(via EE Times) – Arrow Electronics gave its semi-autonomous motorcar (SAM) design team a little under a year to enable a quadriplegic to drive a race car. As a practical matter, they did it in less than five months.
The essence of every engineering challenge is the tension between goals and constraints — invent, improve, add (and so on) versus money, time, personnel, tools, etc. It’s not that unusual to have to account for the traits of potential users, but it’s the rare project in which user traits so completely dominate all other variables, including those having to do with hardware, software, and resource.
In fact, when it came to hardware, the SAM car design team anticipated that they’d be able to use mostly off-the-shelf technology, and they did. The challenges of the SAM car project would be defined by an end user with a profoundly limited range of motion.
There was one other uncommon constraint in the SAM car project: the stakes. An implicit element of the project goals was that the design team could not kill the driver. There’s no telling if anyone at Arrow ever said it out loud, but it is not possible that anyone involved could have failed to intuit it. Everything that the SAM car team designed, they designed explicitly with safety foremost in mind.
It’s not as if user safety isn’t something that engineers don’t deal with all the time, whether they’re designing controls for an elevator or the life support systems in a jet or a smartphone that ideally should not blow up in users’ hands. The difference with designing any kind of system for auto racing, however, is that recklessness is baked into the endeavor — it is, to use techie terminology, a feature, not a bug — and that’s when the competitors are able-bodied.
And now it’s personal
Somewhere along the line — and this is more that went unsaid — each team member also had to have realized that those stakes were going to be personal. Any solution that they devised would require one of them to crawl into the vehicle and act as a human failsafe should something go wrong when some guy with severely limited motor control was screaming around a racetrack at over 100 mph using whatever human-machine interface (HMI) they rigged up for him.
The members of the SAM car team first convened in the summer of 2013. They consumed no small amount of time on the obligatory mechanics of becoming an actual team, evaluating what skills each person brought to the party and figuring out how to work with each other while spec’ing out the project.
They also met their driver, Sam Schmidt. Schmidt was no average driver; he was a racer who had won an IndyCar event in 1999 in Las Vegas. In the 2000 offseason, driving on a track in Orlando, Florida, he crashed his car. From that moment forward, he hadn’t driven anything other than an electric wheelchair. But he enjoyed racing so much that he’d stuck with it as a team owner, and when presented with the thoroughly unexpected opportunity to get in a car again, he was eager to take it. Arrow Electronics was determined to put him in a Chevrolet Corvette and have him run a few test laps at an upcoming Indianapolis 500.
Arrow’s corporate office had embarked on the project in 2012 and, by 2013, had done some extensive conceptual work with several development partners (see accompanying story). In 2013, Arrow pulled the design of the prototype SAM car in-house.
Noel Marshall was a new employee at Arrow at the time, hired in 2012 after she had earned her degree in mechanical engineering, which she’d gotten into because she had always loved cars. In 2013, she received a one-sentence corporate email — “Would you like to volunteer for a race car project?”
“Well, yeah, duh,” she had thought. “Not knowing what I’d signed up for.”
Once the membership of the SAM car team was finalized, they were told what they’d signed up for. Paraplegic. Corvette. 2014 Indy 500.
Sorry — no ‘CAN’ do
Marshall and her colleagues, a half-dozen engineers from all over North America, evaluated what had been done thus far. One of the existing ideas that the team liked was one that had been developed by Arrow partner Ball Aerospace, which had created a motion-tracking system for capturing drivers’ head movements.
The basic concept will be familiar to anyone who’s seen how the film industry uses motion-capture technology to track the movements of actors standing in for characters whose ultimate appearance will be digitally rendered, such as the alien Na’vi in “Avatar” or the chimpanzees and gorillas in the “Planet of the Apes” reboot.
In the film industry, the approach involves placing numerous dots on the actor’s face, torso, and limbs and capturing his or her movement by tracking those dots with motion-capture cameras. Arrow and Ball Aerospace adopted a modification of that approach; they used infrared (IR) cameras placed in the vehicle’s cockpit to track head motion by detecting signals bouncing off of reflective dots attached to a baseball cap that would be worn by the driver.
The communications system in automobiles is the controller area network (CAN). The SAM car team knew that the key to building a successful HMI would be the ability to integrate the head-tracking system (and whatever other subsystems that they devised) with the CAN so that they could have direct access to the car’s steering, engine, and brake systems.
GM was uninterested in the project, however, and denied Arrow open access to its CAN. The SAM team hadn’t anticipated that. Without GM’s cooperation, integrating directly with the car’s electronics — the easiest course of action — simply wasn’t going to happen. The only thing that they would be able to do with the CAN was read OBD-II data — the on-board diagnostics (OBD). It was the same level of access that a Jiffy Lube mechanic has.