could this sensor on an iphone be used? That is, what are other potential applications of this sensor on the iphone? List three.

3 Question 4 As discovered by Newton, force and acceleration are related by the famous equation: F = m a where F is the force being applied to the object of mass, m, and a is its acceleration. As you know from your physics classes, acceleration is defined as the rate of change of velocity. What are simple examples of acceleration encountered in our everyday lives? List three. Question 5 Imagine, after graduating from UVa with a degree in engineering, the company you founded is developing accelerometers for NASA. The purpose of your accelerometers is to monitor the amount of acceleration an astronaut experiences on a mission. Your accelerometer is attached to the astronaut who is standing-by in the spacecraft. That is, the spacecraft is standing still on the launch pad. The astronaut is strapped into the seat facing the sky. Though the astronaut is not moving, the sensor indicates that there is an acceleration of 1g along the y-axis (see figure at right). A g, as you might know, is the acceleration of an object when you drop it in Earth's gravity, roughly 9.81 m/s 2. Is this sensor reading correct? Is the accelerometer malfunctioning? If the reading is correct, what is the cause of the reading indicated by the sensor? If not, what should the correct sensor reading be and why?

4 Question 6 During standby (when the spacecraft is not moving but is on the launchpad), the astronaut s back is pulled down into the seat in the y-direction by gravity. This feels similar to how his/her back would feel in a car that is (circle one): Question 7 accelerating forward (speeding up) standing still decelerating (slowing down) Now suppose that the rocket starts to lift off with an acceleration of 3g. That is, the rocket accelerates at 29.43m/s 2. What would the accelerometer referred to in Question 5 read? Question 8 Now imagine that the accelerometer attached to the astronaut was calibrated while sitting still on the launch pad. This calibration would set the accelerometer to zero for all directions ( x, y, and z). During the aforementioned lift-off, what y-axis acceleration would you expect to read on the calibrated accelerometer? Is this the same or different from the registered acceleration identified in the prior question? Why?

5 Question 9 Urban legends indicate that the light in the refrigerator really doesn t turn off and stay turned off when you close the refrigerator door. You are determined to test this. How could you test it? What sensors would you use? You want to count the number of times people enter a room, and you want to get one count for children and another count for adults. Propose a way you could do this using sensors a conceptual idea is what we are looking for, with the types of sensors identified, their location, and any key information described. You think your roommate has been taking some stuff out of your fridge and you want to figure it out for sure before you confront her. You are freaked out by webcams, so you don t want to use one of those. Propose two ways you could determine if your fridge is opened w/o using a camera conceptual ideas are what we are looking for, with the types of sensors identified, their location, and any key information described.

6 Question 10 RFID tags are small microchips with antennas that are capable of sending small amounts of information wirelessly over a short distance. For example, in cities such as New York and Washington, DC, you can get a transit card with an RFID chip, which let's you pass through the metro station without even taking your card out of your wallet! What are some other examples of RFID technology in use today? List three (and cite any sources).