Sticking an accelerometer on a driver?

Hey guys, I’ve been thinking about this for awhile, and wanted to get some feedback just to see if the concept is viable.

Does it make sense to design a driver that has an accelerometer based (or assisted) UI? Or what about an ALS (ambient light sensor) that automatically adjusts the output? I think there is plenty (a.k.a, several square mm :smiley: ) of room to squeeze one into a 20mm driver, probably even a 17mm. It seems to me that we want our flashlights to have a lot of modes and features, but don’t want to cycle through them all with a single button interface. An accelerometer would allow you to get to a mode with a single gesture, without having to push a button several times.

What do you think? Is this a stupid idea or not?

It already exists. Maglite XL200. Interesting UI actually.


I like the idea. Maybe it’s not going to be as great as a regular UI with a side switch, but you can custom tailor the UI to your liking. The Maglite uses a rotating motion to increase or decrease brightness. So it’s using the accelerometer as a G-force sensor. But you can also use the same sensor to register tapping, or a tapping pattern as an UI input. To make it work successfully you do need to fiddle with the firmware. Honestly it sounds like good fun to me if you have the capability to do this. :sunglasses:

I’m pretty comfortable with hardware design and pcb layout, and somewhat competent with writing code. I have done a couple projects with accelerometers before, so they’re nothing new to me.

Sounds like an awesome project then; it’s going to be really unique. I would also say that it’s not about whether using an accelerometer is already done or not, but how you’re going to implement it. I’d say go for it! :partying_face:

I’m interested in non-standard UIs, but it seems to me like there would be too much accidental activation with an accelerometer based UI. The flashlight is going to be moving all around during the various activities we use lights for. Maybe it could work well if the gestures were unique and defined well.

Yeah, I agree. Maybe something like moving it in a clockwise circle for more output, counterclockwise for less. Pretty hard to mistake a gesture like that.

I think it could be cool. Implementing the feature into the driver would be really good.
I made a light with a simple mercury switch controlling auxiliary red LED’s. Fun.

nitecore SENS have gesture control, but not sure if its uses accelerometer.

It is not a stupid idea at all. Some people realize that a single button may not be the best way to control a flashlight with many different modes.

“Imagine the folly of an automobile with one pedal replacing the brake and accelerator (press once to accelerate, press three times and hold to brake)!” (Source)

Using more buttons, control rings or sliders is one way to go. Sensors that make the light ‘smarter’ is another.

  • Nitecore uses a remarkable ‘Active Dimming Technology’ in their SENS series (review). I do not like rotating the head to switch the light on/off and for me the light is too small to be useful. But once you got it running the brightness adjustment works amazingly well. I would love to see that on a 17 mm driver for larger lights.
  • Maglite’s ‘Motion Control’ system on the XL100 lets you rotate the light around its axis. Strange. Here is a view at the internal components.
  • Surefire uses a light sensor for its ‘Intellibeam’ technology. The output power immediately adapts to the amount of light reflected.
  • Petzl uses a distance sensor on their NAO headlight.

Fenix E20 2014 also have some type of acelerometer:

Which accelerometers have you worked with?

I’ve worked with LSM303D (3 axis accelerometer + 3 axis magnetometer) and LSM6DSL (3 axis accelerometer + 3 axis gyroscope).

It would be good for mountain biking, automatically going to low when going really slow or stopping.

Being able to sense actual speed and filter out bumps to make lighting levels speed sensitive would be the best. It would maximize battery life and minimize overheating allowing for smaller helmet mounted lights. It would probably require mounting the accelerometer on the wheel with a wireless connection.

If you were just going to do gesture based commands, can it be done on an attiny or would it require a more powerful mcu?

Nice, if the implementation is well done, it’ll be quite useful. Unfortunately, even well known flashlight manufacturers haven’t done anything novel with it.
I’ve worked with some accelerometer from AD (analog voltage output) and they’ve worked pretty well too.

It would be really neat if it could use the accelerometer to sense speed, but in practice this is extremely difficult, even more so on an attiny.

Many (if not most) accelerometers have built in gesture recognition algorithms, so I think it’s not too much for an attiny to handle.

I think I had something like that on my bike when I was 8 years old. A headlight, powered by a small motor that rested on the wheel. The faster I biked, the brighter the light! If I stopped, no light. Maybe not the safest kind of bike light, but back in the good ol’ days, we kids were disposable.

This is a really cool idea. I have no where near the right kind of skills to do anything with it, but the possibilities seem endless.

Use the button to lock out gestures, only allow them to be recognized when held to prevent accidental input.

Here is just an idea of what a UI could look like.

  • Hold button and rotate around minor horizontal axis to ramp brightness. (How cool would it be to control ramp speed by how fast you flick your wrist!?)
  • Rotate left then right around minor horizontal axis to check battery voltage
  • Hold button and rotate around major axis to change modes
  • Hold and shake for strobe. (Or just get rid of strobe entirely!)
  • Enter config mode with 3 sharp taps (Just tap it on a table or something)

I really like those features, especially the first one.

Another idea: if you integrated a magnetometer, you could even turn it into a crude compass. Might be useful to hikers and outdoorsy people.

By the time you add all the features, aren’t you just trying to invent a smart phone?

Yea, it might be a bit complex to start with. But on the other hand, I know that when multimode lights were introduced, the same kinds of things were said. Look where we are now!