Control Engineering

Paul Grayson

Team #24 Magic Highway USA
August 27, 2007

Battle short / battle override

Most equipment has of built in safeguards to protect it from faults that would cause itself damage - build in self-preservation.  Sometimes in warfare it is more important to sacrifice the equipment rather than protect it, circumstances where it may be more important that it keep running as long as it can, even if it means total destruction of the equipment.  That is where the terms "battle short" or "battle override" comes from.  On warships it may be a procedure such as replacing fuses with jumpers or as sophisticated as a master switch labeled "Battle Short".   

In the case of the Urban Challenge race since you have one shot at crossing the finish line and $3.5 million dollars at stake, it might be a good idea to consider things like including a battle short switch and designing systems to fail to the "keep racing" mode.  For instance the Manual Stop circuit can be set up either that the stop switches open the circuit or close the circuit to stop the vehicle. The fail-safe approach would be to use open to stop, that way if a manual switch is opened or an open develops in the wire, the vehicle will stop.  If you use close to stop, damage to the Manual Stop wiring that causes an open will not actuate the stop relay - which would be an example of failing in the "keep racing" mode.   

For us here at  AIM, we want everything to be in the "Fail Safe" mode since we are in close proximity to the vehicle while testing.  Knowing we are not going to be in the "Final Event" allows us a greater degree of freedom than the 20 finalists, we do not have to include a "Battle Short" switch in our design.  Although I did see a box of jumpers here in the shop that are color coded yellow to make them easy to spot if installed. 

Team #24 on my DARPA Urban Challenge list is Magic Highway USA.  The name puzzled me until I did a web search and found out it is also the title of a special Disney episode aired in 1958 about cars of the future.  I may have seen that one as a kid. 

A portion of the Disney episode talks about moving map displays and autodrive... all things that team Magic Highway USA are working on.  So finally, after all these years, the 89 teams are going to make it happen this on November 3, 2007.  I am looking forward to that.

As you can see in this picture of Magic Highway USA's car the sensors are clustered on a light bar.  How many and what kind of sensors will it take to win the DARPA Urban Challenge?  Watch on Nov. 3, 2007 to find out.

Posted by Paul Grayson on August 27, 2007 | Comments (0)