BeaKon Anchor installation

Calibration processes

The goal of the calibration is to know precisely the X, Y and Z coordinates of each anchor. The position of an anchor is measured from its LED placed in the center of its front face. The white rectangle around the LED helps you see the anchors center from far away.

The rest of this tutorial lists different methods to measure the anchors position. It is up to you to decide which method to use depending on your application.

Anchor calibration using the Leica Disto S910

The Leica Disto S910 can be used to quickly measure the anchors position in an efficient and easy way. To calibrate the anchors with the Leica Disto S910, you will also need a PC with Wifi connectivity and the "DISTO transfer PC" software installed on it.

For an easier manipulation of the S910, we recommend using the smartbase FTA360S along with the tripod TRI 120 from Leica.

To measure the position of anchors with the S910 :

• Place the S910 in a steady spot, where it has line of sight with :

  • The origin of your coordinate system (0;0;0)
  • A point along the X axis positive direction
  • As many anchors you need to calibrate as possible

If you can't see all the anchors from a single spot :

You can reiterate the following steps from different places until all the anchors coordinates are measured.

• Turn on the S910 and check that its connectivity is set on WLAN hotspot.
• Connect the PC to the "DISTO xxxxxxxx" WiFi network and start the "DISTO transfer PC" software.

• Once the connection is established, got to the "Measurement Log" tab.

• On the S910, open the "WLAN data transmission" function.

• Follow the calibration steps instructed by the S910.

• Once the S910 is calibrated, point it at the origin and take the first measurement.

To take a measurement :

You need to press the "ON DIST" button (or the middle tactile button) once to power on the laser. You can then place the laser where you want to measure. When the laser points at the right direction, press the button a second time to take the measurement.

• Click on the transfer button (right side) to see the X, Y and Z coordinates of the point measured on the "Measurement Log" tab of the DISTO transfer PC, they should be "0;0;0".

• Point the S910 on the point along the X axis (positive direction) and take a second measurement. Transfer the measurement to the PC.
• Check that the X coordinate's sign of the point measured is positive. If the coordinate is negative, you will need to pay attention and invert the X coordinates of the anchors positions you will then measure once you enter them in the system.
• For each anchor, point the laser at their white rectangle, take a measurement and transfer the coordinates to the PC. Make sure to recall the serial number of the anchors with each measurement.
• You can then input the values measured in the Eliko Dashboard.

Anchor calibration using a simple rangefinder

The anchors position can be measured using a simple laser rangefinder if :

• their height from the ground (Z coordinate) can be easily measured
• their distance from multiple points of known coordinates (calibration points) can be easily measured

If thoses conditions are met, you can use a laser rangefinder along with a simple python script to determine the anchors X and Y coordinates by just measuring their height and their direct distance to the calibration points. All the measurements you take have to be inputed in a file called anchors.json :

• First, you have to enter the x, y and z position of the calibration points (named with a letter). There are 6 calibration points present by default in the file but you can add more if needed. If you don't use all the calibration points, you don't need to delete them from the file.

"calibration_points": {
        "A": {
            "x": -1,
            "y": 0,
            "z": 0.85
        }
},

• Second, you have to fill in for each anchor their height (Z coordinate) and their direct distance to as many calibration points as possible.

"anchors": {
        "0016E2": {
            "name": "0016E2",
            "height": 1.967,
            "A": 3.372,
            "B": 4.461,
            "C": 3.690,
            "D": 2.246,
            "E": 0,
            "F": 0
        }
 }

• Tips :
  • The height of the anchor is the distance from its LED (center of the white rectangle) to the Z = 0 plane. If you measure from the bottom of the anchor, add 45mm to the measure (distance LED - bottom of the anchor).
  • To measure the direct distance from a calibration point to an anchor, use a laser rangefinder placed at the calibration point and aim at the white square of the anchor.
  • Each anchor is referenced by its serial number. You can also add a name for each anchor (like "front stage right") for a better visibility.
  • You have to measure the distance of each anchor to at least 3 calibrations points for the script to work.
  • For a better result measure the distance to a many calibration points as possible (the more the better).
  • If you don't have the measured distance to a calibration point (or if you don't use this calibration point at all), enter 0 for this particular point for the script to not take into account this measure.

• Lastly, once the config file is written and saved, you can run the script by opening a bash where the script and the file are located and runing the following command :

python calib_anchors.py

• The position (X, Y and Z coordinates) of each anchor will then be calculated and outputed in the bash.

Anchor ID: 0016E2 - 0016E2
Estimated Anchor Position (x, y, z): -1.914, 2.459, 1.967
Distance to A: 2.739
Distance to B: 4.004
Distance to C: 3.122
Distance to D: 1.084

• You can then input the values measured in the Eliko Dashboard.