Automakers Opting for Model-Based Design

Automotive engineers at the recent SAE Convergence 2010conference in Detroitsaid they are increasingly employing model-based design in the development of vehicleelectronics, ranging from engine and transmission controllers to bodycontrollers and battery management modules.

At a pressconference sponsored by The Mathworks,engineers from General Motors, Lear Corp. and Tata Technologies, Ltd. saidthey are now using model-based design for prototyping of electroniccontrollers, including development of software algorithms and auto-generationof code, as well as verification and validation of those products.

"In atypical program, we can save 40 percent in the development phase and 60 percent in validationby using model-based design," noted Jason Bauman, engineering manager forsystems integration engineering at Lear Corp. "Typically, we'll also have zerodefects on our ECU (electronic control unit) products." Lear recently used TheMathworks' Simulinksoftware to develop body controllers, alarm systems, battery management modulesand interior lighting systems for Ford Motor Co. vehicles.

Engineerssay the move toward model-based design has naturally evolved from thecomputer-aided design techniques of the 1980s. A decade ago, many engineers stillcreated control systems by talking to customers, writing assembly code, andthen testing the design by physically flipping switches on a prototype. Morerecently, however, model-based design has given engineers a mathematical andvisual methodology to develop embedded software for the creation of complexcontrol systems. In the automotive world, the digital simulation of suchsystems has enabled automotive teams to create and test features before theybuild a prototype.

That wasthe case for General Motors in the development of the Chevy Volt. GMengineering teams said they employed model-based design and simulation in theprototyping of the Volt's propulsion and battery management systems, even asthe technology was barely emerging from the research stage.

"We progressedon the Volt's development without having the battery technology in place yet,"noted Karla J. Wallace, senior manager for electronics engineering, integrationand software. Wallace said that GM started modeling with Simulink, thengraduated to Real-TimeWorkshop Embedded Coder to create the C code that went into the Volt'selectronic control system.

Similarly, Tatabuilt a four-passenger city car called the Nano by making heavy use of model-baseddesign. The India-based automaker said it employed Simulink, Real-Time Workshopand Stateflow forthe creation of the Nano's engine management system and powertrain controller.

"We've usedit mostly in the prototyping stages," said Prasanta Sarkar, project manager forTata Technologies. "We used it for the prototyping of an ECU for a continuouslyvariable transmission, and we've seen huge benefits in testing and validation."

The automakersand suppliers at the press conference also agreed that model-based techniqueshave laid the groundwork for future projects. "It has increased our efficiencybecause we don't have to keep re-interpreting requirements over and overagain," Wallace said. "The C code can be seamlessly integrated into othersystems. It becomes a re-usable asset."