denkbots' cRi3D_2018

cRi3D POWERUP The Reveal

We used the tools discussed in Part 1 – Game Theory to determine our strategy in Part 2 – Strategy and Research which allowed us to defined our Robot Requirements in Part 3 – Robot Requirements for this season’s game (and game manual).  Now we are ready to build a robot.

The Reveal

To keep this conceptual Robot in Three Days as approachable as possible, we are going to start with the AM14U3, KoP Chassis (am-14u3) from AndyMark. We will build our kit in the 31.5″ wide and 24.3″ long configuration.

Next we will setup our CUBE intake.  First we will open up the front of our robot with the simple AM14U3 Frame Opening Kit (AM-14U3-FRO) from AndyMark. If we look at the largest possible profile of the CUBE (13″x13″), we find that we should open up our front so there is an ~15″ opening.

Next we will build a simple CUBE intake carriage, which is nothing more than 15″ x 4″ rectangle with two arms coming out in a slight V-shape. At the two ends of the V are small drill motors driving 2″ Compliant Wheels to roll things into the V.  At the mid point of the two arms of the V are another set of wheels belt driven from the same drill motors.  You will need to play with the angle of the V to optimize CUBE intake.

Next we need to build our lift system to elevate our CUBE intake carriage.  We will mount two linear slide rails (the rails listed are 55″ so we will need to trim an inch or two off the top so we can fit inside the starting configuration and have ground clearance) towards the back of our robot, by attaching them to the chassis then mounting a crossbeam from the front of our robot up to the top of our linear slide rails (think two big right angle triangles) with a crossbeam across the top.

Now that we have a nice range of travel, we will mount our CUBE intake carriage to the lift system with four Slide Bushings, two on each side of the 15″ x 4″ carriage frame.  This gives us a solid mechanism for lifting a CUBE up and down as fast as we can power it.

Since our goal is to teach the concepts and not give the answers, we will leave how the mechanism is powered up to the imagination.  Maybe a pulley system, maybe multiple pneumatic pistons set for desired heights, maybe a friction drive against the slide rails themselves!

One final note, teams building a system like this will need to make sure they calculate the center of gravity of their robot to ensure fast acceleration doesn’t cause their robot to tip over!


cRi3D Evaluation

This robot can Cross the Auto Line, a.k.a Auto-Run (5 points) and place  CUBE on the SWITCH (2, + 2 points per second), is optimized to have a cycle time of 5.2 seconds to the VAULT and 5.4 seconds to the SWITCH, but does not have a mechanism to be Climb (take a look at the Winch, Shift-to-Neutral, Ratcheting Gearbox from iR3 and the Afterburner Winch Kit to get your brain cooking).

Applying our game theory tool to this conceptual robot, we should be able to achieve the following:

  • “cRi3D_MAX” Autonomous Mode: 31 pts
  • “cRi3D_MAX” Teleoperation Mode: 201 pts
  • “cRi3D_MAX” End Game: 35 pts

The “cRi3D” would be capable of achieving 267 pts by itself in a match.


Novel Ideas

One thing to keep in mind when using an approach like this is to never close your mind off to eccentric and novel ideas.  At first glance a crazy idea like one our students had, which we dubbed the “Japanese Parking Garage” seems unrealistic and out of scope.  The idea was to build a robot that opened up and allowed robots to drive into it, then elevate the robots up within itself, and finally reach up and grab the bar – achieving a HANG for all three robots.

Ideas like this are what make FIRST worth doing.  A novel concept like this allows you to view the technical challenges in a whole new light, and when contemplating ways to accomplish something so outlandish, you might just stumble across real practical solutions for problems you are having with your current design.

Just remember our motto, and the second letter in FIRST:



Hopefully these articles can help new teams, teams in transition, or teams that are just looking for a new and improved way to approach robot design to learn and apply an analytical requirements based approach this season.  If you want to learn more about this process, check out our presentation from the 2017 Purdue FIRST Forums on Robot Requirements! If you have any questions, feel free to reach out to us on Facebook or e-mail us at denkbots(at)gmail(dot)com!

Be Excellent To Each Other
Be Excellent To Each Other
As always, feel free to join the conversation on our Facebook or Twitter with your questions, thoughts, and feedback on these articles!

Leave a Reply