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GeigerROS

A ROS enabled Geiger counter radiation sensor for easy robotic use. We use it on a Turtlebot3 robot for testing.

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GeigerROS is a hardware and software package for robot-mounted Geiger counters. This will allow robotic users to easily integrate radiation sensing capability onto existing robotic designs and interface with the sensor through ROS. We hope that engineers and makers can use this project to explore and map areas that are contaminated, use it to support nuclear weapons disarmament, or simply to explore an unseen facet of the surrounding world.

Geiger counters are the easiest possible way to detect ionizing radiation. The main part of a Geiger counter is a Geiger-Müller tube, which can turn that radiation into a voltage pulse. The tube needs a supply voltage of several hundred volts. GeigerROS uses three simple geiger counter setups, controlled by an Arduino Nano. The nano provides the measurements as ROS topics. By using three detectors, it is not only possible to measure radiation at a given point but also to estimate the direction of the source. Because of limited range of alpha and beta radiation in air, we expect the detectors to mainly detect gamma radiation.

We currently install the sensor on a TurtleBot 3 "Burger" robot. Our final goal is to create a prototype that can autonomously create a radiation & room map in an indoor setting. The map will not only include the strength of radiation, but also some information about directionality.

For the project, we selected the same Geiger-Müller tubes and control/high voltage electronics that have been used in devices developed Safecast Project, e.g. the bGeigie nano. The Safecast project was founded after the Fukushima nuclear accident and aims to provide crowd sourced radiation maps, it is still active today.

The development of our ROS enabled radiation detection sensor is part of a bigger project that aims at developing robots for nuclear weapons disarmament and non-proliferation (preventing new countries from getting nuclear weapons). For non-proliferation applications robots could be employed in existing facilities use for the purpose of civilian nuclear energy production. Already today, these facilities are regularly inspected by human inspectors to make sure that no civilian material is diverted for the purpose of building a nuclear weapon. Usually, the number of inspectors allowed to inspect a facility is limited, and inspection time is typically regulated. In the future, robots might support human inspectors by carrying out search tasks. Our robot equipped with Geiger counters is a small test-bed for a bigger robot that will be equipped with neutron detectors to search for neutron sources.

Besides the ability to search for existing radiation sources, the robot could also be used to make sure that there are no radioactive sources present in a room. Of course, there will always be background radiation, but our setup should enable us to distinguish this from point-like additional sources. A nuclear arms control application would be the check of a room for "emptiness" before the room would be used for example to dismantle a nuclear weapon.

Besides nuclear disarmament and non-proliferation there are other applications for a robotic radiation sensor - it is easy to imagine a similar setup for radiation safety applications. Robots could check contaminated areas after nuclear accidents. For high levels of radiation though all electronics would have to be hardened against radiation damage - likely other robotic platforms than TurtleBot 3 would be needed.

geigerROSsketch.zip

Arduino IDE Sketch for three sensors and a buzzer, providing three ROS topics

Zip Archive - 1009.00 bytes - 05/23/2018 at 00:29

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SensorCase.stl

STL file for the Geiger Counter case

Standard Tesselated Geometry - 1.07 MB - 05/22/2018 at 05:05

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SensorCase.ipt

Inventor part file for the Geiger Counter case

ipt - 903.50 kB - 05/22/2018 at 05:05

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TurtlebotRing.stl

STL file for the mounting ring for the Turtlebot

Standard Tesselated Geometry - 584.36 kB - 05/22/2018 at 05:05

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TurtlebotRing.ipt

Inventor part file for the mounting ring for the Turtlebot

ipt - 457.00 kB - 05/22/2018 at 05:05

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  • Radiation Counting - Ready for ROS

    Moritz Kütt19 hours ago 0 comments

    After we got a single radiation detectors to work with an Arduino Nano, the next step was to connect three of them to the board and write a sketch that provides the data as ROS topics using the rosserial package.

    Instead of using a breadboard to connect the Arduino Nano to the detectors (and the little buzzer, see previous logs), we decided to solder it onto a half-size proto board. This makes most connections somewhat more reliable. The cables to the detectors where connected using angled pin headers.

    The Arduino runs this sketch. Same as for one detector, but now with three. And with the ability to provide ROS topics. To compile the sketch, it is necessary to install the rosserial libraries for the Arduino IDE. The package provides an include file that has to be used in the sketch.

    As the Nano does not have a direct connection to the ROS network, it is necessary to run an additional bridging node. For our setup, the Nano is connected via USB to the RaspberryPi of the Turtlebot3. The bridge is provided by `rosserial_python` command. Here is a small drawing possibly helping the explanation:

    +---------------------------+        +---------------------------+         +---------------------------+
    |                           |        |                           |         |                           |
    |        `rosserial`        | Serial |    `rosserial_python`     | Network |         `roscore`         |
    |      on Arduino Nano      +-------->      on RaspberryPi       +--------->         on Laptop         |
    | collecting radiation data |  over  |  bridging serial to wifi  | (WiFi)  |   providing ROS master    |
    |                           |  USB   |                           |         |                           |
    +---------------------------+        +---------------------------+         +---------------------------+
    

    After we compiled and loaded the sketch on the Arduino Nano, and started the bridge node on the RasberryPi, three new ROS topics became available - gamma1, gamma2 and gamma3 for the three detectors. The topics only provide output whenever one respective detector detects an event, the output is the time since the startup of the Arduino Nano in micro seconds.

    It all worked well, until we started to put the other parts of the Turtlebot 3 back together. Suddenly, we ran into problems with the serial bridge. Of course - the situation is more complex than depicted in the drawing above. The Turtlebot 3 is run by OpenCR, a control module made by Robotis. It also connects to ROS over a serial/USB connection via the RasbperryPi (not shown in drawing above).

    On various reboots, we figured that the USB serial devices switched the enumeration of /dev/ttyUSBx for both devices, which confused the Turtlebot Launch files. To avoid this to happen, we resorted to using the entries in /dev/serial/by-id/ for all relevant commands. For example to launch the serial bridge for the Arduino Nano:

    rosrun rosserial_python serial_node.py /dev/serial/by-id/usb-FTDI_FT232R_USB_UART_AH06N8i02-if00-port0

    instead of 

    rosrun rosserial_python serial_node.py /dev/ttyUSB1

    We also needed to change launch files of the Turtlebot 3 repository to the respective filenames. This included the file 'turtlebot3/turtlebot3_bringup/launch/turtlebot3_core.launch', and also the file 'turtlebot3/turtlebot3_bringup/launch/turtlebot3_lidar.launch' as the LIDAR also has a USB-Serial connection. The actual /dev/serial/by-id/ filenames are easy to find out - just unplug every other device except one. After doing this, we were ready to go, and all USB-Serial connections could be found after rebooting.


  • Turtlebot3 Burger Integration

    Peter Landgrena day ago 0 comments

    With the sensor case and electronics complete it’s time to put our sensors on a real robot and unleash it into the wild!   We’ll be using a Turtlebot3 Burger from Robotis because it’s one of the most popular educational robotics platforms and we already have one handy.  We decided to mount three sensors on our Burger to enable better sensitivity.

    The Burger is conveniently built as a series of “plates,” with each plate comprising a level that holds electronics/motors/sensors.  We’ll just be adding a level to the Burger that holds three of our radiation sensors, along with an arduino to interface with the onboard Raspberry Pi via ROS.  

    To enable simple sensor mounting, we 3D printed a ring that interfaces with the holes on the Burger and has attachment points for the sensor case mounts.  

    Fortunately the ring turned out well on the first try, so we put it on the Turtlebot3, connected everything with the arduino inside, and put the top plate back on.  See the instructions for more details on this assembly process.

  • Sensor Casing Prints and Assembly

    Peter Landgren2 days ago 0 comments

    Now that the sensor casing design is finalized it’s time to print two more to complete our three-sensor setup for the turtlebot3.  Each case also needs heatset inserts and covers. Our covers are lasercut from acyrlic, but can be 3D printed if need be. For assembly instructions see the instructions page.

    Here is one case with covers before assembly:

    Here is one case/sensor full assembled:

    Here are the three assembled sensors in their cases with covers:

    The case is designed to mount on a robot using long (20 mm) M3 screws via two holes spaced 40 mm apart.  This will allow easy connections with robot projects. In the coming weeks we’ll be mounting the sensor on a Turtlebot3 Burger, so stay tuned!

  • First radiation counting

    Moritz Kütt6 days ago 0 comments

    Before connecting three detectors to the Arduino Nano, we made sure that one would work. Using the iRover HV Board/signal processor, connection is simple. The HV board uses 3.3V supply voltage to provide 500V for the Geiger-Mueller tube. It also does some basic signal processing, and outputs a clearly defined pulse (approx. 130µs long) per detected event. The output can directly be read at one of the digital input pins of the Nano.

    The iRover HV Board has a header with three pins. It is not the same header as used on the Arduino or other boards, but ones that go under the name "Swiss Machine Pin" (or similar names like "swiss round machined pins" etc.). We simply solder three female headers to male jumper wires and stabilized it with shrink tube.

    We added a small buzzer to the circuit that clicks for every event. This was very helpful for debugging - the closer you bring a test source, the higher the click rate. If you can't hear clicks, probably something is wrong, e.g. a loose cable. The buzzer is also driven by a digital I/O pin, with a 100 Ohm resistor between pin and buzzer to limit the current it can draw from the pin.

    The code for this setup has not yet ROS compatibility, but just displays events on the serial output and clicks when an event happens. Here is the sketch:

    #define DETECTIONDELAY 140  // in micro seconds
    
    const int detectorPin = 2;
    const int buzzerPin = 5;
    unsigned long nextEvent = 0;
    
    void setup() {
      Serial.begin(115200);
      delay(2000);
      Serial.println("GeigerROS");
       
      pinMode(detectorPin, INPUT);   
      nextEvent = micros() + DETECTIONDELAY;
    }
    
    void loop(){
      if (digitalRead(detectorPin) == HIGH) {     
        if(micros() > nextEvent) {
          nextEvent = micros() + DETECTIONDELAY;  
          tone(buzzerPin, 1000, 2);   
          Serial.print(micros());    
          Serial.println(" µs: Event detected");
        } 
      }
    }

    After we check if the input pin is 'high' we check if enough time has passed since the last event. We know that the pulses remain 'high' for about 130µs. So we just set a delay of 140µs to be on the safe side. The clicks are produced using the 'tone' function of the Arduino library.

  • Sensor Casing Design Version 1.1

    Peter Landgren05/15/2018 at 19:54 0 comments

    Version 1.1 of the sensor case is complete and printed!  The design changes were successful and the Geiger Tube and PCB fit much better now.  Here are a few images of the final case design.

  • Sensor Casing Design Version 1.0

    Peter Landgren05/15/2018 at 19:18 0 comments

    Version 1.0 of the sensor case is complete and printed!  Our goal is to design a radioactivity sensor package that is physically robust, simple, and easy to construct.  We will be using a Turtlebot3 Burger robot for initial testing but also want the sensor package to be easily affixed to other robots, so the sensor attachment system also needs to be flexible.  

    The design is made to be 3D-printed, and encases the Geiger tube and electronics, keeping the high voltage components shielded from wandering fingers.  The PCB is also angled back from the Geiger tube to prevent shielding effects.

    Everything is held in place using M3x8 mm screws and Heatset threaded inserts.  The inserts worked quite well.

    Version 1.0 turned out well, but needs some slight modifications.  In particular, the cavity for the Geiger tube is too tight and the electronics section is slightly too far again from the Geiger tube, which strains the cable. We also need to widen the connector hole on the back and deepen the electronics cavity.   It’s not bad for a first iteration, and we’ll be making these changes soon and printing Version 1.1.

View all 6 project logs

  • 1
    Sensor Case Assembly

    First, 3D print the sensor case and either lasercut or 3D print the Geiger tube and PCB covers.

    Next, insert the M3 heatset inserts using a soldering iron.  Place the insert into the hole, insert the hot iron tip into the insert, and gently press in until it’s flush.  The case uses 12 inserts in total, including two in the back.

    Then, insert the Gieger Tube and PCB into the case, and screw in the PCB

    Then screw the Geiger Tube and PCB covers in place.   These covers are really important as the Geiger Tube is only covered by a thin membrane, and the PCB has an exposed 500V lead!

    All done!

  • 2
    Assemble Breadboard (Protoboard) for Arduino Nano
    Either on a breadboard or on a Proto board, assemble the following circuit:

    (We use a protoboard and angled pin headers)

    To connect the sensors, take three sets of three jumper wires (female on one side for angled pin headers), and solder "Swiss Machine Pin" female headers onto the other side. To prevent shortcuts, pack each single wire in shrink tube, also shrink a bigger tube around the header to get a stable connection.

  • 3
    Software for the Arduino Nano & ROS connection

    This assumes you have ROS and the Turtlebot3 software installed on the RaspberryPi of the robot. It also assumes that roscore (ROS Master) is a laptop/additional computer. To prepare compilation of the sketch using the Arduino IDE first install the rosserial libraries for the IDE (not necessarily on the Pi - we used the ROS master laptop/computer for this):

    sudo apt-get install ros-kinetic-rosserial-arduino
    sudo apt-get install ros-kinetic-rosserial

    Assuming your Arduino libraries ("sketchfolder") are stored under ~/Arduino/libraries, execute the following commands to create the libraries.

    cd ~/Arduino/libraries/
    rosrun rosserial_arduino make_libraries.py .

    This allows now the compilation of our sketch. After flashing it onto the Arduino, connect the latter to the Raspberry Pi.

    To avoid confusion with USB-serial connections, check their respective IDs on the RaspberryPi. If all (Lidar, OpenCR and Arduino) are connected, typing

    $ ls /dev/serial/by-id/

    should give an output similar to this:

    usb-FTDI_FT232R_USB_UART_AH06N802-if00-port0
    usb-ROBOTIS_OpenCR_Virtual_ComPort_in_FS_Mode_FFFFFFFEFFFF-if00
    usb-Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0 

    No you have to find the launch files for the turtlebot package on the Pi (turtlebot3/turtlebot3_bringup/launch/turtlebot3_core.launch and turtlebot3/turtlebot3_bringup/launch/turtlebot3_lidar.launch) . They are likely located in your catkin workspace under src. You have to change the paths for the devices to what you found above. ...OpenCR... goes into the core launch file and the Silicon_Labs filename into the lidar launch file.

    To start the ROS topics for the geiger counters, run:

    rosrun rosserial_python serial_node.py /dev/serial/by-id/usb-FTDI_FT232R_USB_UART_AH06N8i02-if00-port0

    (probably with a different ID/Filename, also from the output above).

    No, a rostopic list on any rosnode (e.g. the laptop running {roscore) should show three new topics, gamma1, gamma2 and gamma3.

    Ready to assemble!

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