IME-100 ECE. Lab 5. Electrical and Computer Engineering Department Kettering University

Transcription

1 IME-100 ECE Lab 5 Electrical and Computer Engineering Department Kettering University 5-1

2 1. Laboratory Computers Getting Started i. Log-in with User Name: Kettering Student (no password required) ii. iii. iv. IME-100 information (Lab presentation, files, etc.) in folder on desktop Arduino programming software on desktop At the end of lab, Logout of computer; arrange keyboard and mouse 2. Laboratory kit i. Robotic kit with Arduino, motor shield, ultrasonic sensor, light sensor, 9V battery ii. At the end of lab, disconnect battery from robot and Arduino, turn other instruments power off, unplug USB cable from PC, neatly arrange kit on bench 5-2

3 IME-100, ECE Lab5 Robotics In this laboratory exercise, you will do the following: Robotics what and why? Identify the main components of mobile robot Use Arduino motor driver library to drive motors and robot Target distance measurement using ultrasonic sensor Display data to serial terminal Use ultrasonic sensor for obstacle detection Exercise 1: Sonic wander bot challenge Exercise 2: Target Tracking robot Line following robot Exercise 3: Line following robot with safety feature Final Project Opportunity 5-3

4 Robots What? A machine capable of: carrying out series of complex actions automatically or by remote control Aware of its environment programmable using computer Example: Assemble cars Vacuum floors Space exploration Surgical operations Entertainment 5-4

5 Why do we use robots? For increased productivity Manufacturing plants For high precision tasks Electronics assembly Surgical robotics Prosthetics For tasks too boring for humans Assembly, welding, vacuuming The robot works 24/7 without break It never gets tired, nor gets distracted Robots Why? For tasks too dangerous for humans: Exploration - Volcanoes, Nuclear reactors, Landmines, Space, etc. For education and entertainment: 5-5

6 Application Examples Industrial robots in a car factory Warehouse robots da Vinci surgical robot High way platooning Google s self driving car Mars rover Curiosity 5-6

7 What are robots made of? Simple example Arduino based robot platform - Processor or control module - Brain - Power supply (battery) - Mechanical and structural parts - External interface - Input ports - Output ports - Programming and debugging - Actuators: - Motors, hydraulics, pistons, grippers - Sensors - See what is in the surroundings 5-7

8 Motor Driver Board Why Motor driver board? Arduino does not provide sufficient current to directly drive typical DC or stepper motors The motor driver circuit board accepts the low power signals from the Arduino and converts them to levels appropriate for driving motors We can control: Direction of rotation Speed or rotation (using PWM) TB6612 motor driver Motor Power Supply (Battery) MotorB (Left) MotorA (Right) 5-8

9 Motor Driver Board The instructor will assist you in installing the motor driver board (shield) onto your Arduino board. Connect the wires coming from the two motors into the two sets of screw terminals of the motor shield as shown in the picture. Then tighten the screws. Connect the positive wire from the 9V battery to the positive (+) terminal of the motor shield s power screw terminal. Then tighten the screw. 5-9

10 Motor Driver Library The next step is to look at the programming aspect of the motor driver shield. A library is a piece of program that you can use to accomplish a specific task. Here, you will use a motor driver library to enable to you drive the robot motors. The motor driver circuit for each motor needs two Arduino pins. One of them is used for direction control while the second is used for speed control. When you use the library you need to define the actual two pins to be used for each of the motors. For better understanding of how the library works, open the example program from the Arduino menu: File -> Examples -> Motor -> DriveRobotExample 5-10

11 #include <Motor.h> //initialize left motor attached to //Arduino pins 2 and 3 //pin 2 is for direction control //pin 3 is for speed control Motor motorleft(2, 3); //initialize left motor attached to //Arduino pins 4 and 5 //pin 4 is for direction control //pin 5 is for speed control Motor motorright(4, 5); void setup() { //wait 3 seconds after power on //before driving robot delay(3000); DriveRobotExample.pde void loop() { //drive robot forward for 2 seconds //enter speed in the range motorleft.forward(80); motorright.forward(80); delay(2000); //drive robot backward for 2 seconds //enter speed in the range motorleft.backward(80); motorright.backward(80); delay(2000); //turn robot in clockwise direction for 1 second motorleft.forward(50); motorright.backward(50); delay(1000); //turn robot in counter-clockwise direction for 1 second motorleft.backward(50); motorright.forward(50); delay(1000); //stop robot for 1 second motorleft.stop(); motorright.stop(); delay(1000); 5-11

12 Exercise 1: Basic Navigation Write a program for your Arduino to drive the robot on a square path as shown below. 3 ft 3 ft Is your robot following the square path accurately? Explain why. 5-12

13 Introduction to Robotic Sensor Just like the sensing organs in humans, sensors in a robot collect information about its surroundings Sensors are electrical/mechanical/chemical devices that convert environmental attributes to quantitative measurements Robots use their sensors to detect and respond to their environment Touch sensors Ultrasonic sensors Light sensors Infrared sensors Wheel encoders Speed sensors GPS To navigate in an obstacle course, for example, the robot needs to use its sensors 5-13

14 Sense-plan-act algorithm (SPA) SPA is a robot control procedure with three critical capabilities for effective operation: SENSE: ability to sense important things about its environment, like the presence of obstacles or navigation aids. What information does your robot need about its surroundings, and how will it gather that information? PLAN: take the sensed data and figure out how to respond appropriately to it, based on a pre-existing strategy. Do you have a strategy? Does your program determine the appropriate response, based on that strategy and the sensed data? ACT: carry out the actions that the plan calls for. Have you built your robot so that it can do what it needs to, physically? Does it actually do it when told? 5-14

15 Ultrasonic Sensor Basic Operation Ultrasonic sensor measures distances using sound, the same principle that bats and submarines use to find their way around. The ultrasonic sensor then sends information to the robot about the distance to the nearest object in front of the sensor. The wiring between the Arduino and the ultrasonic sensor needs one wire as an output from the Arduino for sending trigger pulses, and a second wire as an input to the Arduino for capturing echoes. The sensor also needs power (VCC and GND). Arduino 5-15

16 Connecting Ultrasonic Sensor The motor driver shield provides female headers for installing the ultrasonic sensors in. It is labeled as JP4-SONAR on the board. The VCC and GND side are indicated on the board. The sensor should be installed facing in the forward direction of the robot. Insert ultrasonic sensor here 5-16

17 Displaying Ultrasonic Measurements on PC Monitor An open source library called NewPing is available for interfacing to the ultasonic sensor. An example program is available from the Arduino IDE. Open from File -> Examples -> NewPing -> NewPingExample A modified version of the example is given in the next slide. The changes are: The serial monitor baud rate is changed to 9600 The pin assignment for the ECHO pin of the sensor is changed to 13 The function sonar.ping_cm() is used to directly read the distance in cm Create a new Arduino sketch (program) and copy->paste the code given in the next slide. Upload the program to your Arduino and observe the ultrasonic sensor measurements in the Serial monitor window. 5-17

18 Displaying Ultrasonic Measurements on PC Monitor // Example NewPing library sketch that // does a ping about 20 times per second. #include <NewPing.h> #define TRIG_PIN 12 #define ECHO_PIN 13 // Maximum distance we want to ping for //(in centimeters). Maximum sensor //distance is rated at cm. #define MAX_DIST 400 void loop() { // Wait 50ms between pings (about 20 // pings/sec). 29ms should be the shortest // delay between pings. delay(50); //unsigned int us = sonar.ping(); //Send ping, get ping distance in cm or 0 if //no ping echo within set maximum distance //variable for storing measured distance unsigned int dist; // NewPing setup of pins and max distance. NewPing sonar(trig_pin, ECHO_PIN, MAX_DIST); void setup() { // Open serial monitor // at the default 9600 baud to see ping results. Serial.begin(9600); dist = sonar.ping_cm(); //output measured distance Serial.print("Distance: "); Serial.print(dist); Serial.println("cm"); 5-18

19 Exercise 2: Sonic Wander Bot Program your robot to wander around on the floor. That is, it moves straight ahead as long as it does not sense an obstacle in front of it within a distance of 30 cm. When it detects an object within the defined range it should avoid it by turning about 90 degrees to the left and then continue to go straight ahead. Bonus: Instead of always turning to the left, choose your turning direction at random. Hint: Arduino offers a random number generation function, called random(). See the reference at:

20 Exercise 2+ (Extra Credit): Target tracking robot In this exercise, you will modify your Wander Bot program so that the robot tracks a target that it finds within a distance of 60 cm. The movement behavior is as follows: - If there is no object in front of the robot within 60 cm distance, the robot stands idle. - When the robot detects an object within 60 cm distance it drives forward until it gets within 30 cm distance to the object. If the object moves further away, the robot should follow it to keep its distance within 30 cm. When it reaches at the 30 cm distance the robot will stop. 5-20

21 Light Sensor Basic Operation We will use a photoresistor as a light sensor A photoresistor s resistance to electrical current changes with the intensity of light illumination. It is also called a light dependent resistance (LDR). A photoresistor is made of cadmium sulfide. It responds to visible light similarly to the human eye. Photoresistor resistance could range between about 200 KOhm in the dark and 500 ohm in a brightly lit room. Application: light sensitive switches e.g. streetlights, vehicle headlights, garden lights, that automatically turn on at dusk 5-21

22 Light Sensor Measuring Brightness Photoresistor Voltage reading is inversely proportional to light levels. Analog voltage reading ranges from 0 ~ 5V based on the LDR value The green wire is the point you read analog voltage from. Let us try to measure the voltage in various illuminations. In your experiment, you can use the light sensor provided to you and mounted in the front of your robot facing towards the floor. 5-22

23 Light Sensor: Hardware configuration photoresistor LED The black tape around the sensors shields it from Ambient light interference when it is used for line following Wire the left, middle and right light sensors to A0, A1, and A2, respectively. Connect the power and GND lines to 5V and GND on the Arduino. LEDs are used to illuminate the surface for the light sensors to detect. 5-23

24 Display the light sensor #define lightrightpin A0 // Analog 0 #define lightmidpin A1 // Analog 1 #define lightleftpin A2 // Analog 2 measurements // variables for the light reading: 0 ~ 1023 int lightright; int lightmid; int lightleft; void setup() { Serial.begin(9600); pinmode(lightrightpin, INPUT); void loop() { lightright = analogread(lightrightpin); Serial.println(lightRight); delay(1000); Modify this code example so that it measure all three light sensors and prints them on the Serial monitor as shown in the output window. 5-24

25 Line Following Robot Line following algorithm: 1. Calibrate the light sensors so the program knows from the sensor readings when the sensor is looking at a black tape of a lighter background color 2. Use the three light sensors to detect if any of the sensors is seeing the line or not. 3. If the middle sensor is on the line, drive the robot straight 4. If the right sensor is on the line, drive the robot slightly right and forward to bring the middle sensor on the line 5. If the left sensor is on the line, drive the robot slightly left and forward to bring the middle sensor on the line. 6. Repeat steps 2 to

26 #include <Motor.h> //initialize left motor attached to Arduino pins 2 and 3 //pin 2 is for direction control //pin 3 is for speed control Motor motorleft(2, 3); //initialize left motor attached to Arduino pins 4 and 5 //pin 4 is for direction control //pin 5 is for speed control Motor motorright(4, 5); #define lightrightpin A0 // Analog 0 #define lightmidpin A1 // Analog 1 #define lightleftpin A2 // Analog 2 //average value for each of the three photoresistors //found in calibration mode, //used to compare with newly read photoresistor //values to determine the color int leftavg; int midavg; int rightavg; void setup() { //Initialize Serial communications Serial.begin(9600); //do light sensor calibration for line following linefollowingcali(); void loop() { //line following algorithm //read the sensor values int lightleft = analogread(lightleftpin); int lightmid = analogread(lightmidpin); int lightright = analogread(lightrightpin); //if mid sensor detect black color, //drive straight forward if (lightmid < midavg) { motorleft.forward(30); motorright.forward(30); delay(10); //if left sensor detect black color, //turn left a little bit if (lightleft < leftavg) { motorleft.forward(10); motorright.forward(30); delay(10); //if right sensor detect black color, //turn right a little bit if (lightright < rightavg) { motorleft.forward(30); motorright.forward(10); delay(10); 5-26

27 void linefollowingcali() { //Initiallize the maximum and minimum //values of the sensors int leftmax = analogread(lightleftpin); int leftmin = analogread(lightleftpin); int midmax = analogread(lightmidpin); int midmin = analogread(lightmidpin); int rightmax = analogread(lightrightpin); int rightmin = analogread(lightrightpin); int compare; //update the maximum and minimum values //of the sensor readings for (int i = 0; i < 1023; i++) { compare = analogread(lightleftpin); if (leftmax < compare) { leftmax = compare; if (leftmin > compare) { leftmin = compare; compare = analogread(lightmidpin); if (midmax < compare) { midmax = compare; if (midmin > compare) { midmin = compare; compare = analogread(lightrightpin); if (rightmax < compare) { rightmax = compare; if (rightmin > compare) { rightmin = compare; delay(5); //calculate the average value of maximum and //minimum read value to get the center points leftavg = (leftmax + leftmin) / 2; midavg = (midmax + midmin) / 2; rightavg = (rightmax + rightmin) / 2; Serial.print(leftAvg); Serial.print(" "); Serial.print(midAvg); Serial.print(" "); Serial.println(rightAvg); 5-27

28 Exercise 3: Line Following Robot with Safety Feature When the robot is moving with the line-following algorithm, we would like to incorporate a safety feature by using an ultrasonic sensor mounted on the top. So when this safety feature is enabled, the robot should immediately stop whenever it detects an obstacle within 15 cm range in front of it. When the obstacle is removed from the robot s way, the robot should resume its line-following movement. 5-28

29 Homework: Making Connections and For the Curious You Due: One week from today Making Connections From the things you interact with every day (at home, in your car, at school, workplace, shopping, restaurant, bank, stadium, the road, ) pick one and identify the electrical and electronic components, sensors, actuators, microcontrollers, robots, program applications,... For the Curious You Research and brainstorm/painstorm with your lab partners and present a specific application (existing or new) for a robotic like system. Think outside the box to consider all kinds of robotic systems (such as mobile, stationary, walking, flying, driving, humanoid). If you choose existing system or application, discuss innovative ways of improving it. Turn in a 2-3 pages report for your answers. 5-29

30 Final Project Opportunity For the curious you: You are given an opportunity to come up with a cool innovative project that uses an Arduino microcontroller, one or more sensors, and wireless Bluetooth communication to a Smartphone or Tablet. Refer to the online tutorial material to learn how the Bluetooth communication works and how you can use it for your application Alternative project: Extend the robotics project you worked on in this week s lab so that a user will have a wireless communication access to the robot from an Android device. The robot will have remote and autonomous modes of operations. In remote control mode a user will be able to control the robot s movements using commands from the phone. The robot will support two autonomous drive modes, as chosen by the user. The first auto mode drives the robot around aimlessly while avoiding obstacles on its way. The second auto mode executes the safe line following algorithm. 5-30

31 Finishing Up (and to get full-credit in the lab) 1. Check-out with the instructor i. Demonstrate your functioning exercises 2. Clean-up at bench Leave it better than you found it! i. Detangle cables and arrange Keyboard, Mouse and Chairs ii. Logout of computer iii. Return Equipment (Arduino, Robot kit, sensors, and all accessories) 3. Leave the check-out sheet with your group names at your station 5-31

32 Lab 5 Check-Out Sheet (to be left at the bench at the end of lab) Group Members (please print name clearly): Instructor (check all that apply): Exercise 1 Demo Exercise 2 Demo Exercise 3 Demo Print-outs of program codes for all three exercises. Include group member names in comment at the top of your program file. Computer Logout Return of equipment Arduino, motor control, ultrasonic sensor, light sensor, Bluetooth module Robot kit with motor wires, and battery USB Cable Additional Comments: 5-32