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Week 3

Chassis Completion

With ordinary talent and extraordinary perseverance, all things are attainable.
     Sir Thomas Foxwell Buxton
In the game of life nothing is less important than the score at half time.

In Week Three, your robot begins to take shape. The Chassis and drive train are being built, robot functions are tested and finalized, the electrical board and pneumatics are coming together. You have a better estimate of the final weight, the programming is well under way, and you can start selecting a competition team.  Parents or team members should have the field components built, and another team member should be keeping the team updated on all of the changes coming down from FIRST, and on all the related discussion on Chief Delphi.

You now have only three short weeks left to complete, test, rebuild, test, and finally ship your robot.  No pressure!



Continue to celebrate team successes whenever you can.  Even if you need to redesign something that team members spent significant time working on, recognize their hard work.


Schedule off-meeting times for a subset of team leaders (adults and students) to discuss how the season is progressing, what tasks need to be done, and what resources are needed to accomplish those tasks.  Meeting in a small subgroup allows retrospection in an environment where the key leaders can see the big picture.


Depending upon the size of your team, this may be easy or difficult to do.  Take a few minutes out of your busy schedule to have a “group meeting” to update everyone on progress.  Sharing these learnings becomes more important the further you are into the build.  Get into a habit to do this on a frequent basis.  It not only assists in getting the robot built, it provides those students, who have not been directly involved with the build, an appreciation of the problems and potential solutions being examined to solve them.

MOE 365 does this during our team dinners during the weekdays.


Understand how your team members are getting along.  With the perpetual long hours and constant working together, even good friends can start to grate on each other’s nerves.  Identify these situations as soon as you can and have sit-down discussions where possible to resolve the situation.  Try to have an adult who can be purposeful and does not take sides be the mediator.  Also, do your best to work from your team expectations and treat similar incidents in a similar manner for the sake of fairness.



By now you should have demonstrated your basic functionality with simple prototypes. If this is not completed, then you need to do your best to complete it by the end of the week..

Once a component is fully built, the team needs to test how it works in conjunction with the rest of the robot and if it is effective doing what it was designed to do.

Based on past experience, very few parts / designs were perfect the first time.  After almost every test, changes need to be made.  We have found connections that were loose, pieces that fit too tightly or too loose, and parts that were placed too close together or too far apart from each other.  Get used to testing, re-engineering, and re-testing, until you are satisfied.  It is much better to test your functions now, then when you are out on the playing field for a real match.

By the end of Week 3, you should have completed the design of the major components and start fabricating the final parts.  


Never forget you are building a robot to compete in the FIRST Robotics Competition.  It is in your team’s best interest to routinely check the rules to ensure that your game strategy, robot design, parts, and material selection still conform to the rules in the official FIRST documentation.

When you arrive at the regional competitions, your robot will be inspected, weighed, and checked for conformity to the volume and cost thresholds before being allowed to compete on the field.  The last thing your team needs to find out at that time is that your robot is out of specifications.  This requires constant vigilance during the build phase.  

Team members should familiarize themselves with the rules, but to ensure everything remains in order, consider tasking two team members the be the point people for all rule and material questions.  It should be their job to ensure that all materials and parts used on the robot conform to established competition rules.


Estimate and monitor your robot weight.  Keep a record of the current weight and ensure that weight is a factor in major design modifications.

*DOWNLOAD* Component Weight Table


The transition between the autonomous code and the remote control code happens asynchronously.  In other words, you will not know which loop-through of the autonomous code will be the last loop.  If the autonomous code leaves a mess behind for the remote control code, chances are good that your robot will behave erratically for the remainder of the match.  If you choose to tackle the autonomous part of the game, a logical division of effort is to have a remote control programmer and an autonomous programmer.

The autonomous and the remote control programmers must decide early one which variables will be shared between the two sections of the code.

These shared variables are usually what are referred to as state variables.  They contain information about the status of various components of the robot.  For example, did the autonomous code close a gripper?  If it did, the remote control code needs to know this when it takes control of the robot or it needs to have an initialization section where it sets every state variable to a known and correct value.

If you have decided to have more than one autonomous routine resident in the controller memory – usually a very good idea – you need to provide a mechanism for the competition team to select which routine will be run.


Putting mode switches on the robot is the most straightforward way to do this, but it takes away the ability to make a last second change of strategy.  Mode switches on the robot can be read at all times by the robot controller.  Mode switches on the operator interface cannot be read by the controller during autonomous mode.  The radio link is disabled.  If you want your autonomous mode selection switches on the operator interface, you must write your control program so that it continually reads these switch settings before the match starts.  Once the match starts, the autonomous program will read the last value.


Discuss with other subteams what control functions (range of motion, degree of control, and desired mode of control) will be required for each mechanical system.  Discuss with competition team the preferred way to map joystick / pushbuttons and to design the auxiliary control box.  Design and order all parts for the auxiliary control box.  Discuss to assure adequacy of I/O ports for desired control functions.  Begin assembly of prototype operator interface.

The control station is how your competition team controls the robot.  The FIRST kit provides everything you need to implement most control functions.  The joysticks with multiple triggers and buttons can be programmed to handle various functions.

One decision you need to make is if you plan to have single or dual joystick control.  Using a single joystick to control your robot is probably what you are used to.  Most video games use single joystick operator interface.  If you decide on the dual joystick scheme, the control inputs are similar to driving a tank, or a zero-turning radius lawn mower.  Most teams seem to find the single joystick set-up easier to use.

The rules have always allowed for two operators to control the robot.  If you decide to split the control responsibilities, you need to give some thought to the ergonomics of your control station layout.  In the heat of a match you do not want your operator combo banging into each other as they try to score points.  You will need to provide each operator with his/her own dedicated controls on one portable panel.  One operator could have a joystick for driving and the other a bank of switches for controlling the warp drive.

When you design your operator control station, keep in mind that it must be able to quickly and easily be setup and removed.   FIRST gives you very little time between matches and provides a skinny shelf behind the Plexiglas™ of the alliance station for your control station to sit on.

It is preferable to mount everything on a board or metal plate so the control station travels as a unit.  Don’t forget to leave access so you can plug in the interface cables that are part of the playing field.



So you have a strategy, a robot design, and the team is frantically prototyping, coding, etc.  Now, you need to start thinking seriously about who is going to be operating the ‘bot out on the competition field.  The earlier you have this team identified, the more time these students will have to ready themselves.  

NOTE: Some teams may have determined this group much earlier in the season.

The competition team is comprised of those team members that perform out on the competition field with the robot.  Typically, this is a chassis driver, a features or robot function operator, a Human Player, and a coach.  The coach role can be filled with a student or adult mentor.  All other roles must be students.  

Beyond desire and ability to operate the robot, the “comp team” members should know the robot, game rules, and your team strategy inside and out.  They should also be cool under pressure and be able to communicate effectively with other teams in their alliance.

MOE has selected team members in the past by using an eligibility matrix, which tracks what we believe to be the key criteria

*DOWNLOAD* Competition Team Elegibility Matrix

Although you may not have a robot running on the floor yet, the earlier you select the competition team, the earlier those students can begin mentally preparing for their roles.  Encourage selected candidates to study the game rules.  You may even want to pull together a Game Rules exam as a way to inject some objective criteria into your selection process.

Select comp team alternatives in addition to your primary team.  You never know when an illness or other personal situation may prevent one of your primary team members from fulfilling his/her role.



Continue to check and distribute learnings from the FIRST Team Updates and updated answers from the FIRST Q&A board and/or Chief Delphi.