Low Cost Robotics: Using Vex in FRC

1. Low Cost Robotics: Using Vex in FRC Art Dutra, III: mentor & Arthur Dutra, IV: team member FRC Team #228 “GUS” Robotics

2. Introduction If your team can’t: • Build an entire “practice” playing field • Build a second “practice” robot • Test multiple drive train configurations • Test multiple manipulator designs • Easily teach students programming • Test sensors and autonomous code during the build season • Assess your robot’s scoring potential before competition begins • Have hours of driver training before your first competition • Develop game strategy before competition begins • Have exciting and interactive demonstrations or recruiting Then Vex might be able to help

3. Scaled FRC using Vex 1:3 Scale was chosen based on FIRST’s 2005 Vex Challenge pilot program. The scale works well for building accurate scale versions of FRC robots and playing field components which perform well together. FRC Team 228 2005 “GUS” 1:3 Scale FRC Vex “Mini G”

4. Playing Field Creation 2005 Triple Play Vex Version • All playing field components were built from materials readily available at the average home improvement store. • Playing field walls 9’x18’ - cost $143.86, w/ 1/8” Lexan @ driver stations - add $150.00 • Playing field Soft Tile mat - cost $520.00, or commercial carpeting - cost $340.00 • Scoring Tetras - cost per tetra $2.90 • End Goals - cost per goal $4.75 • Center Goal - cost $6.25 • Loading Stations - cost per unit $5.89 • Complete practice field - $800 - $1200

5. Playing Field Savings Time Space Cost • Less than one week to build entire practice field. • Goals and other large field objects do not need to be disassembled for storage. • All materials can be purchased at local “Home Depot”. • Entire playing field will fit in a standard classroom. • Maximum robot height limit less than 6’. • Entire field 9’x18’, with human player and driver areas 15’x24’. • Entire field will store in the average closet without disassembling goals. • Entire playing field cost $900 - $1200 • Playing field components in future years (less mat and walls) cost $230 - $330. • Components damaged during practices or demonstrations are less expensive to repair or replace.

6. Robot Creation photos from www.syraweb.com 2005 Triple Play Vex Version • Practice robots need not be built entirely from Vex components. Keep robot accurate to full sized robot. • 2005 dimensions 9.3”x12.5”x20”. • Starter Kit, cost $299.99 • Extra Hardware Kit, cost $79.99 • Gear Kit, cost $12.99 • Chain & Sprocket Kit, cost $29.99 • (2) Omni-Wheel Kits, cost per kit $19.99 • Motor Kit, cost $19.99 • Limit Switch Kit, cost $12.99 • Power (battery) Kit, cost $49.99 • Total Robot Cost $525.92

7. Robot Savings Time Space Cost • One or two days to build Vex robot using one or two experienced students. • Different prototypes can be built every day or two. • Practice robot is up and running long before full sized robot is completed and shipped. • Changes to full sized robot can be duplicated on practice robot quickly. • Practice robot fits in a milk crate. • Six or more robots, spare parts, batteries, chargers, and operator interfaces will fit in a storage cabinet or closet. • Workspace for building and repairing robot is less than 4’x8’. • Entire practice robot cost $400 - $600 • A fleet of practice robots can be built over a few years. • Consumable components less than $100 per robot per year. photo from www.vexlabs.com

8. Prototyping Drive Trains • Nearly any idea imaginable for possible robot drive trains can be reproduced in Vex. The following robot drive systems can be made out of Vex components: • 2, 4 or 6-Wheel Tank-Drive • Tank Treads • Crab (swerve) Drive • Holonomic Drive • Other ideas, including mecanum drives, can also be built using custom made components Vex. photos from vexlabs.com

9. Prototyping Pneumatics • As with the full-size robots, pneumatic components can also be used with Vex. • Innovation FIRST and VexLabs sell Vex-compatible pneumatics kits. • The kits are easy to work with, and can accommodate both single and double-acting pistons. • The solenoids can plug directly into the digital outputs on the Vex Controller without any need for an external power supply. • The solenoids can be controlled via the Vex Transmitter using simple EasyC™ coding. photo from www.vexlabs.com

10. Prototyping Manipulators • Using Vex components, a wide range of arms, elevators, and manipulators may be built. • When geared correctly, powerful, yet fast, arms can pick up objects weighing several pounds. • When used with pneumatics, the diversity of designs increases vastly. photo from www.vexlabs.com photo from www.vexlabs.com

11. Programming • With the new Vex Programming Kit, endless possibilities are opened. Now, robots can autonomously navigate obstacles using a variety of sensors. • Using a simple graphical user interface (GUI), novice programmers with no C programming experience can jump right in to EasyC™. • EasyC allows for drag-and-drop simplicity for generating code, while still allowing for advanced line coding. • MPLAB can also be used to program the Vex robots. Screenshot from www.intelitek.com photo from www.radioshack.com

12. Sensors • Currently, there are six different sensors available through the Vex line. These are: • Limit Switches • Bumper Switches • Ultrasonic Sensors • Shaft Encoders • Line Tracking Sensors • Light Sensors • In addition to the Vex sensors, non-Vex analog and digital sensors can be connected as well. These non-Vex sensors may include potentiometers, accelerometers, gyros, and more. photos from www.radioshack.com

13. Autonomous Code • Using either EasyC or MPLAB, autonomous code can be easily written and executed. • Novice users can easily write code to test in EasyC. • Developing autonomous code by using Vex robot can be much safer than having a full-size 130-pound robot’s code go amok. • Since Vex robots can also be built much faster than a full-size robot, the development and testing of autonomous code can begin much quicker, since they would have separate (Vex) robot to test on. photos from www.syraweb.com (from the WPI Frontiers Savage Soccer Game)

14. Driver Training • Since a Vex robot can be built within a matter of hours, driver training can begin much sooner than usual. • Teams can create a scaled-down version of a team’s full size robot in Vex (with an accurate arm/manipulator) and scale playing field components. • By allowing the drivers to practice with Vex robots, this does not disturb the build crew as they work on the full-size robot. photos from www.vexlabs.com

15. Scoring Potential • Teams can accurately estimate their scoring potential by running their Vex robots on a scale Vex playing field. • During the design phase, teams often end up with two radically different designs about how the robot should be built. • Both teams can now build their ideas to test them head-to-head, to see which idea really works better. • Actual practice with real robots beats any scoring simulator, as this accurately represents the real world variables (such as driver skill, coordination, robot interference, etc) in a real world application.

16. Game Strategy • An entire 1:3 scale playing field can fit into one classroom, and multiple vex robots can be built for under $1000. • This allows for teams to build radically different robots, and have these different Vex robots compete, as if one were an opponent. • This can find the strengths and weaknesses in any particular strategy better than anything else. photo from www.usfirst.org

17. Recruiting and Demonstrations • Team demonstrations can now become much more interactive with the use of Vex. • Because of safety concerns, letting random people drive a full-size robot cannot be allowed. • But because Vex robots are small, and are not dangerous, people with no experience can drive robots as much as they want with little supervision. • By being able to drive a robot and interact with it, potential team members will be more likely to join a robotics team.

18. The End Thank You Additional Information can be found at: www.vexrobotics.com www.vexlabs.com www.chiefdelphi.com www.team228.org www.syraweb.com