In today’s off-highway industry, both end-user demands and design and manufacturing practices are substantially different from those of the consumer automobile industry.
However by 2020, off-highway companies will rely on processes that more closely resemble those of automakers. The two divergent markets share one strategic imperative: in a field whose challenges are growing more complex with each passing year, there is ever more pressure to balance product quality, cost, and timeliness to stay competitive.
The growing demands of electrical complexity
Nowhere is the above more true than in the influence of electrical subsystems on vehicle design. Electrical complexity in cars is increasing dramatically. Some of today’s luxury cars have up to 80 electronic control units (ECUs), each populated with unique embedded software. These units control and monitor almost every vehicle feature related to safety, engine, and braking functions, and more. These same types of ECUs are finding their way into off-highway vehicles, managing climate settings, control panel functions, etc.
Other consumer and technology trends foreshadow developments in off-highway vehicle features. Consumers expect good fuel economy, and government regulators demand low emissions. The solution to both challenges involves electronic fuel metering and timing control—features sure to find their way into more off-highway applications.
Lastly, electronic sensors and controls have become ever more integrated with the pneumatic and hydraulic systems that lift loads and till earth. All of these mechatronic systems must be connected, and many of them must communicate with one another. This implies an increasing number of in-vehicle digital networks, often operating at higher data rates than in the past.
The expansion of options and variants adds another dimension to complexity. For years, auto manufacturers have been dealing with wiring harness configurations in the thousands and even millions. While off-highway designers are not likely to confront this much proliferation, there is still a need for solutions that can provide proven, pretested harness designs.
A model approach to complexity management
What is the best way for off-highway companies to handle this impending growth in complexity? I believe the best approach is to leverage the hard-won lessons and practices from another industry that has successfully dealt with exponential growth in electrical system complexity.
Thirty years ago, manufacturers of integrated circuits saw the complexity of their designs cross a threshold. Their designs had surpassed the practical limit of human comprehension. It was no longer possible for any one designer to manage the electrical and physical constraints of processors and chip sets containing millions of transistors.
A few years later, makers of printed circuit boards (PCBs) reached a similar impasse. Their products had to route and interconnect thousands of signals in high-density, multilayer circuit boards.
Both industries turned to electronic design automation (EDA) tools to develop higher-level models that were easier for designers to comprehend. This approach has become known as model-driven development (MDD). Companies such as Mentor Graphics that made MDD a reality for PCB and silicon-design applications are now bringing their in-depth knowledge to vehicular wiring design, embedded software development, and more.
MDD offers the designer a higher level of abstraction when low-level details become too complex to handle. Within platforms such as Mentor Graphics’ CHS electrical system design tools, a software-based model abstracts numerous specifications and rules that apply to lower-level entities. A hierarchy of models encompasses four disciplines that enable all possible configurations: configuration requirements, connectivity, mechanical constraints, and design rules.
The data that must be tracked and evaluated in today’s wiring harness design, for example, ranges from signal frequency to wire lengths and even color coding. A high-level model “bundles” all of these factors into one executable component. When executed, the model synthesizes the next level down, conforming to the specifications and rules. The model may itself contain lesser models that in turn synthesize their subordinate levels, and so on to represent a vast number of variables that designers no longer need to manage all at once.
Applying MDD to harness creation is simplifying vehicle designers’ work in the consumer automotive space. MDD manages data and project reporting and, crucially, enables early and progressive design evaluation. Recognizing the efficiency of this approach, many leading automakers have already made the leap to MDD. By 2020, if not before, model-driven development will be a necessity for off-highway products as well—especially the larger machines with complex harnesses and subsystems.
Using MDD tools, designers will connect high-level functions rather than pin-to-pin signals. The tools will handle the pin-level thinking, and the models will accurately predict hardware responses. This approach will reveal any problems while they are still relatively easy and inexpensive to correct.
Co-simulation tools such as Mentor Graphics’ SystemVision that produce multiphysics (electrical, hydraulic, pneumatic) models are available today and will be in common use by off-highway designers in 2020. EDA will bring automotive and off-highway design methodologies closer together while at the same time adapting to the unique demands of each industry.
Standards foster efficiency and competitiveness
Among consumer automobile manufacturers, there is a groundswell of demand for industry standards that will simplify their transition to MDD processes. Just as standardized mechanical parts have long been the norm in all levels of manufacturing, a similar approach will benefit off-highway electrical subsystem design.
The most prominent emerging protocol is AUTOSAR—the Automotive Open System Architecture. AUTOSAR defines a standard software topology for use in vehicular ECUs. AUTOSAR is poised to expand its influence in both consumer autos and off-highway vehicles in the coming decade. Mentor Graphics, with its Volcano family of tools, is an industry leader in AUTOSAR-compliant EDA solutions.
By 2020, off-highway manufacturers will—must—capitalize on standards such as AUTOSAR to stay competitive. A rigorous standard ensures easy migration of features among platforms of all types. AUTOSAR will enable complex subsystems to be developed once and used in diverse applications. Rather than using 20 different ECUs in a vehicle, AUTOSAR could make it possible to use just four or five variants across a broad product line.
Very likely, makers of off-highway vehicles will be able to draw on standards-compliant elements including ECUs and software components from the automotive market.
Walden C. Rhines, Chairman and CEO, Mentor Graphics Corp., wrote this article for SAE Off-Highway Engineering.