Electronic Design

Semi ICs Drive Auto Safety And Control Innovation

To meet safety and energy mandates, as well as add value to their cars, automakers rely on a vast array of semiconductor chips to create safer, more intelligent, and more efficient automobiles.

In the never-ending battle to add more end-user value, the focus among automotive component and car manufacturers has turned to improving safety and control for vehicles. Driver assistance, collision prediction and avoidance, lane-departure warning, and electronic stability control (ESC) are just some of the systems getting a lot of attention these days.

However, “value” isn’t the only driving force behind these technological pursuits. Government mandates are putting the hammer down on manufacturers. Many of these requirements involve “greener” cars with higher fuel efficiency and reduced harmful engine emissions.

Both automotive IC suppliers and tier 1 suppliers see potentially large markets in automotive safety and control. All sorts of active and passive safety systems are in the works. According to several industry research firms, there’s large market potential in automotive electronics for safety and control. In fact, sensors, actuators, microprocessors, memories, field-programmable gate arrays (FPGAs), microcontrollers (MCUs), and DSPs should see greater use in automotive safety and control systems. The trend is to increase the use of semiconductor ICs beyond control functions and into active and passive safety systems.

Increased use of real-time vision systems for advanced safety techniques has called for greater vision-processing capabilities. By installing cameras on cars and using high-performance image processors, auto manufacturers can implement systems for lane tracking, traffic-sign recognition, and parking assistance. When combined with radar, more robust obstacle detection becomes possible.

Devices with highly parallel architectures like NEC’s IMPCAR ASIC, with over 100 Goperations/s, allow for real-time, multiple image-processing applications within the same chip. Also, Analog Devices’ ADSP BF561 dual-core Blackfin processor allows parallel execution of instruction streams on multiple pieces of data, at a 600-MHz clock rate.

Microelectromechanical systems (MEMS) will see wide use in safety, fuel-economy, and convenience functions. “The need to consider the ‘system’ in MEMS is key to the success in introducing many sensor functionalities into vehicles,” says Roger Grace of Roger Grace Associates.

“This is clearly demonstrated by tire-pressure management systems (TPMSs), where an application-specific IC (ASIC) can provide many functions, including temperature compensation, control, battery management, and possibly even the transmit function to the display monitor in the vehicle cockpit,” Grace adds.

He also notes that a major obstacle for MEMS IC suppliers of devices for safety, control, fuel-economy, and convenience functions is to meet the enormous cost pressures imposed by car manufacturers and tier 1 suppliers, while delivering 100,000-mile, 10-year parts lifetime performance.

The challenge for auto makers is to add enhanced safety, comfort, and intelligence elements to their products while lowering costs. As cars take on more sensors and microcontrollers, the move is to implement “sensor fusion.” That involves integrating all of these ICs into central modules, which ultimately reduces complexity, lowers costs, and creates a safer driving experience.

Presently, many active and passive sensor and microcontroller ICs work independently of one another. “With sensor fusion, we’re trying to integrate things to reduce system complexity,” says Markus Staeblin, product marketing manager for automotive microcontrollers at Texas Instruments.

Marc Osajda, Freescale Semiconductor’s global automotive marketing manager, concurs with this trend. He also sees MEMS sensors enabling cost-effective and efficient ESC: “We see an emerging trend of sensor fusion that integrates passive and active systems for more intelligent vehicle control and a better understanding of a car’s environment. There are developments ongoing in sensor communications standardization to make all sensors compatible with an electronic control unit (ECU).”

Working with tier 1 supplier Continental, Freescale developed a custom MCU for ESC called SPACE (Superior Processor for Automatic Control in Electronic braking). The 32-bit electronicbraking system is said to be the industry’s first triple-core MCU design to integrate Freescale’s Power Architecture e200 cores with Continental’s fail-safe electronic braking system.

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A notable development in sensor fusion is the Combined Active and Passive Safety (CAPS) system from Bosch (Fig. 1). The modular system networks active and passive safety systems with assistance systems to reduce the risk of an accident and increase protection for a car’s occupant(s). Future versions will include integrated driver information systems.

One of the most advanced automotive roll-control systems, the Active Stabiliser Bar System (ASBS), was developed by tier 1 supplier Delphi. It delivers a better steering feel, improved vehicle dynamics, superior comfort, and greater tuning capability compared with existing approaches, according to Delphi.

Microcontrollers like the AMIS-30623 smart stepper-motor driver from AMI Semiconductor are also enhancing automotive safety by controlling movable headlamp motors. Adding vertical, horizontal, and advanced front-lighting motor control to automotive headlamps, which are traditionally in a fixed position, results in greater safety for a car’s occupants.

Vertical control helps the driver avoid the glare of an oncoming car’s headlight. When linked to a car’s suspension system, it allows the beams from headlamps to maintain correct positioning for different loads and road conditions. Horizontal control provides improved lighting by illuminating the appropriate part of road curves. With advanced front lighting, the headlight beam can be controlled based on the car’s steering and suspension dynamics, as well as ambient weather and visibility conditions, car speed, and road curvature and contour.

LOWERING THE COST OF RADAR CHIPS
Radar chips are critical elements for collision detection, collision avoidance, and lane-departure warning systems. The high cost of these IC chips, generally made on a gallium-arsenide (GaAs) process, does create a bit of an obstacle, though. As a result, some semiconductor companies are beginning to experiment with silicon CMOS and silicon germanium (SiGe).

Strategy Analytics sees SiGe and CMOS displacing GaAs for automotive radar. It predicts that while GaAs technology will still be dominant over the next few years, all major tier 1 automotivesystems companies will move to silicon technologies, and silicon will ultimately take over the market starting from 2013 onward.

Delphi uses an ACC3 76-GHz forward-warning radar sensor module for collision detection and warning (Fig. 2). The mechanically scanned unit has a 150-nm range, a 15° field of view, and a 100-ms update rate.

The effectiveness of crash-warning systems, which generally use radar, was tested with a laser-based system developed last year at the U.S. National Institute of Standards and Technology (NIST). The goal was to accelerate the development and commercialization of automotive safety systems. NIST used an independent measurement system consisting of cameras and microphones mounted in the cab of a truck. It can also be mounted in a car.

A leading provider of GaAs radar chips is U.K.-based e2V. Its 77-GHz chips are being used mostly by Bosch in Europe for adaptive cruise control and for adaptive control of the braking system (Fig. 3). “With the possibility of Delphi, we believe that we’re the only ones using a Gunn diode approach in our radar chips,” says Ian Duke, head of automotive electronics. “We hope to see adaptive cruise control as standard equipment on cars, not just as an option.”

The long-range radar chips from e2V are used in Bosch’s predictive systems, which consist of a radar sensor and an integrated ECU. Such a system recognizes critical situations in front of a car as well as the active safety system brake force. The brake system is preconditioned to provide drivers with the fastest response time.

If the driver fails to take action, a symbol flashes on the instrument panel, an acoustic signal is emitted, and a short brake “jolt” is provided—all within enough time to give the driver time to react. Even when a collision is unavoidable, automatic braking takes over to reduce the severity of an accident’s impact.

Last year, Infineon Technologies began sampling a range of 76- to 77-GHz SiGe ICs, dubbed the RASIC, that could bring long- and medium-range automotive radar to mid-size cars by the middle of 2010. Volume production is being planned for mid-2009. The first in the series is the RXN7740 integrated chip set, which includes an oscillator, a power amplifier, and four mixers for multiple antennas.

Infineon says its integrated solution will shrink the size of existing discrete-component-based radar systems to one-fourth of present sizes and will reduce system cost by more than 20%. The chip set was developed with the help of Germany’s Federal Ministry of Education and Research (BNBF) as part of the KOKON project. The project allows for temporary use in Europe of 24-GHz shortrange radar in combination with 76.5-GHz long-range radar until 2013. After that, 79-GHz short-range radar must be developed.

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Freescale Semiconductor is also examining SiGe radar chips. “We’re developing a 77-GHz SiGe technology for collision warning and avoidance, which we expect to have by no later than 2012. We’re also developing microcontrollers for this,” says Matthieu Reze, Freescale’s marketing manager for automotive products.

The European Union, under its Information and Communication Technologies (IST) 6th Framework Program, is working on a REPOSIT (relative positioning for collision avoidance systems) project. The objective is to demonstrate the feasibility of new technologies for collision-avoidance systems. These include the use of ultrasonics, lasers, video, and microwave radars. Short-range radar has demonstrated its effectiveness in a variety of applications. These include adaptive cruise control with stop and go functionality, collision avoidance and mitigation, blindspot monitoring, reverse and forward parking assistance, lanechange assistance, and rear-crash collision warning (Fig. 4).

Researchers at the University of Florida and the Semiconductor Research Corp. reported progress on an automotive radar system based on 130-nm CMOS technology. They suggest that a CMOS radar chip can be produced for about $10, making it an attractive option for automotive uses. A CMOS low-noise amplifier and a 50-GHz sine-wave generator that uses a phase-locked loop (PLL) for oscillator stability was already demonstrated.

Fujitsu Labs is developing a CMOS technology for millimeterwave radar. At this year’s IEEE International Solid State Circuits Conference (ISSCC), it reported on the first CMOS-based power amplifier that operates at 77 GHz, with 8.5 dB of gain and 6.3 dBm of saturated output power. Another 60-GHz amplifier was developed with 8.3 dB of gain and 10.6 dBm of saturated output power.

TEAMING UP WITH VIDEO
Video is also being used with radar for advanced driver assist and safety systems. A leading proponent of this approach is U.K.- based Conekt, a consultancy arm of TRW Automotive. Originally known as the Lucas Research Centre, it began putting radar on cars in the 1960s. It developed vision-based systems for lane and obstacle detection in 1991 using transputers and DSPs.

In fact, in 1994, it demonstrated a vehicle on a public highway that could keep itself in the lane and follow the speed of traffic using radar and video without a driver’s hands and feet. Conekt produces both short-range 24-GHz and long-range 77-GHz systems for adaptive cruise control and lane-departure warning.

STMicroelectronics NV in Switzerland and Mobileeye NV in the Netherlands have sampled the second-generation system-on-a-chip (SoC) for automotive vision-based driver-assistance systems, the EyeQ2 chip.

It features real-time visual recognition and scene interpretation, pedestrian detection, lane-departure warning, adaptive headlight control, traffic-sign recognition, collision avoidance, and forward warning—all within one processor. A first-generation product, the EyeQ1, is in production on GM’s Cadillac and Buick models, as well as Volvo’s XC90, V70, S80, and XC70 and the BMW 5 series.

The EyeQ2 increases processing power sixfold over the EyeQ1. “The EyeQ2’s detection capabilities, even in harsh environments, allows for both notification and crash mitigation, increasing safety for road users dramatically,” says Marco Monti, STMicroelectronics’ vice president for the Automotive Product Group.

Vision is proving useful for a wide range of automotive applications, according to Kyocera. Using some six to 10 viewer and sensor cameras per car can provide a comprehensive range of safety, comfort, and control applications (Fig. 5).

Vision systems are also being used to provide drivers with a view of backing up and who’s behind them, how close they are, and how fast something is approaching, providing them with an additional level of safety and control. However, many of these vision systems, as well as systems based on ultrasonic sensors, require cutouts of the back bumper for their use. As an alternative, Visteon and 3M Corp. joined forces on a concept that eliminates the use of rearbumper cutouts by using capacitive sensors mounted behind the bumper.

The new system works by sensing the electrical capacitance in an area behind the bumper and then infers resistance from the capacitive output. By calculating the resistance, the backup system knows it’s approaching an object. Of course, this approach doesn’t allow drivers to see vehicles behind them and their driving manner, although it makes for safer and less expensive intelligent parking assistance.

KEEPING AN EYE ON THE DRIVER/
One way to increase driver safety with vision systems is to monitor driver behavior using in-car mounted cameras that operate on a 24/7 basis. That’s just what DriveCam Inc. offers. For $75 a month, its system monitors reckless driving by teenage drivers. The system uses a very sophisticated algorithm that monitors a three-axis accelerometer, along with a GPS signal and car speed data, to determine whether or not the risk of an event would make it valuable enough to a trainer to warrant uploading event data.

“We have a video buffer so we can see what the driver sees and what the driver does before, during, and after a triggered event. Our Risk Predict algorithm then screens the recorded events, so we just upload those that were, in fact, risky,” says Peter Ellegaard, DriveCam’s vice president of hardware and firmware engineering.

Ultimately, vision sensing combined with the proper algorithms can be tied into a vehicle’s adaptive cruise control and adaptive braking system to recognize traffic signs and signals. It can provide the driver with advanced warning signals (Fig. 6). This has been demonstrated by a number of tier 1 suppliers, including Siemens VDO (now Continental).

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