Predicted Arrival Time Li Ren Zhou, Michal Pao, Michael by morgossi7a7


									                                                                             System Overview                                                                                                                                        PAT Algorithm
                                                                                                The onboard hardware components                                      PennBus West serves West Philadelphia between the
                                                 Rayming TN – 202 GPS Receiver
                                                                                                consist of the GPS receiver, the iPAQ                                intersections of 33rd and Walnut and 48th and
                                                                                                and a mobile-phone. The position and                                 Baltimore. This route has been divided into 28 regions.
                                                           HP iPAQ 3815                         speed of the bus are recorded on the                                 Distance between the bus and desired stop is
                                                                                                iPAQ via the Rayming GPS Receiver.                                   calculated by summing the distances between the
                                                                                                This data is then transmitted to the                                 current regions of the vehicle and desired stop. Arrival

                                                 Samsung SGH-E 105 Cell Phone
                                                                                                server over a mobile-phone                                           time is projected by dividing distance by the average
                                                                                                connection.                                                          velocity of the last 120 samples, adjusted by a scaling

       Arrival Time
                                                                                                                                                                     factor based on the current position of the bus.
                                                                                                On the server side, the speed and

          Michael Pao
                                                            PAT Website                         position data are then processed by
                                                                                                the PAT Algorithm to produce a                                                                                                      User Interface
                                                                                                projected time of arrival. The PAT
         Michael Smeets                                                                         and position data are relayed to the                                                                                                                                      A web-based graphical
                                             End User        End User        End User
                                                                                                user, along with a map generated by                                                                                                                                       user interface empowers
           Li-Ren Zhou                                                                          MapQuest.                                                                                                                                                                 users to simultaneously
                                                                                                                                                                                                                                                                          track a bus’s real-time
            Abstract                                              Software Architecture                                                                                                                                                                                   location and projected
                                                                                                                                                                                                                                                                          arrival time. This
The Projected Arrival Time (PAT) system                                                                                                                                                                                                                                   feature also allows the
uses the Global Positioning System (GPS)
                                                 PDA                                 No                                                  Interface       Server
                                                                                                                                                                                                                                                                          user to intuitively grasp
to provide accurate, real-time arrival        GPS Data                  New Queue                                                       Wait For New   Data Access                                                                                                        if the bus is
estimates to users of a bus system.
                                               Event                      Item?                                                          Connection       Bean
                                                                                                                                                                                                                                                                          experiencing operating
PennBus West was used for purposes of                      Shared Object   Yes                                        Bus Thread
                                                                                                                                                       Insert Data
                                                                                                                                                         Into DB
                                                                                                                                                                                                                                                                          problems or detect
evaluating the project. Each bus carries       Add GPS
                                                                                                                                                                                                                                                                          system malfunction.
                                                                        Connect to            Transmit GPS   TCP/IP                     Create New
an onboard GPS unit which transmits
                                               String to                                Yes                             Poll For Data
                                                                         Server?                  String                                  Thread

data to a central server running the Java                                  No
2 Platform, Enterprise Edition (J2EE) with                                                                              Parse GPS
                                                                                                                                                                     The box plot below illustrates the actual arrival time
Enterprise JavaBeans (EJB) technology.                                   Attempt

On the backend, positioning and velocity                                                                                                                             minus the estimated arrival time of data collected on
data are combined to predict arrival                                                                                     Determine                                   PennBus West. Upper and lower quartile results satisfy
                                                                                                                                                                     the 120 second threshold requirement set at the
times, which users call via a webpage.
                                                                                                                                                       Retrieve DB
                                                                                                                                                       Information   beginning of the project. Moreover, there is an upward
The PAT system adjusts to variations in                                                                                  Insert Data                                 skew, i.e. actual arrival times lagged estimated times.
weather and traffic patterns. However,                                                                                                                               This was purposely integrated into the algorithm, as it
conditions do arise which severely                                                                                                                                   is preferable for the end user to be slightly early than
hamper the ability of buses to run on                                                                                                                                to miss the bus altogether.
schedule, such as extreme weather and
breakdown. Despite its limitations, the                                                                                                                                                                                                 Prediction Error vs. Zone Distance of the PAT System
system is reliable to the point where it                                                                                                                                                                         250
can be deployed commercially as a

                                                                                                                                                                     Prediction Error (Actual - Estimated) (s)
trustworthy convenience.

            Advisors:                                                                                                                                                                                            100


       Siddharth Deliwala                                                                                                                                                                                          0

          Philip Farnum                                                                                                                                                                                           -50


      Demonstrations:                          (Left) Onboard hardware: receiver, iPAQ, null-modem and
                                                                                                                                                                                                                        1   2   3   4      5    6    7   8    9     10    11      12   13   14     15      16      17      18      19      20

       April 21st, 2005
                                                                                                                                                                                                                                                                                            Source: 100 Samples per Zone Distance, Collected on
                                                                                                                                                                                                                                                                  Zone Distance                    12/7/04, 12/17/04, 1/19/05, 1/26/05, 4/8/05

                                               (Right) PennBus West on break
   RCA Lab, 1:30 – 3:30 PM                                                                         Department of Electrical and Systems and Engineering

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