E&RT Systems Field Trials CSCI P545, Computer Science Department , School of Informacstics , Indiana University

P545 Project Field Trial

Field Trials were concluded on April 27 under cloudy skies and widely scattered showers. Results: Team 1, 1st place; Team 2, 2nd Place; Team 3, 3rd place. All teams qualified and ran the unpublished course.

The Computer Science Embedded & Real-Time Systems course will hold field trials demonstrating this year's class project: autonomous GPS navigation for a computer controlled vehicle. Anyone interested in observing the trials, learning about the vehicle, or the subject of embedded systems is invited to attend and encouraged to talk to the participants. This document describes the trials and what you can expect to see.
What: Demonstrations of autonmous navigation.
The E&RT course laboratory is a golf car modified for computer control. This semester's project assignment is implementing autonmous navigation based on the Global Positioning System (GPS). Three student groups will demonstrate their solutions to this assignment, following two pre-defined courses.
When: Wednesday, April 25, 2:30PM.
Trials are expected to last about three hours. If conditions do not permit testing on this date, The alternate date is Friday, April 27 afternoon. Watch [HERE] for status and forecast information.
Where: The parking area North of Assembly Hall on 17th Street.
Between Assembly Hall and the Tennis Pavilion

About the Trials

The vehicle's sensory array includes a Global Positioning System (GPS) sensor which acquires lattitude-logitude readings at regular intervals. The navigation system uses this information together with a pre-loaded course of waypoints (GPS coordinate and target radius) to guide steering and speed.

A good solution will ``plan ahead'' to negotiate turns and other maneuvers in an economical way. Each of three project teams will first demonstrate their navigation solutions on a course published in advance of the trial. These trial runs last approximately fifteen minutes.

If their system passes that test, the team qualifies to run a ``blind'' course, disclosed at the time of the trial. These trial runs last approximately twenty minutes.

Evaluation criteria include:

  1. Passing sufficiently close to each waypoint.
  2. Steering a direct course, with evidence of path planning. Ideally, the vehicle will stay within a corridor determined by the waypoint radii.
  3. Handling certain disruptive conditions, such as manually overriding the navigation system.
  4. Elapsed time of the trial.
  5. and others
GPS Course

What You will See

Test Driver.The vehicle always has a Test Driver, seated behind the steering wheel. Should the any conditions arise that infringe on safety, the Test Driver will abort the trial by forcing the vehicle into a manual operating mode. Otherwise, you will see that the Test Driver does not touch the steering wheel, brake pedal, or accellerator once the trial has started.

Benchmark Trial. The first trial provides a performance benchmark, using a very basic navigation program. You will see the vehicle moving through the course, possibly missing target points or circling around trying to hit one.

First Trials. Each of three student groups will perform a trial on a pre-published course. The trials last 10-15 minutes each, including time change personnel, hook up computers, and clear the test field. A team of Scorers will keep a score sheet for each trial.

Second Trials. Those groups who pass the First Trial will test their navigation software again on a more advanced, un-published course that they will be given at the start of the trial. These trials will 15-20 minutes each

Retries. After the two rounds of trials, groups who may wish to make a second attempt at either course, will do so.

About the Vehicle

The E&RT laboratory is a golf car modified for computer control. The initial instructional implementation was developed by members of the Computer Science Department's Faculty and Technical Staff. As they are learning learning embedded-system concepts and design methods, E&RT students are assigned to solve guidance problems such as GPS navigation and obstacle avoidence.

As higher functionality develops over time, the E&RT lab vehicle is targetted for future research in two primary areas:

  1. Embedded Systems Research. Principles, methods, and tools advancing the practice for systems containing purpose-specific software. This broad range of applications includes robots, vehicles, ``smart'' appliances, hand-held communications and media devices, to name just a few.
  2. Situated Intelligence and Learning. Intelligent systems are expected to function in ever more more sophisticated ways, adapt to changing conditions, and even learning how to perform better. Development is aimed at providing a flexible platform for experimental research in artificial intelligence, computer cognition, and on-the-fly adaptation.

About GPS Navigation

The Global Positioning System is an array of low-orbit satellites broadcasting positioning information world-wide. A GPS sensor is a device that calculates its lattitude, longitude, and altitude by ``triangulating'' signals from some of these satellites.

A course is a list of GPS waypoints, containing a target postion, and an accuracy radius (how close is close enough). The navigation problem is to steer the vehicle through these waypoints in the order given by the course.

GPS Waypoint
The vehicle Navigator is a program that samples the GPS sensor at regular intervals and adjusts the vehicle's heading and speed to guide it through the waypoints. The Navigator must contend with several issues, including:


  • GPS Scatter and Drift. Successive GPS sensor readings are ``fuzzy.'' At a given place and time, successive readings ''hop around'' the correct position in a statistical pattern. From day to day, the statistical average may drift, depending on the positions of the sattelite array and other factors. The resulting errors are in the range of a few meters.
GPS Scatter
  • Path Planning. Like a human would, better navigation software will perform maneuvers that anticipate the pattern of waypoints that lie ahead. For example, it might swing a bit to the right in anticipation of a sharp left turn, or slow down when approaching an S-curve. The vehicle path shown below is an illustration of poor planning; although the vehicle passes close to each waypoint, an ``intelligent'' navigator would plan a more elegant path through the course.

Baseline GPS Navigation
A trial scores more highly if the vehicle is visibly exhibiting path-planning behavior. Ideally, the vehicle will remain inside a corridor determined by connecting the specified waypoint accuracy radii. However, in a complex maneuver, this may not be possible. GPS Corridor

Tue Apr 24 12:45:30 EDT 2007 [SDJ]
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