Hi,

I’m Mike DeVault, Lead Designer for NASCAR 09, and welcome to the first installment of our weekly NASCAR blog.  I’m here with Designer Eric Busch and Software Engineer Will Frost.  These guys worked directly on the implementation and improvement of our 09 A.I. system.  They took some time out of their busy schedules to help me put together some content for this week’s blog, which will deal specifically with some of the new A.I. systems found in NASCAR 09.

When we set out to work on the A.I. improvements for NASCAR 09, one of our first goals was to address the issues that the community was encountering with the A.I. in NASCAR 08.  A lot of the feedback revolved around the A.I. aggressiveness and their behavior in general.  In order to address the feedback we knew that we needed to take a look at their overall behavioral characteristics to make some wholesale changes and improvements.  Eric and Will worked very closely on this and the end results were very positive, so we thought we’d outline a number of these behavioral changes for you.

Aggression – As I noted above, the overall consensus was that the 08 A.I. cars were overly aggressive.  So starting on 09, we at least knew that we could make our A.I. cars drive aggressively.  Now the challenge was to work on scaling that aggressiveness and seeing if we could take advantage of it. 

We were able to create a system that takes into account each individual A.I. driver and their particular tendencies.  Not to call anyone out, but some drivers are more aggressive than other so we wanted to capitalize on that.  In NASCAR 09 you will notice that drivers that are historically more aggressive are also that way in the game.  This will not only manifest itself against the player, but also A.I. vs. A.I. as well.  When an aggressive A.I. driver pulls up on another less aggressive A.I. driver, the less aggressive driver is likely to make way and give up his line once the aggressive driver begins to “apply pressure”. 

Just like in real life this makes for some interesting matchups, since when two aggressive drivers get nose to tail in a race, the lead A.I. car will attempt to block while the trailing driver is trying to apply pressure.  Needless to say it makes for some realistic situations out on the track.  Overall we think that players will notice that overall the A.I. aggressiveness towards the player has been significantly reduced.

Status – In a field of NASCAR drivers there is a distinct pecking order.  A Sprint Cup Champion has more credential in the sport than a rookie running in his first series race.  Status is an A.I. attribute we added in 09 to bring this element to the forefront. 

Each of the A.I. drivers in the game has an individual rating which indicates their place in the hierarchy of NASCAR.  So using the example I outlined above, if a Sprint Cup Champion is driving up on a rookie driver or any other driver with less status, that driver will give up their racing line and allow the driver with more status to pass.  That scenario is fairly extreme and makes the assumption that the rookie driver does not have high aggression.  Additionally, a driver’s status will also help determine whether other A.I. cars are likely to draft with them.

As you’ll see in the game, the A.I. behaviors created for NASCAR 09 were designed to work and play off of one another.  This helps things seem a bit more lifelike and prevents predictability.

Consistency – This is an important element of racing.  A driver’s ability to be consistent in driving their racing line around the track will, more often than not, result in better times and better information back to the crew.  This was also an important aspect in achieving more realistic looking and feeling A.I. drivers.  A human element of inconsistency was what we were shooting for.

In NASCAR 09 each of the driver’s has their own unique ability to drive consistently.  Obviously some are better than others and you’ll notice this when you are driving along with them out on the track.  Based on their consistency, some drivers will hold neat and consistent racing lines around the track. Less consistent drivers will miss their marks and take different entries into a turn for example.  A driver with little consistency might have breaking points which vary each lap, while consistent drivers hit their breaking points on each lap.  Inconsistent drivers in NASCAR 09 will also make driving errors which could lead to wrecks out on the track.

Reliability – This isn’t something that a driver can always control, but it is definitely a big factor in NASCAR.  We wanted to add in a reliability factor to each of the A.I. cars to reflect their real world tendencies.  So be careful, that guy that you’re drafting with at Talladega could blow up right in front of you.

Passing – Each of the A.I. drivers have a constant picture of other cars around them.  Just like if they each had their own individual spotter.  This helps them determine when there is enough room or if it’s beneficial for them to attempt a pass.  Some of the other behaviors start to come back into play here as well.  Take aggressiveness for example…a more aggressive driver may try to squeeze into a space that a more conservative driver would wait to open up. 

A pass attempt is not always successful in racing and we wanted to reflect that in our game as well.  When an A.I. car starts a pass, things could change on the race track that cause them to determine that they cannot or should not complete the pass.  Again, the other behaviors have an effect on this.  A.I. cars will abandon a pass when necessary in order to save them from an adverse situation on the track.

Pitting – The A.I. cars have the ability to create pitting strategies during a race.  This helps add a strategic quality to the race and gives the computer controlled cars a more realistic feel.  As the race progresses, a caution could occur at any moment which in turn creates new fuel strategies for drivers and teams.  In NASCAR 09 we gave the A.I. cars the ability to dynamically plan new fuel strategies based on cautions and the laps remaining from their current or last pit stop.  As a result the A.I. will make two tire stops and take a single can of fuel if it’s to their advantage.  You could even see some gas ’n go’s towards the end of the race if things shake out correctly. 

All of this A.I. behavior allows for more strategic thinking from the player as well, since they will have to choose their pit options carefully to keep up with their computer controlled opponents.

Aero  – The NASCAR 09 A.I. has the ability to recognize and take advantage of the draft.  When you give the A.I. the ability to draft other cars, you also have to give them the ability to strategically pick drafting partners and draft lines.  So some of the other behaviors that we discussed above get added into the equation that determines an A.I. car’s drafting tendencies.  They will look primarily at the speed of the cars around them and will look to partner with cars that are producing the highest draft speeds.  However, status also becomes a factor.  Drivers may partner up with higher status drivers to draft with.

Aerodynamic effects from damage have also been improved this year.  A.I. cars will have greater speed reduction due to aerodynamic damage.  This effect was implemented and tuned so that track type would be a factor on aero drag effects.  This allows the aerodynamic effects of damage to play less of a part at the short tracks, whereas at the superspeedways it plays a large role.

A big thanks to Eric and Will once again on the effort they put into the A.I. improvements for NASCAR 09.  We really think you’ll enjoy the improvements that have been made.  As always we look forward to your comments and suggestions on the forums regarding the A.I. as well as other areas of NASCAR 09.