ESC 100: Exploring Engineering. Fall Lab 2: Calibrating An Infrared Distance Sensor

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Norman Parsons
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1 ESC 100: Exploring Engineering Fall 2013 Lab 2: Calibrating An Infrared Distance Sensor Name Date Section/Professor Please indicate with whom you worked with on this Lab Exercise (if applicable): I affirm that I have carried out my academic endeavors with full academic honesty: Signature:

2 Lab 2: Calibrating An Infrared Distance Sensor The purpose of this lab is to learn how to use the Arduino and an infrared sensor to measure distance. An infrared sensor emits infrared light and then senses the quantity of that light reflected off of a surface. The output of the sensor is a voltage value that is related to the distance of the object. To use the sensor to measure distance, we need to know the relationship between the sensor output and the object. Procedure: 1. Add the push button, battery pack, and IR sensor to your circuit 15 as shown in Figure 1 (attached). 2. Download Lab2.ino from nexus and put it into the Arduino IDE. Read over the Arduino code and figure out what it is doing and what it outputs to the LCD. 3. Tape a piece of white paper to the wall. 4. Position the IR sensor so that the front of the bracket is 0.5 inches from the wall. 5. Press the button and record the number outputted to the LCD in Table 1 (attached). 6. Move the IR sensor an additional 0.5 inches from the wall. 7. Repeat 5 and 6 until you have a reading for 8.0 inches 8. Repeat 4 7 until you have four readings for each distance. 9. Use the IR sensor the measure the length of objects A, B, and C by recording the LCD output value for each object. Analysis and Discussion: 1. Using Excel, make a plot of your average sensor output (x axis) versus distance measured (yaxis). Be sure to carefully label axes. You might want to refer to the LabWrite website resource on making graphs: homepage.htm. 2. Develop a calibration curve for your sensor using the Excel trendline function. This should yield an equation for the distance as a function of the sensor output. 3. Use your equation to estimate the size of objects A, B and C. Report the values with an estimate of each measurements variability (i.e. the size of A was found to be 10 ± 1 m). Report: Format: Individual memo style lab report Due Date: Start of lab period on 9/26. Review the online guidelines for writing a memo report. Note: You may share your data and discuss your results together but you need to make your own plots and write your own lab reports.

3 Figure 1. Circuitry needed to use the infrared sensor. This circuit is to be added to Circuit 15 for full functionality.

4 Table 1. Sensor output readings. Distance (inches) Reading 1 Reading 2 Reading 3 Reading 4 Average Reading Table 2. Sensor output readings for objects A, B, C Object Reading A B C

5 IR Sensor Code #include <LiquidCrystal.h> const char buttonpin=7; //The pushbutton is connected to pin 7. This line creates an 8 bit number that can't be changed and stores "7" in it. const char sensorpin=a0; //The sensor is connects to pin A0. This line creates an 8 bit number that can't be changed and stores "?" in it. int sensorval=0; //Value read by analog input...will be from 0 to float sensorvoltage=0.0; //Voltage corresponding to sensorval boolean buttonval; //Boolean variable to record if button has been pushed. LiquidCrystal lcd(12,11,5,4,3,2); //creating a LiquidCrystal variable (object) named lcd. void setup() { pinmode(buttonpin,input_pullup); //Button Pin is an input and we want it connected to a pull up resistor. lcd.begin(16,2); //Get RedBoard ready to talk to the lcd (this is an lcd with 16 cols and 2 rows) lcd.clear(); //Clear the lcd screen; Serial.begin(9600); //Get Redboard ready to talk to your computer over the usb cable void loop() { buttonval=digitalread(buttonpin); //Check to see if the button is pushed and store the value in buttonval // (1=not pushed 0=pushed)) if (buttonval==low){ //If the button has been pushed lcd.clear(); //clear the lcd sensorval=0; //set the sensor value to zero //We are going to take ten sensor readings and then average them. for (int i=0;i<10;i++){ //set up a for loop that will run ten times sensorval=sensorval+analogread(sensorpin); //add the current sensor value to the running total sensorvoltage=float(sensorval)/10*5.0/1024.0; //calculate the average and convert to voltage lcd.setcursor(0,1); //move the sensor value to the first position of the second row lcd.print(sensorvoltage); //print the sensor Voltage value on the lcd Serial.println(sensorVal); //send the sensor Voltage to your computer. Serial.println(sensorVoltage); //send the sensor Voltage to your computer.

MECH 307 Group Project Arduino Code Fall 2014 Group 31

/* MECH 307 Group Project Arduino Code Fall 2014 Group 31 -Code integrates weather sensors (Thermistor, BMP183 Barometric Pressure/Alitutde Sensor, and Wind Speed Sensor (Anemometer)) with LCD displays,