brendan mccloskey

I've designed a grain-synth, using an FSR/touchpad interface. I have mapped the touchpad X-axis to buffer-playback position (grain sample-location), such that motion across this axis 'reads' through the buffer file. It would be cool if I could cross-couple this modality with grain-pitch, by extracting acceleration data from the touchpad (using Max objects, natch). The only 'delta' -type object I can find is [mousestate], which works really well, giving increasing values the faster the cursor moves, and, more importantly, generating a zero when at rest. Oh, I just thought, isn't there an Max object called [mean]? But, would this give false readings, in the case where high position values changed slowly, I'd still get a high acceleration value, or low position values changed quickly giving low values. Hmmm. I'll go and check [mean].

edit- I'm not using [mousestate], I'm using Arduino to [serial]..

Hallo Board
I've designed a grain-synth, using an FSR/touchpad interface. I have mapped the touchpad X-axis to buffer-playback position (grain sample-location), such that motion across this axis 'reads' through the buffer file. It would be cool if I could cross-couple this modality with grain-pitch, by extracting acceleration data from the touchpad (using Max objects, natch). The only 'delta' -type object I can find is [mousestate], which works really well, giving increasing values the faster the cursor moves, and, more importantly, generating a zero when at rest. Oh, I just thought, isn't there an Max object called [mean]? But, would this give false readings, in the case where high position values changed slowly, I'd still get a high acceleration value, or low position values changed quickly giving low values. Hmmm. I'll go and check [mean].
Brendan
edit- I'm not using [mousestate], I'm using Arduino to [serial]..


acceleration-maths-from-not-quite-n00b

Here's my favorite velocity/acceleration abstraction. It's another way to do just what Jesse posted, only with an added stage to calculate acceleration given velocity.

here's an equally elegant solution from timlloyd

https://cycling74.com/forums/work-out-the-rate-of-change-or-similar-accelerometer-data

Thanks everyone
here's an equally elegant solution from timlloyd
https://cycling74.com/forums/work-out-the-rate-of-change-or-similar-accelerometer-data

Does it mean that the faster I am drawing on the LCD object (see below), the higher the values will output ? (and so the higher the dial will rise ?)

I am looking forward a similar thing (or maybe it is exactly this one but I am not sure). I would like Max to output low values when I am drawing slowly and high values when I am drawing faster. But can we make it without a return to 0 on the dial object ?

- very slow moves keep the values near 10 on the dial

- slow moves keep the values near 30 on the dial

- very fast moves keep the values near 120-127

(I ask the question for the LCD object, but in fact I would like to make it work on sensors too (accelerometers or magnetometers or both), which is not the same problem since the LCD drawing traduces a sort of speed instead of the sensor values reception which works at a 25 Hz reception rate for example. Damn it is hard to translate a slow movement into a little number and a faster movement into a bigger one with accelerometers).

- very slow moves keep the values near 10 on the dial
- slow moves keep the values near 30 on the dial
...
...
- fast moves keep the values near 100
- very fast moves keep the values near 120-127 

Ok in fact I would like to output my movements velocity/speed (I have the 3 axis accelerometers values).

(But I am having trouble calculating the acceleration norm and then the precise velocity (m.s-2) to make a slider move correctly.)

I'm trying to implement the same idea, and I added to timlloyd's patch to generate a 'running average' (without using [mean], [peak] or [trough] objects) of the acceleration values; I don't think it's very elegant, perhaps someone else can implement those objects I mentioned to generate a more stable running average.

The problem with this example is that it cannot account for changes in acceleration during motion, unless acceleration returns to zero first. Damn I wish I'd paid more attention in Maths class.

Hi Mayou
I'm trying to implement the same idea, and I added to timlloyd's patch to generate a 'running average' (without using [mean], [peak] or [trough] objects) of the acceleration values; I don't think it's very elegant, perhaps someone else can implement those objects I mentioned to generate a more stable running average.

The problem with this example is that it cannot account for changes in acceleration during motion, unless acceleration returns to zero first. Damn I wish I'd paid more attention in Maths class.


I am currently trying to find a good way to get the velocity in the main referential when we have the 3 axis acceleration with a sensor. I think it is a good solution to our problem but I still have some difficulties.

acceleration Maths? from 'not-quite' n00b