Automakers Opting for Model-Based Design

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

At a press conference sponsored by The Mathworks, engineers from General Motors, Lear Corp. and Tata Technologies, Ltd. said they are now using model-based design for prototyping of electronic controllers, including development of software algorithms and auto-generation of code, as well as verification and validation of those products.

"In a typical program, we can save 40 percent in the development phase and 60 percent in validation by using model-based design," noted Jason Bauman, engineering manager for systems integration engineering at Lear Corp. "Typically, we'll also have zero defects on our ECU (electronic control unit) products." Lear recently used The Mathworks' Simulink software to develop body controllers, alarm systems, battery management modules and interior lighting systems for Ford Motor Co. vehicles.

Engineers say the move toward model-based design has naturally evolved from the computer-aided design techniques of the 1980s. A decade ago, many engineers still created control systems by talking to customers, writing assembly code, and then testing the design by physically flipping switches on a prototype. More recently, however, model-based design has given engineers a mathematical and visual methodology to develop embedded software for the creation of complex control systems. In the automotive world, the digital simulation of such systems has enabled automotive teams to create and test features before they build a prototype.

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

"We progressed on the Volt's development without having the battery technology in place yet," noted Karla J. Wallace, senior manager for electronics engineering, integration and software. Wallace said that GM started modeling with Simulink, then graduated to Real-Time Workshop Embedded Coder to create the C code that went into the Volt's electronic control system.

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

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

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