denkbots' cRi3D PartTwo: Strategy and Research

cRi3D STEAMWORKS Strategy and Research

FIRST

With a thorough understanding of the this season’s game and game manual along with tools discussed in Part 1 – Game Theory we are ready to talk strategy!

Strategery

Now that we have a tool to evaluate the optimal scoring of an FRC game we can add constraints to our rational agent (for example, the robot is only allowed to score in the low goal) and approximate the scoring potential of other strategies and confirm/deny our initial assumptions.

The optimal strategy we found in Part 1 had no constraints, the robot could do everything. We will consider this our “MAX” points to start.  The evaluation from Part 1 determined the following scores:

  • MAX Autonomous Mode: 75 pts
  • MAX BOILER Teleoperation Mode: 66 pts + 1 RP
  • MAX GEAR Teleoperation Mode: 80 pts
  • MAX End Game: 50 pts

The “MAX” strategy achieved

  • MAX BOILER Total: 191 pts + 1 RP
  • MAX GEAR Total: 205 pts

OPTIMAL

But what if we could blend these two maximized modes? For example, what if we designed the best robot for doing everything? We will call this our “OPTIMAL” strategy.

Assuming a robot could do everything, including picking up FUEL from the floor, we will recalculate our cycle time as follows (starting at the KEY in the end of :auto mode)

  1. ~ 1 s to travel to the HOPPER
  2. ~ 2 s to align the robot to engages the opening mechanism
  3. ~ 4 s for the FUEL to be collected
  4. ~ 1 s to travel to the KEY
  5. ~ 3 s to align the shot
  6. ~ 10 s for 50 FUEL to be deposited in the High Efficiency Goal

Cycle Time: 22 s
Total Time: 22 s

Cycle Points: 16 + 2/3 pts, 16 + 2/3 kPa
Total Points: 16 + 2/3 pts, 16 + 2/3 kPa

After scoring, the robot (the rational agent) decides to go get a GEAR and FUEL:

  1. ~ 1 s to travel to the LAUNCHPAD LINE
  2. ~ 4.5 s to travel to the Retrieval Zone
  3. ~ 2 s to align the robot to receive a GEAR + 20 FUEL
  4. ~ 2 s for the GEAR + 20 FUEL to be collected
  5. ~ 1 s to travel to the HOPPER (nearest the Retrieval Zone)
  6. ~ 4 s for 50 FUEL to be collected
  7. ~ 4.5 s to travel to the Airship
  8. ~ 2 s to align the GEAR
  9. ~ 1 s for GEAR to be deposited
  10. ~ 1 s to travel to the KEY
  11. ~ 3 s to align the shot
  12. ~ 13 s for 70 FUEL to be deposited in the High Efficiency Goal

Cycle Time: 39 s
Total Time: 61 s

Cycle Points: 23 + 1/3 pts, 23 + 1/3 kPa, 1 GEAR
Total Points: 40 pts, 40 kPa, 1 GEAR

Next, the robot again decides to go get a GEAR and FUEL (we assume there will be another 20 FUEL at the Retrieval Zone):

  1. ~ 1 s to travel to the LAUNCHPAD LINE
  2. ~ 4.5 s to travel to the Retrieval Zone
  3. ~ 2 s to align the robot to receive a GEAR + 20 FUEL
  4. ~ 2 s for the GEAR + 20 FUEL to be collected
  5. ~ 4.5 s to travel to the HOPPER (second down from the Retrieval Zone)
  6. ~ 4 s for 50 FUEL to be collected
  7. ~ 1 s to travel to the Airship
  8. ~ 2 s to align the GEAR
  9. ~ 1 s for GEAR to be deposited
  10. ~ 1 s to travel to the KEY
  11. ~ 3 s to align the shot
  12. ~ 13 s for 70 FUEL to be deposited in the High Efficiency Goal

Cycle Time: 39 s
Total Time: 100 s

Cycle Points: 23 + 1/3 pts, 23 + 1/3 kPa, 1 GEAR
Total Points: 63 + 1/3 pts, 63 + 1/3 kPa, 2 GEARS

Finally, the robot decides to go get a final load of FUEL (we assume there will be another 20 FUEL at the Retrieval Zone):

  1. ~ 2.5 s to travel to the HOPPER
  2. ~ 2 s to align the robot to engages the opening mechanism
  3. ~ 4 s for the FUEL to be collected
  4. ~ 2.5 s to travel to the KEY
  5. ~ 3 s to align the shot
  6. ~ 10 s for 50 FUEL to be deposited in the High Efficiency Goal

Cycle Time: 24 s
Total Time: 124 s

Cycle Points: 16 + 2/3 pts, 16 + 2/3 kPa
Total Points: 80 pts, 80 kPa, 2 GEARS

Finishing up Teleoperation Mode, this leaves us with the 2 GEARS necessary for one turning ROTOR (+40 pts). We assume the robot can travel from the KEY and be Ready For Takeoff in ~ 11 s.

With this optimized strategy worked out, the following scores can be determined:

  • “OPTIMAL” Autonomous Mode: 75 pts
  • “OPTIMAL” Teleoperation Mode: 120 pts + 1 RP
  • “OPTIMAL” End Game: 50 pts

The “OPTIMAL” strategy can achieve 245 pts + 1 RP.

MID

But what if the robot could only deposit FUEL in the High Efficiency Goal?  We will call this our “MID” strategy.  Repeating the exercise from Part 1 (since the robot can not hang a fifth cycle of 50 balls will be assumed), the following scores can be determined:

  • “MID” Autonomous Mode: 15 pts
  • “MID” Teleoperation Mode:83 pts + 1 RP
  • “MID” End Game: 0 pts

The “MID” strategy can achieve 98 pts + 1 RP

MIN

Finally, we ask: What is the bare minimum a robot able to navigate the easiest objectives of the game could score?  We will call this our “MIN” strategy.  Since we are dumping FUEL in the Low Efficiency Goal instead of shooting into the High Efficency Goal, we will assume it takes half the time.

  1. ~ 1 s to travel to the HOPPER
  2. ~ 2 s to align the robot to engages the opening mechanism
  3. ~ 4 s for the FUEL to be collected
  4. ~ 1 s to travel to the KEY
  5. ~ 2 s to align the shot
  6. ~ 5 s for 50 FUEL to be deposited in the Low Efficiency Goal

This gives us a first cycle time of 15 s and a score of 5 + 1/2 pts, 5 + 1/2 kPa.

Using the same travel times from our MID strategy, the second cycle would take 18 s, the third cycle 21 s and the fourth cycle 24 s.  With plenty of time remaining (63 s spent), the robot will go collect the final HOPPER of FUEL

  1. ~ 5.5 s to travel to the HOPPER (nearest the Retrevial Zone)
  2. ~ 2 s to align the robot to engages the opening mechanism
  3. ~ 4 s for the FUEL to be collected
  4. ~ 5.5 s to travel to the KEY
  5. ~ 2 s to align the shot
  6. ~ 5 s for 50 FUEL to be deposited in the Low Efficiency Goal

This gives us a fifth cycle time of 24 s.  Assuming FUEL will have accumulated at the Retrieval Zone by this point in the game, the robot will finish the match by collecting two loads of FUEL from the Retrieval Zone (24 s cycle time).  This gives us 7 cycles of 50 FUEL into the Low Efficiency Goal and the following scores can be determined:

  • “MIN” Autonomous Mode: 8 pts (3 + 1/3 kPa)
  • “MIN” Teleoperation Mode: 38 pts (38 + 7/9 kPa)
  • “MIN” End Game: 0 pts

Combining the Pressure accumulated between Auto and Teleop Mode, the Pressure Threshold is achieved and one RP is earned.

The “MIN” strategy can achieve 46 pts + 1 RP

Decisions Decisions Decisions

After reviewing different strategies with our new tool, we can make some observations:

  • The 1 RP awarded in the qualifying rounds for reading the Pressure Threshold is equal to 20 pts in the playoff rounds, which is approximately equal to ~ 3 LOW cycles or ~1 HIGH cycles.
  • The 1 RP awarded in the qualifying rounds for ROTOR achievement is equal to 100 pts in the playoff rounds, which is approximately equal to 18 LOW cycles or 6 HIGH cycles.
  • By specializing on one task, a robot can have the largest individual impact on a qualifying OR playoff match by depositing GEARS.
  • By focusing on FUEL, a robot can assure at least 1 RP per qualifying match and 20 pts per playoff match.
  • Per second, a robot can score points the most optimally in Autonomous Mode.

During a qualification match, on average with our models, approximately 28% of points will be scored in Autonomous Mode, 58% of points will be scored in Teleoperation Mode, and 14% of points will be scored in the End Game.

Before we choose a strategy, we have to decide what we want to accomplish with our robot.

  • Do we want to build a robot that might perform average in the qualifying matches, but will position us to be picked onto a strong Alliance for the Finals?
  • Do we want to build a robot that will best position us to win all of our matches and be a top Alliance Captain?
  • Do we have limited resources and want to build the simplest robot that can give us the highest impact in any given match?

That is up to each team to decide for themselves, as a group. Approach this question realistically, but don’t sell yourself short. Pick an attainable goal and stick to it. For the purposes of this article, we are going to choose to accomplish a goal in-between winning over 50% of our matches at any given event and winning a world championship: We are going to compete for a State Championship.

To accomplish this goal, our robot will need to qualify for the State Championship by winning a District Event.  We will define this goal as our Robot Mission Statement. This term will be the basis of our next article, so tuck it in the back of your head for later.

Given our models, observations, and Robot Mission Statement; we are going to choose the strategy that allows us to have the largest individual impact on a qualifying match. This means we will evaluate designs for a robot that can most efficiently retrieve and deposit GEARS.

Now this is a very good stopping point for your first “brainstorm/strategy” meeting. Before students leave, we always give the most important homework assignment of the season: RESEARCH EXISTING TECHNOLOGIES!

Research

Once you have gone over the game, ran through the game theory, and reasoned out an initial strategy it is time to step back and gather perspective on your assumptions and aspirations.  A great way to do this is to see what other teams were able to accomplish in previous games with similar scoring objects and objectives.  For example, this year’s game has Wiffle-style balls and a climbing objective.

If we look back at previous games that had Wiffle-style balls we don’t find much, but if we look at games that have small spherical game pieces in general, we find:

If we look for games where robots had to lift themselves off the ground and hang, we find:

If we look for games where robots had to both deal with sperical game pieces and lift themselves off of the ground, we find:

Yet all of these games require hanging off of a bar… If we look extra hard though, we can even find a game that required teams to, in a fashion, scale a “rope” type obstacle:

By researching the strategies used in previous games with similar scoring objects and objectives, and by researching the mechanisms teams used to manipulate those scoring objects and complete those objectives, students can put into perspective what is possible and begin to formulate better and more efficient ways of accomplishing the game objectives by building on the work of their forerunners.  This is the same approach college engineering students use when evaluating their Senior Design Projects, scientists use when writing papers to be published, and inventors use when patenting new creations.  This process allows us to, as Sir Isaac Newton once said, stand on the shoulders of giants.

Below are the game animations for the aforementioned games to research and a match from each game:

Summary

So what value did these exercises add?  By maximizing each individual scoring objective, and questioning our previous assumptions, we were able to determine the impact of each scoring objective.  By walking through the optimal match flow for each maximized scoring objective, new strategies and design considerations can be found.  By researching previous games with similar scoring objectives, strategies can be put in perspective and novel approaches can be uncovered.

These exercises also build buy-in with the students and mentors on a strategy, reducing confusion and conflict later in the season, and provide a focus moving forward for defining Robot Requirements.

Head on over to Part 3 – Robot Requirements for more fun!

Please feel free to join the conversation on our Facebook or Twitter with your questions, thoughts, and feedback on these articles!

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