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 operate on ground level) 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 AUTO Mode: 53 pts
- MAX TELEOP Mode: 120 pts
- MAX End Game: 40 pts
MAX TOTAL: 213 pts
BOTTOM
What if we could only score a POWER CELL in the BOTTOM PORT of the POWER PORT?
Assuming a robot could only place a POWER CELL in the BOTTOM PORT of the POWER PORT we could model a match as follows (holding the same assumptions and cycle times from Part 1):
| Cycle | Action | Time | Total |
| 1 | Starting Half Cycle | 16 | 16 |
| 2 | ROTATIONAL Cycle | 5 | 21 |
| 3 | POWER CELL Cycle 1 | 20 | 41 |
| 4 | POWER CELL Cycle 2 | 20 | 61 |
| 5 | POSITIONAL Cycle | 5 | 66 |
| 6 | POWER CELL Cycle 3 | 20 | 86 |
| 7 | POWER CELL Cycle 4 | 20 | 106 |
| 8 | POWER CELL Cycle 5 | 20 | 126 |
With this strategy, we secure (30) POWER CELLS (30pts) then complete the ROTATIONAL (10pts) and POSITIONAL (20pts), then we hang (40pts). Also, our autonomous mode is the same as before, except we score in the LOW PORT (21pts).
NOTE:While we assume we are playing “by ourselves” in an imagined scenario where both of the other robots are just KOP Chassis bots, while we can safely assume in any given match that we will still gain at least 5pts each from the other bots driving onto RENDEZVOUS POINT we don’t have enough for the SHIELD GENERATOR OPERATIONAL.
Below are the scores for each mode of this strategy:
- MIN AUTO Mode: 21 pts
- MIN TELEOP Mode: 60 pts
- MIN End Game: 40 pts
MIN TOTAL: 121 pts
OUTER
What if we could only score a POWER CELL in the OUTER PORT of the POWER PORT?
Assuming a robot could only place a POWER CELL in the OUTER PORT of the POWER PORT we could model a match as follows (holding the same assumptions and cycle times from Part 1):
| Cycle | Action | Time | Total |
| 1 | Starting Half Cycle | 16 | 16 |
| 2 | ROTATIONAL Cycle | 5 | 21 |
| 3 | POWER CELL Cycle 1 | 20 | 41 |
| 4 | POWER CELL Cycle 2 | 20 | 61 |
| 5 | POSITIONAL Cycle | 5 | 66 |
| 6 | POWER CELL Cycle 3 | 20 | 86 |
| 7 | POWER CELL Cycle 4 | 20 | 106 |
| 8 | POWER CELL Cycle 5 | 20 | 126 |
With this strategy, we secure (30) POWER CELLS (60pts) then complete the ROTATIONAL (10pts) and POSITIONAL (20pts), then we hang (40pts). Also, our autonomous mode is the same as before, except we score in the OUTER PORT (37pts).
NOTE: While we assume we are playing “by ourselves” in an imagined scenario where both of the other robots are just KOP Chassis bots, we can safely assume in any given match that one of them will be able to be lifted.
Below are the scores for each mode of this strategy:
- MID AUTO Mode: 37 pts
- MID TELEOP Mode: 90 ptS
- MID End Game: 40 pts
MID TOTAL: 167 pts
REVIEW
After evaluating three strategies we have the following:
| MODE | MAX | MID | MIN |
| AUTO | 53 pts | 37 pts | 21 pts |
| TELEOP | 120 pts | 80 pts | 60 pts |
| END | 40 pts | 40 pts | 40 pts |
| TOTAL | 213 pts | 157 pts | 121 pts |
We can see that the difference between MID and MIN is 36 pts, the difference between MAX and MID is 56 pts, and the difference between MAX and MIN is 92 pts. This highlights that the increased accuracy of a dumper could provide an advantage over an OUTER PORT shooter with medium accuracy.
Decisions Decisions Decisions
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 POWER CELLS in the BOTTOM PORT.
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 poof-style balls and a climbing objective.
If we look back at previous games that had similar poof-style ball, we find:
If we look for games where robots had to lift themselves off the ground and hang on a single bar, we find:
If we look for games where robots had to manipulate standard sized balls into a goal, we find several examples but we are just going to pick just a few of our favorites:
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.
Hop on over to Part 3 – Robot Requirements for more fun!
If you want to learn more about this process, check out our presentation from the 2017 Purdue FIRST Forums on Robot Requirements!
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