Lesson 3.1 Teacher Notes (VEX)

Career Exploration

Students will continue to explore careers related to engineering and engineering technology by completing the activity Career Demand, Salary, and Education. Students will investigate further into the career field that they chose during Unit 2. Student research will be centered on facts relating to the specific career field. Students may consider career trends nationally and locally related to demand, salary, and educational training. The Career Demand, Salary, and Education activity should be completed during Unit 3 and submitted to the course instructor at the completion of Lesson 3.3.

VEX®Battery Charging

The smaller form factor 7.2V Robot Battery NiMH 2000mAhshould only be charged using the Safe setting on the Smart Charger. The Fast setting can damage the battery and should not be used.

VEXRobotics Platform and ROBOTC Software

The Cortex and Joystick should have the most current firmware loaded on each device. Follow the Cortex Configuration Over USB instructions in the robotics reference guide in the student resources as needed.

Listed below are resources to use ROBOTC software on the VEX robotics platform.

  • VEX Cortex Video Trainer
  • Use this resource for more information about using ROBOTC with the VEX robotics platform.
  • PLTW VEX Kit
  • This is a list and description of each component within your specific PLTW VEX Kit in the student resources.
  • ROBOTC Programming Software Download and Resources()
  • Download ROBOTC programming software from Carnegie Mellon University (CMU).
  • This link also provides great resources to assist you in becoming familiar with the basics of VEX and ROBOTC.
  • VEX and ROBOTC support (two methods).
  • Use this email for all VEX and ROBOTC related support.
  • Use this forum for all VEX and ROBOTC related support.
  • Robotics Reference Guide
  • Download from the student resources.
  • Troubleshooting Guide
  • ROBOTC general troubleshooting tips in the student resources.
  • VEX Inventor’s Guide
  • A tool to help you get accustomed to all features and functionality of the VEX Robotics Design System. Download from student resources.
  • VEX RoboticsCompetitions
  • Color coding within ROBOTC program
  • ROBOTC uses colors to distinguish elements of the program as shown below.
  • Access this reference with the ROBOTC software. Set the user level to Expert by clicking Window, Menu Level, then click Expert. Click View, Preferences, Detailed Preferences. Click the Editor tab.

ROBOTC Program Color Codes

Activity 3.1.1 Inputs and Outputs

The ROBOTC programs used in this lesson are provided as a zip file in the Answer Keys and Asessment Rubrics section of the lesson.

There are enough components in the POE VEX kit to build most of the testbed allowing one kit to support two groups of two students. Each group of two students will build a testbed with the exception of installing the Servo Motor, Ultrasonic Sensor and Light Sensor. One group will continue to install the one available Servo Motor while the other group installs the one Ultrasonic Sensor and one Light Sensor. Students will complete activity 3.1.1 with the inputs and outputs available on their testbed. They will exchange testbeds to complete the activity with the remaining inputs and outputs. Note that a 393 motor can be used to replace a 269 motor to accommodate the VEX kit in the classroom.

ROBOTC version 3.05 and later includes testbed options. Selecting a testbed configures the motors and sensors to align with the corresponding testbed build instructions. Students should configure the motors and sensors as shown in the activity at least once so the skill is practiced. Use your judgement for when to allow students to use the testbed configuration option.

Testbed Motor and Sensor Setup

Programming Planning (VEX)

Flow charting is another valid approach to program planning that visually oriented students may find more manageable. An alternative approach to developing the program logic is presented in Creating Flowcharts.

Activity 3.1.6Open and Closed Loop System

Students are to develop their own programs. A programming technique to efficiently test code is to temporarily comment out a line that may be used again later. This is done by inserting two forward slashes (//) at the beginning of a line of code that should not be executed. The example below showsan efficient method to switch the behavior from a time-based limit to a sensor limit through the use of the comment prompt, //.

startMotor(rightMotor, -67); //Start the motor rotating CW

waitInMilliseconds(500); //Wait for time

// untilTouch(reverseSwitch); //Wait for limit switch

stopMotor(rightMotor); //Stop when reach limit switch

Problem 3.1.7 Machine Control Design Problems

These problems are to be completed using VEX POE kits and ROBOTC. It is recommended that you conference with each team to make sure that their plan meets the necessary goals as described in the problem statement before they begin construction. Specific problems and the amount of problems to be solved should be based on student abilities and the amount of time available to complete the problems.

© 2012 Project Lead The Way,Inc.

POE Lesson 3.1 Teacher Notes VEX – Page 1