Project Overview  Introduction  Clawbot Build  Design Modification  Design Development  Programming  Sensors  Advanced Sensors  Open design challenges  Project evaluation

LESSON 04

LESSON 4 STARTER Key words: Programmable, environment, design, manufacturing and application Learning objective: Learn about wireless technology and its application to robotics. Apply knowledge of robot design to solving a design challenge. Develop a robot to improve its performance. What is wireless? Wireless technology is benefiting product design in a modern world where wires are no longer needed to allow products to communicate with one another, or even to charge up their batteries. Wireless technology refers to the use of electromagnetic waves that carry signals over the communication path. Wireless refers to the most basic and obvious sense where communication is sent in the absence of wires and cables. It encompasses all, the wireless technologies, wireless computer accessories and the cellular communications. Common examples of wireless products: - Cellular phones providing connections between portable/mobile devices - Global Positioning Systems (GPS) allow navigation devices to locate their positions on the earth using satellites - Cordless computer mice, keyboards and printers - Home-entertainment systems where multiple devices provide surround sound

Working Wirelessly Wired VS Wireless Benefits and draw backs of WiredBenefits and draw backs of Wireless I like wired, and I like wireless, but which one is best? There’s only one way to find out… Create the following table in your Engineering notebook. Once you have created it, propose the benefits and drawbacks of wired and wireless connectivity to every day products, including robots.

Working Wirelessly Introducing wireless control The VEXnet Joystick can connect using the USB to USB orange cable, but introducing the VEXnet key will allow for wireless control. How to connect: To set up your wireless keys take the following steps: 1. Connect the joystick to the cortex and operate it wired. 2. Turn off both the joystick and cortex and replace the wire with two wireless keys. 3. Turn on the cortex, then the joystick. 4. Allow the pair to connect to one another. 5. Operate your robot just how you did with a wired connection.

Working Wirelessly Develop your controls Look at the joystick. Notice that there are numbers labelled on the surface of the plastic casing. 5 6 What are the numbers in reference to? The direction of arrow for numbers 1-4 denote the direction of movement motors can move in using these controls. E.g. The default code that is installed on all Clawbot kits results in the motors on the base (that drive the wheels) will respond directly to the joystick dials. Pushing forward/backward with 2 and 3 at the same time will drive both motors forward. Using programming software allows the default code to replace that on the cortex so that a personal operation can be designed.

Working Wirelessly Changing the response of the cortex when receiving signals from the joystick In this brief tutorial, you are going to learn how to change the operation of the cortex when the joystick is controlling it wirelessly (and wired). Using EasyC to change the controls: 1. Create a standalone project - Joystick project (Wifi) 2. Your main programme will look like this > 3. Bring a “While Loop” into the programme from the Program Flow section. 4. Under Joystick, you can bring in an arcade or tank programme which will control two or more motors. 5. Under Joystick you can also bring in a “Joystick to motor” programme which will control 1 motor. 6. Under Joystick you can finally bring in “Joystick to Digital motor” which will allow you to apply 5/6 buttons to the control of a motor. A PREVIEW LOCATION OF RIGHT MOTOR ON CORTEX + DIRECTION LOCATION OF LEFT MOTOR ON CORTEX + DIRECTION NUMBERED CONTROL ON JOYSTICK NUMBERED LOCATION ON JOYSTICK LOCATION OF MOTOR ON CORTEX + DIRECTION NUMBERED LOCATION ON JOYSTICK DIRECTION & SPEED OF MOTOR TO BUTTON 1 LOCATION OF MOTOR ON CORTEX DIRECTION & SPEED OF MOTOR TO BUTTON 2

Working Wirelessly The programme of the previous tutorial will look like this The outcome Arcade2 (1,2,1,1,10,0,0) Controller 1 will use controls 2 and 1 (the right joystick) to drive motors 1 and 10, without inverting (changing direction) the motors. JoystickToMotor (1,3,5,0) Controller 1 will use control 3 to drive motor 5, without inverting its direction. JoystickDigitalToMotor (1,5,1,127,2,-127,6) Controller 1 will use control 5 and buttons 1 and 2 to drive motor 6. Button 1 will drive forward at 127 revolutions/second, and button 2 will drive backward at 127 revoluations/second. Note 127 refers to the fastest rotation a motor can achieve. The minus value refers to a reverse of the motor. By reducing the number, the motor will operate slower.

Working Wirelessly Select 1 of these 3 challenges for your robot Read all three of these challenges, and select one you would like to take on. Each will need to be completed in 2 minutes. Copy down the challenge into your Engineering Notebook. In your teams, consider the way in which your robot needs to move and operate in order to achieve success. Does it need to be fast or slow? Does it need to turn with a 0 degree position or around a corner? Do you need to focus on the operation of the claw or the drive? Challenge 1 Design a programme that allows your robot to transport an open cup of water without spilling it. The cup will be a white polystyrene cup and the water half full. The cup must be moved in a straight line from one end of your classroom to the other without spilling it. Challenge 2 Design a programme that allows your robot to pick up and move pebbles from one location to another. The pebbles will be stored on one side of your workbench, and the container to drop them into on the other. You will need to move three pebbles. Challenge 3 Design a programme that allows your robot to navigate through a tight corridor, around a single corner, and then to its end where it will need to hit a target with the claw. The claw will reside above the clawbot head. The corridor width will measure the widest diagonal of the clawbot base.

Working Wirelessly Task: Design your controls for easier operation Using EasyC, develop a small joystick programme in a “While Loop” that will allow you to change the control of your robot. Plan your programme in your Engineering Notebook first

Working Wirelessly Task: Load your programme and carry out Load your EasyC programme onto your cortex and test the robot to prove it can fulfil its task. Record your findings and note proposals to change the programme (if it needs it) Challenge 1: drive forward with a cup from zone 1 to zone 2. Challenge 2: drive around corners to deposit the pebbles on repeat quickly. Challenge 3: drive forward and around a corner in a narrow corridor.

LESSON 4 PLENARY As a class, let us consider the following questions? A. What is the relationship between the joystick and the cortex and the motors? B. How many motors can any single control on the joystick move at any one time? C. Why did all of these challenges need wireless control? D. How does changing the programme change the behaviour of the robot?

Summary Today you have:  Learnt about wireless technology in the context of VEX Robotics.  Applied knowledge from a previous design project to a new design challenge focused on programme development.  Developed a functional product to tests its functionality. Learning objective: Learn about wireless technology and its application to robotics. Apply knowledge of robot design to solving a design challenge. Develop a robot to improve its performance.