Flexible controls architecture for hybrid-electric vehicles

General Motors and Motorola collaborate on a prototype vehicle for PNGV.

Developing an electrical control system for an ultra fuel-efficient hybrid-electric vehicle (HEV), such as the General Motors Precept, required a rapid design methodology that used low-power electronics capable of being integrated with controls from earlier engineered subsystems. The Precept is a technology demonstration concept vehicle developed to address GM's commitment to the U.S.'S Partnership for a New Generation Vehicle (PNGV) program, which calls for an 80-mpg gasoline equivalent, five-passenger vehicle. This concept vehicle is an example of an energy-efficient vehicular control system developed using a requirements-to-software development process and electronic controller infrastructure. The development process incorporated vehicle-worthy rapid prototyping parts and tools that were flexible enough to accommodate evolutionary development of control algorithms.

To demonstrate and iterate capabilities of this vehicle quickly, an efficient and rapid means for developing requirements, mapping these into an electrical control and communications architecture, and developing prototype systems was needed. The three-fold leap in efficiency required for the PNGV program demanded that attention be paid to pervasive and, in some cases, even extreme efforts toward vehicle-wide improvements. These improvements were focused in areas such as powertrain, chassis rolling resistance, aerodynamics, vehicle mass, thermal and climate efficiency, and electrical accessory load reduction. This required levels of complexity in the vehicle's electronic controls that had not been encountered before by the company. As an example, electrical load sharing required coordination between many controls processes. Also, integration of an overall traction and energy operating strategy involved extensive algorithms requiring more capable microprocessor-based controllers than had been used in the typical automotive application.