Project Details

Intro: why we do it!

Hello everybody, we are Team Tunnel Gott Erkenner, German for Tunnel God Detector and we tackled the “When Landslides Strike” challenge during NASA Space Apps Challange 2017.

Our house in Stuttgart shakes regularly because of a tunnel construction site nearby with targeted detonations. This and other movements like landslides, earthquakes or avalanches should be detected and located. In this way Emergency teams can respond faster. Furthermore the negative impact on humans and environment caused by vibrations and noise is documented.

We used cheap accelerometers synchronised with GPS. Many of them combined can detect and locate the magnitude and origin of tremors. On the very left and very right of the command prompt you see in the demo in the video, you can see here two sensors and in the middle a time synchronising ping every second. Last night we already detected two targeted detonations on the construction site next to our location.

Satellites in space cannot look underneath the surface, but combined with our detectors, we can achieve that. Let’s do that!

Our Code on Github

Contact the team: tunnelgott(at)aerospaceresearch.net

Solving the problem: Why the strange (german) name?

The reasons we worked on this topic are deeply personal. Several members of the team experienced earth movements already.

• local detonations of Stuttgart21 tunnel dig project, shackspace members feel each day.
• the Skopje, Macedonia earth quake in 2016 one of our teammates experienced
• Sustainable Development Goals (SDGs), adopted by the United Nations General Assembly Goal 1.5 and Goal 13.1

Next to shackspace, the location of SpaceApps Stuttgart event, is the construction site for the Stuttgart21 (S21) project. A federal, regional and local improvement project of the train infrastructure. There are several detonations each day to drive the tunnel further underneath Stuttgart and we hve shaking windows and floors for about 2 years now. This is annoying, but not dangerous. And as a meme for not knowing when these tremors come and where they are digging now, shackspace members start comparing it to a mystical, ancient god living underneath us demanding sacrifices by making the earth shake. This deity was just called Tunnel Gott, which means Tunnel God in German, and mostly everytime the house is shaking, someone is saying that Tunnel God speaks to us. So this meme became our fitting project name.

But besides this amusing sounding story, one of our teammates experienced the Skopje Earthquake in 2016 with mb5.2 strength and more than 100 people have been injured and sought medical assistance. She explained that in 1963, a Mw6.1 earthquake hit Skopje destroying about 80% of the city and many dead people. So people still think of this shocking event when other earth quakes hit. Every minute saved in that you have data about the quake makes emergency teams faster and saving people.

Combined, these two facts lead us to tackle the challenge to help people by providing this data faster. We also included related effects like landslides and avalanches because we decovered these as most likely effected by the climate change and causing possible threats to everyone living in mountainous areas, no matter if in the developed or developing countries. So, our working group chose the "When Lands Strike" challenge and we came up with the following mission statement.

Mission Statement

Saving people in danger by supporting emergency respond teams by tracking seismic activity and calculate origin of bursts faster. For that, cheap and open-source distributed sensors on ground in collaboration with satellites (space segment) and in combination with existing data in data-bases shall be used, that everyone can build or obtain easily and join creating the essential data.

Components: You can build your own sensor hardware < 50€

To bring the Tunnel-God-Detector to each corner of this world, we want it to be affordable and available by each and everyone. Otherwise not all seismic events can be tracked. We did not YET achieve this yet, because our prototype is working but it is still rather costly. The hardware includes...

1. Raspberry Pi micro-computer
2. ADS1115 and GY-61
3. MMA7455L or MPU6050
4. Adafruit Ultimate GPS Breakout

and those parts are quite favourite amoung makers everwhere. So we can harness the power of open source to make people understand our design and improve it and making it cheaper in their very own crowd-sourced way.

And it was so simple, it just took us one day from airwires to the sensor-board.

How it works

• measuring seismic activity with accelerometers with high sampling rates
• time synchronizing the sensor-node with GPS to be independent from an outside (Internet) source.
• storing the seismic data according with the exact time of arrival
• correlating each seismic event of one sensor-node with the other nodes according to the time of arrival
• positioning the origin of the seismic activity by applying trilateration mathmetics, like the Global Positioning System (GPS) is doing we all know and use.

One of our teammates is working on the Distributed Ground Station Network (Hacladay Prize 2016 entry) for tracking cubesats in orbit around space by their transmitted radio signal. So we used the same basic approach for something that is below the Earth' surface and that is sending out "signals" a "bit" slower than the speed-of-light.

So the method is pretty well known and we as a team decided to focus on designing and building the node itself, because we wanted it to work and then to be as cheap and open-sourced as possible.

Where is the "space" in it?

You might think now, how this is a space application? It is in two aspects.

This first and easiest is, that we use the Global Positioning System you know most likely just as GPS. GPS uses satellites in orbit to provide global services you use for finding your location and we use for time synchronizing all stations no matter they are deployed. Only in this way it is possible to timetag the received signal worldwide to the same source. So we use space tech for our ground based sensor network.

But the more important aspect is the merging of data. NASA has land data taken from orbit. We provide additional data directly taken on earth and together it allows further analysis of what happened below the surface. And perhaps even further layers of data will be added by this open appraoch.

RESULT

We managed to design and build our prototype sensor-board in one day and deployed it. While we slept it started measuring the vibrations of the window we sticked it on. The sensor faced the construction site and detected several detonations. We knew for sure because at 11:38 a.m we were polishing our code for the submission and felt the tremors. We checked our data and the time matched the accelerometer data perfectly. It is the big spike at Unixtime 1493545086. The pattern we saw at that time also looks familiar to the first big spike on the very left of the graph below. This graph shows almost a full day of recorded vibrations and a small part you listened to in the above video.

We're quite happy we managed to have a running prototype as our proof of concept. We can not detect and document vibrations caused by detonations and other sources at every location on this planet.

We are taking this as our basis for further future improvements and helping people in danger and also to improve their quality of life by helping them reduce their vibration sources and doses.

You can find all of our vibration records in our Tunnel-Gott-Erkenner Github repository. Have fun with the raw data!

Future

Our SpaceApps prototype is able to detect local tremors so that we can locate regional events like the tunnel construction work up to several kilometers. The design was discussed from the start on to have a proof of concept and solving our local problem next to our house.

Now that we know it is feasible, the future upgrade we and everone else can work on includes...

• increasing sensitivity by using better sensors (ADC range and samplingrate)
• increasing the detection range by designing a "foundation" concept to anchor the sensors on (currently the window serves as a membrane, but a resting mass dampening system should be discussed
• increasing the precision of positioning of the sesismic origin. Depending on Primary- or Secondary-Waves, or sensor-nodes allow 8 or 5 meters accuracy with about 1000 Hz samplingrate of the accelerometers.
• Making it cheaper and better! The Raspberry Pi is a great platform, but the samplingrate we reached with our Python script can be better. Dedicated HW like microcontrollers can help here
• join our and external sources for further derivated data products

For now, we needed to remove our temporary test setting in shackspace. With your help, we will finish it and bring Tunnel-God-Detectors wherever the earth is moving!

Build your own sensor today.