Drive Systems... ...The FIRST Arms Race?

[Jaine Perotti]

Originally Posted by Joe Johnson

I have not really been on a team for 3 seasons now -- perhaps 4 depending on how you count things. From the outside looking in, I seems to me that FIRST has become an Arms Race of sorts, every year there are more and more teams with more and more motors devoted to their drive system with grippier and grippier treads.

There are a number of reasons for this trend.

• FIRST game designs have encouraged pushing matches.
• Too many motors have been introduced to the kit [1]
• The FIRST KOP transmissions have encouraged 2 Motors per side (4 motor drives)
• It has become easier and easier to implement multimotor drive systems with very grippy tires [2]

Dr. Joe -

I definitely haven't been involved in FIRST for as long as you have, but within my scope of experience (5 years in FIRST), I disagree when you say that defense has been on the rise. Even back in 2002 (the year before I joined my team), a strong drivetrain and lots of pushing power was very important. In 2003, defense was king. Ever since 2003, I feel that defense has actually been steadily de-emphasized. In 2004, defense and offense were about equal in importance (the ideal balance in my opinion). In 2005 defense was almost completely eliminated from any place of importance. Last year, defense was slightly more emphasized, but you still couldn't win the game on defense alone. It's tough to make a call about defense this year yet, but certain rules (i.e. - you aren't allowed to de-score opposing ringers) lead me to believe that FIRST (the GDC at least) is trying to balance the forces of defense and offense (if not outright giving offensive teams the advantage).

Also, the addition of more motors to the kit does not necessarily mean that FIRST is trying to encourage a drivetrain arms race. More motors could mean more easily facilitated (and more complex) offensive arm designs as well.

I'm not going to disagree with you on your last two points, but I don't think that those two facts are necessarily a bad thing. How many teams would want to use the KOP transmissions if they felt that they would be inadequate in terms of pushing power? Correct me if I am wrong (you are probably in a better position than I to judge this), but I don't think multimotor drivetrains are any more prevalent than they were in 2003, my rookie year. I think that in encouraging teams to use 2 motor/side transmissions, FIRST is just trying to level the playing field by providing a competitive solution that is accessible to all teams.

Originally Posted by Joe Johnson

BUT... ...from FIRST's point of view, I think this is bad situation.

• It is harder on the field elements
• It is harder on the other robots
• It makes teams do a lot of extra work just to keep up, for limited competitive value and almost no inspirational value.
• It is no fun to watch (imho)

I am unsure about your first point. I think the wear and tear on the field elements is highly dependent on the nature of the particular game. I would say that most damage to field elements are more commonly the result of intense offensive play, as opposed to defensive play. For example - the tetras in 2005 broke frequently as a result of long falls from offensive arms. Balls in 2004 were popped by grippers and claws and rollers. The 2006 balls were chewed up by shooting machines. However, one could attribute carpet damage and other field damage to defensive play. It seems to go both ways and I am not sure of the overall effects of offense vs. defense on the playing field.

As for your second point, yes, you are probably right. More defense will result in more damage to other robots. However, one could say that this encourages teams to be come up with more robust designs (a good thing, IMO. It's important to engineer robust solutions in the real world - not just elegant or showy ones).

I definitely disagree with your last two points. I really don't think it is too much extra work to design for 2 motors/side as opposed to 1. If I'm going to sit down and design a transmission, it would probably take me the same amount of time regardless of how many motors I wanted to use. Plus, the 2 motor solution is easily facilitated by the KOP (or at least it was in 2005 and 2006).

My main disagreement, however, is with the statement "limited competitive and inspirational value." Innovative drivetrains have certainly shown their value in competition. On my old team, 716 (and many other teams, I'm sure), the drivetrain was always placed at the very top of our priority list. We knew that we would not be able to do anything effectively if our drive system could not meet our needs. For example, we decided that we wanted 2 speeds so that we could play defense effectively, but still be fast enough to move around the field and complete our offensive tasks. This meant that we needed to design and manufacture our own custom transmissions.

How is it less inspirational to design a custom transmission than to design an end effector? How is it less inspirational to design and manufacture a mecanum wheel than to design a turret? I think any design project like this is a beneficial experience to the students on the team. It doesn't matter whether it's a part of the drivetrain or a part of the arm; as long as the students see the end result of their work, both are inspirational. Just look through the pictures on CD media tagged with "drivetrain", "wheel", and "transmission", and try to tell me that there is no innovation occurring within those disciplines!

Also, I think that defense is a very important and necessary part of the game (strategically and in terms of its "interestingness"). However, I do believe in a balance between the two elements. In the perfect game, an excellent offensive team should be able to beat an average defensive team, and an excellent defensive team should be able to beat an average offensive team. 2004 was the perfect example of a "balanced" game - good defense AND good offense could win a match. In 2003, the scales were tipped too much in favor of the defensive teams; conversely, in 2005 the scales were tipped too much in favor of the offensive teams.

On a side note, how can anyone say that defensive play is boring to watch? I will never forget the 2004 finals and semi-finals on Archimedes when my team, 716, was faced off against some of the strongest defensive (as well as offensive) bots in the world! That defense was some of the most intense (and visually and emotionally awesome!) that I have ever seen (494, you are amazing). It was heart pounding and exhilarating - I wouldn't ever want to trade that for a technically interesting, but rather boring exhibition of robots that are just scoring (and no one is trying to prevent them from doing so). The presence of defense makes it even more amazing to see high-scoring robots perform - knowing that they are experiencing difficulty, yet are still able to overcome!

Definitely do not impose limits on the amount of power in the drive system. As it is right now, the amount of power a team can have is already somewhat limited by their coefficient of friction against the ground, so potential power is not infinite (after a certain point, the wheels will just begin to spin against the carpet in a pushing match). Yes, the extra power will help in acceleration, but there comes a time when too many motors becomes more costly in terms of its draw on the battery (and less motors available for other manipulators) than it is worth. I don't fear that defense will intensify in the likes of an "arms race" for these reasons (as well as the fact that it's obviously not being encouraged by the GDC). Also, it would be costly in terms of battery power to use ALL of the motors in the KOP. Thus, teams will have to learn about restraint in their designs and make responsible choices about motor selection.

Thanks Dr. Joe for bringing up this discussion. It's very interesting, and I hope I don't sound as if I am being argumentative. Just trying to share my two cents! You definitely have a much greater perspective on the evolution of FIRST than I have.

-- Jaine