gps/examples/maps/server.js

A GPS NMEA parser library

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

var Sylvester = require('sylvester');
var Kalman = require('kalman').KF;

// var file = '/dev/cu.usbserial';
// var file = '/dev/ttyUSB0';
//var file = '/dev/tty.usbserial';
var file = '/dev/tty.usbmodem1411';

const { SerialPort } = require('serialport');
const { ReadlineParser } = require('@serialport/parser-readline');

const parser = new ReadlineParser({
  delimiter: '\r\n'
});

const port = new SerialPort({
  path: file,
  baudRate: 4800
});

port.pipe(parser);


var GPS = require('gps');
var gps = new GPS;

// Simple Kalman Filter set up
var A = Sylvester.Matrix.I(2);
var B = Sylvester.Matrix.Zero(2, 2);
var H = Sylvester.Matrix.I(2);
var C = Sylvester.Matrix.I(2);
var Q = Sylvester.Matrix.I(2).multiply(1e-11);
var R = Sylvester.Matrix.I(2).multiply(0.00001);

// Measure
var u = $V([0, 0]);

var filter = new Kalman($V([0, 0]), $M([[1, 0], [0, 1]]));

gps.on('data', function (data) {

  if (data.lat && data.lon) {

    filter.update({
      A: A,
      B: B,
      C: C,
      H: H,
      R: R,
      Q: Q,
      u: u,
      y: $V([data.lat, data.lon])
    });

    gps.state.position = {
      cov: filter.P.elements,
      pos: filter.x.elements
    };
  }

  io.emit('position', gps.state);
});

app.get('/', function (req, res) {
  res.sendFile(__dirname + '/maps.html');
});

http.listen(3000, function () {

  console.log('listening on *:3000');
});

parser.on('data', function (data) {
  gps.update(data);
});