Can we have some clarification on the maximum arm length please?
Reading the 2017 rules [1], it seems that the limiting factor for our Darwin platform’s length is the 1.5 * H_{top} (p.16) - but if I remember rightly our platform is just within acceptable range with no modification? This doesn’t make sense given these rules, so we’d like to make sure to avoid any issue during robot checks.
I’m a little confused as to what you are referring to. There is no maximum arm length that changed related to last year, the only thing that was added is a minimum arm length, which is basically as long as the robot’s upper body excluding the head. The Darwin’s arms are much longer than that, so I don’t see any issue. Then the arms limited in length by other factors as well, for example the maximum expansion, but this has not changed this year. So the standard arms of the DarwinOP are still acceptable and will pass the robot inspection.
Sorry for the confusion, we want to extend the arms on our Darwins as we have added studs and our arms are physically too short for getting up. This isn’t regarding a recent rule change, it’s a general question.
What we would like clarification on is the maximum arm length - or at least the limiting factors. Are we right in understanding the limiting factor on arm extension is 1.5 * H_{top} when the arm is fully raised?
If I’m still not being clear, please let me know and I will try to be clearer.
Just taken another look, it appears that the 2015 rules [1] state the following:
The sum of the lengths of the two arms and the width of
the torso at the shoulder must be less than 1.2 *
H_{top}. The length of an arm is defined as the sum of
the maximum length of any link that forms part of the
arm. Both arms must be the same length.
We believe this was the specification we were just within limit for previous rules. Confusingly, the rule change is not marked for the 2016/2017 rule changes [2] and looking at Git blame [3] shows that the modification was made before the LaTeX files were uploaded to Git 7 months ago.
Are you able to clarify what has happened here and whether we should follow the new rules on this or the older rules with regards to arms length?
I have no idea where the explicit ‘max arm length rule’ went, but the 1.5 * Htop for an extended robot should be even a little bit more relaxed and leave room for some improvements.
The previously defined maximum ‘wingspan’ of 1.2 * Htop would leave a maximum arm length of 0.6 * Htop (assuming a zero width of the robot).
If the robot may extend to 1.5 * Htop, we have a head of 0.05 … 0.25 * Htop (which starts at the shoulder) to be added to 0.5 * Htop. Thus the smallest maximum arm length (for a head of 0.05* Htop) would be 0.55 * Htop, whilst the largest maximum would be 0.75 * Htop (for the largest possible head).
(If I remember correctly, the typical human arm length, including hand, is somewhere around 0.45 * Htop.)
((Maybe for the future we should define that the robots have to stay within some percentile of real human dimensions.))
Thanks for clearing that up. It was the relaxation that made us think that we may be missing something.
Is this likely to revert/tighten next year, or will this now carry over? There’s no much point in us making changes for something that won’t last very long in the rules.