mpu9250

A node.js library for communicating with the MPU9250. Based initially on the mpu6050 library (https://github.com/jstapels/mpu6050) by Jason Stapels.

Dependencies

Install

npm install mpu9250

How to use it

var mpu9250 = require('mpu9250');
// Instantiate and initialize.
var mpu = new mpu9250();
if (mpu.initialize()) {
  console.log(mpu.getMotion9());
}

Parameters

// default value
var mpu = new mpu9250({
    // i2c path (default is '/dev/i2c-1')
    device: '/dev/i2c-1',

    // mpu9250 address (default is 0x68)
    address: 0x68,

    // Enable/Disable magnetometer data (default false)
    UpMagneto: true,

    // If true, all values returned will be scaled to actual units (default false).
    // If false, the raw values from the device will be returned.
    scaleValues: false,

    // Enable/Disable debug mode (default false)
    DEBUG: false,

    // ak8963 (magnetometer / compass) address (default is 0x0C)
    ak_address: 0x0C,

    // Set the Gyroscope sensitivity (default 0), where:
    //      0 => 250 degrees / second
    //      1 => 500 degrees / second
    //      2 => 1000 degrees / second
    //      3 => 2000 degrees / second
    GYRO_FS: 0,

    // Set the Accelerometer sensitivity (default 2), where:
    //      0 => +/- 2 g
    //      1 => +/- 4 g
    //      2 => +/- 8 g
    //      3 => +/- 16 g
    ACCEL_FS: 2,

    // Set DLPF Value
    DLPF_CFG: mpu9250.MPU9250.DLPF_CFG_3600HZ,
    // Set Accel DLPF Value
    A_DLPF_CFG: mpu9250.MPU9250.A_DLPF_CFG_460HZ,
    // Set ratio (between MPU9250.SAMPLERATE_MIN and MPU9250.SAMPLERATE_MAX)
    SAMPLE_RATE: 8000,
});

Calibration

All three sensors can be calibrated and the calibrated values provided as options. See the example.js file for how to apply the calibrated values. Run the calibrate_accel.js, calibrate_mag.js and calibrate_gyro.js to calibrate the relevant sensors. The output will display some JSON text, copy and paste this into your code. See the relevant JavaScript source file for the documentation on the calibration.

Integration of Calman Filter

Example :

#!/usr/local/bin/node
console.log('------------------(START SCRIPT)------------------');
var port = 3031;
var io = require('socket.io').listen(port);
var mpu9250 = require('mpu9250');

var mpu = new mpu9250({UpMagneto: true, DEBUG: false, GYRO_FS: 0, ACCEL_FS: 1});

var timer = 0;

var kalmanX = new mpu.Kalman_filter();
var kalmanY = new mpu.Kalman_filter();

if (mpu.initialize()) {
  console.log('MPU VALUE : ', mpu.getMotion9());
  console.log('listen to 0.0.0.0:' + port);
  console.log('Temperature : ' + mpu.getTemperatureCelsius());
  var values = mpu.getMotion9();
  var pitch = mpu.getPitch(values);
  var roll = mpu.getRoll(values);
  var yaw = mpu.getYaw(values);
  console.log('pitch value : ', pitch);
  console.log('roll value : ', roll);
  console.log('yaw value : ', yaw);
  kalmanX.setAngle(roll);
  kalmanY.setAngle(pitch);

  var micros = function() {
    return new Date().getTime();
  };
  var dt = 0;

  timer = micros();

  var interval;

  var kalAngleX = 0,
    kalAngleY = 0,
    kalAngleZ = 0,
    gyroXangle = roll,
    gyroYangle = pitch,
    gyroZangle = yaw,
    gyroXrate = 0,
    gyroYrate = 0,
    gyroZrate = 0,
    compAngleX = roll,
    compAngleY = pitch,
    compAngleZ = yaw;

  io.on('connection', function(socket) {
    var intervalTemp;

    socket.on('disconnect', function() {
      if (interval) {
        console.log('client is dead !');
        clearInterval(interval);
      }
      if (intervalTemp) {
        clearInterval(intervalTemp);
      }
    });

    socket.on('stop_data', function (data) {
      console.log('stop send data');
      if (interval) {
        clearInterval(interval);
      }
    });

    socket.on('send_data', function(data) {
      interval = setInterval(function() {
        var values = mpu.getMotion9();

        var dt = (micros() - timer) / 1000000;
        timer = micros();

        pitch = mpu.getPitch(values);
        roll = mpu.getRoll(values);
        yaw = mpu.getYaw(values);

        var gyroXrate = values[3] / 131.0;
        var gyroYrate = values[4] / 131.0;
        var gyroZrate = values[5] / 131.0;

        if ((roll < -90 && kalAngleX > 90) || (roll > 90 && kalAngleX < -90)) {
          kalmanX.setAngle(roll);
          compAngleX = roll;
          kalAngleX = roll;
          gyroXangle = roll;
        } else {
          kalAngleX = kalmanX.getAngle(roll, gyroXrate, dt);
        }

        if (Math.abs(kalAngleX) > 90) {
          gyroYrate = -gyroYrate;
        }
        kalAngleY = kalmanY.getAngle(pitch, gyroYrate, dt);

        gyroXangle += gyroXrate * dt;
        gyroYangle += gyroYrate * dt;
        compAngleX = 0.93 * (compAngleX + gyroXrate * dt) + 0.07 * roll;
        compAngleY = 0.93 * (compAngleY + gyroYrate * dt) + 0.07 * pitch;

        if (gyroXangle < -180 || gyroXangle > 180) gyroXangle = kalAngleX;
        if (gyroYangle < -180 || gyroYangle > 180) gyroYangle = kalAngleY;

        var accel = {
          pitch: compAngleY,
          roll: compAngleX
        };

        var magneto = mpu.getCompass(values[6], values[7], values[8]);
        console.log(values[6] + ' ' + values[7] + ' ' + values[8]);
        console.log(magneto);
        socket.emit('accel_data', {accel: accel, magneto: magneto});
      }, 1);
    });

    intervalTemp = setInterval(function() {
      socket.emit('temperature', {temperature: mpu.getTemperatureCelsiusDigital()});
    }, 300);
  });
}