Zuken’s E3.series: Wired for Speed
If you were to ask a mechanical engineer to describe their heaven, they might tell you about something similar to the Branam Innovation Center at the Rose-Hulman Institute of Technology in Terre Haute, Indiana. Alright, it doesn’t have free-flowing craft beer. Other than that, everything else fits.
Opened in 2011 as a home for the student race teams associated with Rose-Hulman’s Advanced Transportation System program, the 16,000 square foot facility has all that is needed to design and build just about anything that moves. Add in enthusiasm and ingenuity from some of the top engineering undergraduate students in the United States, and you have a combination of passion and technology that creates a little bit of gearhead nirvana in a college town.
Dr. Zachariah Chambers is associate professor of mechanical engineering at Rose-Hulman, and he is the director of the Advanced Transportation Systems program. He is justifiably proud of his school, of the Innovation Center, and of his students. “We have been ranked number one in engineering undergraduate education since 2000,” explained Dr. Chambers, referring to the school’s ranking for American colleges with a focus on undergraduate education.
Winning Human Powered Vehicle Challenges
Part of this success stems from Rose-Hulman’s emphasis on giving students hands-on engineering by being involved in competitions that relate directly to their studies. “Students might be willing to take a ‘C’ on a test,” says Chambers, “but they really don’t want to look stupid in a competition.”
Rose-Hulman students are looking anything but ‘stupid’ these days. They are ranked top overall in the ASME Human Powered Vehicle Challenge. They have won awards in the ECOcar challenge, and they have achieved 1,800 mpg (US miles per gallon, or 4,250 liters/km) in Shell’s Eco-Marathon Americas Competition.
Building upon the success of these teams, the students made a return to full-on, open-wheeled racing three years ago. No doubt they were inspired by the Indianapolis Motor Speedway, just a ninety-minute drive away. The school’s Formula SAE team takes part in one of the largest and most challenging post-secondary race challenges: designing vehicles that excel in everything, from autocross to endurance racing.
CAD modeling is pretty standard for most Formula SAE teams, and the chassis design is invariably placed through a rigorous series of finite element analysis and computational fluid dynamics test runs. Rose-Hulman’s team has a secret weapon in their design arsenal, however, in the form of Zuken’s E3.series electrical CAD software. Rather than just an electrical overlay typical for most mechanical CAD packages, E3.series goes from the ground up to make excellent designs of electrical and fluid power systems.
Formula SAE team member and Rose-Hulman student Brandon Hassenaur had used the software as part of his summer internship work placement. He immediately saw the potential advantages E3.series could offer the racing team. Representatives from Zuken visited the campus to set up a pilot project, and it paid dividends immediately.
The students used tutorials (supplied by Zuken) to learn the software themselves, and managed to knock a full fifteen pounds (7 Kg) off the car’s wiring harness. The cable harness design was part of the CAD model development process; it collects into one bundle all the electrical wires that go from point A to B.
According to Dr. Chambers, students were frustrated with the wiring, because it was done in a hurry at the end of the build period. This resulted in occasional failures, including a critical failure in the fuel pump circuit. This illustrated how even the very best mechanical designs are only as good as the quality of the electrical system. After the Formula SAE team added E3.series to their software arsenal, it improved the performance and reliability of their vehicle’s electrical design. This was not lost on other Advanced Transportation Systems teams, and so the ECOcar2 challenge team will be including E3.series software as part of their design, hoping to find similar improvements in performance and reliability.
Electrical Design in Formula SAE
It isn’t only Rose-Hulman that has come to find the advantages in using the same high-end electrical CAD software as automakers and industrial designers. Formula SAE is an international competition in Europe. Students from Hochschule Esslingen are tearing up the track and last year took home the top overall award at Formula SAE Spain against international competition.
Located near Stuttgart, Germany, Hochscule Esslingen is in the same neighborhood as the high-performance heart of the European automotive industry. (See www.estall-esslingen.de/eve-13.) A short drive from the school are automakers Mercedes-Benz and Porsche, and car parts manufacturers such as Bosch. The Esslingen Formula SAE team lives up to the area’s reputation for automotive excellence by not only dominating the field with their traditional internal-combustion engine SAE race cars, but also by pushing technological boundaries. They developed an electric Formula SAE race car that uses a 600-volt lithium battery pack and custom-built motors; the motors are, unfortunately, software-limited to 85kW to comply with the Formula SAE rulebook.
Alexander Achstatter is a third-year student in electrical engineering at the university. He is leveraging experience from the ‘combustion’ car to help design the electric racer. While he was familiar with mechanical CAD systems, he had never worked with an object-oriented electrical CAD system before. Like the students at Rose-Hulman, Achstatter found E3.series software surprisingly easy to learn. “Zuken gave us a three-day workshop,” he explained, “and it was enough to get started. Then we had one month to get used to it, and we were very effective.”
Using E3.series gave the team confidence to design a professional-quality wiring harness for the vehicle. “Last year, it was just, ‘We think we need a wire here’,” explained Achstatter, referring to the common but haphazard process of trying to wire up a machine as an afterthought. “It wasn’t really professional. Someone would ask me which components we used last year and we would have to follow the wire. Yes, there was a circuit diagram, but when we looked close it required much work.”
This year the team took advantage of the E3.formboard component of the software to design a real electrical harness for the vehicle. “This was the first year we used E3.formboard. We printed the sheet out so we could lay the cables out,” he explained. He described the process of taking the symbolic description of the various electrical connections and turning them into a neat, tidy, reliable package of carefully wrapped wires and connectors. “With E3.series, [it] was no problem building the harness. This year’s harness is lighter, looks better, and was fast to build,” he concluded.
The software also took care of a lot of details for the team’s technical report on their vehicle where, every cable, every connector must be documented. Achstatter explained to me the challenge of doing that using their previous design process, and then added, “This year, we have the program [that] makes the list for us, and then we import it into Excel or Word.”
“The biggest advantage is that you can make changes really quickly,” he adds, describing one of the benefits of Zuken’s object-oriented software model used in E3.series. Every component, connector, or wire is fully described as an object, making it impossible to update a drawing or schematic without seeing those changes reflected in every other drawing or table that references that particular part. This has been of great benefit given the complexities of designing the new electric race car where dozens of sensors, from deflection sensors (to measure the twist of the frame), to acceleration sensors for tracking performance were added.
“The most important sensors were wheel speed and steering angle.” he points out, describing how the electric car has been built to use a separate motor for each of the rear wheels, rather than a differential. The team will write code to compare the steering angle to the wheel speed and adjust the motor speeds independently to give the vehicle improved performance in a variety of cornering situations.
The seamless integration of the E3.series software with a variety of mechanical CAD software has paid off for the Esslingen team. “The combustion vehicle team has more sensors, more connectors,” he states, “but the electric vehicle requires thicker cables, 1 cm and bigger. To get these around tight corners is really hard.” This year, they have already planned the components, planned the connections, and laid out the wiring carefully measured to meet the requirements of the vehicle.
The hard planning work is paying off as not only is the combustion vehicle team continuing their winning ways, but the new electric vehicle team is starting to shake off some fossil-fuelled prejudices. Achstatter describes the first test of the electric vehicle, held just three days before our interview: “The combustion team teased us, saying ‘That’s not a real engine.’ Then they saw us accelerate!” Apparently, the combustion team is now finding a new respect, both for electric vehicles and for quality electrical design.
After speaking with representatives of these two teams, I couldn’t help but compare their high performance vehicles to human athletes. When I think about legendary athletes of any sport, they don’t look different from any other professional athlete. They aren’t bigger, they aren’t stronger, and there are no physical clues to belie their greatness. So if greatness doesn’t come from how they are built, then perhaps it comes from how they are wired?
It certainly seems that this is true for the mechanical athletes of Formula SAE. At two different schools on two different continents, the top teams realize that they can pursue greatness by wiring their vehicles better than their competitors using E3.series software as part of their design.