[robocup-humanoid] Decision on Foot Size Reduction

[Marcell Missura]

Dear Participants of the Humanoid League,

After an intensive debate, the Technical Committee of the Humanoid League and the trustees of the RoboCup Federation have decided to postpone the annual reduction of the maximum allowed foot size. In the upcoming competition in Eindhoven, the foot size restriction will be the same as it was stated in paragraph 4.3.1 of the Humanoid League Rules for the competition last year in Mexico, namely a rectangular area of a size up to (H*H)/30. In the following, information about the events that lead to this decision will be given, and other options that have been discussed will be named.

For the 2013 competitions, an arrangement was made with Robotis about a special offer that allows RoboCup participants to purchase DARwIn-OP robots for a reduced price. This special offer was made public in the call for participation. Unfortunately, the stock DARwIn robot would not be compliant with the 2013 rules after the new foot size restrictions take effect and this detail was not explicitly stated in the call. Neither the Technical Committee, nor the trustees were aware of this. This leads to the unpleasant situation that KidSize teams may have been mislead to believe that they can purchase a team of rule compliant robots from the special offer without the need for modification. The same assumption has implicitly been underlying the arrangements made with Robotis, a valued sponsor of the RoboCup events.

After this problematic situation has been brought to the attention of the trustees, it has been decided that a survey among the participants of the Humanoid League should shed light on how many teams are negatively influenced by the foot size reduction. The results of the survey showed that there is indeed a small number of teams that has purchased the robots from the special offer and/or has problems reducing the size of the feet on their own.  The trustees carefully considered that many of the teams have already made modifications to their robots to meet the planned change in foot size restriction, and therefore acknowledged that there is no perfect solution that will be fair to everyone. In the end, voiced by the president of the RoboCup federation, the trustees have strongly advised that all things considered, postponing the foot size restriction is the best course of action to take.

Furthermore, during the detailed discussions, an issue has been discovered in the way foot size and robot proportion restrictions have been traditionally defined in the rules. While taking the height of the robot into account may have served a valid purpose in the past, at the current state of development it imposes a disadvantage on teams that use robots with a human like mass distribution, because instead of the actual height of the center of mass, the height of the robot becomes the limiting factor that defines the maximum allowed foot size and other robot proportions. In order to be able to use larger feet, teams may be encouraged to artificially increase the height of their robots, for example by wearing weightless paper hats. A detailed explanation of this problem is given in the attached document.

The Technical Committee has discussed other options, such as decoupling the robot size restrictions from the height of the robot, or applying a small modification only to the foot size restriction rule as an intermediate solution. Crafting a set of new size restriction rules requires careful consideration of the repercussion on all teams and can only be done for 2014. A temporary, local modification of the foot size restriction rule only for 2013 would essentially be the same as postponing the decrease in maximum allowed foot size.

Especially with regard to teams who have already modified their feet, the majority of the Technical Committee expressed the opinion that continuing with the rule progression as planned and helping the teams in need would be their preferred way to resolve this issue, but with respect to the advise of the trustees, the TC has come to terms that freezing the foot size restriction for this year is the least inconvenient solution for all participants.

We apologize for any inconvenience that this situation may have caused to the participating teams.

Best regards,
The Humanoid League's Technical Committee
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