Sensor Fusion app Examples

This page contains examples of how to use the Sensor Fusion app:

 Stream Data to MATLAB

This is a short example of how to streamdata to MATLAB from the Sensor Fusion app, more detailed instructions and a complete example application is available as part of these lab instructions.

  1. Download the zip archive with the support functions and unzip the files to your MATLAB path (eg, the current directory).
  2. Start MATLAB and run script startup.m.
  3. Execute the following code snippet starts a small server to receive measurements from the Sensor Fusion app in MATLAB and starts processing data as it arrives: 
    import('se.hendeby.sensordata.*');
try
  %% Create data link
  server = StreamSensorDataReader(3400);
  % Makes sure to resources are returned.
  sentinel = onCleanup(@() server.stop());

  server.start();  % Start data reception.
catch e
  fprintf(['Unsuccessful connecting to client!\n' ...
    'Make sure to start streaming from the phone *after* '...
           'running this function!']);
  return;
end

while server.status()  % Repeat while data is available
  % Get the next measurement set, assume all measurements
  % within the next 5 ms are concurrent (suitable for sampling
  % in 100Hz).
  data = server.getNext(5);

  if isnan(data(1))  % No new data received
    continue;
  end

  % Process data
  % data(1)         Time [ms]
  % data(1, 2:4)    Accelerometer; x, y, z [m/s^2]
  % data(1, 5:7     Gyroscope; x, y, z [rad/s]
  % data(1, 8:10)   Magnetometer; x, y, z [uT]
  % data(1, 11:13)  GPS [deg North, deg East, alt m]
  % data(1, 14)     Pressure [hPa]
  % data(1, 15)     Light [lux]
  % data(1, 16)     Proximity [cm]
  % data(1, 17)     Temperature [deg C]
  % data(1, 18:21)  Orientation [normalized quaternion]
  % data(1, 22:27)  Uncalibrated gyroscope; x, y, z, bx, by, bz [rad/s]
  % data(1, 28:33)  Uncalibrated magnetometer; x, y, z, bx, by, bz [uT]
  %
  % Nan values indicate missing data.
end
  4. Make sure the Sensor Fusion app tires to connect to the correct IP and is set to stream data and press start to begin processing data.NB: It is essential to start the server before pressing start in the Sensor Fusion app.

Read a Log File offline in MATLAB

The following code snippet illustrates how to read in a log file produced by the Sensor Fusion app into a large matrix. A similar method can also be used to read the log file in an online-like manner. (See the jar-documentation for how.)

import('se.hendeby.sensordata.*');
dataFile = FileSensorDataReader('sensorLog.txt');
dataFile.start();

% Normal measurement data
dataFile.reset();
data = dataFile.getAll(5); % Typically group things separated less than half a period

% Process data
% One row per time stamp

Re-Stream a Log File

The provided jar file contains a program to stream a given log file to a server. The program simulates measurements from a Sensor Fusion app running on a smartphone, based on measurements collected in a log file from the same app. Run the program instead of pressing start in the Sensor Fusion app.

Usage:

  java -classpath sensordata.jar se.hendeby.sensordata.StreamSensorDataFile [--ip <127.0.0.1>] [--port <3400>] [--] logfile