The University of California at Davis (UC Davis) was among 15 North American universities to participate in the 2001 FutureTruck Competition. This competition gives students an opportunity to apply skills learned in school to a real-world engineering project: Participants must reengineer a sport utility vehicle so as to reduce emissions and fuel consumption without sacrificing vehicle performance or safety. As a FutureTruck sponsor, The MathWorks provided its software for students to use throughout the competition.

UC Davis won the 2001 FutureTruck championship and the MathWorks Vehicle Modeling & Dynamics award. Their "plug-in" hybrid electric version of a conventional 2000 Chevrolet Suburban was judged to have the best combination of low tailpipe emissions, high fuel economy, low global warming gases, and good powertrain performance.

The team used MATLAB, Simulink, and a Simulink based vehicle modeling program called PSAT to develop the powertrain strategy for their vehicle. "I feel that our vehicle won because we had the best success in implementing our hybrid powertrain and control strategy, and MATLAB and Simulink played a very important role," says UC Davis Future Truck advisor Dr. Mark Duvall. "Using Simulink, thestudents could develop systems models that were both accurate and easy to modify."

Challenge

Each team needed to develop a hybrid electric vehicle powertrain control strategy to determine how the vehicle's engine and transmission should react to driver inputs. The strategy had to balance three objectives: reduce fuel cycle greenhouse gas emissions by 66%, reduce the fuel consumption to half that of the standard Suburban, and meet California's Super Ultra Low Emissions Vehicle standards. Students were also evaluated on the completeness of their representation of the vehicle model.

"MATLAB and Simulink allowed the students to construct mathematically complex simulations quickly and easily."

Solution

The UC Davis team developed a comprehensive vehicle model based on PSAT (Partnership for a New Generation of Vehicles Systems Analysis Toolkit), a Simulink based modeling program developed by Argonne National Laboratory. They simulated their Suburban's four-wheel-drive powertrain to determine a control strategy, settling on a combination of charge-depletion and charge-sustaining strategies. In charge-sustaining vehicles, the onboard battery is recharged by the combustion engine while the vehicle is being driven. During charge-depletion, electric energy from the battery powers the vehicle. The vehicle is recharged when the driver returns home that night.

Since the PSAT powertrain control strategy is intended for charge-sustaining vehicles only, the team had to rewrite many of the model's control algorithms. Because PSAT is based on Simulink, this was easy to do: "One of the strengths of Simulink is the open source nature of the program," Duvall says. "The students can go into the Simulink code for PSAT and make improvements or modifications that better suit their objectives."

The UC Davis team embedded portions of the vehicle control software directly in the PSAT simulation. They imported the Suburban's C-language microcontroller code into PSAT using a Simulink S-function. This allowed them to accurately simulate several modes of operation. They improved the control algorithms and simulated the changes in PSAT. Once the simulation results met their targets, they transferred the final algorithms directly to the vehicle controller for immediate use in the vehicle.

"The students could have developed models using C, but they would have expended more effort developing the software," Duvall says. "With MATLAB and Simulink, they could dedicate more time to developing the vehicle models and optimizing the designs." The students acquired engineering experience that cannot be taught in a classroom. They worked with software tools used by engineers in industry and learned firsthand how to apply these tools to problems in the real world. As a result of their work on FutureTruck, the team has been awarded several patents for hybrid vehicle control strategies.

Results

Products Used

• Simulink®

Reducing noise-from road, wind, and engine, as well as from power seat adjusters, power mirrors, and other components-has become a key automotive design requirement. Until recently, noise-reduction efforts focused on the overall sound level. Engineers now recognize that other attributes, including sharpness, loudness, and fluctuation, affect perceptions of sound quality.

To ensure an acceptable acoustic environment without conducting expensive and time-consuming listening studies, engineers must obtain objective sound-quality (SQ) metrics that correlate with subjective impressions of sounds.

Ford's research and advanced engineering and product development groups generate reliable SQ metrics for the company and its worldwide suppliers with a suite of SQ analysis tools developed in MATLAB. In fewer than three weeks, Ford turns metrics developed with MATLAB into stand-alone applications using the MATLAB Compiler so that relatively novice users can execute the applications without any programming.

Challenge

The only metric with an implementation standard-ISO532B-is stationary loudness. All other SQ metrics are vendor-specific: they vary depending on the vendor's particular implementation techniques.

Ford set out to develop an easy-to-use, scalable measurement and analysis tool that would be inexpensive to distribute with SQ metrics that could interface as plug-ins with third-party analysis systems. The stand-alone version of the tool had to provide basic functionality for recording, playing, and editing; working with databases; analyzing signals; and producing SQ metrics that correlated well with subjective impressions of sound quality.

Solution

Ford chose the MATLAB product family as their software platform to rapidly develop algorithms, acquire and analyze data, and build and deploy applications. Using MATLAB with the MATLAB Compiler, they deployed their SQ metrics to different third-party analysis systems using a single version of the MATLAB source code.

Using MATLAB and the MATLAB Compiler, Ford integrates with supplier's third-party analysis systems by generating MATLAB based DLLs. Third-party SQ analysis systems written in other languages pass signals and data among systems to the generated DLLs. Moreover, Ford used MATLAB to develop a GUI front end for the Simple Sound Quality Tool (SSQT), which they compiled with the MATLAB Compiler before distributing it to their suppliers as a stand-alone application.

With this approach, Ford has saved up to six months in development time by avoiding the process of rewriting the MATLAB application to another language or making the application available to run outside of MATLAB. This approach also enabled them to simplify application maintenance by requiring them to only update the original MATLAB application. They distributed MATLAB based stand-alone application plug-ins to more than 25 worldwide suppliers, enabling them to use their third-party systems for data acquisition and to analyze data using the SSQT metrics.

Using the Signal Processing and Statistics toolboxes, engineers developed versions of SQ metrics for loudness, sharpness, and fluctuation strength, which objectively measure perceived volume, spectral density, and modulation. They use the metrics to evaluate the sound quality of electric motors for seats, pedals, and mirrors as well as switches, wipers, and other interior features.

Engineers also developed algorithms to process several types of time-varying sound, including wind gusting, impulsive engine noise, and spark knock, which are difficult to characterize using standard objective SQ metrics. They used MATLAB development tools and the MATLAB Compiler to develop and run these sound metrics as stand-alone applications.

Ford also uses the Data Acquisition Toolbox to run their spark knock detector and analyzer application in "real time." Unlike other SQ metrics that are first saved to a file and analyzed at a later time, Ford's spark knock application uses the Data Acquisition Toolbox so that sound acquired from a standard PC sound card can be analyzed in MATLAB while the acquisition is still in progress. This application enables engine calibrators to detect spark knock while adjusting engine calibration parameters. It is through advanced spark timing that Ford maximizes engine torque output and minimizes fuel consumption.

MATLAB continues to be widely used to develop Ford's SQ metrics, while the MATLAB Compiler eases the process of turning these metrics into user-friendly applications.

Results

Products Used

• Data Acquisition Toolbox
• MATLAB®
• MATLAB® Compiler
• Signal Processing Toolbox
• Statistics Toolbox