E&RTS 2009 Field Trials
CSCI P545  Embedded & Real-Time Computing Thu Sep 24 12:57:06 EDT 2009 [SDJ]

Field Test Status
dec 11 2009
12:00 hrs
  GO   Friday: Caleb says he will take ERTS to the test field at 13:30 today. [NWS]

P545 Project Field Trials

The Computer Science Embedded & Real-Time Systems course will hold field trials demonstrating this year's class project, autonomous GPS navigation with obstacle avoidance, for a computer controlled vehicle. Anyone interested in observing the trials, learning about the vehicle, or the subject of embedded systems is encouraged to observe and speak with the participants.
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), in the presence of simple obstacles. Additional individual projects in implementing a vision system may be demonstrated.
When: Monday, December 7, 1:00PM, conditions permitting.
Trials are expected to last about three hours. If conditions do not permit testing on this date, alternate dates are Tuesday, December 8 at 1:00PM and Wednesday, December 9 at 1:00PM. Watch [HERE] for status and forecast information.
Where: The parking area North of Assembly Hall on Fee Lane. [MAP]
Presentation: A presentation describing ERTS and the trials is scheduled for Monday, December 7, 11:45AM, in Lindley Hall 101.

Photo by Hillary Demmon

About the Trials

ERTS is a computer controlled golf car supporting research and instruction in the School of Informatics. Development of its systems for navigation and control is an ongoing project in the P545 course. ERTS'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) for overall guidance.

    The navigation system (NAV) is given a list of GPS waypoints defining a closed course on the test field. An ERTS trial is expected to run three laps of this course autonomously.

  • This a short-range (4m) range sensor to detect obstacles. The class challenge is to integrate obstacle avoidance in the GPS navigation system. Thus, while the GPS course gives ERTS an overall mission, it must negotiate around obstacles in order to accomplish it.

  • This year, the class has begun to integrate a vision system, which eventually will be used to augment tactical maneuvering. Preliminary results of vision functionality will be discussed at the presentation.

The field trials have the following components:

  • A trial consists of three laps around a GPS course provided at initialization.
  • As ERTS traverses the course, it will encounter a number of immobile obstacles. A trial fails if ERTS hits any of these obstacles.

  • A good NAV will ``plan ahead'' to maneuver in an economical way. On successive laps, NAV would be able to anticipate obstacles it has already seen and improve its path around them.

Evaluation Criteria (in decreasing order of importance):

  1. Completing three labs around the GPS course. The trial fails unless three full laps are completed.
  2. Successfully avoiding all obstacles. A penalty is assesed for each obstacle ERTS strikes.
  3. Staying within the course boundaries. If ERTS strays beyond the prescribed course boundaries (see below) a penalty proportional to the severity (time and distance) is assessed.
  4. Elapsed time. The faster the better.
  5. Path planning. NAV should show evidence of anticipation in tight maneuvers.
  6. Learning. Successive laps should show improved path planning around turns and obstacles.
  7. Stopping. A bonus is awarded if ERTS stops entirely within the final waypoint.
GPS Course

GPS Course

What You Will See

Photo by Hillary Demmon For safety, ERTS always has a Test Driver seated behind the steering wheel. The Test Driver can abort a trial and override computer control should conditions require it. Otherwise, the Test Driver does not touch the steering wheel, brake pedal, or accellerator once the trial has started.

Each Experimenter in turn will perform their first trial. Once all systems have been tested, additional trials are done in a first-come first-served basis.


About ERTS

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

GPS Waypoint 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. The vehicle Navigator (NAV) 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 Corridor

GPS Corridor The course boundary is defined by lines connecting the waypoints as illustrated to the right. A vehicle is not required to "hit" the waypoint's GPS coordinates but rather to stay within this course "corridor."

Path Planning

Baseline GPS Navigation 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 here 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.

About Obstacle Avoidance

ERTS's obstacle sensor is a Laser Detection and Ranging (LADAR) device that sweeps a laser beam from side to side, measuring the reflection time to estimate a distance to the reflecting object. From this and other information, NAV computes the bearing of the obstacle, initiating a steering action if necessary to avoid it. Graphical rendering of the ranging laser reading

© Steven D. Johnson and The Indiana University Trustees