RoboCupMechanical2008

This page houses the current RoboCup Mechanical efforts. The 2007 efforts can be found here. All development work will be done in Autodesk Inventor 2008. How to use Inventor and get it can be found on the Inventor How to Guide. Inventor is also available on our CAD Machines in Tin.

Mechanical team meets Monday at 7pm and after the general meeting on Thursdays at 6:30

A developement rendering of a 2008 RoboCup robot

Systems

• Drivetrain
  • Omni Wheels
  • Motors/Gearing
  • Drive Module
• Integration
  • Shell
  • Chassis
• Ball Control
  • Dribbler
  • Kicker
  • Chipper
• Test Rig

Schedule

• deadline for completion of Everything Box - 11/30/07
• completion of ONE DRIVING, COMPLETE robot - 1/7/08

Specifications

• maximum robot weight - 1.8 kg
• ball speed after being kicked - 10 m/s
• dribbler bar speed - 8000 rpm
• compress time (time for dribbler to absorb ball's energy and compress) - .2 seconds
• no more than 20% of the ball's area (seen from top view) may be occupied by the robot - a critical Robocup SSL Rule
  • see

Meetings

• 9/6/07 - Update for new members, organized testing plan and ideas
• 9/13/07 - Organized most of the required tests into one device that will be designed starting on monday when we get CAD computer's back in the TIN.
• 9/20/07 - The Test Rig aka "The Everything Box" is being designed and components spec-ed out. The hunt continutes for the dribbler motor.
• 9/24/07 - Everything Box still being designed, would like to start ordering parts on Monday 10/3/07. Idea generation started on the dribbler system such as suspension and damping systems
• 9/27/07 - Test Rig nearing completion. Concepts of ball control system discussed as well as the use of solenoids or some other actuator for the kicker
• 10/1/07 - A cheap treadmill is being looked at for the testing rig. Conceptual planning is being done on the ball control system. Throughout the week, different ideas for the profile of the dribbler will be made on the lathe and then tested.
  • the shaft output of the dribbler bar must be 3mm in diameter to fit in the gear of the current dribbler
• 10/4/04 - Dribbler prototypes designed and parts are being ordered to make it. The dribbler motor was chosen and is being ordered as well. Work still continues on the kicker and chipper actuation. Lets work some over fall break! yah...!
• 10/11/07 - Dribbler prototype drawings made. Ball control system still in discussion.
• 10/15/07 - Everything Box design done, parts ordered tomorrow. Drive modules nearing completion.
• 10/18/07 - Everything Box is under construction
• 10/22/07 - Everything Box is under construction, other parts are being designed
• 10/25/07 - Everything Box design complete and parts are being fabricated
• 10/29/07 - Everything Box still being fabricated
• 11/1/07 - No Robocup meeting due to the Virginia Tech football game
• 11/4/07 - No Robocup meeting. Everyone busy.
• 11/7/07 - Mechanical and electrical components for Everything Box being fabricated.
• 11/26/07 - Everything Box is nearly complete, as are the electronics for it. Electronic controls are also nearly done for to control the new drive motors - giving the CS team a platform to use for testing. The machining of a few parts will be outsourced to different suppliers.
• 11/29/07 - Remainder of parts made, as well as some drawings of parts
• 12/2/07 - Everything Box is done, dribbler is nearly finished, drawings still continue to be made to posted for outsourcing
• 12/17/07 - After a break for finals work resumes. Majority of parts ordered for the prototype, design nearly complete - still a bit of tweaking remains. Carbon fiber is being researched for shell.
• 12/18/07 - McMaster order picked up. Kicker solenoid spec-ed out, documentation of design continues.
• 12/19/07 - Spring for the dribbler was designed and selected. Postion of drive modules will be moved. CAM software tested and g-code created for both drive module plates.

Testing

Dribbler test

Functions:

Trap ball

• Ball speed- speed the ball can hit the without moving back. Use a spring and a speed trap to measure the speed.
• Ball angle- rotate the robot
• Rebound- distance the ball bounces back

Hold ball

• Center time- measure time in seconds
• Climb ball- measure change in normal force on the measuring platform
• Pull force- angle of loss of contact. Measure what incline the measuring platform is required for the dribbler to lose contact
• Reverse speed- have the robot on a treadmill and measure when the ball comes lose
• Lateral speed- have the robot on the treadmill but have the dribbler facing tangential to the motion
• Rotational speed- rotate the speed of the carpet and see when the dribbler loses control

Material Test

• Measure either the lifetime of the dribbler under continuous operation and visually inspect the dribbler.

Kicker Test

• Control speed- speed trap measuring velocity versus voltage
• Accuracy- impact test to measure where the ball impacts a wall
• Lifetime- how long does the kicker last both with a ball being hit and when there is no ball. Also measure changes in speed and accuracy over time.
• Frequency- how long between successive firings

Chipper Test

• Range- to where the ball lands
• Angle- accuracy to how close the ball lands
• Lifetime analysis same as kicker

Shell impact Test

• Maximum speed ball at different areas of the shell until it breaks

Omni wheels Test

• Traction- run the robot up an incline

Quick Notes

• field area 5 meters x 3.5 meters
• max ball speed - 10 m/s
• ball diameter - 43 mm
• ball mass - 46 grams
• 1 rpm = .105 rad/s
• ball material - DuPont Surlyn Ionomer Dupont's Surlyn Page
• coefficient of static friction of golf ball on felt carpet - .66
  • last two points from Cornell 2003 Mechanical Documentation

Parts

• System Components and Bill of Materials
• Parts to Order

Useful Links

• Cornell Documents (Look at 2003)

• Eagle Knights Dribbler Testing

• Mechanical Engineering Tips

• G-Code Tutorial

• Overhead camera footage from Robocup 2007 Championship Match

• Dr. Gear - Gear Encyclopedia

• Cornell 2004 Mechanical Documentation

• MIT Design Handbook Index (VERY GOOD)

• Global supplier and CAD drawing database