mypapers/eyebot-battery/eyebot-battery.html

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   8 <title> Eyebot battery lifetime measurement\\Test report</title>
   9
  10 <H1 align="center">Eyebot battery lifetime measurement<br>Test report </H1>
  11
  12 <H3 align=center>2000-06-27 </H3>
  13
  14 <H3 align=center>Petter Reinholdtsen </H3>
  15
  16
  17 <p>
  18
  19 <H2> Abstract</H2>
  20   When preparing CIIPS Glory, our team of robot soccer players for
  21   participation in the RoboCup 2000 world cup, it was necessary to
  22   have some indication on the battery life time on our robots.  This
  23   short note describes how we measured the battery lifetime and the
  24   measured results.
  25 <p>
  26
  27 <p>
  28         <H2><A NAME="tth_sEc1">
  29 1</A>&nbsp;&nbsp;Test setup</H2>
  30
  31 <p>
  32 To avoid loosing the measured data when the battery was flat, I used
  33 radio communication to transmit the current battery status.  The
  34 battery status where read OSGetAD() on channel 1.  This 10 bit value
  35 is then transmitted with the current timestamp to a listening PC.  At
  36 first they where read every 60 seconds, later I started reading every
  37 10 seconds.
  38
  39 <p>
  40 When testing, a freshly charged battery where inserted into the robot,
  41 and a program where loaded from Flash ROM to run the test.  This
  42 program initialized the radio communication using the CIIPS Glory
  43 language library, and started transmitting battery status.  The
  44 measurement ended when the Eyebot died with no power left.  Only the
  45 measurements transmitted over radio where used.
  46
  47 <p>
  48 To test if the battery lifetime changed depending if the sensors and
  49 features used, I tried with two different programs.  One (sniffer.c -
  50 ``radio'') only initializes the radio, the other (motor4.c -
  51 ``everything'') tries to use as many sensors and actuators as possible
  52 and drives randomly and moves the camera servo from side to side while
  53 reading the PSD values and camera images.
  54
  55 <p>
  56 I did not test with a compass connected, as none of the robots had
  57 this sensor connected when these measurements were done.  With this
  58 exception, I believe the ``everything'' battery test gives a good
  59 indication on the battery lifetime during robot soccer competition.
  60
  61 <p>
  62         <H2><A NAME="tth_sEc2">
  63 2</A>&nbsp;&nbsp;Results</H2>
  64
  65 <p>
  66 The results as given in figure <A href="#fig:batstatus">1</A> was quite
  67 surprising.  With only the CPU and the radio in use, the battery
  68 lifetime where just above 3 hours (with one exception).  When driving
  69 around, the robot died after about 30 minutes.
  70
  71 <p>
  72
  73 <p><A NAME="tth_fIg1">
  74 </A>   <center>  <img src="battery.png" alt="battery.png"><br>   <center>Figure 1: Battery status over time</center>
  75   <A NAME="fig:batstatus">
  76 </A>
  77 </center><p>
  78 <p>
  79 Robot C did not have a camera mounted when I ran these tests, so I
  80 decided to test other robots with ``everything''.  When I first tested
  81 B3 on robot D, I suspected something wrong with the robot.  Measuring
  82 the same battery on a different robot showed the same behavior.
  83
  84 <p>
  85 There seem to be significant differences between batteries, and not so
  86 much differences with different CPU frequencies.  I did not do a
  87 complete test with all combinations of batteries and robots, as this
  88 seemed as wasted time after discovering the half hour life time when
  89 driving around.
  90
  91 <p>
  92         <H2><A NAME="tth_sEc3">
  93 3</A>&nbsp;&nbsp;Conclusions</H2>
  94
  95 <p>
  96 The batteries used by our Eyebot soccer robots have different
  97 lifetime.  We need to test the all our batteries and only use the best
  98 during competition.
  99
 100 <p>
 101 We should modify our robot soccer programs to report the battery
 102 status to a off-field monitoring system, and make sure to replace
 103 batteries when the power status as read from the A/D converter falls
 104 below 750-800.
 105
 106 <p>
 107
 108 <H2>Appendix A - Technical details</H2>
 109
 110 <p>
 111
 112 <H3>The batteries</H3>
 113
 114 <p>
 115 The batteries used in our Eyebot soccer robots are marked ``Universe
 116 UR-S4 Li 1350 mAh 7.2V Li-ion''.  I tested with 3 different batteries.
 117
 118 <p>
 119
 120 <p><A NAME="tth_tAb1">
 121 </A> <center> <center>Table 1: Battery serial number</center>
 122 <A NAME="table:batteries">
 123 </A>
 124
 125 <TaBle border>
 126 <tr><td>Battery </td><td align="right">Serial # </td></tr><tr><td>
 127 <tr><td>B1 </td><td align="right">071853 </td></tr>
 128 <tr><td>B2 </td><td align="right">071808 </td></tr>
 129 <tr><td>B3 </td><td align="right">071855 </td></tr></TaBle>
 130
 131 </center><p>
 132 <p>
 133
 134 <H3>The robots</H3>
 135
 136 <p>
 137
 138 <H4>Robot C</H4>
 139
 140 <p>
 141   RoBIOS 3.1d (eyecam)
 142   40 MHz
 143   1 MB RAM
 144   512 KB ROM
 145   3 PSD distance sensors
 146   418 MHz radio
 147
 148 <p>
 149
 150 <H4>Robot D</H4>
 151
 152 <p>
 153   RoBIOS 3.1d (eyecam)
 154   40 MHz
 155   1 MB RAM
 156   512 KB ROM
 157   3 PSD distance sensors
 158   1 Camera servo
 159   1 EyeCam
 160   418 MHz radio
 161
 162 <p>
 163
 164 <H4>Robot E</H4>
 165
 166 <p>
 167   RoBIOS 3.1d (eyecam)
 168   35 MHz
 169   1 MB RAM
 170   512 KB ROM
 171   3 PSD distance sensors
 172   1 Camera servo
 173   1 EyeCam
 174   418 MHz radio
 175
 176 <p>
 177
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