Lab 8 – Problem Solving Lab Procedure
Contents
1. Class Time _ Check Out Procedure Problem Solving Project Labs Points to Note Your instructor or GTA must sign this sheet before you leave each lab session e You may not collect a signature late For example you may not collect a signature for Lab 1 when you come to Lab 2 e The penalty for missing signatures or a missing sheet is 20 points which is 10 of the lab grade Lab I Lab II Lab Il Checked Checked Checked Checked Item Description Qty Checked Out Checked In Out In Out In 1 Model Train Engine inside plastic container 1 USB cord unplugged and neatly wound 1 Track Arduino board 1 12 volt DC Adapter unplugged and neatly wound Clean Table Lab I Instructor TA s Signature _ ee Date __ Lab II Instructor TA s Signature _ SS Date ___ Lab III Instructor TA s Signature Date ___2. For example if your Arduino is connected to COMS type a arduino COM3 Do NOT type the arduino command without assigning it to the variable a using the equals sign If you do use the clear commands issued above in Steps 4 and 5 7 MATLAB will attempt to connect to the Arduino 8 If you get an error message double check that you have followed the above steps exactly as listed repeating steps as necessary If you try again and get the same message ask a member of the instructional staff for assistance 9 Examine the command window output Notice how Servos are Detached and Digital Pins are Unassigned If you do not see the output Repeat steps 4 5 and then repeat the command a arduino COM without the semi colon that suppresses output to the command window 10 Ifthe connection is successful a message will display FE Train Shield Script File detected 11 Clear the command window with a clc Task 2 Set up the Servo motor that controls the crossing gate 1 Your gate servo is wired to servo port 1 on the Arduino controller 2 To attach the servo to the Arduino type the command a servoAttach 1 and hit Enter This command must be issued every time the Arduino is reconnected Note When using any Arduino command it must be prefaced with a Note the period This tells MATLAB to perform the command on variable a which was created with the Na ardu
3. Lab 8 Problem Solving Lab Procedure It is expected that you have already read the Problem Solving Lab Project Description Document Before starting a Task read through the instructions for the entire task This will help you understand what you are going to accomplish during that Task Getting Started 1 Plug the 12 Volt Power Module into the power strip on the table and make sure the power strip is on Plug the barrel connector on the wire from the 12 Volt Power Module into the mating connector located at the outside edge of the Train Project Setup Connect the USB Cable from the Train Setup to a USB port on the front of your computer Confirm that the red LEDs on the Break Beam Sensors are on Also confirm that the yellow LED on the Arduino board is also on If any of those lights are not on get help from your instructional team Go to LAB 8A on the course website and locate the link to the Zip file for the MATLAB Train Simulator This contains the files needed to communicate to the Train 5 1 Right Click the link and select Save Link as 5 2 Save the file to your MATLAB folder on you Z drive 5 3 Open your MATLAB folder and locate the Zip file you just downloaded 5 4 Right click on the file select Extract all and click Extract on the pop up window 5 5 Rename the extracted folder to Lab_8_Train_Project Open MATLAB and change the Current Directory to the recently created Lab_8_Train_Pr
4. Write 15 1 One of the LEDs should now be on Which LED Record the answer in the worksheet 4 Logical 0 turns the LED off and logical 1 turns the LED on Use the command line to turn on both LEDs ie a digitalWrite 15 0 turns off digital pin 15 5 You can assign the pin numbers to a MATLAB variable in order to keep track of which pin controls which LED To do this you might enter the command right LED 15 then use the variable ri ght LED in the digitalWrite command in place of the number 15 The new command would be a digitalWrite right LED 1 Repeat with the left LED use Left LED 14 Task 4 Move the Train 1 Carefully place the train on the track at the location where the black piece of track has wires connected to it from the Arduino Look at the train wheels very carefully to be certain that all train wheels are properly on the track Check with the instructional team if needed 2 The train has three states of motion forward backward and release Release is a command that can be used to stop the train To enable the train to move forward type the command a motorRun 1 forward Nothing happens until you set the speed in the next command This command must be issued every time the Arduino is reconnected 3 To set the train speed use the command a motorSpeed 1 S where S is a value between 0 and 255 as described below IMPORTANT In order to over
5. caled voltage to the Arduino that will be used by your MATLAB Train Control Program to determine if the Train has broken through the optical path in the sensors Hence the name Break Beam Sensor 4 Inthe command window execute approach 2 and a analogRead approach The command window will display a value Enter that value into the worksheet This is the value of the unobstructed sensor Repeat the anal ogRead command at least 5 times Enter 2 more values into the worksheet 5 Does there appear to be a pattern to the values Answer Sometimes the analogRead command does not read a correct value at first So when using analogRead take five readings throw away the first four and use the fifth value Hint in your Train Control Program you can easily do this with a small for end loop 6 Have a group member block the approach beam with his or her fingers While blocked verify that the green LED on the sensor circuit board lights up Once again use a analogRead approach several times Enter that value into the worksheet This is the value of the obstructed sensor Enter 2 more values into the worksheet Answer the following questions in your worksheet e Does there appear to be a pattern to the values How do these values differ from the unobstructed values e Are the values always consistent Why might this be important when it comes to writing a program 7 When using the analogR
6. come static friction the engine motor requires a minimum value of S before it will move Therefore the useable range for train speed is from S 170 to S 255 If you set the train to move and you hear the motor whirring but there is no movement immediately pull the train off the track set the motorSpeed to 0 and then try again with a larger value for S 4 Use the command a motorSpeed 1 255 to make the engine run at full speed If it does not run alert an instructional team member 5 Stop the train with a motorSpeed 1 0 6 Run it again at full speed use up arrow to retrieve previous MATLAB commands and stop it with a motorRun 1 release Aftera release command you must execute a motorRun 1 forward before entering new motor speed commands Try it Task 5 Test the Break Beam Sensors 1 Unlike the Servo the LEDs and the locomotive s motor the Break Beam Sensors do not need any initial setup The sensors will be called the approach gate and the departure gate see Problem Solving Lab Description Document for clarification The Arduino analog port 2 is connected to the approach sensor and analog port 3 is connected to the departure sensor 2 For clarity create MATLAB variables and assign them values approach 2 and departure 3 This will help you keep track of the sensors 3 The Break Beam Sensors send a numerical value actually a s
7. ead command in a MATLAB script file you must execute it four times before using the returned value For example a analogRead approach a analogRead approach if a analogRead approach gt 250 end For purposes of your Train Control Program the Train is on the Town Side of the track layout when it is in Crossing Gate portion of track that is between the Break Beam Sensors The train is in the Country Side of the track layout when it is not in the Town Side Notice the green trees in the Country Side Task 6 Write a Train Control Program 1 2 In order to effectively control the train for an infinite period of time an m file should be used Open a new m file in MATLAB After putting your group name individual names and class information at the top of the file you should include the following commands clear all close all delete instrfindall Che The next command should be the command learned in Task 1 to connect to the Arduino Next you need to use the commands you have learn in Tasks 2 through 5 to initiate the components you will need to use and create start up conditions Insert an infinite while loop using while 1 Infinitely Looping Code here end Inside this loop you will write the remainder of the train control program for Task 7 Task 7 Calculate the Train Speed In Task 7 you will write a
8. ino COM command Also Arduino commands are CaSe SeNsItIvE 3 To check your servo type the command a servoStatus And you see that servo 1 is now attached that means the Arduino can now tell it what to do 4 To control the servo use the command a servoWrite X 6 where X is the servo number and 9 is angle in degrees This lab only uses servo number 1 IMPORTANT Always use a value of 0 that is between 10 and 170 degrees Using a value outside of this range can damage the servo motor 5 Enter the command a servoWrite 1 165 The crossing gate should now be approximately horizontal 6 Now experiment with angles between 50 and 80 to find the specific value of O that makes your crossing gate go vertical Write the answer in the worksheet Task 3 Set up and test the Crossing Gate LEDs 1 In order to control the Crossing Gate LEDs the digital pins on the Arduino must be assigned a mode input or output and a state on or off The LEDs on the crossing gate are attached to digital pins 14 and 15 on the Arduino 2 First the digital pins that control the lights must be set as outputs This is done by typing the commands a pinMode 14 output and a pinMode 15 output each followed by the Enter key This command must be issued every time the Arduino is reconnected 3 To change the output state of digital pin 15 enter the command a digital
9. obtain and print only one value when the Break Beam sensors are triggered Notice the train has a window the sensor can occasionally see through it plan accordingly to avoid an error The train s speed may be slightly faster if it runs for a long period of time A summery guide to the MATLAB Arduino commands is available at the end of the Problem Solving Lab Description Document It provides quick explanations of the MATLAB Arduino Commands A guide to the Train Simulator is available as a Word document located inside the Zip file for the MATLAB Train Simulator all available on the Course Website under LAB 8A After you have the program working enter the values required into the worksheet Save the complete worksheet and the m file created in Task 7 These will be included in your project notebook Post Lab Assignments 1 Revise your Initial Program Outline Now that the Arduino commands have been introduced revise your previously submitted Initial Program Outline Assignment using the MATLAB Train Control Commands and the things you have learned in Lab 8A This revision of your Initial Program Outline should be called the Revised Program Outline and it is due at the beginning of Lab 8B as a team assignment 2 Submit the results of Lab 8A at the beginning of Lab 8B Print a copy of the Problem Solving Lab Worksheet and the m file Train Control Program and submit them at the beginning of Lab 8B Team Name Instructor Name __
10. oject folder Download and save the Problem_Solving_Lab_Worksheet from the website to your Lab_8_Train_Project folder Task 1 Connect your PC to the Arduino 1 Open Windows Device Manager 1 1 Click Start on the bottom left toolbar on your Windows desktop 1 2 In the search box at the bottom type Device Manager and press the enter key Click OK on the error message After the Device Manager opens click the arrow next to Ports COM amp LPT This process will cause the Arduino USB Drivers to be installed automatically on your PC After the Arduino USB Drivers have finished installing you will see Arduino Uno COM listed where is number of the COM port to which the Arduino is attached Write the number in the Problem Solving Lab Project Worksheet under Task 1 and close the Device Manager In the MATLAB command window clear all variables and clear the command window by typing the commands clear all close all and clc hit Enter after each command Note Do not copy paste any MATLAB commands from this procedure or from Word documents type them manually MATLAB does not correctly interpret Word text formatting 5 Next enter the command delete instrfindall This will clear any previous Arduino connection 6 Inthe MATLAB command window type a arduino COM where is the COM port number you found above and hit Enter
11. program to measure the speed of the train and record the results in the Problem Solving Lab Worksheet Train Control Program Requirements Start the train on the Country Side of the track Calculate the train speed between the approach sensor and departure sensor Run the train at full speed i e a motorSpeed 1 255 Write the calculated time and speed in an fprintf statement to the Command Window Display the time in seconds for each half loop Display the speed in miles per hour AND inches per second Repeat continuously until stopped manually Do not use the Pause function Program MUST contain user written comments If you are unable to complete Task 7 by the end of the Lab period you can use the supplied Train Simulator to develop and test the code for Task 7 Instructions how to use the Train Simulator can be found in the document Train Simulator Student User Manual docx located in the Lab_8_Train_Project folder created at the beginning of this procedure The Simulator can only be used to test that your code works properly you will have to record the actual speed data during LAB SB Useful Information Use CTRL C on the keyboard to stop a program Use F9 to run only a portion of your code Use tic and toc to determine time intervals The diameter of the train track layout is 22 5 inches Since MATLAB can continuously gathers data 120 samples second find a way to
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