Wiring is certainly a key aspect for design tools but to have a more complete look, other areas must be examined. Two additional topics include model-based design and hardware in the loop. Additionally, in this final section, different approaches to tools and methodology are demonstrated.

Model-based design (MBD) can be applied to many different areas to address control problems and for code generation problems. MBD use is essentially universal in powertrain development. In this process, both OEM and powertrain control suppliers use the MathWorks products. Some users develop models to test out and design algorithms and some have the goal of automating code generation. “Where a lot of them are moving now is in rigorous processes — making sure that they can version control both the models and the code,” said John Friedman, marketing manager for MathWorks. “They are also looking to link those codes back to their initial requirements and then to link the tests that they have created to the requirements.” Figure 5 shows the concept of model-based design. Verification of these models must occur at the component, systems, and total vehicle level.

With the established and recognized position of design tools in several areas, many companies work together to provide optimum synergy of each company's tools. These partnerships exist in several areas. For example, Synopsys' Saber, MathWorks' Simulink and dSpace's rapid prototyping tool are shown working together in Figure 6 to provide closed loop correlation in an electronic throttle model^[4] .

Hardware in the loop (HIL) testing fits in the design validation side of product development. Essentially, HIL takes the embedded controller with the control algorithm and connects it to a computer running a real-time operating system (RTOS). The controller reacts as if it was in an actual vehicle. This allows a much lower test cost, as well as quicker testing, more test iterations, and greater flexibility.

“You can do it more quickly, you can do more tests, and you can get greater boundary tests,” said NI's Washington. An example of a test that could be conducted using this approach is simulating an oil leak until the point that the engine no longer operates. With real hardware, this would be a single occurrence test. With HIL, engineers can test areas that may not be practical to test — such as those at or outside of boundary conditions. In addition, Washington pointed out an example where one LabVIEW user, MicroNova electronic GmbH, used a LabVIEW FPGA module and National Instruments' PXI-7831R reconfigurable I/O module to develop a 12-cylinder fuel injection HIL simulator. The HIL solution allowed development before the actual hardware was available.

Specific activities at design tools companies reveal some of the variances in approaching electronics complexity. Five examples include a chip-based starting point, networking, microkernel/RTOS, power electronics and testing.

“What we see is primarily in three areas: the first one is mixed- signal, analog/mixed-signal (AMS), the second is around verification, verification certainly at the chip level and the third is system-level design challenges,” said Kelly Perey, vice president, marketing, Cadence Verticals Cadence Design Systems Inc.

Cadence-focused areas correspond to the three automotive levels: semiconductor, tier ones and OEMs. “The verification and system-level design issues are particularly interesting because they cross all three segments,” said Perey. “And what those three segments need varies slightly.” Cadence has a methodology called Plan to Closure that provides system-level verification all the way down to verification at the chip level. Customers in automotive and tier ones such as Bosch use the Plan to Closure system.

From its roots in semiconductor technology, Cadence links to the system level to other tools such as MathWorks, which is heavily used across automotive to capture system-level information. These links include language-level links into Cadence analog and mixed signal simulators that allow Cadence to validate that the chip works in the context of the system specification in MathWorks. This produces a verified model of the IC and verifies that the model works inside the system specification.

In powertrain and chassis control, the increased usage of the CAN and other protocols in feedback control systems that have to communicate with each other on a relatively frequent basis is an area of interest to Mentor Graphics. To simulate the actual network traffic, the user enters all the producers of signals and all the consumers of signals (i.e., engine speed, temperature, air flow, etc.). Mentor Graphics tool schedules all the signals to make sure the maximum latency of the signal is not exceeded and automatically packs all the frames in the desired protocol for data transport. A signal that does not satisfy the requirements is flagged for a design change.

For automotive electronic control units with minimal or no off-chip memory, such as those in in-car head units, handsets, dashboards and body electronics, Green Hills Software Inc.'s recently introduced micro-velOSity provides a royalty-free real-time microkernel and new CAN driver software for next-generation office-in-the-car systems. Addressing the low end in the platform architecture with a ROM footprint as small as 1600 bytes and RAM footprint as small as 1000 bytes, the micro-velOSity is API compatible with the company's velOSity, a mid-range real-time kernel, and INTEGRITY, a real-time operating system (RTOS). Green Hills integrates its family of operating systems with its MULTI development tools package.

Ansoft's Simplorer addresses power electronics applications and the interactions between electrical, electromechanical, electrothermal, electrohydraulic, and mechanical loads in these systems. Together, with its Maxwell finite-element-based electromagnetic field simulation software, the two tools provide a high level of accuracy in automotive design. Maxwell calculates inductance, resistance, torque, force, and other parameters in sensors, actuators and motors and generates a behavioral model of the device that includes the calculated parameters for use in Simplorer. Simplorer can be used as a circuit and block diagram simulator as well as state machine and VHDL-AMS design and is ideally suited for development in advanced hybrid vehicles according to Mark Ravenstahl, product marketing manager, Ansoft.

Since measurements with simulation reduce the number of tests, National Instruments wants users to make the most of the tests that are performed. Instead of just determining if a test passes or fails and then archiving the data, measurement and simulation allows correlation with models — the tools and equations on the design side — to improve the quality. To perform a higher percent of the design phase in simulation, the models have to get increasingly better so testing and correlation with real world measurement is essential. In mechanical design, NI has been working with mechanical design companies to allow this process to be easy and trackable to take measurements of a physical system and correlate these in the mechanical model. For the mechanical device, this can ensure the models and the boundary conditions are accurate.

1. Walden C. Rhines, Mentor Graphics presentation, http://www.mentor.com/

2. Ove Josefsson (Volvo Car Corporation), “AUTOSAR Overview (AUTomotive Open System Architecture), Snart Conference, Skövde, 2005-08-17.

3. Thorsten Gerke (Synopsys GmbH) and Carsten Petsch (Volkswagen AG), “Analysis of Vehicle Power Supply Systems Using System Simulation,” SAE 06M-98.

4. Liang Shao (Hitachi America Ltd.) and Jian Lin (General Motors), “An Electronic Throttle Model with Automatic Parameter Tuning,” SAE 2005-01-1441.

Randy Frank is president of Randy Frank & Associates Ltd., a technical marketing consulting firm based in Scottsdale, AZ. He is an SAE and IEEE Fellow and has been involved in automotive electronics for more than 25 years. He can be reached at r.frank@ieee.org.