Converting AIDS data to MKS units

Parsing_ADIS_messages.ipynb

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  "name": "Parsing_ADIS_messages"
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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Parsing ADIS Messages"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Lets start with the raw packet from the pcat file and then pick out the first ADIS message and get just the data (message header unpacking should already work):"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "message_raw = \"\\x2D\\x08\\x06\\x00\\x04\\x00\\xF7\\xFF\\x28\\x01\\x01\\x00\\x00\\x00\\x9F\\x04\\x8D\\xFF\\xC8\\xFD\\x3C\\x00\\x00\\x00\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 80
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Using struct we can unpack the message"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import struct\n",
      "adis = struct.unpack('<12h', message_raw)\n",
      "print adis"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "(2093, 6, 4, -9, 296, 1, 0, 1183, -115, -568, 60, 0)\n"
       ]
      }
     ],
     "prompt_number": 81
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Okay, those numbres look good. We should still be on the ground, so roll numbers are small, and x acell is close to 300 which is about 1 g (we'll see this later)\n",
      "\n",
      "Now we can do unit conversion:\n",
      "\n",
      "Starting with voltage. We have LSB, the ADIS datasheet tells us how to get to mV"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "power_mV = adis[0] * 2.418  # From datasheet\n",
      "print power_mV"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "5060.874\n"
       ]
      }
     ],
     "prompt_number": 82
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "And now to MKS we want volts. mV to V is $\\frac{1}{1000}$"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "power_V = power_mV / 1000.0\n",
      "print \"ADIS main bus voltage: %0.3f V\" % power_V # Rounding here because there is noise in the lower bits and float conversion "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "ADIS main bus voltage: 5.061 V\n"
       ]
      }
     ],
     "prompt_number": 83
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "And now the rest with the same strategy:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "gyro = []\n",
      "for i in xrange(3): gyro.append(adis[i+1] * 0.05) # deg/s\n",
      "accel = []\n",
      "for i in xrange(3): accel.append(adis[i+4] * 3.33) # mg (milli gee)\n",
      "mag = []\n",
      "for i in xrange(3): mag.append(adis[i+7] * 0.5) # mG\n",
      "temp = adis[10] * 0.14 # C\n",
      "spare = adis[11] # Unused"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 84
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Now to get to MKS we do some math.\n",
      "\n",
      "##### Degreess to radians:\n",
      "\n",
      "$$\\times \\frac{\\pi}{180}$$\n",
      "\n",
      "##### mg to m&middot;s<sup>-2</sup>\n",
      "\n",
      "$$\\times \\frac{g_0}{1000}$$\n",
      "\n",
      "Were $g_0$ is `9.8066`\n",
      "\n",
      "##### mG to Tesla\n",
      "\n",
      "$$\\times 10^{-7}$$\n",
      "\n",
      "G is Gauss\n",
      "\n",
      "#### &deg;C to K\n",
      "\n",
      "$$+ 274.15$$"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import pi\n",
      "for i in xrange(3): gyro[i] *= pi/180.0\n",
      "for i in xrange(3): accel[i] *= 9.8066/1000.0\n",
      "for i in xrange(3): mag[i] *= 1.0e-7\n",
      "temp = temp + 274.15"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 85
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "And now we have MKS units from the ADIS:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print \"XYZ Gryo: (\" + ', '.join('%0.5f r/s' % v for v in gyro) + ')'\n",
      "print \"XYZ Accleration: (\" + ', '.join('%0.3f m/s^2' % v for v in accel) + ')'\n",
      "print \"XYZ Magnatometer (\" + ', '.join('%0.2e T' % v for v in mag) + ')'\n",
      "print \"temperature %0.0f K\" % temp"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "XYZ Gryo: (0.00524 r/s, 0.00349 r/s, -0.00785 r/s)\n",
        "XYZ Accleration: (9.666 m/s^2, 0.033 m/s^2, 0.000 m/s^2)\n",
        "XYZ Magnatometer (5.91e-05 T, -5.75e-06 T, -2.84e-05 T)\n",
        "temperature 283 K\n"
       ]
      }
     ],
     "prompt_number": 86
    },
    {
     "cell_type": "raw",
     "metadata": {},
     "source": []
    }
   ],
   "metadata": {}
  }
 ]
}