Glass Cockpits

 Building Cars, glass cockpit, Metrology  4 Responses »
Jul 062012
 

When I first saw on twitter that Brian France had said NASCAR was looking at “glass cockpits” for the future, I was a little mystified.  (You can see exactly what he said on @nateryan’s twitter feed.) Everyone knows that there’s no glass on a NASCAR race car.  Lexan, yes, but no glass.  Plus, where would you put all the decals?  Thanks to @chrisneville84 for pointing me in the right direction.

Sure ’nuff, when you look up the term in quotes, glass cockpit does mean something definitely different from the literal expression.

The term “glass cockpit” originated in aviation.  If you look at old WWII movies where the pilot is in a dive, you’ll see a mechanical altimeter with the numbers flipping around dangerously.  The problem was that, as airplane technology advanced, the number of gauges and controls increased.  Writing in the book “Airborne Trailblazer“, Lane Wallace noted that by the mid 1970′s, an average airplane had more than 100 cockpit instruments and controls.

The problem is that a dashboard gives you limited space.  The more gauges and controls, the more crowded your dashboard becomes.  In an emergency, about the last thing you want to have to do is to look for the right gauge amongst a field of readings you don’t need.

The glass cockpit uses digital display of information, but it’s function is far more than just replacing 100 analog gauges by 100 digital gauges.  The glass cockpit allows you (or a software program) to change the information that is presented (and even how it is presented) so that you have the right information at the right time.  Those 100 controls can be shown to you in groups of five or ten.

Most of the initial innovation in glass cockpits was done by  NASA and Boeing and, in addition to engineering, there was a fair amount of research on perception and psychology.  They were worried not only about what information the pilot needed to know, but also what the best way was to present it to him (and it was mostly “hims” at the time).

Let’s look at this in terms of NASCAR.  Knowing your speed is only really critical on Pit Lane, where you get penalized for going too fast.  The rest of the time, all you care about in terms of your speed is whether you’re going faster than the cars around you.  A glass cockpit-type display might put a speedometer front and center anytime the driver dropped below racing speed — or when the driver flipped a switch.  The software architects also would have to think about whether it would be more helpful to a NASCAR driver to have red, yellow and green lights to tell him (or her) when they were in danger of exceeding pit road speed, or whether it would be better to have a digital display that shows them the actual number.

”"The figure to the left is an example of an aftermarket ‘glass cockpit display’ from Chetco.com. It is digitally generated, so you can decide which gauge you want where.  It’s got some color coding (red, yellow, green) to help your brain figure out the information a little faster.

There are a lot of cars already on the market that have replaced most or all of the analog gauges (the needle and dial) with digital gauges.  The first ones that pop up in a Google search are the 2011 Ford Edge (which has a modifiable display) and  the Range Rover.  But even the resurrected Dodge Dart (a ~$16,000 car) will have glass cockpit features.

We’ve already become familiar with multiple menus that group information:  I don’t need to see the radio options when I’m using the GPS to tell me how to get where I need to go.  The menu system lets me display the information I need (a map) at the moment in the largest possible form.  Once I know where I’m going, I need the radio information.

Another feature increasingly being used by the military is ‘heads up’ displays, where the information is projected onto a surface that the driver (or pilot) can see without having to move his or her eyes too far from the road.  If you’ve ever looked up from the radio or speedometer to find that the person in front of you has slammed on the brakes, you appreciate how much time you lose when you have to divert your attention from the direction the car is going.  That technology is going to be headed into passenger cars at some point in the future, too.

This doesn’t automatically mean that the information is going to be sent to the pits during a race, or that the drivers will have access to much more information.  It could be implemented with the same gauges that are currently allowed.  NASCAR might give teams the option of having the water temperature be the largest gauge at plate races, where it is very important, and something else taking that space at other tracks.  They might allow more information.  No telling at this point.

NASCAR and the manufacturers who compete in NASCAR have a renewed emphasis on making the cars look much more like the cars you and I can buy.  I don’t begrudge the COT phase, even though the car moved pretty far away from the looks of their street counterparts.  They’ve already modified the bodies in the Nationwide series and will do the same in Cup next year.  Changing the gauging will likely not have a whole lot of impact on the racing, but it’s another step in letting us maintain the fantasy that we’re Jeff Gordon or Carl Edwards as we’re racing down the expressway.

 

Can You Really Bring Back the “Same” Car? (Or the Same Track?)

 Aerodynamics, Bristol Motor Speedway, Bruton Smith, Building Cars, Chad Knaus, Jimmie Johnson, Metrology, Tracks  3 Responses »
Mar 302012
 

Every week we hear at least one driver say that they are bringing back “the same car we raced at…”.  This is a little misleading because — unlike Indy or ALMS racing — each shop builds multiple cars, each specialized for a specific track.

NASCAR ChassisLet’s start by examining the anatomy of the stock car.  I think of the car in three major components:  The chassis, the body and the bolt-on parts.

The Chassis

The skeleton of the car is the chassis, a purpose-driven structure welded together from very strong round and square steel tubing.  Shown at right, the structure consists of a front clip (to the left), a rear clip (where the fuel cell sits) and the roll cage (located in the center).

The plans were provided to teams via an AutoCAD file – which should give you some idea of how precise NASCAR expects the teams to be in implementing the chassis plan.  Since the design was developed to optimize safety, teams aren’t allowed to modify the chassis at all.

How faithful teams were to the original blueprint is determined using  coordinate-measuring machines (CMM). CMMs consist of a probe (which may be mechanical, optical or other) and a reading device that transmits data back to a computer that processes and stores the information.  Mechanical CMM devices include the Romer and Faro arms, which are brand names of popular CMMs.  These devices really do look like arms, with joints that mimic the elbow, wrist and fingers. Those joints allow motion along all three axes (up/down, left/right and back/forth), plus the ability to rotate about each of these axes. (Check out this interview with the inventor, Homer Eaton.) To measure something, the arm is touched to the car in specific spots. The probe transmits its three-dimensional coordinates to the computer.  The pictures below shows a Faro arm.

NASCAR uses a Romer arm to certify the chassis (testing over 100 distinct points), and for measuring the body (as I’ll explain in a moment). One of the challenges using mechanical CMMs is that they have to be accurate over a very large volume. The NASCAR system measures over a 13′ x 20′ area defined by a set-up plate. To improve the measuring accuracy, 5/8″ diameter touchpoints are mounted in the plate every three feet. The placement of the touchpoints is verified during surface plate installation using laser triangulation. Before measuring the car, the CMM is touched to any three of the points to ensure that the probe uses the same origin every time and measurements are consistent from car to car.

Triangulation is also the basis for the CMM.  The distance from the origin to the arm’s pointer is the unknown length of one leg in a triangle. If you know the length of one side and two angles of your triangle (which you do using your reference points on the plate), you can calculate the lengths of all sides and all angles.

After verifying the chassis, NASCAR attaches RFID (Radio Frequency IDentification) tags to strategic points.  Those tags are scanned at the track to make sure that the chassis hasn’t been changed.  For example, if a car was in an accident, these measurements tell the team whether the chassis has been even slightly bent or twisted.  Very small changes can compromise safety, so accuracy is very important.

The Body

The roof, hood and decklid (a.k.a. trunk) are supplied by the manufacturer.  The remainder of the body is fabricated by scratch from flat sheets of steel.  The steel that makes up the body is surprisingly thin – in the the range of 25-30 thousandths of an inch thick.  Most people who see a stock car up close are surprised at just how flimsy the metal is. (Ask Kevin Harvick and Carl Edwards how easy it is to accidentally dent the hood of a car during a fight discussion.)  The only parts on the body that aren’t metal are the front and rear fascia, which are made from a carbon-fiber/Kevlar composite.

NASCAR uses Romer arms to measure  body position and sheet metal thicknesses, as shown at right.  We’re talking accuracy to the thousandths of inches level.  Teams can take cars over to the R&D shop anytime to have them checked with the ‘official’ equipment, although most have one or more Romer arm systems in their own fabrication shops.  It’s not a small investment:  A Romer system costs about $60,000.  That’s not including installing a surface plate, which has to have no more than a few thousandths of an inch variation in height across a distance of 12 x 20 feet.

It is impractical to bring a Romer arm and surface plate to the track.  At the track, NASCAR uses a template structure – similar to the one shown here (from the Super Chevy website) to check that each car conforms to the rulebook. The template grid is not the most sensitive measuring device. I have watched inspectors tap the template to “make” it fit more than once. The template makes it easy to see gross violations, but racing these days comes down to thousandths of an inch and that is why the cars have to be brought back to the R&D center for measurement.

The video below shows the template grid system and the body.  After the templates are lifted off, the body rises to reveal the chassis underneath.  (In reality, of course, the body doesn’t just lift off the car – it’s attached with rivets and welds.) I think this demonstration (from the Hendrick museum and video courtesy of Santa Fe Productions) illustrates well the difference between the chassis and the body.

The “parts” as I call them are all the pieces that are bolted to the car:  suspension component, transmission, engine, windows, etc.  Because they aren’t welded to the car, these pieces can be changed during the course of a practice or even a race.

What Does “Same Car” Mean?

When a driver or a crew chief talk about ‘bringing back the same car’, they are almost always talking about the chassis.  When you give “a car” a name, you’re naming the chassis, not the bodywork and certainly not the A-arms or the engine.  When a car comes back to the shop after a race, the engine is removed, most (if not all) of the bolt-on parts are removed and more often than not, the body is removed.  The engine is stripped down and entirely re-built before being used again.  All of the bolt-on parts are  inspected for wear and possible damage.   In theory, the body could be left on and all the parts re-used.

It is rare, however, for a team to be satisfied with how a car ran — even if the car won the race.  Teams are always looking for advantages, so there may be different bolt-on parts used for the next race, or the crew chief may want to modify the body slightly (within the rules, of course) to make it more aerodynamic.  When a team talks about “a car”, they’re almost always talking about the chassis — which is changed only when it has been damaged.

Can You Bring Back “The Same Car”?

In their recent appeal, the 48 team claimed that the car that had been deemed illegal was the ‘same car they had used” for all plate races in 2011.  How is that possible if so much changes from race to race?  I guarantee you that there wasn’t one speedway car sitting in a corner in the Hendrick shop under a cover waiting to be brought back out for the next plate race.

The key is laser scanning.

Mechanical arms are really nifty pieces of technology; however, they measure specific points.  The more complex a curve (or the more subtle its departure from the specification), the more points you have to measure.  Laser scanning takes accuracy one step further.

We can make measurements similar to those made with a Romer arm using a laser.  We know exactly how fast light travels (300 million miles meters every second), so measuring how long it takes for a beam of light to travel to and from a surface lets us calculate the distance from where the beam is emitted to the object.

A slightly more complex setup is used for 3D scanning.  A laser stripe is projected on the car.  If the surface onto which the line is projected is flat, the line will appear straight.  A curved surface distorts the line, with the distortion proportional to the amount of curvature.  A sensor looks at the line and back-calculates what surface shape would cause the observed line to appear as it does.  Most of the big teams have their own laser scanning system and scan every car before and after it goes on track.  Subtle differences in curvature could mean a few hundredths of a second improvement per lap.  Everyone knows that the days of finding a half second per lap are over.  A few hundredths can make a huge difference.

I suspect that the 48 team was able to produce laser scans of each of their speedway cars for the last year and show how the C-posts on those cars compared to the C-posts on the car that was deemed illegal.  I can’t say anything about the decisions that were made on the basis of those measurements, but the routine laser scanning of cars provides a pretty solid documentation of everything about a car.

Putting Bristol “Back”

Cars aren’t the only thing laser scanners measure.  Laser scanning is also used (in a slightly different form) to scan tracks.  NASCAR.com’s Raceview and iRacing provide amazingly accurate pictures of the tracks.  Those graphics are due to 3D laser scanning that allows them to measure every dip and every oil spot on a track.  The video below shows how iRacing does it.

Bruton Smith definitely has access to very detailed measurements of the pre-2007 Bristol from a variety of sources.  Does that mean he can put it “back” the way it was?  If he can, does that mean racing will go back to the way it was?

No.  Definitely not.

Our ability to measure accurately far exceeds our ability to replicate accurately.  There is a huge human element, whether it be making a car or re-surfacing a track.  Sure – you can replicate the track dimensions pretty accurately — but how do you duplicate exactly a concrete surface that has been weathered by decades of weather and use?  Bruton hasn’t announced exactly what he’s going to change, but we’ll analyze it when he does.