We’re really excited for the 2018-2019 FIRST Tech Challenge game, Rover Ruckus! Before we get started with Build Blitz, we’re going to strategically analyze the game to help determine what robot actions we should focus on.
One of the important factors in doing strategic analysis is working within your team’s resources to maximize your strategic impact. It’s important to be honest and realistic about your team’s resources and what you will be able to achieve before competitions begin. For example, if your team doesn’t have a strong programming foundation, it’s unlikely that you’ll be able to achieve an autonomous routine that requires complex field navigation. However, this doesn’t mean you’re doomed! Doing this kind of strategic analysis allows you to break down the game and focus your team’s efforts and resources on things that are going to allow you to maximize your impact, and (hopefully) win more matches. You don’t always have to do everything!
As we’ve said before, the goal of Build Blitz is not to make a fully custom world championship caliber robot. Instead, we’re trying to work within the means of an average team. This means constructing a robot with common off the shelf (COTS) components, basic hand tools and some light (but optional) 3D printing.
The strategic design process is broken down into 3 main areas:
1) Read the game manual
You can’t begin to break down a game if you haven’t read the rules.
1b) Re-read the game manual
Seriously, you should make sure you know the rules inside and out before even considering building something. Take it from us, there’s nothing more disappointing (read:heartbreaking) than spending a ton of time on a “game-breaking” mechanism, that turns out to be illegal.
2) Understanding the ranking system
We’re going to assume that your goal at a competition is to seed high and win the event. While there are several paths you can take to winning an event, seeding high is always going to increase your chances of doing so. Understanding tiebreakers can also help you understand the priority of scoring options in a game.
3) Understanding scoring and what actions are required to score.
In almost every game, you need to score points to win matches. Understanding the weight of different scoring tasks is imperative to strategic analysis. For example, if Task A is worth 2 points and can be repeated 8 times in a match, but Task B is worth 5 points and can only be repeated twice, which task should you focus on?
Additionally, understanding the actions required to complete a scoring task is vital. Making a list that includes actions required for that task will help clarify what actions your robot will need to be capable of.
We’ll assume all of you have read the Rover Ruckus manual (twice) by now, and will skip to step 2, understanding the ranking system.
In Part 1 of the Rover Ruckus game manual, section 5.8 calls out the ranking criteria:
Since the primary ranking criteria is winning matches, there’s a high likelihood that multiple teams will end up with the same win/loss/tie record. This means that tie breaker criteria are going to be extremely important.
The secondary sorting criteria is TieBreaker Points. This means that while you want to win a match to get 2 Ranking Points (RP’s), you want to keep the final score close to maximize your TieBreaker Points. (i.e. It’s much more beneficial for you to win a “nail-biter” than a blowout) Since this criteria is based on the sum of an alliances points, it’s unlikely that the 3rd and subsequent sorting criteria are going to be used often.
Now that we understand the ranking criteria, let’s move on to understanding scoring tasks and the robot actions associated with it. Keep in mind that this is not meant to be an all encompassing list. It’s important that your team goes through this exercise on their own to make sure you consider all possibilities.
The highest possible (penalty-free) score if you scored every Mineral would be 1,070 points.
The formula for this “perfect” match is a 2 robot landing bonus (60 pts) + 2 autonomous claiming bonuses (30 pts) + 2 autonomous sampling bonuses (50 pts) + 2 parked robots in autonomous (20 pts) + 94 scored gold in Depot (470 pts) + 68 scored silver in Depot (340 pts) + 2 latched robots in the end game (100 pts).
Now, scoring all 162 Minerals would require an average cycle time of less than 3 seconds. So it’s unlikely we will ever see this. Instead, let’s look at the cycle time required to score half of the Minerals on the field (81). This would require an average robot cycle time of less than 6 seconds and would net an alliance 670 points.
When we talk about cycle times, we’re talking about the average time it takes to acquire a game object(s) and score it. This is important to keep in mind when deciding things like what scoring tasks you should attempt, how fast your robot needs to be at doing said task, etc.
Next it’s time to look at the actions listed in the table above and figure out how important they are to our robot.
With the exception of Landing, every task requires driving. Yes, you could play this game without moving, but that is not something that a team with average resources could easily achieve.
Though it may seem redundant, the ability to drive is the #1 robot function in almost any robot game. Even if you only field a reliable drivetrain, you can still play defense or push objects into the Depot to contribute to your alliance’s score. Likewise, even if you had the best scoring mechanisms, your robot won’t be very good without a reliable drivetrain.
Driving Into the Crater (6/10)
This was almost as important as driving, but there are still ways you can play this game without ever driving into the Crater. Being able to drive into the Crater opens up a lot of scoring options for your team. You can park in the Crater during autonomous for 10 points and park completely in the Crater during the end game for 25 points. That’s 35 points you can score for your alliance just by being able to drive in the Crater!
Driving into the Crater also gives you another option to retrieve game objects. There are lots of different ways to do this, including reaching into the Crater. However, some of these can be non-trivial mechanisms. So you have to ask yourself, what are you gaining by not driving into the Crater that’s going to make up for the 35 points you’re leaving there?
Picking Up Minerals Off The Floor (4/10)
This is a requirement if you’re going to score Minerals in the Cargo Hold. Scoring Minerals seems like a given, so the importance of this task seems low. However it’s possible for you to contribute to a match without scoring Minerals at all.
Let’s assume that each robot equally contributed to the 610 point match we talked about above – so 305 points each. 130 of those points were scored without even touching a Mineral. So it’s possible for a single robot with a perfect autonomous mode (80 points) and the ability to latch at the end of the match to make a significant contribution to their alliance. If you want to think about it another way, that 130 points is worth 13 Minerals in the Cargo Hold.
Picking Up Minerals From Crater (3/10)
Since the vast majority of Minerals start in the crater, this is pretty much a given if you are planning on scoring Minerals. There are two options where you don’t have to do this:
A) You’re planning on only picking up Minerals off the floor. There are 9 Minerals on the floor to start a match. If you score all of those into the Cargo Hold that would be 45 points. In addition, teams will inevitably drop Minerals as they are trying to score them into the Cargo Holds, or push them out of the Crater as they drive in and out of it.
Another possibility here is that if your opponent doesn’t claim their Depot, you can steal objects from their Depot. If you do this, you’re actually creating some pretty significant point swings by taking 2 points from them and adding 2-5 points for yourself. That makes each object you steal from your opponent’s Depot really worth between 4-7 points!
B) You decide not to score Minerals at all.
Drop Off Mineral (3/10)
This is similar to picking up a Mineral off the floor. If you’re planning on scoring Minerals, you’re going to need some way for dropping or dumping them into the Depot or the Cargo Hold. There is a very interesting tradeoff that Rover Ruckus presents.
When you’re scoring in the Depot you don’t care about what’s in your possession. However, when you’re scoring in the Cargo Hold you need to sort at some point during the cycle. This means you’re either going to look for 2 of the same object on the floor/in the Crater or you’re going to need a way to drop off one type of Mineral and then the other. Most likely this is going to add additional time to your cycles.
Keep in mind that scoring in the Depot can be a big risk if it is not claimed during autonomous mode. If this is the case, your opponent can steal Minerals from your Depot which, as we explained, above can be a big hit to your alliance.
Lift Mineral Up To Cargo Hold (2/10)
This is a requirement if you’re planning on scoring in the Cargo Hold. The reason this is lower on the list is because you can still score a Mineral by just dropping it in the Depot. Lifting a Mineral up to the Cargo Hold is only required if your analysis determines that those additional points are worth your time.
Attach To Lander Bracket & Lift Off Ground In <30 Seconds (1/10)
This is the highest of the actions that were listed once because it’s worth so many points. Think about it like this. If you give up climbing and are going up against a robot that has the ability to climb, you need to be able to score score at least 50 points in that 30 second to make up the difference. This is the equivalent of 10 Minerals in the Cargo Hold, which breaks down to 5 cycles with an average cycle time of 6 seconds. We imagine this is going to be incredibly difficult for a robot to pull off.
Alternatively, you could park completely in the Crater and score 5 Minerals in the Cargo Hold. Assuming it takes you 5 seconds to park in the Crater, you are left with 25 seconds to run 3 cycles, which means your average cycle time has to be about 8.3 seconds. This is a little easier, but still requires some elite level speed and execution from your robot.
While we say this needs to be done in less than 30 seconds, ideally you want to be faster. Every second you can shave off this task, buys you another second to continue scoring Minerals, playing defense, etc.
When evaluating the value of a given action, this type of tradeoff analysis can often help you to get a feeling for what is ‘most important’ or not. This can also extend into tradeoffs in the middle of a match. For example, there are 10 seconds left in a match. Do you stop and go for a climb you might not finish and therefore get 0 points for, or do you try and score another Mineral or two?
Lower From Lander (1/10)
8 and 9 seem like they go hand in hand, but lowering from the Lander has more importance because if you can start on the Lander, but can’t lower your robot from it, you effectively didn’t show up to your match. The landing bonus is a high scoring task you can do in autonomous and doesn’t require any complicated sensing and navigation to achieve this. We think this can end up being one of those tasks that “looks hard, but is (fairly) easy”.
Start on Lander (1/10)
This is really 8b since you need to start on the Lander to get the landing bonus.
Remove Mineral From Sample Field (1/10)
Removing only gold from the Sample Field is worth 25 points if done in autonomous. Since it’s the second highest point value in autonomous it ends up down here. This is interesting because it can dually reward you. For example, say your method of removing gold is to just pick it up off the floor. If you use dead reckoning (always picking up the Mineral in one of the three specific locations) to try and achieve this task and you pick up a Silver Mineral instead of a Gold Mineral, you will forfeit the 25 point bonus, but will start with 1 object in your possession. This means right out of driver control, you can go pick up another object and score it. However, if you use dead reckoning and do manage to pick up a piece of Gold, you then get the 25 points AND you start with one object in your possession.
Starting with an object in your possession is important because it’ll cut down your first cycle time, which will help lower your average throughout the match, thus allowing you to maximize your Mineral scoring potential.
Remove Only Gold From Sample Field (1/10)
This is related to “Remove Mineral From Sample Field”. While your immediate reaction when you see “Remove Gold From Sample Field” is to start pouring resources into an advanced autonomous routine that can detect Gold. However, as mentioned above, if you use dead reckoning you and miss, you’re still starting the driver controlled period with a Mineral in your possession, which is still helpful.
With that in mind, this action was weighted below “Remove Mineral From Sample Field”. This is another example of a tradeoff your team will have to evaluate as they analyze Rover Ruckus.
Deploy Team Marker (1/10)
This task is interesting, as you can only get points for it in autonomous. This means that if your alliance isn’t planning on scoring in the Depot it might not be worth doing this at all. However, if you think there’s even the slightest chance that you’ll need to score in the Depot, you should probably do this since it goes toward claiming your Depot and preventing your opponent from stealing objects. As we mentioned previously, stealing objects from your opponent’s Depot and scoring them for yourself has a greater impact on the score than scoring objects from the floor or Crater for yourself.
That’s a pretty simple priority list for Rover Ruckus. This should hopefully be a pretty good starting point that your team can reference when they go through this process on their own. We can’t stress enough how important it is that teams complete this process themselves. Each team will have a different set of resources and priorities, so it’s impossible for there to be a one-size-fits-all ranked priority list that applied to teams. When doing this on your own, be realistic about your team’s resources and capabilities. It’s good to challenge yourself, but make sure you’re not going overboard and taking on more than your team can handle.
If you want some additional tools to help you out when figuring out your robot strategy, we’ve created a calculator that breakdowns scoring and cycle times in Rover Ruckus. It can be downloaded here: https://link.vex.com/RR-Cycle-Calculator