Hi @ilust ,
Thank you for your question!
We are working on a new design of the kick power measuring device as we speak. Although the actual constants are still being determined, we expect the ball speed not to go over 1 meter per second.
Hope this helps!
hi has there been any update so far? when will the new design be released. teams need this information to design their robots
If 1meter per second is still the constant, it is easy to use (almost) the same measuring device and just reduce the gap between the plates to 2cm, so that the golf ball can not slip through. However, the “initial step”, the small vertical line is to high for the golf ball.
If the 1m/s stays the constant I can “design” a new device. Give me a day…
get it here : https://github.com/stiebel/bohlebots/tree/main/kicker_measure
You can change anything you want or just use the zip-file to order at the pcb shop of your choice.
But be aware : This is not the office measurement device but only the BohleBots - device.
Something different:
There is the rule, that the single camera is not allowed to have a commercial lenses with an angle of more then 140 degrees horizontally.
To get omnivision a “normal” team has to prepare mirrors and seeing a golf ball on a self made cone mirror at the other end of the field is near to impossible. So I wonder if we could change rules for 2023+, not 2022:
either : only one camera (with no reglementations about the field of view to give normal teams the chance to buy fish-eye lenses…
or : field of view is max. 140 degrees. It is not allowed to use any mirrors or lenses to increase the filed of view.
Why that?
Well, either it does not make a difference how to get the omnivision as bought one solutions are cheaper than good made ones,
or the challenge is especially not to have omnivison to increase the software skills and creativity to find out where to find the ball with a “human-like” field of view.
What do you think ?
(And again, this is not suggested for 2022, the rules have changed enough…)
Hi!
It’s worth noting that ability to see golf ball across full field is depends on your ball color. We bought balls from 2 different brands, one is much more brighter than other. And our robots can easily detect brighter one, but struggles with darker.
Allowance to use fish eye lenses (while remaining allow to use mirrors) might be good idea to give teams more choice and easier access to omnidirectional viewing systems. Though I don’t see how complete ban of all types of such a systems can improve gameplay.
Hi @mareksuppa! Thanks for your clarification on the 1ms⁻¹ ball speed cap.
We do have a few follow-up questions, namely:
It would be great if we could get an update soon on the actual ruling for “kicker” power as teams are likely finalising designs for regional competitions, and the impact of “kicker” design and size are rather significant in view of the 18cm robot size cut. Thanks!
Hi @stiebel ,
These are all good questions – let’s try to spin a discussion on them in a separate thread 
Hi @ilust ,
This is indeed something to keep in mind and also something that the rules have a very hard time regulating. In principle, we could add a sentence stating something like “the ball should be colored in bright orange” but what actually constitutes “bright” and “orange” is still rather subjective.
This will be the case at least for the time being (that is, the 2022 rules), and potentially beyond as well.
Hi @neohaojun ,
As it currently is, the “chip kick” is in a separate section so that it can be easily referred to and perhaps to plant a seed, so as where could the league be headed in the future. It is not “officially” part of the gameplay part of the rules, in the sense that it would be necessary for it to be specifically regulated.
Thank you for these back-of-the-napkin calculations! Would you mind sharing the steps that led you to the results you presented?
In principle, however, you are indeed right that 1 m/s essentially renders the whole idea rather useless. That said, as we currently do not have much experience with matches that would make use of the golf ball, the intention of the rules is to lean on the safe side, even at the expense of “chip kick” not being possible as part of the normal gameplay (at least for now).
Let me assure you that we (the Soccer Committee) have spent a massive amount of time discussing that and finding a solution that would be
seems to be quite a tough challenge. For the time being, it seems we’ll try to utilize a similar kick testing mechanism as was used in the past versions of the rules. We’ll have the final draft soon – I’d be happy to go into details then.
Hope this helps!
Hi.
I read in the draft version of the rules that the voltage will be 9V starting in 2023.
If the purpose of this rule is to reduce the speed of the robot, I think it would be better to include a current limit in the rule instead of a voltage limit. Motor power is proportional to current.
For example, a 10A blade fuse is mandatory for the open class, and a 5A blade fuse is mandatory for the lightweights. (Glass tube fuses should not be allowed to be used because they do not respond well to overcurrent.)
For athletes, replacing batteries is a huge expense. I think it would be better to impose a current limit instead of a voltage change.
Thanks.
Hi @seizo_mori ,
Thank you for your feedback.
We’ve spent quite some time debating this issue within the Committee and our assessment was that if we required something like a mandatory fuse, this simply prevents a large number of newcomers from participating (i.e. thing LEGO or FisherTechnik-based robots). If possible, we’d very much like not to prevent them from competing by default.
That said, we are looking at ways of trying to limit the robot speed in ways that would make it
While our current thinking does indeed revolve around limiting the voltage but we’d very happily consider other suggestions along the guidlines outlined above – that’s also partially why the note is there
If you could think of some interesting ideas, please do not hesitate to let us know in – they may easily end up making it to the rules.
Thanks!
One more thing about voltage: It lowers either your torque or your max rpm for motors of same shape, size, weight. This is due to back-emf: With increasing motor speed magnets induce a voltage that counters battery voltage and reduces the voltage effective in creating torque. Therefore with less voltage the same motor produces less stall torque and to get to the same stall torque you have to switch to motors with lower kv that have steeper torque drop-offs with rpm. Look up “back emf” for a better description. This is a step we can take to cut off “stupid fast” agility that is fairly easy to implement for both teams and event organizers. If we see that robots have too much force (i.e. torque) available and that impedes game play a fuse might be a good addition.
@seizo_mori I will bounce off of Marek’s response and bring up some of the concerns about fuses we brought up to see if you (or anyone reading this thread) may have more insights:
Battery voltage is a simple test with a voltmeter or at the very least reading a label off of a battery/cells. How can one ensure inspectors are seeing a fuse inline with the main power supply especially if integrated into a printed circuit board with several layers? To avoid modifying standard battery connections, we could ask for the inline fuse to be plugged directly to the positive end of the battery, but that could also cause some teams to struggle to find the appropriate cables/connectors.
How can we know that all fuses are the correctly rated/typed? Even if we use standard automotive fuses (which may be available internationally), there may be significant differences in tolerances/types/availability to cause similar issues we found with the field carpet. Asking event organizers to supply fuses could allow for all teams at the event having the same fuse but that may lead teams open to blame “bad fuses” if they are handed out (I’ve seen this back in the day when we used to hand out radio crystals at another robotics competition).
Exceptions could be made for kit bots like Lego (which probably have their own circuit protection integrated already) - but how do we keep and maintain a valid list of exceptions to the inline fuse rule with so many different options?
I’m open to having some sort of current limitation, just don’t see a practical way of implementing it just yet.
Hi @Mike
Here are some of my thoughts.
- Battery voltage is a simple test with a voltmeter or at the very least reading a label off of a battery/cells. How can one ensure inspectors are seeing a fuse inline with the main power supply especially if integrated into a printed circuit board with several layers? To avoid modifying standard battery connections, we could ask for the inline fuse to be plugged directly to the positive end of the battery, but that could also cause some teams to struggle to find the appropriate cables/connectors.
The person in charge of inspecting the car should be able to see that the power does not turn on after removing the fuse. I don’t think it’s necessary to examine the circuit too closely. Even now, even if they put a boost circuit on, there is no way to check it.
(It is the mentor’s job to correct the player’s injustice.)
- How can we know that all fuses are the correctly rated/typed? Even if we use standard automotive fuses (which may be available internationally), there may be significant differences in tolerances/types/availability to cause similar issues we found with the field carpet. Asking event organizers to supply fuses could allow for all teams at the event having the same fuse but that may lead teams open to blame “bad fuses” if they are handed out (I’ve seen this back in the day when we used to hand out radio crystals at another robotics competition).
I am aware that there are only three different size standards for automotive fuses. They are usually color-coded by current value, so it is good to be able to recognize them at a glance.
It is natural for products to have tolerances, but I don’t know if that is a big problem in robotics competitions. If you can show us the data, I think we can have a better discussion.
I don’t know about the carpet problem, but the mainstream thinking of Japanese teams is to design and build robots to work on any carpet. Is it different in other countries?
If the competition organizers were to distribute fuses, there would be no problem if they distributed multiple fuses to each team.
Fuses and crystal oscillators are not comparable in their effects on robots.
- Exceptions could be made for kit bots like Lego (which probably have their own circuit protection integrated already) - but how do we keep and maintain a valid list of exceptions to the inline fuse rule with so many different options?
I don’t think there are many robot kits that can’t incorporate a fuse between the battery and the main body. If there is something other than LEGO that applies, why don’t we have each country report it to us ?
The International Committee doesn’t have to look into everything.
Thanks for the opportunity for a good discussion.
We do not have data on variances in automotive fuses. Gathering this data would involve buying and characterizing fuses from different manufacturers all around the world. That is to say to determine if tolerances are or are not large enough to be considered unfair would incur considerable expense and effort.
This could be a problem for many smaller competitions (qualification tournaments, smaller national tournaments) that already are close to the limit of what they can implement as it is. I’d like to avoid as requiring more of them than we absolutely must to keep barriers to entry low.
You are likely to be right but teams or entire schools building their first robots would have one more thing to take care of and to comply with as a prerequisite to being able to compete that is not actually about playing soccer.
I don’t think that using fuses or limiting voltage would be feasible to address the problem of the speed of robots.
There are 3 major problems with using fuses.
The first is that all fuses have different switching speeds. So what that means is that even when a fuse has a nominal switching current 10A current of 15A can pass but just for a limited time and this time varies from tens of milliseconds to multiple seconds. This might be a problem for example when two robots push each other. One with a fast blow fuse and the other with an ultra-slow blow fuse. When they are pushing each other there will be higher current through motors(stall current) and one robot with a slow blow fuse might be able to push the other because of the higher temporary current allowed through motors. Some examples of fuses:
https://www.swe-check.com.au/pages/learn_fuse_speed.php
https://www.mouser.sk/datasheet/2/240/Littelfuse_Smart_Glow_MINI_Blade_datasheet-1291256.pdf
https://www.mouser.sk/datasheet/2/240/Littelfuse_Forklift_CCK_CBO_Datasheet-1372320.pdf
https://www.mouser.sk/datasheet/2/240/Littelfuse_MINI_Datasheet-1077557.pdf
https://www.mouser.sk/c/circuit-protection/fuses/
The second is that there is that all of the robots must use the same type of fuse and that is not possible even before the shortage of components caused by the pandemic.
And the third is that even when everyone would have the same current through motor it does not mean that everyone will have the same speed and tongue of motors because motors have different effectivity on for example some expensive Maxon motors such as Maxon RE Motor 339150 with Maxon 5.8:1 Gearhead 166157 for 310euros would have speed 1658rpm and stall tongue 1.55Nm with just 68mA of no-load current and Pololu Metal Gear Motor with 9.68:1 reduction would have speed 1030rpm with tongue 0.314Nm with no load current 300mA but would cost ‘only’ 20euros. So it would create an even bigger gap between ‘rich’ teams who can afford more effective motors and ‘poor’ teams who can afford only cheap motors.
By reducing voltage to only 9V there would be no reduction of speed because you can buy motors for 9V with the same parameters as for 12V but with a higher current and there would be the same problem about effectiveness and price of motors as already mentioned above.
So I think that the best way to reduce a robots speed would be to measure the time that it would take to move from one goal to another on a straight line on maximum gameplay speed and set a minimum time required(1.5s or something like that). This time could be measured by a stopwatch for example on phone. Also, this measurement would be repeated for instance 5 times.
Another way is to mount a camera about the field and measure the speed of all robots during gameplay. This camera can be for example raspberry pi or even a beater smartphone with a custom app. By using this approach it will be ensured that no speed limit will be exceeded but I think that the first method is more feasible for this year because it is much simpler for implementation in real-world but the second one would be useful for next years and maybe even some data can by collected and used for some machine learning models and it might be next big step to get closer to major leagues.
To address maximum ball speed after being hit by a kicker there are multiple ways to measure it but I think that the best way is to place the robot into the bottom left corner of the playground in such a way that the ball would be on the edge of the white line and kickball next white line towards the opposite wall. The robot would pass the test when the ball would not exceed the white line boundaries after being bounced from the opposite wall(a smaller distance would be of course also allowed). Advantages of this testing method ower currently used one are that it would be possible to do this without any additional equipment and for all types of balls as well as that it would take into consideration a carpeted surface(a higher string of carpet would slow down ball more rapidly so it would travel smaller distance so the kicker strength can be increased).
@bukajlag I actually wrote a draft with your speed suggestions and we came to the conclusion that they would not be practical for this year. A stop watch would not be accurate enough given the 0.25 second average reaction time. Also this discounts any acceleration so would not be a true speed test. Finally, it is a mute point since any team could easily program their bot or change speed some other way during inspections (this could be said about the kicker test as well however the rules do state the kicker can be tested at any time and is a pretty straightforward test to run)
I agree a camera could be used, but as @Dave suggested, this would put a large burden on event holders. We also looked into apps that measure speed or rpm (e.g. strobe tachometer) and they are also not ideal solutions right now.
The voltage drop rule opens up the idea that teams that push the edge of what’s capable may begin to have to think about how much current they are using throughout a match. Cells could be placed in parallel but that also pushes against weight limits. A drop from 12V to 9V may not be too much of a change now, but it can be restricted more just as size and mass.
I know other competitions have budget restrictions on the bots but the focus of the voltage rule change is to limit speed (not only to be more “refereeable” but to also match the conditions of a human soccer player where one cannot outrun the ball - increasing kicker strenght is an option in that regard but that then balances with safety) and not address cost. Some organizations are able to invest in high end components like motors and pass them down through generations of teams.
It’s good to see many of the same suggestions we discussed being brought forth here. Thanks to those that backed up the points against fuses - maybe that issue can be put to rest for now? As for speed/current, please keep replying with ideas.
