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Comfortably alert
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01/05/2007
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What buyers want and what governments will allow are not always the same thing, and creating ideal conditions for the driver does not automatically satisfy the other passengers. Steve Snook looks at resolving the conflicts
Life would be simpler for vehicle designers and safety experts if all cars had one seat and they could devote all their efforts to ensuring the safety and comfort of the sole occupant. Most of us, however, prefer the option of at least one passenger seat, and many of us have no option but to put up with the four or more seats needed to take our families with us – even if we still do much of our mileage alone
This ‘compromise’ has a huge impact. Alone, we have control of the vehicle and our environment – temperature, airflow, listening choice and sound levels, interior lighting. With other occupants present the dynamic shifts; their presence, and their needs, can be both a stimulus and a distraction outside our control.
Conflict also arises because the OEMs continually want to add features in order to attract buyers who have decided they want them, whereas the safety lobby views all such additions as potentially dangerous.
Comfort itself is a multi-faceted topic. It is perceived, experienced and assessed with all the senses. This fact alone highlights the complexity behind the term. Although objectively measured variables can indicate the existence of typical aspects of comfort – good climate, balanced suspension or pleasant feel – none of these variables reflect subjective human perception. Developing comfort means bringing technical features into line with sensory perception, adapting technology so it offers people a positive experience.
Vehicle engineers must know how to avoid discomfort and how to achieve comfort for car occupants. They also need to know what appeals to car drivers on an emotional level, how they sense comfort and to what extent they perceive comfort consciously or expect comfort subconsciously.
In sports cars the driver is paramount and the passenger generally has to put up with the driver’s choices for climate control or entertainment. Fortunately, the interior space is small (at least when the roof is closed) and variations are small. In larger saloons, SUVs or MPVs, the needs of other occupants require greater consideration.
For the new C-Class, digital prototyping enabled Mercedes to check how the air conditioning system would perform. For example, engineers were able to verify whether all occupants always had warm feet when driving in winter. They subsequently developed two air conditioning systems. The Thermatic system is specified as standard, but the optional Thermotronic system allows three-zone climate control in the car interior – said to be a first in this vehicle category.
TIM, the German acronym for ‘thermophysiological occupant model’, is an instrument used by Mercedes to calculate and optimise climate comfort. It enabled the engineers to ascertain several features of the C-Class HVAC system at an early stage of development, such as the desired output, the number of ventilation outlets required and the size of outlet needed. TIM was also linked to other computer programs that divided the interior into around 7.8million spatial units and measured the airflow, temperature and other parameters at each of these points.
The TIM computer model simulates most of the human body in a total of 14 areas, taking into account blood circulation and heat generation. The result is a virtual but entirely representative car occupant who can be sent to all the climatic zones of the world by computer and supplies Mercedes engineers with a mass of data. These are intended to answer only one question: do the occupants feel comfortable?
In the finished C-Class system, sensors ensure that the ideal temperatures desired by the occupants are kept constant. Two sensors, in the overhead control panel and next to the electronic ignition lock, measure the interior temperature and provide the system with data so it can react more quickly to temperature fluctuations. Four more sensors monitor the temperature of the air flowing out of the ventilation outlets, enabling a continuous comparison between the desired and actual temperatures. A further sensor records the intensity and direction of the sun’s rays.
Many other comfort tests were run for the C-Class before any ready-to-drive prototypes had been produced. The Mercedes Ride Simulator, combining multibody simulations and state-of-the-art test rig technology, was programmed with data for real test-track surfaces and the necessary C-Class chassis and function data. A driver and a front passenger sat in the test rig’s two seats and proceeded to drive the new saloon – a purely digital but highly realistic exercise.
Dual-view screens are another development that can serve the needs of both driver and passenger without compromise. Alpine is one of several suppliers to have developed a dual-view screen to allow driver and front seat passenger to see an entirely different image on the car’s central display (European Automotive Design, October 2006). The technology allows the passenger to watch a DVD or game while the driver can only see the navigation. It prevents the driver from being distracted by moving images, substantially increasing safety, according to Alpine’s UK managing director Dave Sheen.
“Dual view allows designers to make the screen a more prominent feature of the in-car experience because it allows the front seat passenger to have full functionality while the driver is restricted to a safe level of vehicle information. I can see possibilities offering a gaming environment, for example, or in-car cinema, features previously only available in the rear.”
Utilising a parallax barrier, light from the backlight is divided into the individual viewing cones for passenger and driver. Alpine’s engineers have defined an optimum position from the screen 30 degrees from centreline as ideal for the eye point for each occupant. The technology is switchable, permitting the screen to display conventionally and allowing both occupants to see the same image when required. Alpine’s screen is featured in the Jaguar C-XF concept, which uses a 262,144 colour amorphous silicon TFT screen 17.7cm across, a size now typical in this segment of vehicle.
In general, creating ideal conditions for the drivers should be the priority, making them comfortable for long periods and yet keeping them alert enough to react immediately to any changes outside the vehicle. It can be frustrating for engineers and designers that new technologies introduced to reduce driver workload or improve their alertness are sometimes viewed in the first instance as doing the exact opposite and decreasing safety. Additionally, new functions are usually put under greater scrutiny than older established procedures that can be just as distracting. The use of mobile phones (with or without hands free capability) has been identified as a major issue, but eating, smoking, reaching for something across the seats or watching an accident scene as you drive past are at least as likely to lead to an accident, according to researchers at the Mayo Clinic in the US.
UK insurance company Privilege reports that almost half of UK drivers surveyed say they have lost concentration after being distracted by accessories. Afifth of motorists have been so distracted when fiddling with a cockpit instrument that they have veered out of lane; 5% have lost control of the vehicle, 3% have veered right off the road, and 3% have actually had an accident.
As a result, Privilege reports, almost 40% of drivers say they now avoid using any gadget that is not essential to the smooth running of their car. These drivers go further, and call for manufacturers to limit the growth of the car gadget culture.
But this still leaves a sizeable majority who do want the latest technology. And what is also unclear from the survey is whether the sceptics were using factory-fitted systems, bolt-on aftermarket products, or portable devices. Controlling an iPod using the vehicle’s existing controls and large central display seems less of a risk than trying to find tracks via menus on the device’s own screen.
A study carried out last year by TNO in The Netherlands concluded that using a navigation system could actually increase driver alertness and reduce driver stress. It also reported that using a navigation system improved driving behaviour and performance and reduced the workload when driving in an unfamiliar area and to an unfamiliar destination. A separate survey by TeleNav found that women drivers, in particular, get a sense of security and reassurance from their GPS system that reduces stress levels and should improve driving performance.
But while proponents argue that any new process the driver undertakes is no more distracting than a previous process, they can appear to be missing the point. Safety legislators are adamant that they will require the driver to become less distracted, rather than maintain the same potential distraction levels as before. And systems designed to help the driver can also cause unanticipated behaviour changes – driver passivity or reduced alertness – that could affect safety.
A US survey published last month suggests drivers who used to check their tyre pressures and re-inflate regularly are now happy to hand over the responsibility to the tyre pressure monitoring system, even though the warning threshold (typically a 25% pressure drop) may be considerably lower than the level that would previously have caused them to act.
A four-year study to evaluate how drivers balance their attention between the road and other activities has concluded that no single measurement tool used today adequately captures the effects of distraction – or workload – on driver performance. But the research highlights the need to correlate laboratory results with onroad, real-world data to truly assess how driving performance is affected by multi-tasking – another area where simulators are coming to the fore.
Competing demands
The Crash Avoidance Metrics Partnership – Driver Workload Metrics (CAMP-DWM) project involved Ford, General Motors, Nissan Technical Center North America and Toyota Technical Center USA with the US National Highway Traffic Safety Administration.
“Today’s drivers face competing demands for their attention,” says CAMP-DWM researcher Dr Linda S Angell, a GM technical fellow.
“We also know many drivers are increasingly technology-dependent. We want to help ensure that vehicle technologies are not distracting drivers from what should be their first priority: keeping their eyes and their minds on driving.”
At Central Michigan University, psychology professor Richard Backs is using brainwave patterns and heart activity to study drivers’ attention while behind the wheel. DaimlerChrysler has done similar work in Europe (EAD, October 2002). At CMU a series of psycho-physiological tests of driver responses are being conducted using a desktop driver simulator provided by GM.
“We are simulating how people use their attention while driving to better understand distractions such as navigation systems, cell phones and other portable wireless devices,” says Backs. “In normal situations our driving performance is not affected by these distractions. We may think we are driving safely, but physiological measures show how our attention is actually focused on these other devices. We hope to learn how to minimise distractions from these types of devices.”
A key focus of Backs’ research is on how driver attention changes as people age, focusing on adults aged 65 and older. He also plans to expand his research to focus on adults with attention deficit hyperactivity disorder and other diagnosed attention disorders, to learn how these affect their attention while driving and help to develop remediation strategies.
“Not only d we want to understand how we use our attention as we drive, we also want to develop programmes to educate people on how to better distribute their attention while driving,” says Backs.
Japanese researchers are also studying brain activity in an attempt to isolate the effects of music, and of different types of music, on driving performance and alertness. The work at Aichi University is at an early stage, but it seems that up-tempo music not only makes us drive more quickly but also improves our ‘steering stability’ at all speeds because we are less likely to become drowsy.
In practice, just how well onboard controls can be operated is being investigated by most OEMs using increasingly sophisticated simulators. DaimlerChrysler, for example, has developed a human-machine simulator in which a subject is required to carry out a specific task. During a normal drive in a car without critical situations, the driver is called upon to operate a certain system. The demands this places on the test subject’s attentiveness can then be evaluated on the basis of objective and subjective criteria.
In addition to recording deviation from the ideal travel path, a gaze monitor on the simulator records how often the driver diverts his or her attention to the operating system and thus away from the road. Where appropriate, manual input behaviour is also analysed. These parameters enable the engineers to calculate the extent of the driver’s distraction from the traffic.
This type of research is leading to real solutions. Dozing and lapses of concentration are responsible for around 25% of traffic accidents in Germany. In the USA, where highways can proceed in a straight line for many kilometres, exhaustion is considered the cause of 40% of accidents. Truck drivers are in particular jeopardy, because they often drive at night and are at the wheel for longer. Drivers who are not concentrating properly do not react to dangers quickly enough, or they react incorrectly.
Siemens Driver Attention System, introduced at the 2006 IAA commercial vehicles show, operates with an infrared camera that continually monitors the driver’s face. The system, due in 2009, will also be available for passenger cars. Because it records infrared wavelengths, the system works reliably day and night with the software evaluating the images in real time. It analyses the direction of sight and the number and duration of eye blinks. In the case of fatigued drivers, there is a significant increase in the number of slow blinks. If the software registers exhaustion, the system reacts step-by-step and warns the driver: First the seat vibrates. If the driver then continues driving, he or she will hear a chiming tone that becomes incrementally louder, urging them to take a break.
Psychological assistance
“We all want to make life easier for drivers,” says Gerhard Mauter, head of Audi’s haptics team. “The less they are distracted while operating the controls the better. Customers’ expectations also have to be taken into account when new control concepts are designed. Their expectations are the result of processes they have learnt, which therefore represent memorised action models. This is why psychological assistance is required for haptic evaluation. An operating process is a very complex matter and has to be analysed in detail.
“You can’t satisfy every customer, but you can maximise customer satisfaction. If we achieve 80%, that means we have a very good haptics concept. It is far from easy to achieve figures as high as that. It is difficult to express haptic qualities in figures and units because evaluation is very subjective. Our task is to make it objective and more generally applicable.”
As advanced driver assistance systems (ADAS) become more common in vehicles they can relieve drivers from tasks that may distract their attention from the traffic around them. However, even though such systems are now able to provide more functions than before, they will never be a complete substitute for the driver.
“An assistance system has to be supportive, not patronising,” says Klaus Kompass, director of integration driver assistance systems and active safety at BMW. “The driver should be able to switch it off if he wants to. The technology has to keep the driver on a ‘mean activation level’, preventing either fatigue or stress. The systems are only intended to play the role of a co-pilot.”
The interaction between vehicle and driver is at present quite functional – and physical – but future systems could be based more on monitoring and influencing the emotional state of the driver and making more use of physical data drawn from vehicle sensors to identify driver strain.
As driver behaviour becomes modified by the acceptance of new support technology, what happens if those systems fail? Every safety system has built-in back-up and this should never be an issue, but DLR, the German aerospace centre, has started to consider the unthinkable.
Working with other German institutes within the DESCAS programme, DLR researchers are developing a “safety-oriented development process” to design driver assistance systems more reliably, but also working out strategies in case – despite redundancy or alternative procedures – an active safety system fails.
“In aviation, components are sometimes installed in quadruplicate,” says DLR’s Jürgen Rataj. “If one fails, there are still three remaining. Nevertheless, high safety standards require the pilot to receive information and instructions in order to approach the next airport. In road traffic, the driver relies on his electronic support. If it collapses, the driver needs to be informed about it and he has to learn how to deal with the situation.
“For instance, ESP brakes all four wheels with a different intensity to avoid a pulling of the car. A brake assistant prevents a car from colliding with the car ahead. What happens if the system fails? If, for example, a laser supposed to detect other cars ahead stops working? Or if the electronics system collapses? Or if distance and velocity measured are not correctly interpreted?”
We must all hope the comfort/alertness balance will always keep us on our toes and ready to respond if our electronic co-pilot falls asleep at the wheel.
Conflicting pressures on the industry
Lewis Booth, executive vice president, Ford of Europe and Premier Automotive Group, spoke about some of the conflicting pressures affecting the auto industry at the New Powertrain Technologies Conference in Amsterdam in March.
“Over the past decade, the improvements in CO2 emissions from cars in Europe have largely come through improved engine technology. Since the 1970s the auto industry has invested billions to improve the environmental performance of our products. That level of spend is growing. ACEA estimates it to be around E20bn a year, or roughly 5% of the industry’s turnover in Europe. The largest proportion of our R&D spend at Ford is now on environmental matters. But as we continue to climb the mountain of CO2 reduction, so the slopes become steeper and steeper.
“The existing near-term target of 140g/km is very challenging. The Commission’s proposal for 130-120g/km represents a very difficult goal.
“As we’ve made improvements in vehicle technology, we’ve also been affected by other factors which are detrimental to CO2 performance. We’ve faced more stringent emissions regulations, a worsening of aerodynamic drag through legislated requirements, such as larger frontal area mirrors, and additional weight as our customers – who are becoming larger themselves – want larger vehicles.
“We do not exist in a command economy and it won’t be the EU, national governments or even OEMs that make the final decision. It will be our customers.
“We also must recognise that iconic solutions do not address the overall CO2 problem. A few expensive hybrid cars with limited customer uptake concentrated in a few metropolitan areas is, quite frankly, no answer.
“We need to continue to engage with governments to achieve harmonisation of standards. We also need policy-makers to focus on the outcome, not the technical solution and we need greater clarity from policy-makers on whether their real intention is to change consumer behaviour or to punish the consumer.”
Emotional responses
Emotions have a strong influence on motivation and behaviour, play a major role in decision making, and have been identified as a factor contributing to crashes.
Research findings suggest happy drivers are better drivers, although negative emotions do not necessarily impair driving behaviour. Being worried could, to a point, be a prerequisite to performing the driving task safely. To reduce driving speed, road traffic researchers from the Netherlands have taken the counterintuitive design approach of augmenting drivers’ confusion by suppressing traffic signs. The absence of guides such as line markings confuses drivers and forces them to cut their speed.
Future ADAS systems could be capable of recognising the level of risk and responding by activating technological cues that will generate emotional reactions. This is an approach radically different from the traditional design approach. Existing ADAS can issue an audible, visible or vibration warning to indicate danger. The design of such a warning system is currently focused on what, how, where and when such a cue should be issued, rather than what type of emotion should be evoked.
Andry Rakotonirainy of the Queensland Centre for Accident research and Road Safety in Australia has been studying emotional design under a French-Australian science technology programme: “Emotional design is still in its infancy, but technological interfaces that focus on multiple senses to induce uncomfortable feeling are appealing to improve road safety. Instead of intervening on the car automatically, we use an appropriately designed device to trigger some type of emotion that will in turn provoke physical reactions. The intended reaction would be a safe behaviour.
“For example, amplifying the inclination of the vehicle in curves could viscerally help the driver to reduce the speed. The amplification could be applied on the driver’s seat, or visually by tilting the windscreen through virtual reality means. Augmenting cabin vibration in order to decrease the ‘safe’ perception of the car could suggest a need to reduce travelling speed.”
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Author
Steve Snook
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