Robust momentary/tactile switch with velocity or force sensing: does it exist? - Page 1
Forum section: electronics / projects

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 22, 2021, 11:29:09 pm
content: I want to create a game whose real "score" is actually a measure of how pissed off that player is, based on how hard he mashes its buttons. Frivolous, although this concept could have applications in UI design.But does such an off-the-shelf switch exist? There are small tactile switches with dual activation points (don't know the technical term), but they're rare and seem fragile. This same concept is used in electronic keyboards for velocity measurement, and you can even buya section of a piano-style keyboard with this functionality, although it doesn't seem particularly robust and of course looks like a piano keyboard.Force sensing is also a potential although it seems more difficult.Is there an off-the-shelf solution?

author: ataradov
author_rank: Super Contributor
timestamp: January 23, 2021, 12:06:35 am
content: One place where such thing is common are digital cameras. The trigger button is always two step. And from the teardowns of cameras I've seen they all roll their own mechanical solution from two separate buttons. Which makes me think it is not as easy to have in one button.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: January 23, 2021, 04:58:47 am
content: How about a piezo such as used in drum pads and electronic cymbals etc?

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 23, 2021, 08:31:52 am
content: Thanks for the suggestions. Because of the mechanical complexities of dual-switch solutions, I'm now leaning towards using solenoids as velocity sensors. They're robust, cost about $2 a piece, and tests on a couple do seem to produce voltages in the tens of millivolts when actuated (though I don't understand how, since the rod isn't magnetic ... I expected I'd need to "bias" the coil with a small current and detect back-EMF, but current is generated in a completely passive setup). If this doesn't work out I'll investigate piezoelectric.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 23, 2021, 09:33:54 am
content: Turns out an official solution for this sort of button does exist ... it's just eye-wateringly expensive,USD $65 each. Clever though ... uses a Hall effect sensor to measure velocity. But not in my price range.

author: Ian.M
author_rank: Super Contributor
timestamp: January 23, 2021, 09:43:33 am
content: Remnant magnetization. *NOT* reliable, as you can magnetize an iron or steel rod by aligning it with the Earth's field and repeatedly hammering its end. You *NEED* to bias the coil with enough current to get an output that swamps that due to remnant magnetization.It may be worth looking at arcade buttons that use a replaceable microswitch, so you only have to make a sensor in microswitch form factor, and don't have to worry about 'ape-proofing' the actual button. TheFSR400force sensor (available fromSparkfun+ others), in a 3D printed Microswitch form factor housing, with a rubber disk between it and the button's actuator would probably do the job nicely. The FSR400 sensor appears to be 8mm dia, so you'd need a button that takes a miniature microswitch (~10.3mm thick), not a subminiature one (~6.5 thick).

author: Rerouter
author_rank: Super Contributor
timestamp: January 23, 2021, 09:51:14 am
content: solenoid with a spring, integrate the voltage vs time per press,the solenoid type looks to be about $3 per unit with a built in spring, so just need some buttons and a way to attach themyou could also create a fun self playing mode demo where the buttons pull themself down :por a hard mode, where certain actions in the game disable certain buttons for a few seconds by holding them downOther possible way would be getting a PCB stencil for the fingers, fit them with small strain gauges and put springs under the end of the fingers, its more a measure of difflection, but with some math you can work it out.

author: tooki
author_rank: Super Contributor
timestamp: January 23, 2021, 11:18:01 am
content: Quote from: I wanted a rude username on January 22, 2021, 11:29:09 pmIs this for a handheld controller or for a larger thing like an arcade cabinet? If it’s the latter, perhaps just detect the force with an accelerometer? That’d give you a pretty decent idea of how hard the cabinet is being jolted.But a very plausible approach for a handheld controller would be to use ordinary surface mount tact switches or membrane switches on the front of the PCB, but have the reverse side of the PCB free, but with a strain gauge applied to it under each button. Combined with careful design of where the board is supported, you could measure board flex under each button.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 24, 2021, 06:33:42 pm
content: Look in the direction of the tenzo sensors.