e d u c a t i o n Detect Dark Line Objectives Connect Teacher s Notes

Transcription

1 e d u c a t i o n Objectives Learn how to make the robot interact with the environment: Detect a line drawn on the floor by means of its luminosity. Hint You will need a flashlight or other light source for this activity. Connect Using colored lines or wires is one of the simplest ways to guide the movement of mobile robots in a given environment. In this activity you will use a Light Sensor and make your robot detect lines. Open your software and click through the Challenge Brief of Tutorial 16.. Then follow the Building Guide and Programming Guide and make your robot detect the dark line. 38

2 Construct Build your Robot Build the Driving Base and Light Module Down following the Building Guide, or using the Building Instruction booklet pages 8 to 22 and pages 32 to 34. If you have pre-built your robot, we suggest you remove unnecessary extensions and only use a robot as shown in the Building Guide Make sure the Light Module Down is connected to port 3 Test the functionality of the model. Loosening bushings can reduce friction Make sure that all wires are clear of moving parts, the rear wheels move freely and all tires are put on correctly. Build your Program Open and download the program 4a_detect_dark_line.rbt Or otherwise: Name your program with a meaningful title Follow the Programming Guide In steps four to six of the Programming Guide you will be asked to fill in some values based on actual Light Sensor readings. First use the View function of the NXT Brick, or with a robot connected click on the Wait for Light block. Then place the Light Sensor first over the black line and then over a white area Write down the values of luminosity of the black line and the white area, and calculate the average. Then fill in the average of the two readings in the configuration panel When you are done, save the program Make sure the robot is connected to the computer before downloading the program to the NXT. Place your Robot Place your robot on mat no. 1, starting position 5. 39

3 Contemplate STEP 1 The robot will drive forward and then stop when it detects the first black line. STEP 2 Then, change the program to make your robot continue past the first black line and stop when it detects the second black line. One way to solve this is by making the robot first search for a black line, then for a white line, and then finally another black line. Some students will try looping the program and most will be unsuccessful in finding the second line when they do so. It is important that alternative programs allow the robot to clear the first black line before searching for the second line. Some might be successful in adding an additional Move block that allows the robot to clear the first line. Hint To help the students realize the different steps in the program, try using the Wait for Time block at strategic places. This can help them see how each part of their program performs. The program 4b_detect_second_dark_line.rbt shows one way to solve the problem. STEP 3 Next, place the robot at the opposite end of the colored lines (starting position 6) and change your program to make your robot stop at the first white line. The Light Sensor reads almost the same values from the red and the white lines. Therefore it is important that the program takes the red line into account. The program 4c_detect_white_line.rbt shows one way to solve the problem. You can further extend the activity by having your students: Use the Comment Tool to explain their programs and what each block does Program the robot to stop at the gray line. 40

4 Continue React To Light STEP 1 Open Tutorial 23. React To Light. View the Challenge Brief and follow the Building Guide and Programming Guide. Save the program before downloading. Place your robot on mat no. 1, starting position 5 or alternatively on the floor or a table. The robot will point turn continuously at varying speeds, depending on the intensity of the light detected. The intensity reading from the Light Sensor is sent from the output plug of the Light Sensor to the power input plug of the Move block via the data wire, thereby determining the speed at which the motor will run. The higher the light intensity reading, the faster the robot will point turn. Students will build the program 4d_react_to_light.rbt. STEP 2 Then, change the program to make your robot point turn more slowly the higher the light intensity. One way to solve this is by adding a Math block. Set input number A to 100 and set input number B to the light intensity reading. Hint This might be the first time students use the data wire tool. It would be a good idea to spend some time training them in how to create and undo links. Then the higher the light intensity reading is, the lower the output will be, i.e. the slower the robot will point turn. The program 4e_react_to_light_slow.rbt shows one way to solve the problem. Optional Try the Tutorials 21. Speed Control and 22. React To Distance Program your robot to go forward at low light intensity and stop when the light intensity reaches a specified trigger point. 41

5 Student Worksheet Name(s): Using colored lines or wires is one of the simplest ways to guide the movement of mobile robots in a given environment. In this activity you will use a Light Sensor and make your robot detect lines. Open your software and click through the Challenge Brief of Tutorial 16.. Then follow the Building Guide and Programming Guide and make your robot detect the dark line. Build your Robot Build the Driving Base and Light Module Down following the Building Guide, or using the Building Instruction booklet pages 8 to 22 and pages 32 to 34. If you have pre-built your robot, we suggest you remove unnecessary extensions and only use a robot as shown in the Building Guide Make sure the Light Module Down is connected to port 3 Test the functionality of the model. Loosening bushings can reduce friction Make sure that all wires are clear of moving parts, the rear wheel moves freely and all tires are put on correctly. Build your Program Name your program with a meaningful title Follow the Programming Guide In steps four to six of the Programming Guide you will be asked to fill in some values based on actual Light Sensor readings. First use the View function of the NXT Brick, or with a robot connected click on the Wait for Light block. Then place the Light Sensor first over the black line and then over a white area Write down the values of luminosity of the black line and the white area, and calculate the average. Then fill in the average of the two readings in the configuration panel When you are done, save the program Make sure the robot is connected to the computer before downloading the program to the NXT. Place your Robot Place your robot on mat no. 1, starting position 5. 42

6 Student Worksheet Step 1 Step 2 Then, change the program to make your robot continue past the first black line and stop when it detects the second black line. Describe the programming changes you made: Step 3 Next, place the robot at the opposite end of the color lines (starting position 6) and change your program to make your robot stop at the first white line. Describe the programming changes you made: 43

7 Student Worksheet React To Light STEP 1 Open Tutorial 23. React To Light. View the Challenge Brief and follow the Building Guide and Programming Guide. Save the program before downloading. Place your robot on mat no. 1, starting position 5 or alternatively on the floor or a table. STEP 2 Then, change the program to make your robot point turn more slowly the higher the light intensity. Describe the programming changes you made: Hint: Try adding a Math block to your program. 44