mypapers/eyebot-battery/eyebot-battery.tex

   1 \documentclass[a4paper,oribibl]{llncs}
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   3 \usepackage{graphicx}
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   5
   6 \title{Eyebot battery lifetime measurement\\Test report}
   7 \date{2000-06-27}
   8 \author{Petter Reinholdtsen}
   9 \institute{University of Western Australia\\
  10    Mobile Robots Lab at The Center for Intelligent Information Processing}
  11
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  33
  34 \begin{document}
  35 \maketitle
  36
  37 \begin{abstract}
  38   When preparing CIIPS Glory, our team of robot soccer players for
  39   participation in the RoboCup 2000 world cup, it was necessary to
  40   have some indication on the battery life time on our robots.  This
  41   short note describes how we measured the battery lifetime and the
  42   measured results.
  43 \end{abstract}
  44
  45 \section{Test setup}
  46
  47 To avoid loosing the measured data when the battery was flat, I used
  48 radio communication to transmit the current battery status.  The
  49 battery status where read OSGetAD() on channel 1.  This 10 bit value
  50 is then transmitted with the current timestamp to a listening PC.  At
  51 first they where read every 60 seconds, later I started reading every
  52 10 seconds.
  53
  54 When testing, a freshly charged battery where inserted into the robot,
  55 and a program where loaded from Flash ROM to run the test.  This
  56 program initialized the radio communication using the CIIPS Glory
  57 language library, and started transmitting battery status.  The
  58 measurement ended when the Eyebot died with no power left.  Only the
  59 measurements transmitted over radio where used.
  60
  61 To test if the battery lifetime changed depending if the sensors and
  62 features used, I tried with two different programs.  One (sniffer.c -
  63 ``radio'') only initializes the radio, the other (motor4.c -
  64 ``everything'') tries to use as many sensors and actuators as possible
  65 and drives randomly and moves the camera servo from side to side while
  66 reading the PSD values and camera images.
  67
  68 I did not test with a compass connected, as none of the robots had
  69 this sensor connected when these measurements were done.  With this
  70 exception, I believe the ``everything'' battery test gives a good
  71 indication on the battery lifetime during robot soccer competition.
  72
  73 \section{Results}
  74
  75 The results as given in figure \ref{fig:batstatus} was quite
  76 surprising.  With only the CPU and the radio in use, the battery
  77 lifetime where just above 3 hours (with one exception).  When driving
  78 around, the robot died after about 30 minutes.
  79
  80 \begin{figure}
  81   \centering
  82   \includegraphics[width=12cm]{battery}
  83   \caption{Battery status over time}
  84   \label{fig:batstatus}
  85 \end{figure}
  86
  87 Robot C did not have a camera mounted when I ran these tests, so I
  88 decided to test other robots with ``everything''.  When I first tested
  89 B3 on robot D, I suspected something wrong with the robot.  Measuring
  90 the same battery on a different robot showed the same behavior.
  91
  92 There seem to be significant differences between batteries, and not so
  93 much differences with different CPU frequencies.  I did not do a
  94 complete test with all combinations of batteries and robots, as this
  95 seemed as wasted time after discovering the half hour life time when
  96 driving around.
  97
  98 \section{Conclusions}
  99
 100 The batteries used by our Eyebot soccer robots have different
 101 lifetime.  We need to test the all our batteries and only use the best
 102 during competition.
 103
 104 We should modify our robot soccer programs to report the battery
 105 status to a off-field monitoring system, and make sure to replace
 106 batteries when the power status as read from the A/D converter falls
 107 below 750-800.
 108
 109 \section*{Appendix A - Technical details}
 110
 111 \subsection*{The batteries}
 112
 113 The batteries used in our Eyebot soccer robots are marked ``Universe
 114 UR-S4 Li 1350 mAh 7.2V Li-ion''.  I tested with 3 different batteries.
 115
 116 \begin{table}
 117 \centering
 118 \caption{Battery serial number}
 119 \label{table:batteries}
 120 \begin{tabular}{|l|r|}
 121 \hline
 122 Battery & Serial \# \\
 123 \hline \hline
 124 B1 & 071853 \\
 125 B2 & 071808 \\
 126 B3 & 071855 \\
 127 \hline
 128 \end{tabular}
 129 \end{table}
 130
 131 \subsection*{The robots}
 132
 133 \subsubsection*{Robot C}
 134
 135   RoBIOS 3.1d (eyecam)
 136   40 MHz
 137   1 MB RAM
 138   512 KB ROM
 139   3 PSD distance sensors
 140   418 MHz radio
 141
 142 \subsubsection*{Robot D}
 143
 144   RoBIOS 3.1d (eyecam)
 145   40 MHz
 146   1 MB RAM
 147   512 KB ROM
 148   3 PSD distance sensors
 149   1 Camera servo
 150   1 EyeCam
 151   418 MHz radio
 152
 153
 154 \subsubsection*{Robot E}
 155
 156   RoBIOS 3.1d (eyecam)
 157   35 MHz
 158   1 MB RAM
 159   512 KB ROM
 160   3 PSD distance sensors
 161   1 Camera servo
 162   1 EyeCam
 163   418 MHz radio
 164
 165
 166 \end{document}