Teaching your car to feel

Internal and external proximity sensor technology for cars

A study carried out by the Steinbeis Transfer Center for Automotive Engineering examined and evaluated the key sensory principles involved in monitoring car body openings. Cars are becoming increasingly complex, not just in the way they are made and work: drivers and passengers expect more comfort and safety. This means that “man and machine” will have to communicate with each other more often. One way to accomplish this is with proximity sensors.

The five senses allow us to see, hear, smell, taste, and feel. Sitting in your car, you probably don’t think about all the new perceptory functions cars have been gradually introducing. For example, cars now use ultrasonic sensors to “see” the best way to maneuver into a parking spot. Crash sensors “hear” impacts. Air conditioning systems can “smell” harmful fumes outside the car and regulate fresh air. An increasing number of car makers are now looking at proximity sensors and contact sensors. Components are being developed that can sense a person or a part of their body approaching and detect even the slightest touch. They do this by generating physical parameters and converting them into electronic signals that are translated into actions by a control device.

The aim of the study into proximity sensors was not to look at things happening away from the car with video and radar technology. Instead it was all about looking at things in close-up: car body surfaces, inside the cockpit – movements only inches away from the car’s “skin”. The reason it’s important to monitor movements just outside the car, or in openings – places where automatic electronic motors open and close doors or any type of “shutter” – is that people should not get hurt. Inside the car the priorities are easeofuse and ergonomics – making it easier to select or set comfort and safety features. In principle there are two key aspects to sensor technology inside and outside the car: tactile and non-tactile perception.

Tactile perception outside the car is central to anti-trap protection (ATP) on automatic windows and sunroofs. The standard (indirect) approach until now has been to work out what is happening to the current or speed of the electronic motor. This keeps international safety regulators happy, but there is still plenty of room for improvement as the static and dynamic properties of car bodies have a major influence on actuation power and malfunctions.

The more direct approach involves detecting trapped parts electronically with a contact strip inside rubber liners. The advantage is that the car can react to small movements much more quickly and reliably, but integrating the technology into linings and incorporating sensors in the right way is a complex process. Engineers are currently working on “seeing” intrusions using optical fibers built into a contact strip: when you touch the sensor it changes the electromagnetic properties.

There are a number of ways to monitor car openings with non-tactile sensors. In principle, to detect intrusions all you need is a video-based optical sensor. But installation and computation requirements make this approach costly; so automotive engineers are placing their bets on IR beams which can be used to monitor movements around folding roofs and sliding doors. Ultrasonic systems emit pulses and detect echoes before comparing movements with stored references, if necessary triggering a control device. Direct detection using capacitive sensors – examples of which we see in keyless access systems such as “Keyless Go” – are already in limited use in serial production. As somebody approaches, an electric field between two electrodes changes within the sensor system altering the capacity. To monitor complex 3D modules more development work is needed as measurements are easily influenced by environmental factors. Precisely because this approach is so dependent on environmental factors development is still in the early stages.

Modern car interiors are packed with more and more buttons and switches. They may make it easier to control comfort, safety, information, and mobility features but what drivers actually want is more simplicity: enhanced safety and intuitive controls. This is where the new generation of tactile and non-tactile sensors comes in. As well making things simpler, overall they present the passenger with a much more user-friendly driving environment.

To control adjustments to electronic vehicle fittings (such as seats and loading surfaces) using indirect detection, car systems monitor the electric motor and interrupt the movement when they sense a collision.

Some car manufacturers already have electric contact strips in serial production. These are used as an active tactile component to monitor sliding parts and although they can sense intrusions directly they are often expensive to fit. Optical switches which activate at the slightest touch and generate a signal without using electricity – and without wear – are still under development. In the future capacitive touch sensors or multidimensional touch pads will make controls more intuitive by linking operating panels, displays and functions. Many often complex turn/push controls will be enhanced or replaced.

Non-tactile sensors inside the cockpit can work in a number of ways. There are image sensors that are used in intrusion or theft warning devices, occupant detection systems that control safety and comfort features, and switches that activate after evaluating hand and body movements. Infrared and capacity sensors are already in use in serial applications for controlling cockpit illumination, offering a variety of new design options, programmable sensitivity, and zero wear and tear.

Even though tactile and non-tactile sensors inside and outside the car have some way to go, there is little doubt that they will work their way into overall vehicle sensor systems. As car bodies become more complex and more and more cars are fitted with motorized doors, folding shutters, and roofs, we will need higher standards of operating comfort and anti-trap protection around the vehicle. And this can only be achieved by merging proximity sensors that operate through several channels in three dimensions.

Because vehicles now incorporate so many features, car cockpits are continuing to fill up with controls. Probably one of the best ways to reduce the complexity of the dashboard is to introduce these new tactile sensors and especially non-tactile sensors as they will allow us to monitor features automatically and control settings intuitively just by moving our hands – or maybe even via wireless data transmission.

Proximity sensors have the potential to turn vehicles into intelligent beings that can feel, recognize and assess changes or instructions. This will bring benefits to car safety and comfort and, ultimately, major benefits to the passenger. It will also have a tremendous influence on the way drivers communicate with the car, so one thing engineers will need to think about is that this will take some getting used to and will demand a lot of understanding.

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