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Metris helps Belgian Solar Team swiftly cross the Australian desert without a single drop of fuel
Covering 3000 km in between Darwin and Adelaide
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Umicar Infinity’s dynamic wind resistance is six times better than serial-produced sports cars.
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The challenge is simple. Crossing the Australian desert as fast as you can without one drop of fuel. Fourteen selected engineering students of Groep T Engineering School in Leuven, Belgium, have taken up the challenge to hunt for a medal in the World Solar Challenge 2007, the officious world championships for solar-driven vehicles.
From their successor team – ranked 11th in last year’s Solar Challenge – they had inherited a solid, proven vehicle design along with ample know‑how and experience. In partnership with Belgian high-tech companies such as Metris, these youngsters have succeeded in developing the second generation of the solar race car, named Umicar Infinity.
“The focus of our engineering teams in creating the Umicar Infinity is somewhat different than what is usual in regular automotive vehicle development programs,” stated Koen Van Beneden, Head of Solar Team Marketing.
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“To get most out of limited solar cell power, our race car is engineered specifically for low weight, little aerodynamic resistance and high energy efficiency of vehicle driveline mechanisms. The Umicar Infinity is a one-seater that only weighs 175 kg, and features dynamic wind resistance that is roughly six times better than premium serial-production sports cars. With just the electrical power of a vacuum cleaner available, the Umicar Infinity is capable of reaching speeds higher than 140 km/h!”
Pertinent need for metrology-level alignment
To create the race car’s rigid, light-weight space frame, engineers used extruded aluminum tubes that were welded together. To compensate for slight frame deformation, due to the welding heat, engineers counted on metrology technology from Metris. After welding, the positions of key
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The space frame underneath the body shell consists of welded extruded aluminum tubes.
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locations on the frame were measured using the hand-held SpaceProbe of the Metris K-610 system.
This optical metrology solution operates using a fixed carbon-fiber structure that houses three linear CCD cameras. Through triangulation, the system is able to accurately track the positions of infrared LEDs integrated into the SpaceProbe that is held onto the frame point being measured. Based on the acquired frame coordinates, the team was able to verify specific shape characteristics of the frame. Engineers additionally measured datum points to define reference planes to be used for alignment purposes later on in the subsystem assembly process.
According to Pieter Vangeel, Team Manager of Solar Team, alignment is critical, in particular when connecting the completed frame to the suspension subsystems. “The suspension units play an essential role in aligning the three wheels with respect to the body of the race car. The powered rear wheel has a swing-arm suspension unit, while a double-wishbone suspension unit keeps the front wheels in position. Special attention went to the locations on the frame where suspension parts need to be fitted, because they require perfect orientation to one another. Therefore, we relied on the Metris K-610 system to accurately identify the positions of all suspension attachment points on the frame structure. With this information at hand, we were able to weld all connections between the space frame and the suspension units with high positioning precision.”
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To compensate for slight frame deformation, due to welding heat, engineers use Metris metrology.
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Further pushing race car’s operation efficiency limits
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Metris K-610 uses triangulation to track LEDs integrated into the SpaceProbe in order to accurately measure the point held onto the frame.
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The next highly sensitive alignment job was the positioning of the aerodynamic body shell around the rest of the vehicle. Pieter Vangeel mentioned that the Metris equipment, once again, proved very useful in adding metrology accuracy to the attachment procedure of major vehicle subassemblies. “Precise measurements and finishing are an absolute must in order to ensure that the wheels are in their optimum position and orientation. Even the slightest wheel misalignment causes excess tire wear and mechanical friction. This means that we would potentially lose valuable time with additional tire exchange stops, each requiring about ten minutes standstill time. And additional mechanical friction would decrease the dynamic performance of the Umicar Infinity, reducing vehicle speed through lower operation efficiency.” |
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The positions of key locations on the frame were measured using the hand-held SpaceProbe of the Metris K-610 system.
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“Metris truly helped Solar Team to develop a better race car,” Pieter Vangeel stated when clarifying the role of Metris in this ambitious Umicar Infinity project. “Metrology-level assistance in assembling main vehicle subsystems is essential in obtaining higher precision and better vehicle dynamics. Therefore, we will take the mechanical accessory gauge, which was used in Metris alignment test campaigns, with us to Australia to perform wheel alignment tests in between racing days. The gauge will allow us to re-establish the original alignment, in this way compensating for any wheel misalignments that resulted from mechanical and tire wear. Although measurements only take minutes, the impact of precision alignment has a significant impact on the competitive edge of our race car. We are convinced that this will propel the Umicar Infinity to success in the Solar Challenge world championship race.” |
With just the electrical power of a vacuum cleaner available, the Umicar Infinity is capable of reaching speeds higher than 140 km/h!
Download: Metris helps Belgian Solar Team swiftly cross the Australian desert without a single drop of fuel (PDF file)
Download: Metris helpt het Belgische Solar Team om zonder brandstof de Australische woestijn te doorkruisen (PDF file)
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