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Subject: 
Autonomous RCX Racing - formerly Nascar style racing
Newsgroups: 
lugnet.robotics
Date: 
Tue, 17 Dec 2002 01:58:04 GMT
Viewed: 
699 times
  
After some intense fiddeling around I have created a couple working vehicles
or autonimous racers based on the discussions a previous post.  The vehicles
handle like traditional race cars without the ackerman style steering by
having a motor powering each of the rear wheels.  The front wheels are un
linked.  I did this because I was not able to produce a vehicle with a small
enough turning radius to race on a 4x8 sheet of plywood

I am in the first stages of creating a "starter" program to be run by a PC
that will
1) stage and start the race
2) track up to 23 cars on the track by keeping their lap times and order
3) notify vehicles of place each lap
4) recognize errors
6) finish race and log times for future races

I plan to acomplish this by using a serise of single byte messages  from
the RCX to the Tower and vice versa  (0-255 or 000 to 255)

Messages from the tower to the RCX will have the vehicle number (1-24)  as
the first two digits and the place as the third (car four is in third place
would be 43 or 043 car twelve in first place would be 121)  the third digit
as a 0 would be for signaling a pit stop or black flag.  the numbers 000-009
would be reserved for global race functionsfor all cars, such as stop (000)
start (001) and others for staging, time trials etc... 250-255 could be
reserved for human interaction to signal a yellow flag situation

Messages for the RCX would be triggered from an event from the the light
sensor over the start finsh line at the beginning of a straightaway or a
touch sensor for an overhead bar.  the rcx would transmit a single byte with
the first two digits being the racer number and the last digit being the lap
number(for error correction)
.
a race would go something like this:

The Tower would stage each car individually by polling the serial number and
assigning a vehicle # 1-24 ( this would allow multiple tracks to support
times by rcx serial number for calculating pole positions  and allowing an
unlimited number of cars to compete.)

The tower would give three signals to start the race (003) 30 seconds to
start (002) at fifteen second signaling that start may be any moment and
(000) start a random 1-15 seconds after the (002) (I stole this from
motocross) and the tower would start a timer at the beginning of the race

The cars would go around the track using the light sensors to guide them
around the track and away from the walls as they pass the start finish they
will send the byte message described above.  As the tower receives the
message it logs the vehicle lap time in a database, displays it on a monitor
and sends a single byte message notifing the vehicle of its place ( so that
it may modify its driving style to be more offensive or defensive.  This
would go on for a predetermined number of laps and the tower would give its
stop (000) signal

This is all in the conceptual stage, in fact I haven't decided to do this in
Visual Basic (easy gui & easily distributed .exe) or in Python.(freeas in
beer and runs on linux)   I am a novice programmer so I wouldn't mind help
developing this program.  Any advice, input or constructive critiscim

Jeff Wood



Message has 3 Replies:
  Re: Autonomous RCX Racing - formerly Nascar style racing
 
(...) Random thoughts: The way I read it, you can only notify of position down to 9th place. I guess you could treat 9th place as "9th or worse place". Also, you can only send a count of up to 9 laps, limiting either the race length or the error (...) (22 years ago, 17-Dec-02, to lugnet.robotics)
  Re: Autonomous RCX Racing - formerly Nascar style racing
 
(...) What about 5?! (...) What message would the 11th place car get? Right off the bat, I'd say 23 cars is too many. It won't leave any room to move around, so they'll spend all their time bumping each other. I'd guess 4 or 6 would be about right. (...) (22 years ago, 17-Dec-02, to lugnet.robotics)
  Re: Autonomous RCX Racing - formerly Nascar style racing
 
(...) Here is a link to Gus Janson's SteerBot ((URL) which I think you will find has great maneuverability as well as a tight turning radius (~6"). I have replicated it several times in the past 2 months for my group's line following event. After (...) (22 years ago, 17-Dec-02, to lugnet.robotics)

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