Measuring Pendulum movement - which sensor ?

Other Hardware Sensors
1

Hi,

I'm working on an application, which already runs on battery.

Now I'm thinking about an "extension", but I'm not sure, which sensor I should use.

Description:

We have an outdoor application (really outdoor, somewhere in the middle of nowhere).
I would like to determine, if an animal has touched "something".
The first idea: using a PIR sensor, but because of several reasons (to much false positives), a PIR sensor doesn't seem to be a good solution.

My second idea is to use a "pendulum", a wooden pale hanging down from a rack, just fixed with a cord. If an animal touches the pale (this will be rather "wild"), the pendulum will begin to move more or less heavily.
My idea ist to place a sensor in the lower end of the pale, connected to the Arduino (better some clone with GPRS-module, which sends e.g. an SMS in the case of of a heavy movement).

If the pale starts to move, the sensor should send an interrupt (cause: outdoor, batterydriven) and wake up the arduino from sleep. The interrupt should ideally only send, if the movement was "heavy", perhaps configurable.

My question:
Which sensor is appropriate for this use-case?

I have already checked the MPU-6050, but I'm not sure, it will fullfil my requirements.

I hope, your have some hints for me.

kind regards,
rocsta

2

from your story the sensor should not sleep.

A magnet in a coil (one or other moves) generates a voltage depending on

  1. movement and
  2. nr of windings of the coil.

Could be your trigger?

3

Thanks for the idea, but ...

robtillaart:
from your story the sensor should not sleep.

A magnet in a coil (one or other moves) generates a voltage depending on

  1. movement and
  2. nr of windings of the coil.

Could be your trigger?

... I don't think so.

Reason:

The pale hangs vertically. If it will be touched, it "swings" and I don't see, if your idea brings enough energy, so a sufficient voltage will be generated.

4

If your not there to see it how do you know the wind did not move it? The wind does blow out in the wild.

Paul

5

Paul_KD7HB:
If your not there to see it how do you know the wind did not move it? The wind does blow out in the wild.

Paul

The place "in the wild" is nereby to my home. So if there would be a storm, I will know it and can ignore the movement.

Reducing false positives during "small wind" is part of a possible "calibration" (like setting the thresholds) or part of the "implementation" (like setting up the pale, so it will have a little "ground contact").

6

How about a load cell that measures a difference in weight?
A big part of the animals that move touch the ground...

An analysis algorithm could distinguish wind from an animal movement.
The latter is more sudden and often only for a short time.

7

robtillaart:
How about a load cell that measures a difference in weight?
A big part of the animals that move touch the ground...

An analysis algorithm could distinguish wind from an animal movement.
The latter is more sudden and often only for a short time.

Not if the animal is a large bird!

Paul