It can be argued that little has changed in the basic operating principles of the internal combustion engine and automatic transmission in the last 70 years. What can't be argued is the continuous developments and greater role that electronic controls play in engine and transmission management.
Today's powertrain control module (PCM) offers 256 times more memory than the first PCM, performing more than 2,000 operations per second. The GM Power powertrain controller has more than 500,000 lines of code and 150,000 calibration values, resulting in GM releases of approximately 60 million calibration values per year.
The volume of code and control capabilities required to meet today's powertrain demands is causing automakers to change their strategy and approach to electronic controls.
At GM, powertrain controls are viewed as the enabler for powertrain advancements, and much of the development work has been brought in-house. With more than 650 GM employees dedicated to powertrain controls, GM considers it intellectual property, and has filed for patent protection for more than 278 powertrain control inventions.The future control strategy for GM is to use a family approach for powertrain controls, which will reduce development time and cost while improving quality.
By developing common software for multiple products, GM can support multiple engine or transmission applications in multiple vehicle platforms with a single application software build.
The goal is to reduce the number of controllers and software application builds. To achieve this, GM will move from 11 controllers and application builds in MY 2004 to three controllers and one application build by MY 2007. Each system will build on the content of the lower content system. Three engine control modules (ECM) will use a common application software build with configurable options to select the level of content. Each application benefits from “best common practice.”
The result will be reduced structural cost by commonizing design and verification for the portfolio; fast-to-market variants from the main line design; and improved quality through reuse of calibration strategies and constants.
Using the family approach is one way to reduce development time and cost while improving quality. The second is to transition development and testing from the road to the lab and math modeling.
Given the speed in which systems must be brought to market and the increasing system complexity, more companies are focusing on the math and lab analysis over vehicle testing.
There are three elements to modeling, simulation and analysis for control systems: functional models, plant models and signal delivery models. Each individual analysis contributes to making decisions for the control system and component requirements. By linking the algorithm, signal delivery and plant models, a complete virtual system analysis can be performed, allowing for variation study, fault analysis and “what if?” trade-off studies. Long-term durability effects can be incorporated to ensure long-term durability. By combining this math development with lab testing, systems will be designed and verified under different situations, which could not be solely tested in a vehicle environment.
This holistic modeling and simulation will eliminate much of the lab and field development work and help ensure each part of the control system fulfills its role without negatively impacting any other portion of the system.
Already, electronic controls enable advanced powertrain technologies such as electronic throttle control, displacement on demand, traction control, variable valve timing, onboard diagnostics, gasoline direct injection, clutch-to-clutch shifting, hybrid systems and emissions controls.
Soon, these technologies will be the price of entry for new powertrains entering the market.
While many will speculate what the next powertrain control technology will enable, the reality for the future is that the level of importance that controls play in powertrain management will continue to increase exponentially. The role OEMs play in the development of these controls will continue to increase as well.
ABOUT THE AUTHOR
Dennis M. Bogden is director of powertrain electronics engineering, General Motors Powertrain Group. He is responsible for engine, transmission, transfer case and hybrid controllers, vehicle electrical interface, controls modeling and simulation, and controls support tools. He graduated with a B.S.E.E from Lawrence Technological University and Master in Business Management from Central Michigan University. Bogden is an SAE member and co-chair of the ‘Designing for Powertrain Electronic Controls TOPTEC.’