Let Detector

[der Stift]

For fun, I built an old school "Let detector" for my club.
It consists of an accelerometer, an LCD, a micocontroller, and battery power source.
The accelerometer hangs off the net,
and an LED flashes when vibration of the net is detected.
Sensitivity can be adjusted by a dial on the microcontroller board.

It is aimed for club play (no umpire),
sometimes (although not often) there were disputes of whether a "let" indeed happened.

I've also built a wireless version in which the microcontroller informs
another remote platform the occurrence of a "let"... perhaps for tournament play.

 

[thisisit]

these kind of things are always cool and helpful, fun to make and dirt cheap.
great job!
fire up kicad, put that stuff on a nice pcb, design a 3d printable case, build and sell a few.

 

[Snek]

Cool, what if ball hits the net after the serve?

 

[jk1980]

Nice attempts, but I can already see issues with some gym floors that transmit vibration on people stomping when serving

 

[Tinykin]

I think that the OP is talking about a ball hitting the net during the serve, which results in a "net" call by the umpire.
A "let" call is something different.

 

[jk1980]

but a net ball on serve that lands on the table afterwards is also a "let"

 

[der Stift]

these kind of things are always cool and helpful, fun to make and dirt cheap.
great job!
fire up kicad, put that stuff on a nice pcb, design a 3d printable case, build and sell a few.

Thanks. Club mate Moitz made a nice 3D printable case (white).
Adjacent to the case is the wireless version.

Can't make $ with this kind of things unless that is a "Butterfly" logo on it 😉

 

[der Stift]

Nice attempts, but I can already see issues with some gym floors that transmit vibration on people stomping when serving

I use a 3-axis accelerometer (X-Y-Z).
Floor stomping might generate dominant vibration in one axis,
but not the other.
So choose detection axes carefully ....

 

[igorponger]

Cool, what if ball hits the net after the serve?

Wow. Good question of yours. Lawn Tennis adopted a such device many moons ago. Umpire has a button to switch off the sensor just after serve is completed.

 

[Tinykin]

but a net ball on serve that lands on the table afterwards is also a "let"

That's what I am describing as a "net" call by the umpire. It's the only time that the umpire says, "net".
If the ball hits the net but does not land on the opponent's side of the table, the umpire simply calls the point for the receivor.
The rest of the time he will call "let", "stop" or the dreaded "fault!" depending on the circumstance.

In practice though, saying "let" for any stoppage is clearly understood by every player.

 

[thisisit]

Thanks. Club mate Moitz made a nice 3D printable case (white).
Adjacent to the case is the wireless version.

Can't make $ with this kind of things unless that is a "Butterfly" logo on it 😉View attachment 36567

you could try showcasing the tech at la large-ish competition.
also, if false positives are actually an issue, you can ML them out, randomforests are more than enough to get it done.

 

[Zezima]

test it in local clubs. Then offer your device in tournaments lets say semis/finals only for now. Then look at the feedback and if it is a success market it. I think many clubs would buy atleast one device for the finals. Just make sure it's easy to apply and use. Maybe you can film it when you actually test it, like a short demonstration. When it comes to technology in TT we are far far behind other sports even though we can get and attain so many interesting stats and also need the VAR help the most (let, edge hits etc)

 

[darucla]

This would be good for local play, as long as the local governing body sets down in the rules that this will be used. To get into major tournaments, it would need to be authorised by the ITTF. Just putting it into a match would very likely lead to objections, quite legitimate, from players. For instance, here in the UK, local leagues could happily specify it, but ranking tournaments could not without further testing and authorisation. That might take years. I'd love it for league play though.

 

[Loop Lob Smash]

Every time I see this title 'Let Detector', my brain reads 'Lie Detector', and I think its another @igorponger post about catching booster cheats

 

[igorponger]

Every time I see this title 'Let Detector', my brain reads 'Lie Detector', and I think its another @igorponger post about catching booster cheats

POLYGRAPHY MATERIALS TO PREVENT CHEATERS.

Am pleased to inform inhear. ITTF gonna to try a new approach to detect illegal manipulations on the sandwich rubbers. In first estimation, this ingenious device would cost a reasonable price beside all the others. ITTF looking forward for cooperation with a famous company engaged in polygraphy industry.

ИТТФ открывает тендер на лучшую формулу для полиграфической краски (printing inks). Чернила должны отвечать следующим техническим условиям:
-- хорошая адгезия с пористой резиной
-- полное или частичное растворение в минеральных маслах, и нулевая растворимость в латексных клеях на водной основе.
-- видимые изменения первоначальной окраски с эффектом размытого изображения blurring, в присутствии минеральных масел.

Пояснительные иллюстрации прилагаютца тут.
▪ Safety Label composition. Submission by EQC ITTF and URC.

https://clck.ru/3MTBZu

▪ Sponge layer treated /untreated

https://clck.ru/3MTBfy

🔴 Лучшие рецепты будут щедро оплачены после практических испытаний в присутствии экспертов ИТТФ.

Yours respectfully,
EQC ITTF

 

[Tony's Table Tennis]

There will be a lot of time where net is moving without ball contact.
so this will be a problem to over come, especially on soft flooring.

 

[Lazer]

Good riddance, I love table tennis because it is (or used to, now there is VAR) be without electronic devices… Any more of this will destroy it for me…

Cheers
L-zr

 

[haggisv]

Every time I see this title 'Let Detector', my brain reads 'Lie Detector', and I think its another @igorponger post about catching booster cheats

Same here!!!

 

[Gtsnake]

How about an edge detector that senses side table contact?

 

[Zezima]

Good riddance, I love table tennis because it is (or used to, now there is VAR) be without electronic devices… Any more of this will destroy it for me…

Cheers
L-zr

you mean you don't want tech in table tennis used?