Robot Navigation Worksheet 1: Obstacle Navigation

Transcription

1 Robot Navigation Worksheet 1: Obstacle Navigation Team name: Group members: In this challenge you will learn about the different features of the Move block, test a range of different turns for your robot, and navigate your way around a simple obstacle course. You will need a two-wheeled robot (e.g., the EduBot) and a basic understanding of the features of the NXT-G software for this challenge. A great way to become familiar with these features is to go through the Getting Started and Software Overview tutorials that appear when you first open the software (Figure W1-1). Figure W1-1: Getting Started and Software Overview tutorials 47

2 1. The Move block The Move block is a powerful way to control one, two, or even three motors. It allows you to control the power, duration, and direction of the different motors assigned to it. You will find the Move block at the top of the Common palette. It can be dragged from here onto a sequence beam (Figure W1-2). Figure W1-2: A Move block being dragged onto the sequence beam Once the Move block is in place, a configuration panel (Figure W1-3) will appear at the bottom of the screen. Figure W1-3: Configuration panel for a Move block 48 Educate NXT

3 The configuration panel for the Move block enables you to control many properties of the motors attached to your robot. The Port feature at the top of the configuration panel enables you to match the ports on your NXT Brick with the wires from the robot s motors. In Figure W1-3, Ports B and C have been selected and match the location of the wires on the EduBot in Figure W1-4. Figure W1-4: Wires attached to Ports B and C of the EduBot You will soon by asked to experiment with the different features of the Move block. When you change a feature and wish to see what effect it has on your robot: Press the orange button on the NXT Brick to turn it on (you will hear a little tune). Connect the USB cable from the computer to your robot. Left-click the Download button found on the work space of the NXT-G software (Figure W1-5). Figure W1-5: The Download button If downloading is successful you will hear a beep from your NXT Brick and see a complete! message on the computer screen. Unplug the USB cable from your robot. Press the orange button on the NXT Brick four times and your program should run. 49

4 Your first task is to explore the rest of the features of the configuration panel for the Move block and write a brief sentence below describing what each feature does. Direction: Steering: Power: Duration: Unlimited: This is a bit tricky we will deal with this later. Seconds: Rotations: Degrees: Next Action: 50 Educate NXT

5 2. Turning When you changed the slider for the Steering feature of the Move block, you should have noticed three types of motion (Figure W1-6). Figure W1-6: Forward, curve turn, and point turn with Move block Steering slider locations You can also use the Steering slider to set the tightness of each turn. After you have set the Steering for each Move block, it will be shown in the bottom-left corner of the Move block (Figure W1-7). Figure W1-7: Different sharpness of turn represented on the Move block 51

6 3. Planning the strategy Your challenge will be to program your robot to navigate between two start markers, avoid the center object, and pass between the two finish markers (Figure W1-8). Before you begin any programming: Plan your strategy and draw your intended route on Figure W1-8. Circle every turn you intend to make on Figure W1-8 and indicate, by writing next to the circle, what type of turn your robot will make (curve or point). 4. Programming and testing Figure W1-8: Basic navigation course Now you will need to convert your plan into a program. For this you will use a series of Move blocks. Whenever you want your robot to go forward or make a turn, you will require a new Move Block. It would be wise to build your program up step-by-step, testing from the start each time you add to your program this is known as trial and error. You can now attempt to get your robot to finish between the markers on the other side of the obstacle. The type of navigation you are using here is called dead reckoning. 52 Educate NXT

7 5. Faster and smarter Q1. What changes could you make to your program or route so that the EduBot will travel between the start and finish markers in a quicker time? Q2. Can you suggest an alternative to using trial and error to find the distance you need the EduBot to travel? 6. Stepping up the challenge Your challenge this time is to get your robot to travel from the start to finish markers but circumnavigate (circle around) the obstacle on the way through to the finish markers. Another diagram (Figure W1-9) is included below for you to plan your route before you commence programming. You may also wish to use the first part of your previous program to get you started. Figure W1-9: Blank diagram for circumnavigation and route planning 53