如何在Android中识别TAP（抖动）模式？

Question

I want to capture a "TAP" on an Android device. For example, say the device is in the user's pocket. And then he touched the phone twice from outside his pocket with a particular pattern. Say, hitting with two/three fingers like `TAP -- TAP.' I want to capture this.

I guess, it should be achievable using accelerometer. Now, I can read, X,Y,Z ... but how can I recognize that it is `TAP - TAP'? Is it possible?

Or, is there other way to achieve this? Thanks.

Answer 1

Thing is that it might be pretty hard to dissociate regular shaking when the user is walking (especially if he has loose pockets) from that TAP TAP. Is it supposed to work like when the user walks, or run ?

To achieve that, I would first osbserve the accelerometer over duration, as well as the TAP TAP incidence on those same accelero measurements. Best way to notice that special action is then to set up a pattern. Here is a first example I could think of (very basic) :

• a threshold (average values + OFFSET) is reached in a certain accelerometer axis, which could be considered as a first tap.
• values turn back around the average.
• the same threshold is reached - that is before X milliseconds
• action detected.

All the works consists in being able to find the correct pattern and the corresponding algorithm, knowing that the accelerometer is very noise-sensitive (especially in a pocket).