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January 30, 2018

Surviving the Robot Inspection Process

Surviving the Robot Inspection Process

Robert C. Tate, Ph.D. & Jeff Rees

Relax.  Inspections are only stressful if you let them be.  The inspectors are here to help you enjoy your FIRST experience and are not out to pick on you.  Many are team mentors and/or engineers as well as inspectors so they know what you have gone through to get to the competition event.  You can ask them for advice on things as well, especially early on Thursday.  Inspectors can spot problems that might keep your robot from performing at its best, and point out these problems to you before they become disasters.  So, if you’re over size or over weight, they can show you how they solved those problems in the past.  Remember, both you and your inspector are trying to enjoy the competition, not stress each other out.

During the inspection, please have a minimum of people present in the pit.  When I inspect robots, I like to have the students who built the chassis, electrical system and pneumatic system to explain the robot to me – ideally only the two or three students who lead the construction effort and perhaps one mentor.  It’s alright if the team wants to watch, but please do it from a short distance away.  It is very difficult for all if the entire team is standing around in a 10’x10′ pit while the inspector tries to look at their robot.  It’s hard for an inspector to ask questions about the robot, and have four people answer.

  1. The purpose of the robot inspection process is not to keep your robot from competing, but to make sure that you can compete with a safe and reliable robot, that will not damage the playing field or other robots, and that no robot has an unfair advantage by means of rule infractions.
  2. To design a robot that will pass inspection, you must read and understand all the rules in the sections on Robot and Game in the Game Manual. Both sections have rules affecting robot design. Remember, a rule is not just a suggestion of something you might think about considering when you build your robot; it is something that you must  Your robot will not compete until it passes inspection, and that means that it must meet all the rules.   Robot rules are like specifications in the real world.  When a company is hired to design a new product, the customer has a list of specifications that must be met.  These specifications depend on how the customer will use the product and may not make sense at first glance, but are important and necessary to the customer.  Think of robot rules as specifications from FIRST that you must meet even if you don’t always understand why.
  3. The official rules are found in the Game Manual on the FIRST web site (www.firstinspires.org). Official interpretations are also found in the Q&A section of the FIRST web site, and teams can request official rulings and interpretations from this source.  Be sure you have read the rules before submitting a question and only ask questions where the rules are unclear.  Keep hard copies of all interpretations if you depend on the interpretations for the design of your robot so that you can show them to the inspectors.  Also, rule updates and changes are posted about once per week, so check the FIRST web site often during the build season right up to the time of your competition.
  4. Things you read on Chief Delphi and other forums are not official rulings.
  5. Over time, rules change. Just because something was legal last year doesn’t make it legal this year.  Read this year’s rules!
  6. All robot systems are inspected, including the frame, mechanics, manipulators, electronics, pneumatics, motors, and bumpers. The inspection will follow a standard “checklist” – the 2017 version of it can be found here – https://firstfrc.blob.core.windows.net/frc2017/AuxDocs/2017FRCInspectionChecklist.pdf

Inspecting your robot before you put it in the bag will help you identify any areas that need attention and make the process smoother.

  1. At the competition, don’t wait until the last minute to get your robot inspected – try to get your inspection done as early as possible, in case you must make major changes. Partial inspections are your friend – you can ask for a partial inspection if some of your systems aren’t quite ready, getting the final inspection when all changes are made.  The scale is usually open for use for a lot of the day.  So, the first thing you should do after un-bagging your robot is to go weigh it.  It makes for an unpleasant surprise if you discover an hour before the pits close for the night that you are over the weight limit.  It doesn’t have to be part of an inspection or any sort of official weigh-in, just get an idea of where you stand.  Get your robot’s weight and sizing done early and the rest should be a breeze.
  2. Your robot must meet the frame perimeter requirements and meet the weight requirements. If the rules say your robot may be a maximum frame perimeter of 112 inches, plan on building it with a frame perimeter of perhaps no more than 111 inches.  Your robot at the smaller size will work just fine, and you won’t have to worry about its being too large.  Also, be sure you build your robot with square corners.  Even if your side dimensions are less than the allowed sizes, it may not fit within the frame perimeter if the corners aren’t square.  This is particularly true for tall robots.  The top of a 48 in. tall robot that is only 1 degree out of square will be shifted over by more than ¾ in. with respect to the bottom of the robot.  Remember, the frame perimeter defines a vertical plane that your robot MUST be inside of at the start of the match.
  3. Pay attention to rules about protruding bolt heads and axles.
  4. Your robot will be inspected to make sure there are no sharp corners, protruding screws, sharp edges or other features that could damage the field or personnel, and that it has no features that could cause it to get entangled with other robots. I don’t like to see blood, especially my own!
  5. All robots must have bumpers as specified in the rules. In recent years, bumper design has become more complicated. In fact, bumper design is sometimes driving the whole design of the robot.  Look closely at the rules on bumpers before designing your robot.
  6. Make sure you are following the team number/lettering rules. They are often overlooked – especially the part about contrasting color. Scouts have a hard time seeing some color combination; judges, referees, and field crew are closer, but don’t like having to work on something that they shouldn’t have to.
  7. This year the maximum robot volume includes the required bumpers, meaning your robot will be evaluated for two conditions – the starting volume, constrained by the frame perimeter of your design and then for the maximum allowed volume for the configuration you have chosen. When you present your robot for the initial inspection, please have the bumpers off, but bring them and all necessary mounting hardware and tools with you.  Following the examination of your frame perimeter, you will be asked to mount the bumpers to allow evaluation of the robot’s maximum volume.
  8. As you build your robot, it is a good idea to maintain a weight budget. Weigh all required components first (wheels, gear boxes, chains, motors, control system, pneumatics).  These weights are fixed and can’t easily be reduced.  As wiring, frame, mechanisms, etc. are added, put their weight on your chart.  It is very difficult to take weight out of a completed robot.  Your local veterinary clinic might have a platform scale you can use to weigh your robot.
  9. Make sure you only use allowed parts. Motors from previous years often are different from the current year motors, even though they appear similar.  Please bring documentation for any parts you are unsure about using (or that you think the inspectors will ask about).  For instance, any large servo motors will require documentation with performance specs, as will any unusual pneumatic cylinders or “nonstandard” pneumatic valves.  Remember, it is your responsibility to prove to the inspector that everything is within the requirements of the rules.
  10. The electrical inspection will look for proper wire sizes and wire colors, correct direction of current flow (don’t connect the negative side of your battery to your main breaker), allowed motors and controllers, correct battery, and proper wiring of sensors. Further, make sure no electrical connections are made to the robot chassis.  Pay particular attention to cameras as many of the common units are internally grounded.  Mounting them directly on a metal part will connect your frame to the electrical ground.  Avoid this by using an insulating material and nylon bolts to mount these components.  Make sure your wire connections are taped up such that there are no stray wires visible.
  11. Be sure to mount your main breaker in a place where field personnel can easily reach it to turn off your robot if it starts smoking. Include clear markings to allow field personnel to find it quickly, if necessary.  Don’t put it where another robot might bump the breaker and shut down your robot.
  12. Mount your battery solidly, preferably with a strong strap or other retention system for easy removal. Your battery has enough energy in it to weld steel, so you don’t want it to fall out of your robot if your robot gets flipped over.  I’ve seen batteries ejected from robots on the field!
  13. The pneumatic system must be composed of allowed parts that are designed to meet certain minimum pressures. Have documentation on any non-kit part showing that it meets specification.  Connect your pneumatic system following the FIRST pneumatic instruction manual (available on the FIRST web site).  Required parts include the Kit-Of-Parts compressor, relief valve (set to 125 psi), vent valve, pressure regulator, accumulators, solenoid valves, approved tubing, fittings, and cylinders.  Other than tubing, no components may be modified.
  14. Mount the vent valve where the field personnel can dump air pressure in an emergency. Include clear markings to allow field personnel to find it quickly, if necessary.  Don’t put it where another robot might bump the vent valve and disable your pneumatic system.
  15. All power for the pneumatics system must come from your on-robot battery, even if your compressor is not mounted on your robot. The off-board compressor must be controlled by the on-board control system.  You may not use any other compressor to charge your pneumatic system.
  16. Decorations (lights, colors, etc.) may not interfere with the operation of systems on other robots (cameras etc.)
  17. Be prepared to show the Inspector a detailed Cost Accounting Worksheet (CAW). FIRST has made a form available for this on the website.  You must list all parts and materials you use on your robot (except COTS items costing less than $5.00 ea.), including everything you use from the Kit-Of-Parts (no need to list KOP parts costs).  If you took advantage of the services of Kennesaw State University in fabricating any parts, be sure to include the costs of the materials and services provided under this program.  The rules explain how to calculate costs for materials and donated items.  Have your CAW ready in a hard copy format or be prepared to show the electronic version to the Inspector. There is no guarantee that someone will be able to print one for you from your jump drive.
  18. Any significant changes to your robot made during competition require a reinspection.
  19. Did I mention that you need to read and follow ALL the rules?

 

Inspectors occasionally do make mistakes.  Inspectors are intelligent and helpful, but knowledge of the rules and their experience is varied.  With the difficulty of interpreting requirements, you must know the rules well.  If you even think you are in a “grey area” of the rules, keep copies of relevant Q&A responses and the rulebook at hand.  If you have a Q&A answer as support for the legality of a robot component, PRINT IT OUT.  If something comes up, do not be afraid to discuss it with your inspector, but be respectful and support your argument with facts.  If necessary, bring the matter to the attention of the Lead Robot Inspector.