USB Mouse Hack For Pachyderm Protection

When most of us think of seismometers, our minds conjure up images of broken buildings, buckled roads, and search and rescue teams digging through rubble. But when [Subir Bhaduri] his team were challenged with solving real world problems as frugally as possible as part of the 2020 Frugal Science course, he thought of farmers in rural India for whom losing crops due to raiding elephants is a reality. Such raids can and have caused loss of life for humans and elephants alike. How could he apply scientific means to prevent such conflicts, and do it on the cheap?

Whether inspiration came from using a computer mouse with the cursor speed turned up to “orbital velocity” is debatable, but [Subir] set forth to find out if such sensitivity could be leveraged for the seismic detection of the aforementioned elephants. His proof of concept is a fantastically frugal low cost seismograph using an optical mouse and some cheap PVC pipe and fittings.

We invite you to watch the video below the break to find out how it works. You’ll be impressed as we were by [Subir]’s practical application of engineering principles. And keep your eyes open for the beautiful magnetic damper hack. It’s a real treat!

If pontificating pesky pachyderms p-waves piques your interest, perhaps you’ll appreciate previous projects which produce data with piezo pickups and plumbing parts.

24 thoughts on “USB Mouse Hack For Pachyderm Protection

  1. I like it, but why not put the mouse at the other end? i.e. place the mouse next to the ‘scratched plastic’, and even use the mouse’s LED illumination. As the central part vibrates, so the mouse sensor will see the scratched plastic move. It keeps all of the active parts together, and removes the need for the laser pointer.

    1. Good question! We wondered if the warning system worked effectively, then the elephants could be distracted much away from the crops where the hunger takes over the cautious mind of the elephants. Knowing that the path ahead towards the destination is full of alert and scary wielding humans, they might just drop the risky plan. We don’t know if this hypothesis will work, but it just may.

    1. Moving magnets induce eddy currents in non-magnetic metals. The eddy currents create a magnetic field which then interacts with the original magnetic field.
      The best example is probably a classic mechanical speedometer in a car. The wheels drive a spinning magnet next to an aluminium disc in the back of the instrument. Eddy currents set up a magnetic field which allows the spinning magnet to drag the aluminium disc around the same axis. The disc has a small spring that resists rotation, and the speedometer needle is attached to the disc.
      Thus, as the car goes faster, the magnet spins faster, and the aluminium disc is rotated further around the axis, against the spring, thus moving the needle. If the car slows down the spring pulls the disc back towards the zero position.
      I expect there is insufficient movement of the magnet in this project to induce eddy currents that would have any effect whatsoever.

  2. I love-love-love this project — except for the obvious problem. Can we just talk about the elephant in the room?! This “cheap engineering” device doesn’t do anything without an expensive computer drawing lots of power, and how many poor farmers would sit up all night watching a seis-mouse-graph after weeding their fields all day?

    Hook it up to a net of Lo-Ra devices powered by a single lithium cell and small solar panel at each end that sets off a siren when something big enough comes through, and you’ve got something a poor farmer can use!

    1. I think you’re being a bit harsh here since there’s nothing in here that forces it to require a PC that couldn’t be replaced with simple radios ranging from close proximity Bluetooth, wifi, 433, cellular, to satellite. Hell, one could attach it to an audio alarm or set off a firework if that tickles your fancy. Setting up a cheap seismograph is the core here and I think he’s done a decent job.

        1. Elliot, you are right. This answers Patrick’s question and also supports Yeshua’s comment. I have used finally an Arduino with a USB shield to log the data. A transmission using LoRaWAN could be a nice addition, but i am worried about the bandwidth of this mode, especially when differentiating elephant signals from ambient seismic noise becomes critical and requires Fourier techniques and filtering etc. One way we were wondering is to convert the acquired signals into sound, but compressing in terms of frequency so that we can here the infrasound signals. In this way the processing and detection of elephant signals can be done by the available human brain of the attending farmer.

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