I'm not sure why, but I need this clock.

[CJ]

Then how does this work on a vehicle, since it varies speed?

Well, theres a few ways. One obviously is the fact they are always on the freeway so they may just hold a certain speed. But, more than likely as mentioned above they are using an rpm sensor. The grid operates off an equation that takes rpm into account, so it would be really easy to sub a sensor to generate that portion and it would work seamlessly. They could also be using a g sensor. Or it's possible there is a motor that spins at it's own speed regardless of your speed, that way it would work stationary.

[Junioropolous07]

Almosst had a seizure watching that thing spinning..

[71chevellejohn]

Well, theres a few ways. One obviously is the fact they are always on the freeway so they may just hold a certain speed. But, more than likely as mentioned above they are using an rpm sensor. The grid operates off an equation that takes rpm into account, so it would be really easy to sub a sensor to generate that portion and it would work seamlessly. They could also be using a g sensor. Or it's possible there is a motor that spins at it's own speed regardless of your speed, that way it would work stationary.

This.
If you notice on the wheels, the image does wobble a little bit as the speed varies.

[Ruffdaddy]

...They could also be using a g sensor. Or it's possible there is a motor that spins at it's own speed regardless of your speed, that way it would work stationary.

I don't think any of these ideas would reliably work. It would more than likely be an RPM or some form of self position sensor....after all that is what really matters...self position.

It looks like some of the other designs just use a resolver.

[thesource]

Music sucks but the clock is cool.

[Z06killinsbf]

Do want!! Nice find.

[CJ]

I don't think any of these ideas would reliably work. It would more than likely be an RPM or some form of self position sensor....after all that is what really matters...self position.

It looks like some of the other designs just use a resolver.

A g sensor would work if it was mounted on the outside of the PCB. It's probably the best of all the sensor variants. Because G's are not relative, they are exact. And it would allow the light arm to maintain an exact RPM regardless of the speed of the vehicle. A simple line of code could be set to ignore momentary spikes from road impacts. The best way to do it is to have a separate electric motor running the arm, and not the speed of the wheel.

[Ruffdaddy]

G sensors (I assume you mean accelerometers) are not exact. I'm pretty convinced you don't know how this would function. All you should care about is self position, software will compensate flash rates for the rate of change of self position. You could easily dothis with a resolved or rotary encoder. No need for all the trouble you're describing anyways.

Having a separate motor will not be exact because the wheel is not fixed. The motor will try to stay at one speed but still has several other factors to consider.

[chuckacosta]

I had something similar to that in the form of a dome that had a spinning "stick" persay. On the end it had led's that would display the time. And when I received a phone call on my landline it would dispaly the caller i.d. I had puchased it at Brookestone.

[CJ]

G sensors (I assume you mean accelerometers) are not exact. I'm pretty convinced you don't know how this would function. All you should care about is self position, software will compensate flash rates for the rate of change of self position. You could easily dothis with a resolved or rotary encoder. No need for all the trouble you're describing anyways.

Having a separate motor will not be exact because the wheel is not fixed. The motor will try to stay at one speed but still has several other factors to consider.

I have a whole lot of experience with LED's and LED controllers actually. Several years ago I use to make LED conversion panels for classic car tail light housings. Finding the position of the LED's on a grid is a matter of how to sample that data, there are many different ways to do this - I was just giving you just about every way you could determine position. I also helped program custom LED panels for business use and so forth.

What I was saying is for this particular product to work stationary you'd need it on it's own motor, that's how I would design it at least.

[Ruffdaddy]

I have a whole lot of experience with LED's and LED controllers actually. Several years ago I use to make LED conversion panels for classic car tail light housings. Finding the position of the LED's on a grid is a matter of how to sample that data, there are many different ways to do this - I was just giving you just about every way you could determine position.

But those don't determine position...just acceleration. Determining position would come from something such as a resolver, encoder, OPS, or other SPS. I figured you had some knowledge on the subject just not dynamic experience. Makes sense that you worked with static assemblies.

[CJ]

But those don't determine position...just acceleration. Determining position would come from something such as a resolver, encoder, OPS, or other SPS. I figured you had some knowledge on the subject just not dynamic experience. Makes sense that you worked with static assemblies.

but how are you going to determine self position if it does not rotate on a sampled axis (such as a wheel)?

[Ruffdaddy]

but how are you going to determine self position if it does not rotate on a sampled axis (such as a wheel)?

All of the aforementioned are based on a central axis. Otherwise an accelerometer would work for a desk top device.

[CJ]

All of the aforementioned are based on a central axis. Otherwise an accelerometer would work for a desk top device.

Right, the initial conversation was the idea it was on the wheel itself. I see what you're saying about measuring RPM's vs. position - I think we were both thinking the same thing, but I was using the wrong term. The RPM is your refresh rate, and the position is your location.

[Ruffdaddy]

Right, the initial conversation was the idea it was on the wheel itself. I see what you're saying about measuring RPM's vs. position - I think we were both thinking the same thing, but I was using the wrong term. The RPM is your refresh rate, and the position is your location.

Absolutely! You have to know self position to keep the images upright.