Control Engineering

Paul Grayson

Sense Of Direction - The Map
December 17, 2007

IT STARTS WITH THE "MAP"
GPS tells the vehicle where it is but for your driverless vehicle to be useful to you it has to have a map.  But not just any map, a computer readable digital  map that shows the vehicles location in relation to the places that you would like the vehicle to go.  The quickest way to explain the extent of commercial digital map coverage is "anywhere you would drive a BMW".  There are "anywhere a jeep could go"  two-track and trails data sets also available.  It is not just a map any more, geographic information systems (GIS) are the new "map" with many more functions than the paper version.  "GIS is a collection of computer hardware, software, and geographic data for capturing, managing, analyzing, and displaying all forms of geographically referenced information." -- ERSI .  

VEHICLES THAT DRIVE THEMSELVES
Any vehicle that drives itself has four basic vehicle functions:  brakes, throttle, steering, and transmission.  So the difference between where your vehicles is and where you want it to be creates the error signal that drives the four basic vehicle functions to eliminate the error.  Since this error signal can not be directly applied it passes through the California Rules Of The Road driving system function, f(x).  Additionally, for safety, the collision avoidance sub-system overrides the driving commands to prevent accidents then return vehicle control to the driving system.   

F(X)
A mathematical function or computer program that translates the many inputs into the four vehicle control outputs has been written by each of the 2007 DARPA Urban Challenge teams.  While the many of the teams have made the size of the program public, the details remain trade secrets.  For many reasons it is desirable to accomplish the conversions of sensor data to control signals with the fewest lines of code practical.  

SENSOR DATA FLOW
As you can see from the pictures of the 2007 DARPA Urban Challenge, which sensors will do the job best is still being worked out.  The object is to eventually produce a clean design where there are no more sensors than are absolutely necessary to get the job done.  Each sensor chosen and put on the vehicle has been selected for the contribution it needs to make to the final driving control signals.  Since the task is to drive on US roads and highways, the examples of what the vehicles need to deal with make themselves apparent each day to us who drive.  The task is to produce the ultimate (electronic) driver who has all of a person’s best driving skills and none of their flaws.  At the current stage of development, many sensors of many types are needed to cover the range of things that need to be detected and at the ranges that they need to be detected.  The data flow from all of these sensors needs to be converted to useful information and for many of the sensors that means plotting what they have detected on the GIS internal map.

MANIPULATING MAP DATA
Once in GIS system, the sensor enhanced computer readable map data can be manipulated,  taking navigation to the next level – not only accurately routing vehicles to their destinations, but also choosing the most efficient path.  Dynamic traffic information can be included to improve routing choices.  The vehicles become use a mobile mapping systems that are fully automatic, generating an integrated multidimensional, 360-degree view of the vehicle’s world.  This map data, generated on the fly, reflects the real world, with landmarks.  This leading edge technology also speeds both the data acquisition and map updating process, to produce fresh, reliable navigation data.  As a result, the vehicle can react to the situation it finds itself in as it proceeds towards its destination.

WHAT OTHERS SAY ABOUT 2007 DARPA URBAN CHALLENGE
http://www.designnews.com/article/CA6509013.html?nid=2333&rid=112574406

GO ROBOTS !
 
Paul F. Grayson - Chief Engineer
AMERICAN INDUSTRIAL MAGIC, LLC
Racing to build technology that saves soldier's lives.
390 4-Mile Rd. S.
Traverse City, MI 49686-8411
(231) 946-0187, (231) 883-4463 Cell
pgrayson@aimagic.org
http://aimagic.org
http://tech.groups.yahoo.com/group/robotcluboftraversecitymi/
http://www.controleng.com/index.asp?layout=blog&blog_id=1180000318

Posted by Paul Grayson on December 17, 2007 | Comments (0)