Low Cost Robotics: Using Vex in FRC

Art Dutra, III: mentor &

Arthur Dutra, IV: team member

FRC Team #228 “GUS” Robotics

Introduction

• 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

If your team can’t:

Then Vex might be able to help

Scaled FRC using Vex1:3 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”

Playing Field Creation

• 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

2005 Triple Play Vex Version

Playing Field Savings

• 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”.

Time Space Cost

• 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.

Robot Creation

• 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

2005 Triple Play Vex Versionphotos from

www.syraweb.com

Robot Savings

• 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.

Time Space Cost

• 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 fromwww.vexlabs.com

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 fromvexlabs.com

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 fromwww.vexlabs.com

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 fromwww.vexlabs.com

photo fromwww.vexlabs.com

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 fromwww.intelitek.com

photo fromwww.radioshack.com

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 fromwww.radioshack.com

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 fromwww.syraweb.com

(from the WPI Frontiers Savage Soccer Game)

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

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.

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 fromwww.usfirst.org

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.

The End

Thank YouAdditional Information can be found at:

www.vexrobotics.com

www.vexlabs.com

www.chiefdelphi.com

www.team228.org

www.syraweb.com