Final Project –Distributed Sensing and Control Framework for
Mobile Robots
Demonstration:
May 2nd 2002, Report Due: May 14th 2002
In keeping with the
procedure discussed in class, this final project will be less structured than
the previous labs. In particular, students will have enormous freedom in
selection of phenomena to study, implementation mechanisms as long as they stay
within the broad guidelines noted below. Groups with questions are encouraged
to discuss their potential projects with Prof. Krovi at the earliest to avoid
many of the pitfalls.
In this final project, we
wish to examine the development and implementation of a distributed sensing and
control framework for a system comprised of: the mobile robot (with its
onboard processor), the base station, which are coupled together by wired
and wireless communication channels. Such a distribution of sensing and
control offers many benefits including reducing the computation loads on
individual processors and extending the capabilities of sensors/actuators but
comes at the price of need for communication protocols, increased overhead of
coordination and ultimately increased complexity. Thus, in this final project
we wish to examine some of these issues using the relatively simple example of
remote-control/operation of the mobile robot by a base station.
When operated in the distributed
sensing (data acquisition) mode, the overall framework/system forms the
basis of an intelligent remote sensor. The mobile robot functions
to serve as the source of the information/data from outside world to the
overall system. The data is acquired from one (or more) analog/digital sources
such as switches, pots, phototransistors etc on the mobile robot and this
information is relayed to the base station using one of the communication
channels for further processing. The processing may take the form of simply
logging the data or may include other post-processing steps including but not
limited to subsampling, averaging and plotting of the results. The overall
system can also be extended into the realm of distributed control mode,
wherein the processed information can now be sent back to the mobile base over
the communication channel. The mobile base now serves as the action agent performing
a set of actions commanded by the base station. It is noteworthy that the
channels of communication have limited bandwidth and that the overall system
can only demonstrate limited capability. However, this paradigm of multiple
processors, communication channels, and coordinated action to
implement an intelligent distributed sensing and control framework for mobile
robot will provide us with an opportunity to investigate and use: (i)
alternative communication protocols (synchronous vs asynchronous) and wired
(SPI, serial, parallel) vs wireless (IR and RF based) communication; and (ii)
Setup of programs with the capability of communicating/handshaking and
distributing tasks.
Processors:
The StampWorks Kit that you used
for some of the preliminary labs will serve as your base-station. Also
investigate the use of StampPlot Lite available freely from SelmaWare Inc. as a
potential mechanism for logging and plotting the processed data
See links
below for information and ideas related to StampPlot:
http://www.selmaware.com/stampplotlite/home.htm
http://www.selmaware.com/stampplot/samples/ic.htm
http://www.selmaware.com/stampplot/samples/samples.htm
The BOE-Bot kit (and the
complementary series of exercises discussed in the Robotics Student Workbook)
provide an expedient method for creating simple wheeled mobile robots
(which will serve as our remote sensor/actuator). In our work, we will build upon the
hardware and software framework to further extend the capabilities of this
BOEBot in this final project.
Explore http://www.stampsinclass.com/html_files/sic_curr/curriculum_robo.asp
and some of the affiliated links for more details about the BOE-Bot and other
useful information. The Robotics Student Workbook v1.5 is available for
download from: http://www.stampsinclass.com/downloads/Robo/rob.pdf
Communication:
IR Communication
Asynchronous Serial IR
Communication between the base-station and remote-robot can be implemented in a
variety of ways and one of the easiest methods would be using the FireStick II.
§
Interfacing Firestick
II to the Basic Stamp: http://www.rentron.com/FS-2.htm.
§
Full color operating instructions (MS Word format) http://www.rentron.com/Files/fs-ii.doc
Asynchronous serial
RF-based communication between the two processors may be implemented easily
using the "8-Bit Remote Control Combo Package"
§
Wireless Communications With BSII: http://www.rentron.com/Stamp_RF.htm
§
8-Bit RC Combo Package: http://www.rentron.com/remote_control/TWS-8-bit-combo.htm.
§
TWS-434 transmitter and RWS-434 receiver module: http://www.rentron.com/Files/rf.pdf
§
433MHz
whipstyle antenna: http://www.rentron.com/remote_control/434-RF-Antenna.htm
§
8-Bit
transmitter schematics using the TWS-434 433MHz RF transmitter with Holtek
8-Bit encoder HT-640. http://www.rentron.com/PicBasic/8-BIT-RF2.GIF
§
8-Bit
receiver schematics using the RWS-434 433MHz RF receiver with Holtek 8-Bit
decoder HT-648L. http://www.rentron.com/PicBasic/8-bit-rf.gif
§
HT-640
Datasheet http://www.rentron.com/Files/ht-640.pdf
§
HT-648L
Datasheet http://www.rentron.com/Files/ht-648l.pdf
The advantage of the above
two methods is that they permit wireless operation but the
disadvantages include the relatively low transmission bandwidth, dangers of
insecure data transmission and the principally unidirectional nature of the
communications
Wired Interfaces
It is also possible to
setup asynchronous/synchronous serial communication between the two processors
using a wired interface between processors, facilitating a dedicated,
secure, bidirectional channel of communication between the two systems. See
the descriptions of SERIN/SEROUT and SHIFTIN/SHIFTOUT in your BS2 manual and
some of the examples for further details.
Devices that may
potentially be interfaced:
§
Displays/Sensors/Actuators
available on StampWorks NX-1000 Board
7-Segment
Displays,LEDs, LCD, Photoresistor, 555 timer;
8-bit serial to parallel and 8-bit parallel chips, DS1620 Digital
Thermometer, DS1302 Real Time Clock, ADC0831, MAX7219, LM358, 12 volt unipolar
stepper motor; Parallax standard servo;
§
Displays/Sensors/Actuators
available with BOE-Bot Kit
Photoresistors (EG&G Vactec VT935G group B),
Infrared receivers (Panasonic PNA4602M or eq.), Infrared LED covered with heat
shrink tubing (QT QEC113)
Ideas:
http://V.webring.com/webring?ring=stamp;list
Basic
Stamp Web Ring
www.al-williams.com/awce/index.htm
Al
Williams web site
www.seetron.com Scott Edwards Electronics web site
www.hth.com/losa List of Stamp
Applications
www.emesystems.com/BS2index.htm
Tracy
Allen’s Stamp resources
In all cases:
Test each subsystem
separately before attempting to integrate into a single large overall system.
Please make sure that you read through the documentation carefully before
attempting to connect up the various subsystems
Reporting:
Provide a self-standing document, which could be used as an
“Application Note” which describes and explains your system and would enable
someone else to replicate your work. Please follow the guidelines provided at http://www.eng.buffalo.edu/Courses/MAE505/ReportFormat.html.
