And Enforces them with Precision Metrology
by Belinda Jones 

The Car of Tomorrow, a new racecar style for NASCAR’s NEXTEL Cup Series, made its debutin March 2007 with much fanfare. Seven years in the making, NASCAR’s Research and Development rolled up their shirtsleeves and concepted their “dream” template. Their ideal racecar would implement the ultimate in driver safety features, and refine component designs to improve performance baselines and overall competition. This was a tall order, but clearly obtainable in terms ofthe engineering and quality control technologies available.

Located in Concord, North Carolina, NASCAR’s Research and Development Center is a $10M state-of-the-art facility housing the industry’s best minds. This team has focused their attention and ingenuity on the overall safety of the sport without forfeiting what makes NASCAR more popular than apple pie - speed, team competitiveness, and fresh new faces entering the racing scene.

While it is no secret that every racing team pushes the envelope to win, the cost to engineer and build multiple cars for different track conditions has spiraled out of control. Well-funded teams have up to 15 cars or more in their backup coffer. The Car of Tomorrow (COT) program has implemented measures to contain product costs and reduce the need to manufacture track specific cars. Their R&D team developed an adjustable rear wing and a front splitter, along with a refined body and a chassis measurement process, that culminate in a level playing field for large and small teams with varying amounts of investment dollars. Four COT body types have been approved: the Chevrolet Impala SS, Dodge Avenger, Ford Fusion and Toyota Camry.

Standardize and Verify

To ensure all race teams are adhering to the exacting standards of the COT, NASCAR has introduced a chassis certification program that includes both dimensional control and metal thickness testing. “We verify some of the dimensions implemented for safety, such as the driver compartment space and more,” states Dan Kurtz, design engineer at NASCAR. “We also have standardized portions of the chassis and body, and those areas are validated too. This approach allows the owner to lean more to the production side of the business, where they do not have to change things for every race like track specific cars or a new trend in aerodynamics. New teams can purchase a chassis from a local maker and know they are getting just as a competitive car as the big teams. Those are the reasons the COT is here, with safety being the most important aspect.”

For the data acquisition and inspection process, NASCAR has implemented two GridLOK systems from ROMER Inc. (Wixom, MI) with portable CMM technology. Used for in-place measurement of large parts, the solution consists of a 7-axis ROMER INFINITE articulating arm with standard probes, the ROMER exclusive patented GridLOK “conical seat” flooring system, and PowerINSPECT software from Delcam plc. The CMM arm rests on a mobile base and is moved around a chassis or car to gather data inside, behind, and underneath the measured object. The articulating arm has a measuring volume of twelve feet. Its integrated counterbalance provides a light, ergonomic feel to relieve operator fatigue during extended usage, plus patented infinite rotation in the primary axes for ease of use throughout extended inspection cycles.

Jerry Kaproth, Safety Coordinator at NASCAR, states, “The ROMER system comes into play every day to verify dimensional controls that were implemented for safety and cost containment.  NASCAR has standardized portions of the chassis and the body, and we validate all of those areas during the certification process.” “Tolerances are much tighter on the Car of Tomorrow than ever before,” stated Kurtz. “Our objective was to make the tolerances reasonable that every organization could build a car and residewithin the tolerance, but to make it tight enough that teams do not build track specific cars to one side or the other of the tolerance. By locking down enough dimensions, the teams will not be significantly different. They may bring different cars to different tracks to rotate them out, but there won’t be major variations in terms of aerodynamics and performance properties.”

Systems are GRIDLOK’d, and Ready to Go

The GridLOK measuring arena resembles a large, invisible coordinate system ready for on-demand measurement. An operator can acquire precision sets of data with the same part origin while working within a 13 x 20-ft. footprint. To achieve this, the system utilizes small (5/8-in. diameter) conical seats flush mounted in a steel plate resting on the floor of NASCAR’s inspection facility. Placed in three-foot intervals, each conical seat is initially certified with a laser tracker during installation. To activate GridLOK, the operator simply touches their ball probe into three different conical seats, and the CMM arm is instantly locked to the common origin. This “locking method” does not interrupt software programs, and requires no use of buttons or computer keyboard selections. If the operator wishes to inspect in another area, he simply moves the arm, and repeats the locking procedure with the conical seats. No matter how many times the portable CMM is moved, GridLOK retains measuring accuracies because the 3D data acquired is relative to the same part origin with no accumulative error. This advanced technology eliminates the old “leapfrog” method used to gather data, which caused an accumulative deterioration of accuracy with every move of the articulating arm.

The Concept Becomes Reality

Kurtz concepted and executed the new measurement procedures from top to bottom. When the COT design standards began to materialize, he built 3D solid models in-house using Pro-Engineer CAD software. Based on the safety initiatives, engineers who worked on that project defined specific parameters for the driver’s cage. “We started off with just the center section of the car, which is the driver’s compartment and the passenger’s side of the car. We wanted to standardize that area, so a CAD model was created inhouse,” shares Kurtz. “We sent the CAD file to a manufacturer in Illinois, and had CNC cut and bent tubes delivered back to us. They are tabbed and slotted to fit together in the proper position to make up the center section of the car. Our most regulated areas are the center section, the rear clip, and the location of the fuel cell. The front clip is defined by rules about the symmetry, not actual locations, and located about a centerline.” So once NASCAR set the rules, they had to devise a method to enforce them. Kurtz created a dimensional verification operation guided by a customized PowerINSPECT inspection routine. Mounted on the wall near each GridLOK inspection station is a large plasma screen displaying the software’s interface. Step-by-step the software prompts for each strategic inspection point(s) with a detailed description, then advances ahead as each critical area is captured until the job is completed. Using the arm’s mouse mode and wireless features of the arm, inspectors are able to interact with the program using the large screen alone; no keyboard interaction is required.  The macro-driven program not only ensures consistency between inspectors, but has proven to be an effective training tool as well.

Gathering Chassis Data

Kurtz inspected the first 75 chassises to prove out the concept, then Jeff Uran, a technical inspector at NASCAR, was brought in to learn the process. Uran was formerly a NASCAR Nextel Cup official, who would go to the track every week assigned to the chassis inspection department. His background as a pit road inspector was a huge plus. Assigned to the COT inspection team, he had the ideal expertise to work closely with Kurtz to refine and evolve the program. With 95% of the teams in the local area, transporting a chassis to the R&D Center for certification has been a fairly smooth process. Deliveries occur nearly every day for first-come, first served inspection. The chassis is placed on the GridLOK measuring area. Uran locks into  the coordinate system, then centers the framework. Each team essentially defines their centerline by a receiver located on the chassis, and the receiver sits upon a defined fixture. The inspectors use a point-line-plane alignment system, and with a slight rotation to zero out on the Y-axis, the chassis centerline and the coordinate system centerlines are rectified and ready for inspection. Using the articulating arm and a 15mm ball probe, Uran methodically works his way around the chassis gathering 3D data for olerance analysis. With nearly 400 nspections under his belt, Jeff averages out 4 inspections a day, but can achieve 5 full certifications per day when the traffic is high. Three other inspectors have been trained to use the portable inspection system.

In a typical session, Uran acquires 100+ points in real-time in approximately15 - 20 minutes. Avoiding grind and weld marks, he starts the probing routine at the front firewall and proceeds to measure the intrusion plate, floorboard, firewall, fuel cell walls, oil casement, frame rails, transmission tunnel, drive shaft tunnel and intrusion plate. Sidemembers are also measured for a symmetry requirement. Because the frame rails are the foundation of the vehicle, they have the tightest tolerance of plus or minus of an eighth of an inch

Once the inspection is complete, the PowerINSPECT software populates an Excel spreadsheet report and the documentation is printed. Areas that failed the inspection will be highlighted for close examination. The inspector will probe the area in question a second time to determine if a surface aberration or other anomaly caused the flawed dimension. Uran states, “After we measure and confirm that each chassis meets our standards, the framework goes back to the shop where the body will be installed. If a team makes modifications or a vehicle is wrecked, the chassis must be returned to the R&D center for a complete recertification. If a car does not pass, we have a verbal discussion about the problem areas, and the team is provided with detailed inspection documentation as to why the chassis failed.”

Concluding the Certification

After the dimensional inspection, Uran proceeds to the metal thickness certification, strictly enforced by the governing body. The entire chassis certification process takes 1 1/2 - 1 3/4 hours. If the framework passes the certification, NASCAR proceeds to apply 10 RFID chips to the chassis for automatic identification. The RFID technology records the serial number and all pertinent data. When the racecar appears at the actual race, all ten chips must be in place for scanning and certification. “When a chassis is presented to us by a COT team, a serial number is assigned to that car for its entire lifecycle,” said Kaproth. “Once certified, 10 RFID chips are immediately catalogued, then applied to specific areas of the chassis. When the car arrives at the racetrack, an inspector scans the microchips and proceeds to conduct their on-site qualification. Without RFID clearance, the car will not see the track.”

 A Work in Progress

With 16 races of the 2007 season using the COT, NASCAR announced it will use the Car of Tomorrow exclusively in 2008, a year earlier than planned. When the COT goes full-time, NASCAR recognizes that more use will translate into more information for future design enhancements. In the first five events of the 2007 season, NASCAR reported an average margin of victory of .505 seconds. When compared to 1.286 seconds in the same five races in the previous season, they emphasize the COT program is on the right track.

“The Car of Tomorrow initiative allowed us to expand on the knowledge base we were accumulating on a race by race case. At the same time, we took the opportunity to look at other important aspects from the racing community as a whole. We wanted to make strides in safety and competitiveness, and at the same time improve the financial health of the sport. In the very first COT race at the Bristol Motor Speedway, 59 cars raced within 6/10 of a second of each other. It was extremely competitive to make the final field of 43. And it is very encouraging to see that some small and new teams have done fairly well to date,” concludes Kaproth.

Safety and Performance

NASCAR’s Car of Tomorrow includes important features that improve driver safety:

• Double frame rail on the driver’s side with steel plating on the outside of the roll cage door bars to help prevent intrusion during impacts.

• Energy-absorbing materials installed between the roll-cage door bars and door panels.

• Enlarged cockpit — roof is 2 1/2 inches higher and the cockpit is 4 inches wider. The driver also is up to 4 inches to the right of where he currently sits.

• Increased strength in the floorboard.

• An enclosed 360-degree steel containment tunnel for the drive shaft.

Aerodynamic features unique to the Car of Tomorrow include a new rear wing design and “front splitter” to improve the car’s handling and the driver’s control. Both can be adjusted during a race to accommodate changing track conditions.