TEAM 2
Solar-Powered Multi-Seat Computer Kiosk
for Tanzanian Classrooms
ECE Facilitator
Telecomm Facilitator
UDSM Solar Advising Professor
UDSM Telecomm Advising Professor
Management
Web
Document
Presentation/Lab
Telecomm
Telecomm
UDSM Telecomm
Jian Ren
Kurt DeMaagd
Dominick Chambega
Aloys Mvuma
Jakub Mazur
Josh Wong
Ben Kershner
Eric Tarkleson
Joe Larsen
Tor Bjornrud
Victor Crallet
Request for Proposal – October 13th, 2008
Sponsored By:
In Cooperation With:
Michigan State University
University of Dar es Salaam
Executive Summary
With the increasing proliferation of affordable, reliable personal computers
into the marketplace, there is a great demand to develop affordable personal
computers for remote and undeveloped areas. One such potential region is rural
East Africa, specifically Tanzania. Before deploying a computer system into such
harsh conditions, several obstacles must be overcome, including source of
electricity, telecommunications, and the savannah climate. The Lenovo Corporation
has tasked this team to develop a solar-powered computer workstation that can
accommodate up to eight users. The solution must be robust enough to withstand
the harsh environment with as little technical maintenance as possible, yet still be
affordable for rural schools.
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Table of Contents
EXECUTIVE SUMMARY
2
TECHNICAL SPECIFICATIONS
4
INTRODUCTION
BACKGROUND
DESIGN SPECIFICATIONS
DESIGN CRITERIA
CONCEPTUAL DESIGN
PHASE I: POWER ARCHITECTURE
PHASE II: SYSTEM ARCHITECTURE PROTOTYPES
PHASE III: POWER MANAGEMENT
PHASE IV: CONTENT
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4
5
5
6
7
8
14
14
PROJECT MANAGEMENT
15
DESIGN TEAMS AND ROLES
15
REFERENCES
16
IMAGES
NOMENCLATURE
16
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Technical Specifications
Introduction
The primary goal of this project is to help promote education in developing
countries by providing grade schools with electronic resources. There are a variety
of other groups that have already initiated solutions to this problem. The most
prominent group is the One Laptop Per Child Association (hereinafter referred to as
OLPC), which has created a cheap, durable laptop known as the XO-1. Other groups
such as the Center for Scientific Computing and Free Software (hereinafter referred
to as C3SL) have made significant strides in reusing older computers for schools;
however, both of those programs have some significant drawbacks.
Background
The primary competitor identified is the OLPC. The OLPC Association is
dedicated to producing low cost laptops and distributing them to low-income areas.
There exist several problems with the program, including the per-deployment cost
and deployment. The original intent was to deliver a laptop to every child for a cost
of $100 per device. The program, however, is unable to deliver the laptop at the
$100 target; in fact, the cost to donate a system is almost $200. Deployments also
require a minimum commitment of 100 laptops. This represents a very significant
financial burden, though once deployed, the XO-1’s are extremely rugged PCs and do
not depend on any external power sources. Once deployed, it is difficult to integrate
multiple PCs into a cohesive learning environment, and this takes away from
educating the students.
C3SL’s solution integrates into school systems better, and was widely
deployed in the Paraná Digital project. This project involved having the multiple
terminals running off of a single computer in multiple schools. This program has
been very successful and shows great promise, but there is a critical flaw. The
program is entirely software, and this software was intended to run in a classroom
equipped with at a minimum basic utilities, such as power and internetconnectivity.
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Our solution is to integrate the OLPC's ruggedness and the C3SL's novel
software solution into one robust package. The design team preceding ours built a
solar powered computer system that can be deployed in a relatively durable
building. They assembled a solar panel, battery, and a charge controller into a selfcontained solution, such that deployment in a wide variety of climates and locales is
possible, but they were unable to decide on the computer system. Our primary goal
for this project of integrating the work of our predecessors with a computer system
that is suitable for educating youth, regardless of regional or socio-economic
boundaries.
Design Specifications
The core of the design is a single computer powering multiple dumb
terminals. There are many ways to create a dumb terminal; these will be discussed
later in the proposal. The entire system is connected to an AC/DC inverter, which is
powered by a large, deep-cycle battery. The battery is charged via a photovoltaic
panel. There is independent monitoring circuitry to ensure the system is functioning
properly, which can gather data to recommend ways of improving system
performance as well.
Once the prototype is complete, we will install it in a school in Tanzania.
Lenovo will also be able to mass-produce the system and package it for sale. A
variety of organizations, such as governments or humanitarian groups, can then
purchase a base station and add any number of terminals. Given that each station
functions independent of a power source or communications source, it can be
shipped to any location and quickly be installed. Once the system is set up, it will
require minimal maintenance, and limited software support will be provided over
the Internet.
Design Criteria
The following requirements are established to decide the feasibility and rating
the desirability of the conceptual designs:

Stability/Reliability
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o The system is to operate in a remote area with as little maintenance as
possible.

Power Consumption
o Solar power is the single power source for the system therefore
minimal power consumption is a priority.

Construction Difficulty
o The team has a limited time frame to complete the project and have it
packaged ready for deployment.

Lenovo Hardware
o Implementing the sponsor’s hardware into the system will help keep
costs down.

Cost
o The system is to be implemented in schools with a very limited
budget, the lower the cost the greater the chances of system
deployment.
The criteria (specifications) to be used in the matrices for deciding the
feasibility and rating the desirability of the conceptual designs are still being
developed, and at least one conceptual design.
Conceptual Design
The conceptual design for this project is split into four phases. The first is
power system design, which for the most part was completed by the previous
semester’s team, but was still reviewed by our team. The next phase is system
architecture, i.e. how the computers and workstations are set up. After that, we
covered power management, and finally, content.
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Phase I: Power Architecture
Figure 1: Power architecture flowchart.
Given that the power architecture was in place when the team received the
project, and that the schedule and budget are limited, we decided to leave it in its
current configuration. A meeting was convened and possible improvements to the
architecture were discussed, which could be considered for the production model.
Starting from the top down is the solar panel. There are two qualities to
consider: efficiency and price. The panel chosen should provide the highest wattage
per dollar spent, giving the greatest value. Several cheap, low efficiency panels
would be preferable to a single high efficiency panel if they provide a higher wattage
per dollar. They would also be more robust; e.g. a single panel could fail and the
system would loose a portion of its power generation capabilities, rather than its
sole source of power. The panel currently used is the Kyocera KC85TS 85W panel,
which operates at 16% efficiency (see Figure 2 for value).
A mid-range standard charge controller (CirKit SCC3) is used to regulate the
voltage from the solar panel to the battery. The standard charge controller could be
improved by replacing it with a maximum power point tracker (MPPT), which is
more capable of handling the surplus voltage (> 15V) generated by the solar panel
in high irradiance conditions (i.e. direct sunlight).
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The battery purchased for the project is a 225 Amp-Hour marine deep-cycle
battery, chosen for its large capacity and ability to delivery current at a constant
voltage for an extended period of time. As in the solar panel, the capacity and price
are the two key qualities in consideration (see Figure 2 for value), the life cycle is
also very important. It tends to not vary throughout the industry with deep-cycle gel
batteries intended for solar use, and therefore did not garner much consideration.
This entire system feeds a 1750W power inverter, which ideally operates at
90% efficiency. From here power can be provided to anything that can operate at
115VAC. This may be an issue depending on the area of deployment; a majority of
the world operates at 220-240VAC, thus interfacing other components into the
power system (such as cell phone chargers) could prove to be dangerous.
Figure 2: Component cost/value table.
Component
Solar Panel
Charge
Controller
Battery
Power Inverter
Model
Number
Kyocera
KC85TS
CirKit SCC3
Capacity
Efficiency
Cost
Value
85W
16%
$468.75
0.181 W/$
N/A
N/A
$44.95
N/A
Deka
Domintator
8G8D
XPower
1750 Plus
225AH
N/A
$399.07
0.564 AH/$
1750W
90%
N/A
N/A
Phase II: System Architecture Prototypes
The ECE team considered four ideas for the architecture of the system.
During a whiteboard brainstorming session, each prototype was sketched, the pros
and cons were weighed, and a cost was estimated, as shown in Figure 3.
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Figure 3: System architecture advantages, disadvantages, and estimated cost table.
Cost Outline:
Total Cost:
Pros:
Cons:
Laptops
Baseline:
- Router with
advanced
features ($200)
Per Seat:
- Lenovo IdeaPad
S10 Latop ($439)
- Mount ($50)
Thin Client
Baseline:
- Server ($500)
Multi-User
Baseline:
- Powerful
Server ($800)
Per Seat:
- Diskless
Workstation
LTSP 1220PXE
Thin Client
($285)
- Lenovo L197
Monitor ($239)
- Keyboard/
Mouse ($30)
Per Seat:
- Lenovo L197
Monitor
($239)
- Keyboard/
Mouse ($30)
- Video card
($30)
- Optional
Software
($100)
Base: $200
Per Seat: $489
Easy, Reliable,
Serverless, Redundant,
Low
Power
Consumption
Base: $500
Per Seat: $554
Easy, Reliable,
Stable, Low
Power, COTS
Small Screens,
Defeats
Purpose of
Designing a
New system as
Opposed to
Donating
Laptops, Security
Concerns
Relatively
Expensive,
Lenovo
Does not Make a
Thin Client
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Blade Client
Baseline:
- Server
($500)
Per Seat:
- Small
Motherboard
with RAM &
CPU ($100)
- DC-DC Power
Supply ($50)
- Keyboard/
Mouse ($30)
- Lenovo L197
Monitor
($239)
Base: $800
Base: $500
Per Seat: $399 Per Seat: $419
Cheap, Lowest Possibly
Power
Cheaper than
Consumption, Thin
Single Point of Client, 100%
Maintenance,
Lenovo
100% Lenovo
Hardware
Hardware
COTS Software
is Expensive
and
Open-Source is
Immature,
Reliability is
Main Concern
Lots of
Enclosure
Work,
Reliability
Laptop Architecture
Figure 4: Laptop system architecture mock-up.
The first prototype was a simple laptop-server setup. Each workstation
would consist of small laptop (a 10” form factor, such as the Lenovo S10). The
laptops would be connected to the Internet either by an Ethernet cable, or even WiFi. Laptops could be run without being directly connected to AC power; a charging
station would be setup by the server.
This style of architecture would be very simple to configure. The server and
the laptops would all be off-the-shelf Lenovo products. The workstations would
have low power consumption, given the fact that the monitor, computer, keyboard,
and mouse are all combined into one device. Should a laptop be damaged, it would
also be very easy to replace, requiring little re-configuration, and no custom
engineering.
Ultimately, Lenovo has specified that it does not want to simply hand out
laptops. The laptops pose a security risk, given that they have value on the open
market. Their portability also adds to the security risk. Their all-in-one design also
makes them much harder to repair.
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Multi-Seat Architecture
Figure 5: Multi-user system architecture mock-up.
One of the most attractive architectures is the Linux multi-seat. Based on
some very interesting test cases found, it’s implemented by building a central PC
with multiple video cards (4-8), multiple keyboards, and multiple mice. Each
workstation would be plugged directly into the server, with individual login names
created. .
There would be a very low cost for such a setup. No thin clients would be
required, only a monitor, keyboard, and mouse. The power requirements would also
be lower, given that the CPU and all of its resources would be shared by all of the
users. The system would also respond much quicker than a thin client, without the
LAN bandwidth and latency issues.
There are many websites dedicated to the subject, and the various open
source solutions. Unfortunately, these options are buggy and unstable, at best. A
for-profit company, Userful, has also popped up, offering a Linux-based closed
source solution that is much more reliable than any of the open source solutions
found. Trial versions of their software were found to be very user friendly, if not
somewhat prohibitive. The largest obstacle was the license, at $100 per seat per
year.
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If the software end of this solution were more mature, Team 2 would highly
recommend this architecture, however, given the reliability needed, it would be
unwise to implement. Given work by some computer science students, and the open
source community as a whole, this could develop into the most robust and costeffective architecture.
Blade-Client Architecture
Figure 6: Blade-client system architecture mock-up.
Another type of architecture discussed was the blade-client (or DIY thin
client). For all intents and purposes, it is a homemade thin client. Each workstation
consists of a small motherboard (mini ITX), with the accompanying RAM and CPU,
but lacking a hard drive. These would be placed inside of a custom enclosure, and
connected to a small monitor (17” or smaller), keyboard, and mouse. Each
workstation would utilize PXE boot to connect as a thin client to a central server.
The entire system could be built using Lenovo components. Custom
enclosures would have to be built for each workstation, but the cost of a
motherboard, CPU, RAM, and enclosure would be significantly less than a thirdparty thin client (especially when taking into consideration Lenovo’s cost vs. market
cost).
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Unfortunately, this system would be the most difficult to implement, given its
the highly customized nature. It would also have slightly higher power
requirements than the traditional, depending on the motherboard and CPU used.
With the high level of customization, it also increases the opportunities for failures
while reducing the reliability, however, Team 2 suggests that Lenovo examine what
resources it would take to build its own production quality thin client.
Thin Client Architecture
Figure 7: Thin client system architecture mock-up.
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Phase III: Power Management
A power management system will be designed to monitor voltage and current
levels at key points in the system and use this information to calculate real-time
data such as percent battery remaining, time until dead battery, and current
charging conditions.
To implement this system we will use a PIC 18F series microcontroller for all
processing functions. Various voltages can be read using the analog inputs. For
current sensing we are using LEM FHS-40P Hall effect sensors. These sensors
measure the electromagnetic field created from the current flowing through the
wire and convert this to a voltage that the PIC can then calculate the current with.
The PIC will communicate with the server using the serial data bus. This is preferred
over USB because it is easier to implement and is more consistent from platform to
platform. A serial to USB converter would be used if the server lacks a serial port.
The power management system will function with or without the server. An
LCD screen will display pertinent information. More information can be accessed via
several buttons that will allow scrolling through a menu. Several LEDs will display
critical information such as power on, low power, and service needed. When power
becomes critically low (less than 20% charge remaining in the battery) the PIC will
initiate a shutdown sequence which will save important data to the server and then
turn off all of the components safely. Once the system has been charged to an
appropriate level the system will perform as usual.
Phase IV: Content
With the majority of potential customers being rural persons that often live
in secluded tribes, the content available on the machines must be carefully
controlled in order to protect the identity of the tribe. The Internet will be white
listed, that is, only a select few websites will be available. Also, other education
content, such as digital encyclopedias must be selected to avoid as much Western
bias as possible.
The Telecommunications teams, both at Michigan State University and the
University of Dar es Salaam, have been tasked with seeking out appropriate
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resources to deliver, without compromising the youth by giving access to restricted
content.
The Engineering team will also develop software to assist in integrating the
machines into the classroom, by offering an electronic hand-in. Students can work
on papers on any machine, and then “hand them in” by submitting them to the
central server using our software. The instructor can then review them digitally,
without having to print them off (infeasible) or collect them manually via USB
thumb drive.
Project Management
Design Teams and Roles
Given the size and importance of this project, Team 2 was put together in
three distinct teams:
Engineering (Michigan State University)
Member
Jian Ren
Jakub Mazur
Josh Wong
Ben Kershner
Eric Tarkleson
Role
Facilitator
Management
Web
Documents
Presentations/Lab
Telecommunications (Michigan State University)
Member
Kurt DeMaagd
Joe Larsen
Tor Bjornrud
Role
Facilitator
Telecommunications
Telecommunications
Tanzania (University of Dar es Salaam)
Member
Dominick Chambega
Aloys Mvuma
Victor Claret
Role
Solar Advising Professor
Telecommunications Advising Professor
Telecommunications
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References
Images
All images on the coversheet were obtained from Wikipedia:
 The Lenovo logo is owned by the Lenovo Group and is being used under the
fair-use rationale.
 The Michigan State University logo is owned by the Michigan State University
Board of Trustees and is being used under the fair-use rationale.
 The University of Dar es Salaam logo is owned by the University of Dar es
Salaam and is being used under the fair-use rationale.
Nomenclature












C3SL – Center for Scientific Computing and Free Software.
CPU – Central Processing Unit, refers to the main processor chip on a computer
motherboard, not the computer as a whole.
COTS – Commercial Off The Shelf, describes hardware or software that may be
purchased rather than designed and built.
MPPT – Maximum Power Point Tracker, a style of solar charge controller.
multi-seat – A type of system architecture in which many workstations are built
onto a single machine.
PIC – The company that produces the microcontroller used, may also refer to the
microcontroller itself.
PV – Photo-Voltaic, i.e. solar panel.
PXE – Pre-boot eXecution Environment, a manner of booting computers over the
network without a locally installed operating system.
OLPC – One Laptop Per Child.
OSS – Open Source Software.
system architecture – The term used within this document to describe how the
style in which the workstations are deployed.
thin client – A client computer that relies on a central server for a majority of its
processing tasks.
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