Stanley at Stanford
A vehicle can contain computerized networks designed to control all of a vehicle’s functions, known as “CAN-bus” systems. The networks comprise several processors that receive data from the connected units, then process and forward the data instantaneously to the right address. The motor, controller and instrumentation, as well as other functions, communicate and exchange information.
Some of the other functions now being incorporated into vehicles come under the aegis of “drive-by-wire“. For instance, if you depress the accelerator in your car, this action is registered by a processor, which sends a command to the engine control system to increase the demand for power by the motor.
As previously noted, one outcome from the most recent, Shell Eco-Marathon is design of a virtual accelerator. Rather than moving, the accelerator pedal, which is made of a composite spring, responds to pressure by deforming.
The recent discussion on the application of in-wheel motors is another example of advanced electronic vehicle interface technology. Electric motors allow for regenerative braking and those same capabilities can be used to improve traction control and prevent skidding. Furthermore, in addition to motor control, such in-wheel systems can feature brake-by-wire and electronic steering control. Development of electronic traction control and vehicle stability systems is underway.
Other functions for more intelligent interfacing include GPS (Global Positioning System) to determine vehicle position worldwide and GSM (Global Satellite Messaging) to receive or request error messages of a CAN bus device. Such functions that convey information to and from the vehicle by telecommunications come under the general heading of vehicle telematics. Stanley’s win is an excellent example of the stage of development now obtained by vehicle telematics.
Originally developed in the 1980s by Robert Bosch GmbH, CAN is a multicast shared serial bus standard for connecting electronic control units. Internationally standardized in 1993 as ISO 11898-1, it is consistent with the seven layer ISO / OSI reference model. CAN “provides two communication services: the sending of a message (data frame transmission) and the requesting of a message (remote transmission request, RTR). All other services such as error signaling, automatic re-transmission of erroneous frames are user-transparent, which means the CAN chip automatically performs these services.”
A CAN system has redundancy and is designed to ensure data integrity, e.g., it uses sophisticated error detection and re-transmits faulty messages. A sender transmits to all devices on the bus. So, in the previous example, the composite accelerator sends a precise electrical signal not just to the vehicle speed control unit, rather the digital signal goes along the CAN-bus throughout the system. All receiving devices read and, if relevant, act on the message. All receiving devices in the system continuously monitor updated information.
In the early 90′s, the Truck and Bus Control and Communications Sub-committee of the Society of Automotive Engineers developed a CAN-based application profile for in-vehicle communication. Those communication functions, in particular the J1939/21 and J1939/31 protocol definitions, have become generally adopted in the industry and are required for a system to be considered J1939-compatible.
Which brings us to one of the most recent new SAE members…
Perplexed, but Wonderful, Mate: “Going somewhere?”
Stanley: “Yes, to Stanford’s graduation ceremonies… To get my diploma.”
PWM: “Diploma? But, but you’re a car!”
S (turns, slowly crosses arms and taps left foot):
PWN (seeing himself in deep water): “I mean… you are a very intelligent, er, um vehicle, but, gosh, Stan, what name will be on the diploma?
S: “Well, we are married, are we not?”
S: “So, now it is Doctor and Doctor.” (icy intonation) “Do you see a problem with that?”
PWN (gulps): “Uh, no”
S: “Well, then, if you will please excuse me, the Department Chair wants to meet and explain that they will announce only the two main honors during the exercises.”
PWN: “Come on, Stan, do I deserve that? You know that I’m very proud of you.”
S (warm tone returns): “O.K. I know that you are.” (walks toward him so they are face to face) It’s just that sometimes you need a reminder that I’m more than a pretty fem.”
PWN (wide grin): “I certainly do!”
S (elfish grin): “And, that’s why you bought me that very nice graduation gift.”
S: “Yep. For all those clock units I put into my thesis. You don’t think all that time I was just sitting there in the ERL (Electronics Research Lab) and you had me “hooked up” to the network should be wasted?”
PWN (perplexed again): “But, if you entered the program then… We weren’t married. We hadn’t even uh, er, you know, ah, started dating.”
S (smiling): “So?”
PWN: “So what name did you use?”
S (bats eyelashes): “Why, my current one, of course. Now I’ve got to run or I’ll be late.”
PWN (laughs): “Another one of your small,” (raise hands and makes quotation marks in the air) “transparent to the user” corrections, huh? Well, are you at least going to let me read your dissertation?”
S (hesitates): “Hm, I guess so… They’ve already classified it, but I don’t think it would do any harm if you read it. Now, I really have to get going.”
S (going out the door): “You know where I keep my most important data.” (waves hand) ” Bye, Lover. Die Luft der Freiheit weht.”