Sensing danger

They can check your tyre pressure, oil and fuel levels, temperature, speed, occupant weight, distance from other cars and objects out of view and even trigger devices to steer you away from trouble when the need arises. With as many as 50 sensors hidden in a mid-range car today, Matthew Beecham looks at some novel ways in which to package them.

Tyre pressure monitoring system

Thanks to last summer’s Firestone recall, tyre pressure sensor systems have become a big safety issue. So much so, that by late 2003, tyre pressure monitoring (TPM) systems will become mandatory. The 2000 Transportation Recall Enhancement, Accountability, and Documentation Act, signed into law in November 2000 by then-President Bill Clinton, requires the National Highway Traffic Safety Administration to modernise the 30-year-old tyre safety standard and to require tyre pressure monitors. Siemens Automotive says it is ready and waiting for the surge in demand for TPM systems. Jean Christophe Deniau, Siemens Automotive Business Development Engineer, says: “Unlike several other sensors under development in the market, our solution also tracks temperature inside the tyre and measures finite acceleration.” This allows, amongst other things, data specific to each tyre to be compared for inconsistencies within safety and operational parameters. The software for this technology can also form part of Siemens remote keyless entry electronic control unit. This enables its antenna and receiver to be used to process transmitted tyre pressure information, which is then sent across a vehicle bus to a driver display.

Figure 1: Siemens Automotive tyre pressure monitoring system

Protection during rollover

Another knock-on effect following the Firestone scandal was the increased attention on rollover accidents. In an effort to alleviate safety concerns about sport utility vehicles, in particular, some carmakers have taken the decision to install curtain airbags. Software engineers at all the major airbag producers are hard at work on the next generation of sensors to detect a rollover occurrence and activate the seatbelt pretensioners and long curtain airbags in a timely manner. Bosch, for example, has developed a new concept in rollover sensing which detects at an early stage when a vehicle is about to tip over. It is based around the data provided by a yaw rate sensor and two acceleration sensors integrated into the central airbag control unit. The yaw rate sensor uses the gyro principle to determine the speed at which the vehicle is rotating about its longitudinal axis; the acceleration sensors measure the horizontal and vertical acceleration of the vehicle. The principal algorithm evaluates the rate of rotation. The data from the acceleration sensors show the type of rollover to be expected and provide a ‘plausibility check’. Bosch says that even when the rotation rate algorithm detects an imminent rollover, the safety devices are not triggered unless released by a simultaneous positive plausibility check.

Figure 2: Bosch’s airbag control unit with integrated rollover function

Pre-crash tactics by the ‘sensitive car’

Boffins at Bosch are also developing radar and video-based systems for cars, claiming that these applications will be capable of assessing the position and motion of objects outside the vehicle and either send a warning to the driver or take automatic emergency action themselves. The German group’s so-called ‘sensitive car’ idea sprang from research showing that 60% of front-end crashes and a third of head-on collisions could be avoided if drivers could react only half a second faster. Bosch reckons that more powerful radar, coupled with video sensors, could in a few years’ time offer directional guidance at any speed, while an extra lane-holding system could soon make fully automatic driving feasible. But ultimately we can expect much more. Bosch sees a market for sensor technology and for supplying components for automatic emergency braking and automatic ”vehicle intervention’ systems for steering and engine management. Dr Martin Zechnall, President of the Semi-Conductors and Electronic Control Units Division of Bosch says: “In addition to video sensors and long-range radar, we are also working on pulling these sub-systems into a network. This vision will require a completely new overall system architecture and safety strategy. … Technical feasibility will not be the only factor determining when comfort and safety systems will be used. Conditions specified by legislators and the growing acceptance of drivers will also decide when these sensing systems will be made available.” Like it or not, the steady march towards developing a ‘sensitive car’ could mean that if you find yourself heading for a crash sometime in 2005, big brother Bosch will step in to help steer you out of trouble.

Figure 3 – Bosch’s vehicle surround sensing system

Figure 4: Bosch’s collision avoidance system

Sensing growth

Reversing into a tight parking space is never easy, especially if you’re manoeuvring in an MPV (multi-purpose vehicle, or people carrier). Slowly does it. But hit that car behind or an ‘invisible’ concrete cone and it could subsequently result in an expensive trip to the car repair shop. Demand for rear sensing technology is, therefore, rising fast. It is reckoned that around 10% of all new cars in western Europe will be fitted with rear sensing systems by 2005, up from 2% this year. In North America, OE fitment levels could blossom to around 12% by 2003, up from just 2% in 1999. Leading the fray are auto electronics giants Bosch, Siemens, Valeo and Delphi.

Figure 5: Siemens’ nearfield detection system

Tomorrow’s cars: Minimising whiplash injuries

Although rear-end collisions are rarely fatal, they are often painful. They
also account in Europe for more than 50% of all insurance claims for personal
injury sustained by car occupants. Damage to their neck arising from a sharp
backwards rotation of the head is known as the “whiplash effect”. In an effort
to minimise injuries, airbag producer Autoliv has developed an anti-whiplash
system specially designed for rear-seat occupants. The company’s new Self-Inflating
Head Restraint consists of a bag in the headrest which is filled with air. As
the following sequence of pictures shows, in a rear-end collision, the air is
pressed to a small bag in the headrest, which then will be moved forward up
to 50mm. This reduces the gap between the occupant’s head and the headrest.
The Swedish group claim their system does not need a sensor to be triggered
or a gas generator to inflate the bag. The system operates automatically with
the occupant triggering the system and inflating the headrest bag by pushing
into the foam of the seatback during the early phase of the rear-end collision.

self-inflating head restraint system


Auto bytes

  • Hey! Mom’s got eyes in the back of her head! In the first of a series of ‘family driven’ concepts, mirror producer Donnelly Corp recently launched its BabyVue system. A camera is mounted in the vehicle’s headliner linked up to a small flip-down screen attached to the interior mirror. For $499, you get one of Donnelly’s electrochromic (auto-dimming) mirrors thrown in.

Figure 9: Donnelly’s BabyVue

Screen folds up and out of the way when not in use

  • Will it really catch on? In 1909 Henry Ford offered his Model T with a windscreen
    as an option. Nice idea. Since then, the windscreen does far more than shield
    the wind while on the move. Like so many other parts of the car, environmental,
    design, safety, security and comfort factors are driving automotive glass
    technology. The major glass makers are working on rain-repellant glazing,
    plastic glazing and “smart” sunroof glazing. Laminated side glass is also
    a growth area, while heated front windscreens are commonplace. But we can
    expect far more from tomorrow’s windscreens. They’ll feature all sorts of
    technical wizardry, enabling drivers to connect with toll collection devices,
    global positioning systems and the internet..
  • What’s in a colour? According to research by vehicle paint producer PPG Industries, the most popular car colours in western Europe are the black-grey-silver segment, blue and red. In North America, green, white and red are most popular. PPG‘s researchers point out that green is peaking in North America, but not in Europe, where the popularity of silver-grey-black has shown a steady increase over the past three years. Japan’s leading vehicle colours are the black-grey-silver segment, white and blue. In South America, where varied and vivid colours are common for architecture and clothing, leading car colours are — conversely — in the silver-grey spectrum. PPG says that colour trends sometimes start on the highstreet, where people with limited disposable income express their individuality and creativity through clothing colours. Emerging colour trends move through clothing fashion, home furnishings and interiors before reaching the automotive industry.

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