Ultracapacitors meet mild hybrids

Valeo and Maxwell Technologies are slated to collaborate on the development of a new stop-start and regenerative-braking system with the emphasis on cost effectiveness. The aim is to create a system using ultracapacitors instead of nickel metal-hydride (NiMH) or lithium-ion batteries, achieving very significant cost savings but still achieving much of the benefit of a conventional mild hybrid application.

The companies have signed a memorandum of understanding (MOU) that involves the incorporation of Maxwell’s BOOSTCAP ultracapacitors in Valeo’s next-generation StARS+X system.

The new 14+X architecture StARS (starter-alternator reversible system) comprises a reversible starter-alternator, a multi-cell ultracapacitor energy-storage module, and other power and control electronics in a 14-V architecture. The system is applicable to standard gasoline and diesel engines. Valeo estimates that the system can reduce fuel consumption and associated emissions by about 12% in normal operation, and by more than 20% in stop-and-go urban traffic.

Valeo’s first-generation StARS provided start-stop technology but did not include a dedicated energy-storage component. The 14+X architecture incorporates enhanced electronics and an ultracapacitor energy-storage module that allows it to capture and store energy from braking. Recovered energy is then available to power peak electrical loads such as deicing and rapid cabin and seat heating and cooling, avoiding increased fuel consumption for such functions.

“Because its energy storage employs high-efficiency, low-cost, ultracapacitor technology rather than costly nickel metal-hydride or lithium-ion batteries, StARS 14+X can deliver 80% of the benefit of a mild hybrid system at 20% of the cost,” said Daniel Richard, Director, R&D Valeo Electrical Systems. “Tax incentives and free access to high-occupancy vehicle lanes have helped to stimulate demand for current premium-priced hybrid cars as niche products, but we believe that mass adoption of low-emission vehicles and much greater benefits in reduced CO2 and other greenhouse gas emissions will be driven by the availability of more cost-effective hybrid architectures.”

Richard said that the flexible 14+X system could be adapted for integration with a wide variety of existing automotive platforms and applied to any new fuel technology, including flex fuel: “It will make time-to-market for new models incorporating it much shorter than more-radical hybrid approaches.”

Valeo and Maxwell Technologies’ MOU also covers terms of a proposed multi-year development and supply agreement through which Valeo will source ultracapacitors from Maxwell.

“This design win is the result of an extensive collaborative development effort, and it reflects the progress Maxwell has made in developing and manufacturing products that meet the very demanding performance requirements of the auto industry,” said David Schramm, Maxwell’s President and CEO.

Continental shows next-generation highly automated car

A highly autonomous driving vehicle needs a suite of advanced technologies and a ready-to-take-control driver.

“We’re using infrared driver analyzer cameras on our next-generation highly automated driving vehicle to collect data for the development of a ‘driver model.’ The driver model would tell us if the driver is attentive. And it would predict the driver’s reaction time to resume control of the vehicle,” said Ibro Muharemovic, head of Continental’s advanced engineering in North America.

Continental’s second-generation concept was featured during a media technology preview at the supplier’s Brimley, Michigan proving grounds late last month. Muharemovic began a two-lap driving demonstration with Automotive Engineering by accelerating the vehicle to a highway speed. He then engaged the full-speed-range adaptive cruise control and activated the highly automated driving mode. The specially equipped 2014MY Chrysler 300 responded by autonomously driving at 60 mph (97 km/h), slowing to 46 mph (74 km/h) to navigate smoothly through a banked turn, then resuming highway speed through a straightaway.

Since August 2014, test engineers in the U.S. have been taking turns in the driver’s seat of the next-generation demonstrator as two in-vehicle cameras recognize and track facial movements during drive time. The accumulated data will aid in the development of a robust computer driver model.

“At this point, I only have a very early version of the driver model that indicates attentiveness when the driver is looking forward and inattentiveness when the driver is looking to the side. As for reaction time, that is a big, big undertaking. This is why we need lots and lots of raw data,” said Muharemovic.

A light bar running the length of the dashboard at the windshield’s base provides the driver a visual reminder of the current driving mode. The technology debuted on Continental’s Driver Focus Vehicle (see http://articles.sae.org/11842).

Driver assistance and full-speed adaptive cruise control engagement is indicated by a green light bar. When the light bar is blue, the vehicle is in the highly automated mode. An orange color indicates a stand-by mode, which means the driver is actively steering. “It’s important to have a straightforward, always visible way of knowing what driving mode the car is in,” Muharemovic said.

To facilitate a more human-like autonomous driving style, high-definition digital map information is being employed on the second-generation demonstrator.

“The HD map is a highly accurate representation of the road environment. It provides us with precise information, such as how many lanes there are, the exact curvatures of those lanes, and the exact location of roadway exits,” said Muharemovic, “HD map information helps us localize the vehicle on the road environment.”

Continental’s demonstrator is fitted with an array of sensing technologies.

Next-generation long-range radar looks forward 250 m (820 ft) with a 120-degree opening. That is double the field of view in the near range and an additional 50 m (165 ft) in the complete range compared to the third-generation technology used on the first-generation demonstrator. Four short-range radars look to the sides at 90 m (295 ft) with a 120-degree opening. The second-generation vehicle demonstrator also has a 360-degree surround view camera system, a feature the first-generation vehicle concept did not have.

The next-generation concept uses a windshield-mounted, forward-facing stereo camera for lane detection and to recognize pedestrians, traffic signs, oncoming high-beam headlights, and other objects.

Redundancies abound.

“The stereo camera has two lane recognition algorithms that were developed by two different teams. It was done that way so we can compare the outputs of each and get added redundancy in one sensor,” said Muharemovic.

There is redundant braking and steering in case something happens with the primary units. In addition to the actuation redundancies, there is redundancy with the power supply. “As an example, the front radar is on one power supply and the stereo camera is on another power supply and communication line,” said Muharemovic.

Continental has three highly autonomous demonstration vehicles in Auburn Hills, MI. First-generation technology was showcased on a Volkswagen Passat. Two Chrysler 300s are now part of the demonstration fleet, with one car being used as a development platform for sensor fusion/sensing architecture and the other car serving as a development platform for redundant braking and steering.

“We share development globally, so whenever my colleagues in Germany or Japan make an update to a sensor or a system or a function, we are able to bring it to this region and vice-versa,” said Muharemovic. “Our partner companies are also developing technologies and as those technologies become available, we’ll make the updates.”

Mazda reveals 2016 Global MX-5 Cup racer at SEMA Show

Based on the 2016 MX-5, the Global MX-5 Cup Car Concept shown at SEMA offers a glimpse of the car to be raced in a new Global Cup series, in North America, Europe, and Asia. Mazda is developing the racecar to be available as an affordable, turnkey, “ready-to-race” platform.

Starting in 2016, multiple Mazda Global MX-5 Cup series will take place around the world, all using identically prepared cars. Full details of the Global MX-5 Cup, including which countries will be involved and when the races will take place, will be announced as they are confirmed, Mazda says.

The Global MX-5 Cup will culminate at the end of 2016 with a Global Shootout at Mazda Raceway Laguna Seca in Monterey, CA, to crown the series champion. The winner will receive, among other prizes, a one-day test in Mazda’s Tudor United States SportsCar Championship SkyActiv prototype racecar.

“Because the MX-5 is inherently such a good car to drive, it is an ideal platform to learn basic and advanced race-craft, and this has made the professional MX-5 Cup series very successful to date,” said John Doonan, Director of Motorsports for Mazda North American operations.

The Global MX-5 Cup racecar will be equipped with a 2.0-L SkyActiv-G four-cylinder engine. Mazda Motorsports plans to undertake a development period this winter to select the optimum tires, suspension, powertrain, and safety modifications. Final specs will be announced in 2015, says Mazda, when it is ready to accept orders for the 2016 series.

Technical partners for the car also will be announced at a later date. The Global MX-5 Cup racecars will be sold “ready to race” from a single supplier—a first for Mazda.

For 2015, the third-generation MX-5 will be used for its final season of professional racing in North America. (For 2016 and beyond, existing MX-5 Cup racecars will be eligible to compete in club racing only, the company notes.)

The 2015 Battery Tender Mazda MX-5 Cup Presented by BFGoodrich Tires will kick off at Sebring in March, and conclude at the Petit Le Mans Powered by Mazda at Road Atlanta in October.

Renault applies model-based systems engineering to dual-clutch transmission

Car manufacturers are facing various and sometimes contradicting constraints such as energy efficiency, high performance, driving comfort, reliability, and safety. In a global context, they must also adapt driveline designs to different markets. Therefore, Renault must handle a variety of powertrain designs. Moreover, due to increasingly intelligent systems, mechanical and controls system design cycles are more and more linked. A common system mock-up is needed.

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Renault has implemented model-based systems engineering (MBSE) to manage these challenges as well as to reduce development cycle and costs. With MBSE, design and integration problems are solved earlier, the number of prototypes and test benches are reduced, and cross-team collaboration is improved. The MBSE approach allows Renault to evaluate, throughout the development phases, the key attributes of the complete vehicle including the engine, transmission, actuators, and chassis.

Renault recently extended its MBSE approach to include a new dual-clutch transmission (DCT) and controls strategies validation and optimization.

The DCT, developed by Getrag, is being integrated into C-segment vehicles such as the Renault Mégane or Scenic, and will be widely applied to other vehicle ranges. The new DCT includes seven gears. Wet clutches allow for increased torque capacity up to 300 N•m (221 lb•ft).

The DCT enables gear pre-engagement when another gear is already engaged and drives power. The gear shifting is limited to clutch switching, without significant engine torque reduction. It makes the whole gear change faster, smoother, and more comfortable than a standard automated manual transmission. The engine control unit just needs to manage a slight torque drop by controlling the fuel injection in diesel engines or spark advance in gasoline engines.

The internal DCT command relies on electrohydraulic actuation for clutches and electromechanical actuation for shifting gears. The electrified command decreases the gearbox’s global power consumption, and it is mandatory when gears are shifted without available engine power (for instance, stop-start applications).

To address different steps of the design V-cycle, Renault must carry out numerous analyses to integrate the gearbox with the various engines and chassis. To cope with multiple simulations addressing different levels of assumptions, Renault has opted for LMS Imagine.Lab Amesim software from Siemens PLM Software as the simulation platform for multi-domain modeling. Using LMS Amesim, various levels of models can be built depending on user constraints and needs: parameters availability, level of details and accuracy, fast simulation constraints, real-time capabilities, etc.

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For the DCT project, Renault has used two levels of models addressing the complete drivetrain:

• Level one model: actuators are assumed to be ideal (excepting delays). This model remains simple and accelerates simulations for controls development and validation. It can be used for real-time applications, such as hardware-in-the-loop or software-in-the-loop to help software development.

• More detailed model: mechanical actuators geometry (barrels, connected finger, etc.) is replicated in the model to accurately compute contact forces between components. Main lines and consumers are included within hydraulic circuits that are pressurized by electropumps for clutch actuation. The speed of electropumps is regulated by the control logic to control pressure on the clutch pistons. This model was built to perform deeper analysis related to transmission actuation control and design.

These models help engineers understand the power flows between all subsystems and components as well as some drivability aspects.

Two types of validation were performed to demonstrate the models’ capabilities and accuracy:

• Functional validation confirms very simple scenarios such as correct gear shifting and providing the right actuators responses to the requests.

• Experimental validation compares measurements and simulation results with various variables such as gearbox in-shaft speeds, side-shafts torques, vehicle longitudinal acceleration, engine speed or actuators positions.

Functional model validation is an important stage in the modeling workflow. This step makes sure that the system will have the right type of behavior and functionality. Then, model correlation with experimental data lets Renault check simulation capabilities.

System simulation is used at Renault throughout the V-cycle for different applications. At the beginning, system simulation is applied to select the best system architecture and evaluate how a solution helps answer customer requirements. Then, simulation is used to evaluate high-level controls laws as well as calibration of actuator regulations to estimate the influence of different controls calibration on the gear shifting quality.

For the DCT project, approximately 60 requirements have been translated into scenarios. Then, the scenarios were simulated to validate virtually that the system and its controls fulfill the requirements. This early evaluation enabled Renault to isolate, understand, and solve several minor bugs and logic design issues that could have become critical if identified later on. Moreover, prototype testing can be accelerated by applying simulation during the pre-validation stage of the controls logic.

In addition, MBSE helps engineers quickly evaluate new designs or controls logic improvements, for example, to reduce fuel consumption with a good balance between the NVH response and drivability.