Virtual Design and Verification Solutions for e-Mobility

Technology News | July 10, 2013

By eeNews Europe

The market for electronic control units (ECUs) alone stood at just under $48 billion in 2010, some 29% higher than 2009. Overall, electronic vehicle content is forecast to grow by just under 8% annually to 2015. Some application areas will show exceptionally high growth (in excess of 50%). These include pure EVs, head-up displays, drowsiness detection, LED lighting, stop/start, lane departure warning and blind spot monitoring. By 2010, electronic systems and software comprised 30% of the cost of conventional (gas) vehicles and 65% of the cost of hybrid and electric vehicles.

Key Electrical Connections

Driver experience (including safety, comfort, ecology, economy)—the connection between the car and its passengers—has become as important as the cars purpose as a means of transport. The industry has focused on how to make vehicles more people-friendly for the last 20-30 years. As a result, electric subsystems feature in many of the car’s systems. Some of the key connections between people and vehicles (both in production and in research) include:

· Electrification of driver comfort and entertainment,

· Electrification of the drive train to reduce emissions,

· Navigation, GPS, cloud navigation giving immediate access to information,

· Electric power infrastructure and minimizing power,

· ‘Platooning’ vehicles together, sign/ pedestrian/road line recognition, and

· Autonomous vehicles, where the driver becomes unnecessary.

Implementing the kinds of connections above makes cars more complex—just how much more complex can be seen in the amount of software that automotive engineers produce.

Automotive systems are starting to approach the same level of software complexity that modern operating systems contain—anything from a staggering 50m to 300m lines of code. In fact, automotive systems are actually more complex than that, since the interaction with the mechatronic system of the vehicle is far more important than in a computer. The car can kill you; the computer probably won’t.

System Challenges

At the 2010 SAE International conference, top engineers from Honda, GM, Ford, BMW, Chrysler, PSA and Toyota took part in a “Carmakers Speak” panel session, which identified the main system challenges for automotive design. These were:

Function and software allocation, and verification: This activity is central to car design today. It involves identifying the functions on the vehicle, and allocating them to hardware and software resources.

System engineering and simulation: Automotive engineers must redesign every system in the vehicle for electrification.

Power generation, management and distribution: The core system of the vehicle is still the generation, management, and consumption of electricity, and is being expanded to include the drive train.

We look at these three challenges in more detail below.

Function and Software Allocation, and Verification

The key challenge for automotive systems engineers is that rather than increasing reliability, software makes the problem harder. Making cars that don’t crash, that serve up driver information without distraction, and that don’t pollute, are among the greatest system engineering challenges that the industry faces. On top of that, success in the industry depends on there being sufficient demand for cars, which means that design teams are constantly under pressure to find the latest “cool factor”.

The essence of system design is to design a distributed computing system that interacts with physical systems, and then defining and mapping the software onto this distributed system. This task was more straightforward when every ECU in the vehicle mapped to a single function and the ECU/software was delivered as a black box—an approach that means it’s now common to find over 100 ECUs in high-end vehicles. In order to reduce the number of ECUs, the technology now exists to consolidate multiple functions into a single ECU. The complexity of functions has also increased so that multiple ECUs must cooperate to implement a high-level function. Tasks like automatic parking or collision avoidance must communicate with and control multiple subsystems.

A big challenge in integrating systems is that components invariably come from multiple suppliers. This compromises safety and quality. At the start of ECU-software integration, there may be thousands of errors present. The later that someone identifies the problems, the more it costs to fix them. Problems that manifest themselves once the car is in the customer’s hands become very expensive to fix. Business Week reported that Toyota’s 2009-10 recalls cost the company more than $2 billion, including legal costs, lost sales and warranty payments.

System Engineering and Simulation

So how can automotive design teams conquer the system design challenges that come with vehicle electrification? The problem scope is not limited to software and electronics—design teams must also consider mechatronics. Potential solutions need to support detailed physical modeling, conceptual design and implementation, and concurrent, multiple tiers of modeling and verification.

The history of car electronics has gone from simple power generation and distribution, through electronic control systems, to electronic drive systems. The cost of electronics has increased from 10% to 60% of the car for electric hybrids. The cost is not in software (manufacturing of software is mostly free) but in the electronic, electrical, and electro-mechanical components that make of up the vehicle.

Model-Based Embedded Systems Engineering (MBESE)

Carmakers need models for multiple purposes:

For analyzing/verifying the product need,

To define software applications of the EE system, and

To support simulation and verification of the plant/multi-physics/car system models.

Consequently, modeling requires the use of many different frameworks:

AUTOSAR—software running on a virtual processor,

EAST-ADL2—software running in an environment (plant included),

VHDL-AMS/MAST—mechatronics modeling and electrical systems,

SystemC/SystemC-AMS—system-level description of SoCs and interconnection of SoCs,

SystemVerilog/Verilog-AMS—SoC implementation, and

SPICE—IC analog.

Bringing together all of these elements requires a platform that is capable of modeling and simulating physical systems, which enables full-system virtual prototyping for applications in analog/power electronics and electric power generation, conversion distribution and mechatronics (Figure 1).

Semiconductors are the basis of all automotive electronics systems, while software runs on all the ECUs, mechatronics is what makes the software do something useful. To be useful, a platform must incorporate an electrical system architecture that links these key system components together.

Power Generation, Management and Distribution

The core function of the vehicle is still the generation, management, and consumption of electricity. This is even more pronounced with electrification since the power train is now a factor in all of these areas. All of the electrical systems need to make use of low-power techniques so that the amount of electricity used by the vehicle can be reduced, and so, too, the battery size.

We can reduce the electrical load on the battery by optimizing 12/24/48V loads, by reducing the amount of wire in the vehicle, and by designing more efficient HVAC (heating, ventilation and air conditioning) systems.

Compared to automotive, other sectors, like the mobile phone industry, have a lot more experience of applying low-power techniques. Battery life plays a large part in determining the success of mobile software platforms like Android. And in turn, software has a large part to play in determining battery life. For example, an application that wakes up the phone every 10 minutes for just eight seconds to perform updates can cut its stand-by time by half. Any software power inefficiency or malfunction can quickly cause a drop of 5x or more in standby time.

The complex, highly distributed software entities for power saving and management must be vertically integrated and cooperate to guarantee an efficient use of the battery in a mobile phone. The phone’s usage scenarios play an important role as they define how it interacts with the environment. However, how can you debug your phone while it is locked in your pocket? How can you make sure that scenarios are deterministic to compare different implementation options?

Debugging power defects comes with another major issue. In low-power modes such as “suspend”, the embedded debug service is likely to be suspended as well. In addition to that, any debug interaction with the device is intrusive and severely tampers the power figures. Furthermore, expensive lab equipment is required to perform a sufficiently fine granular power profiling to determine which of the components is the most critical.

In many ways the challenges that designers face, whether they’re working on mobile phones or electric vehicles, are converging.

Solutions for Automotive Engineering

Synopsys’ design automation solutions help to address many of the emerging engineering challenges that carmakers now face. We have solutions for the design of the silicon itself (system on chip—SoC), provide leading solutions for virtual platform verification of software (Virtual Prototyping) and we partner with the leading solutions for creation of the software. We also have the market-leading tool (Saber) for mechatronics design, and lead the creation of the standard languages used, including MAST and VHDL-AMS. Saber is also the leading solution used in electrical power systems in the vehicle and has powerful capabilities for enterprise-level wiring design.

Virtual Solutions for Function and Software Engineering

Virtual prototypes help vehicle designers to overcome function and software allocation, and verification challenges. They provide excellent debug visibility at the right level of abstraction, such as OS process traces. They can also be instrumented with information that characterizes power usage. Their execution is controlled via deterministic scenario scripts that drive the I/O of the virtual prototypes, such as generating user input via a touchscreen controller, setting GPS coordinates through a UART, initiating a phone call, etc. During simulation, power analysis data is collected, alongside other hardware and software traces, to enable root-cause analysis and debugging that ultimately allows engineers to optimize the software. Increasingly, automotive design teams are shifting from a traditional to a virtual approach (Figure 2) to manage the growth in system complexity.

Figure 2: Virtual Prototyping automotive systems (Synopsys Virtualizer). For higher resolution click here.

A virtual prototype of an automotive system provides a fast, fully functional software model of the interacting subsystems, executing unmodified production code and providing higher debugging analysis efficiency.

System Engineering Solutions

All systems are subject to sources of variation including component tolerances, environmental stresses, or aging. Automotive system engineers want to reduce the effects of variability on system performance by designing systems that are less sensitive to these sources of variation. Saber helps engineers to apply robust design methods, such as Taguchi or DFSS (Design For Six Sigma) and to optimize their mechatronic systems for quality and cost.

Power Management Solutions

The Saber links to TCAD (transistor-level CAD) tools from Synopsys enable engineering teams to achieve faster product design for power electronic systems. By abstracting device-level physics to physical systems, designers can work with accurate, compact Saber models of power components. The abstracted models support behavioral circuit simulation that can be hundreds of thousands of times faster than device-level mixed-mode simulation.

About the Author

David Smith is currently a Scientist at Synopsys, and is responsible for the architecture of the Saber product lines. David is one of the founders of Analogy, where he co-created the MAST language and drove the creation and definition of the VHDL-AMS language. As Vice President of Engineering and Advanced Products, he drove the creation of the Saber Designer (Scope, Sketch, Guide) and Saber Harness products. After Analogy, David was Vice President of Engineering for IronSpire, a startup doing web-based project management collaboration. David joined Synopsys in the Advanced Technology Group, where he lead the team of Language experts that created the SystemVerilog language. He then returned to the Saber products. David is a long time member of the IEEE 1076.1 committee (currently Treasurer), IEEE 1800 (System Verilog) committees, and follows the Verilog-AMS, SystemC AMS, and FAT/AK-30 standards activities. During this 27-year excursion, the automotive industry has been a constant companion, as it has migrated from building mechanical drive trains to electrical drive trains (and the journey continues). David holds a number of patents in the areas of AMS simulation and modeling.