[Firebug-cvs] firebug/doc/chassis chassis.tex,1.12,1.13

[David M. D. <do...@us...>]

Update of /cvsroot/firebug/firebug/doc/chassis
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv16163

Modified Files:
	chassis.tex 
Log Message:
.

Index: chassis.tex
===================================================================
RCS file: /cvsroot/firebug/firebug/doc/chassis/chassis.tex,v
retrieving revision 1.12
retrieving revision 1.13
diff -C2 -d -r1.12 -r1.13
*** chassis.tex	6 Aug 2004 07:11:16 -0000	1.12
--- chassis.tex	27 Oct 2005 21:36:27 -0000	1.13
***************
*** 1,3 ****
! \documentclass{article}
  
  \usepackage{chicago}
--- 1,3 ----
! \documentclass[12pt]{article}
  
  \usepackage{chicago}
***************
*** 16,25 ****
  \begin{document}
  
! \title{Chassis design for motes}
! \author{Kevin Lee, Alex Do, David M. Doolin, Nicholas Sitar}
  \date{\today}
  \maketitle
  
  \section{Introduction}
  Wireless sensors networks (WSN) are currently emerging as solutions to monitor 
  and collect data in situations where traditional ``wired'' sensing components 
--- 16,51 ----
  \begin{document}
  
! \title{Chassis and battery design for wireless sensor motes}
! \author{Kevin Lee\thanks{}, 
! Alex Do\thanks{Grad. Research Assistant, Dept. Mechanical 
! Engineering, University of California, Berkeley, CA}, 
! David M. Doolin\thanks{Asst. Research Engineer,
! Earthquake Engineering Research Center, 1301 S. 46th
! St., RFS 451, Richmond CA 94804}, 
! Nicholas Sitar\thanks{Professor and Director,
! Earthquake Engineering Research Center, 1301 S. 46th
! St., RFS 451, Richmond CA 94804}
! }
  \date{\today}
  \maketitle
  
+ \abstract{Wireless sensor motes present an opportunity
+ to increase the density of data collection while lowering
+ the unit cost per datum in a wide variety of scientific, 
+ engineering and industrial applications.  Packaging 
+ and powering these small devices to provide physical 
+ robustness while allowing environmental conditions 
+ around the motes to be accurately measured is challenging
+ because the mote packaging may influence the sensor 
+ measurements. 
+ %%% Add power here.
+ In this report, we describe our current chassis and 
+ battery designs for balancing robustness, convenient 
+ power and environmental access to Crossbow's Mica2 mote
+ for operation in real field environments.}
+ 
+ 
  \section{Introduction}
+ 
  Wireless sensors networks (WSN) are currently emerging as solutions to monitor 
  and collect data in situations where traditional ``wired'' sensing components 
***************
*** 30,34 ****
  or bridges, industrial manufacturing operations, heating and cooling systems, 
  and an endless addition of other applications.  The technology, however, is 
! extremely early in its lifecycle -- where commercial markets are minute and 
  the bulk of the current customers are comprised of government, academic, and
  corporate researchers~\cite{appropriate_refs}
--- 56,60 ----
  or bridges, industrial manufacturing operations, heating and cooling systems, 
  and an endless addition of other applications.  The technology, however, is 
! extremely early in its lifecycle --- where commercial markets are minute and 
  the bulk of the current customers are comprised of government, academic, and
  corporate researchers~\cite{appropriate_refs}
***************
*** 48,105 ****
  
  \section{Background}
- The architecture of a typical wireless sensor consists of the following layers: sensing, 
- communications, and power.  Because WSN sensors operate in mesh networks rather 
- than through point-to-point communication, the communications boards (motes) are 
- more than simple radio transmitters; they consist of an operating system that manages 
- use of power, operates the sensors, and receives and transmits data packets.  As this 
- is a mechanical design study, we will not discuss software since it has no bearing 
- on the mechanical package.
  
! >>need figure of mica mote
  
- The Crossbow Mica platform isolates the remaining layers into the following physical 
- components: sensor boards, a mote board (along with an external radio antenna), and
- a battery clip that holds two AA battery cells.  The sensor boards connect to the mote 
- using a stackable 52-pin edge connector that allows multiple sensors to be used simultaneously.  
- The battery clip is connected to the mote through two inch-long narrow-gauge stranded wires that 
- soldered directly to the mote board (*footnote: earlier versions used solid wire that was not flexible).
- The mote board is secured to the battery clip with a small piece of foam adhesive.  For the radio 
- antennas, Mica users can choose from a solder-on wire antenna or a removable antenna 
- that plugs into an MMCX connector on the mote board.
  
! While a Mica wireless sensor is functional "out-of-the-box," the default configuration is
! not rugged enough for practical use.  Network testing and deployment requires the motes
! to be physically handled, mounted to walls and ceilings, disassembled and reassembled. The 
! current interconnections between each of the components break or fail, ceasing operation of
! the sensor node until the unit is repaired.  Here is a summary of common problems must be solved 
! in the design of a chassis:
! -the edge connectors do not feature any locking engagement, so the sensor boards can become loosened from the mote or from each other
! -the wires from the battery clips are stressed very highly at the solder junctions, and break frequently even with light handling
! -the foam adhesive is not very strong, so the mote and sensors easily become loosened from the battery clip and often causing the fault above
! -the solder-on antenna becomes stressed from repeated repositioning and breaks off from the mote often
  
! In addition, the current mechanical package does not support for mounting.  It is nearly impossible to 
! secure a bare mote to a tree or a wooden post.  Even in an indoor environment, the only common method
! of mounting a mote is by using Velcro (trademark) or other two-sided adhesive, and still many of the 
! aforementioned problems occur.
  
  \section{Design Objectives}
- Early on we identified the following design objectives in a mounting chassis:
- -Tool-less; requires only hands and possibly a coin to open, disassemble, reassemble (rapid and simple)
- -Separation of modular components: sensing, power, mote, antennas
- -Wiring harness to separate power connection
- -battery cage design to accommodate different battery candidates
- -Supports mounting by: screw, strap, zip-tie, magnet
- -Injection moldable for low-cost high-volume production
  
  
  \section{Design for Assembly}
  >>Boothroyd references
  
  -mounting mote onto chassis; supporting edge connectors
  -using wiring harness to connect power to mote
  
  -pyramid assembly
  -using standoffs as thumbnuts
  -chamfers on the battery clip
  
--- 74,162 ----
  
  \section{Background}
  
! The architecture of a typical wireless sensor consists of the
! following layers: sensing, communications, and power.  Because WSN
! sensors operate in mesh networks rather than through point-to-point
! communication, the communications boards (motes) are more than simple
! radio transmitters; they consist of an operating system that manages
! use of power, operates the sensors, and receives and transmits data
! packets.  As this is a mechanical design study, we will not discuss
! software since it has no bearing on the mechanical package.
  
  
! \begin{figure}
! \begin{center}
! %\includegraphics{
! \caption{Mica2 mote as-shipped from Crossbow.}
! \label{mica2}
! \end{center}
! \end{figure}
  
! 
! The Crossbow Mica platform isolates the remaining layers into the
! following physical components: sensor boards, a mote board (along with
! an external radio antenna), and a battery clip that holds two AA
! battery cells.  The sensor boards connect to the mote using a
! stackable 52-pin edge connector that allows multiple sensors to be
! used simultaneously.  The battery clip is connected to the mote
! through two inch-long narrow-gauge stranded wires that soldered
! directly to the mote board (*footnote: earlier versions used solid
! wire that was not flexible).  The mote board is secured to the battery
! clip with a small piece of foam adhesive.  For the radio antennas,
! Mica users can choose from a solder-on wire antenna or a removable
! antenna that plugs into an MMCX connector on the mote board.
! 
! While a Mica wireless sensor is functional "out-of-the-box," the
! default configuration is not rugged enough for practical use.  Network
! testing and deployment requires the motes to be physically handled,
! mounted to walls and ceilings, disassembled and reassembled. The
! current interconnections between each of the components break or fail,
! ceasing operation of the sensor node until the unit is repaired.  Here
! is a summary of common problems must be solved in the design of a
! chassis:
! \begin{itemize}
! \item the edge connectors do not feature any locking 
! engagement, so the sensor boards can become loosened 
! from the mote or from each other.
! \item the wires from the battery clips are stressed 
! very highly at the solder junctions, and break frequently 
! even with light handling.
! \item the foam adhesive is not very strong, so the mote 
! and sensors easily become loosened from the battery clip 
! and often causing the fault above.
! \item the solder-on antenna becomes stressed from 
! repeated repositioning and breaks off from the mote often.
! \end{itemize}
! 
! In addition, the current mechanical package does not support for
! mounting.  It is nearly impossible to secure a bare mote to a tree or
! a wooden post.  Even in an indoor environment, the only common method
! of mounting a mote is by using Velcro (trademark) or other two-sided
! adhesive, and still many of the aforementioned problems occur.
  
  \section{Design Objectives}
  
+ Early on we identified the following design objectives in a mounting chassis:
+ \begin{itemize}
+ \item Tool-less; requires only hands and possibly a coin to open, disassemble, reassemble (rapid and simple)
+ \item Separation of modular components: sensing, power, mote, antennas
+ \item Wiring harness to separate power connection
+ \item battery cage design to accommodate different battery candidates
+ \item Supports mounting by: screw, strap, zip-tie, magnet
+ \item Injection moldable for low-cost high-volume production
+ \end{itemize}
  
  \section{Design for Assembly}
+ 
  >>Boothroyd references
  
  -mounting mote onto chassis; supporting edge connectors
+ 
  -using wiring harness to connect power to mote
  
  -pyramid assembly
+ 
  -using standoffs as thumbnuts
+ 
  -chamfers on the battery clip
  
***************
*** 212,216 ****
  first each time, then this idea of using rechargeable 
  batteries would not be that much more convenient than
!  having to replace the AAs.  Moreover, if the batteries were to only be used for motes, then they would never be completely discharged.  Luckily, Li-Ion batteries 
  do not have this effect, and it is even recommended that 
  only partial discharges be made before recharging them.  
--- 269,275 ----
  first each time, then this idea of using rechargeable 
  batteries would not be that much more convenient than
! having to replace the AAs.  Moreover, if the batteries 
! were to only be used for motes, then they would never be 
! completely discharged.  Luckily, Li-Ion batteries 
  do not have this effect, and it is even recommended that 
  only partial discharges be made before recharging them.  
***************
*** 227,238 ****
  
  
! Currently we are using 3.7V, 600mAh Li-Ion rechargeable batteries, manufactured by Ultralife Batteries, Inc.  Unlike normal rechargeable batteries that are found in electronic devices, these OEM batteries do not have connectors on them already, only two wires with positive and negative polarities.  What this means is that we also have to decide on the type of connector to use.  Judging from the amount of difficulty we have had with the Molex 51021-0200 crimp housings, it would be nice if some other sort of connector could be used, especially a larger one, since the battery wires are larger than the ones used to attach the battery case to the Molex power connector on the board.
! (to be continued...)
  
! Ideally, it would be nice if we could use the one connector for the entire mote.  This would leave us with three options: use the molex power connector, the adaptor jack, or a mini-USB jack. 
  
  \section{Mounting}
  -strapping (velcro, zip-tie)
  -hooks
  -magnets
  
--- 286,311 ----
  
  
! Currently we are using 3.7V, 600mAh Li-Ion rechargeable batteries,
! manufactured by Ultralife Batteries, Inc.  Unlike normal rechargeable
! batteries that are found in electronic devices, these OEM batteries do
! not have connectors on them already, only two wires with positive and
! negative polarities.  What this means is that we also have to decide
! on the type of connector to use.  Judging from the amount of
! difficulty we have had with the Molex 51021-0200 crimp housings, it
! would be nice if some other sort of connector could be used,
! especially a larger one, since the battery wires are larger than the
! ones used to attach the battery case to the Molex power connector on
! the board.  (to be continued...)
  
! Ideally, it would be nice if we could use the one connector for the
! entire mote.  This would leave us with three options: use the molex
! power connector, the adaptor jack, or a mini-USB jack.
  
  \section{Mounting}
+ 
  -strapping (velcro, zip-tie)
+ 
  -hooks
+ 
  -magnets
  
***************
*** 240,246 ****
--- 313,323 ----
  
  -straight-pull design
+ 
  -avoiding undercuts
+ 
  -constant wall thickness to avoid shrinkage
+ 
  -shelled design
+ 
  -strapping slots ribbed for rigidity