2019 / 2020 Skystone

Game Analysis and Strategy

Playing Skystone well involves a strategy that succeeds in performing all tasks presented in the challenge. The major tasks associated with Skystone are detecting and delivering skystones, moving the foundation and parking during autonomous, acquiring stones and stacking them on the foundation during tele-op, and placing capstones, moving the foundation, and parking during end game. 

With the objective of being able to perform competitively, at a very high level, our first

goal was improving from last year’s robot, place higher, and to be able to choose our

alliance partners. We set out to have the highest scoring robot possible, to help create

strong alliances. We tried to create a robot that was equally strong in autonomous as it

is in tele-op. To accomplish this, we had a strategy and prototyping weekend, where we:

  • Analyzed the game and identified the ways to score points
  • Identified the constraints of the game (the rules, and dimensions of the field and game elements)
  • Brainstormed and prototyped mechanisms to work with the game elements, and used existing drive bases to understand the movement around the playing field

We came up with the following list of tasks and possibilities of performing them during autonomous:

Tasks Time estimateProbability of completionpoints
Repositioning7 sec100%10
Skystones5 s/per100%20 (only if initial 2)
Stones5 s/per100%2
Placing2 s/per75%- VARIABLE4
Navigation3 sec100%5

Based on the above estimates, one robot could move 2 skystones and one additional stone in Autonomous if it also has to reposition the foundation.

Tele-op and end game present a set of challenges that required us to work harder at prioritizing the design for the drive base and mechanisms that would be used. Our analysis of potential scoring scenarios is below:

Scenario 1 (one block skyscraper)Points:
Delivered stones15
Placed stones15
Total points60

We determined that the maximum stable height is 15 blocks.

Scenario 2 (two blocks per level, changing directions)Points:
Delivered stones30
Placed stones30
Levels: 1530
Total points90

Therefore task priorities are:

  • Going under the alliance specific skybridge is a must, otherwise we miss out on potential points.
  • Collect, deliver, and place new stones to increase the height of the tower.
  • If other alliance drops a stone, grab it instead of one from the depot (it saves time)
  • Rearrange already delivered stones into tower in order to make a secure skyscraper to decrease the possibility of it toppling.
  • There is no need to alternate alignment at every level. This is only a concern at higher levels of blocks because it increases the stability of the tower. Doing this at every step is unnecessary and may waste time.

Robot Design Strategy

  • Stacking
    • Ideally the robot would stack blocks perpendicular to each other, but this requires much greater speed.
  • Maximum height
    • The maximum skystone tower we could build by hand was 15 levels — about five feet high.
    • But the robot had to be less than 14” tall to fit under the skybridge.
  • Foundation mechanism
    • Simple, servo-driven hook mechanism which grabs onto the foundation.
  • Skystone Detection
    • The robot needs a camera to determine which stones are skystones.
  • Delivery Mechanism
  • Pick up from the top
    • Able to rotate blocks 90 degrees for placing
    • Needed to be able to build a tower as high as possible
      • If double-stacked, 15 levels
    • Speed – needs to be able to deliver a new stone every few seconds.
    • Lift speed – needs to raise to full height in a second or two.
  • Intake Mechanism
    • Wheeled intake and ramp.

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