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Brains and brakes

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Head on: One of the volunteers uses the driving simulator wearing a cap of electrodes

Car brakes can have a mind of their own and stop the vehicle before an accident takes place, if a team of researchers from Germany have their way. They have found that if the brain waves of drivers are read and the information used to speed up braking, thousands of car crashes can be avoided. Globally, traffic accidents rank very high among the causes of death and are largely caused by human error.

The scientists successfully picked cues of intention to brake from the driver’s brain and right leg in order to automate the process of applying the brake. This, they showed, made the reaction time of drivers facing emergency situations drop by as much as 130 milliseconds than if they actually pressed the brake pedal. For a vehicle that is cruising at a speed of 100 kilometres an hour, this could reduce breaking distance by nearly four metres, said the scientists, led by Stefan Haufe of the Berlin Institute of Technology, in a paper that appeared in the Journal of Neural Engineering last week.

The researchers attempted to retrieve the driver’s intent to brake using two different sets of signals and compared the two. In the first, they tapped muscle tension in the lower leg by capturing what they call myoelectric (EMG) activity, by attaching electrodes to the right leg. This helped them detect leg motion before the leg actually moved to the brake pedal. In the second, the scientists used electroencephalography (EEG) — a technique that attaches electrodes to the scalp — to pick up cues sent out by the brain to apply the brake. When used together with modern driving assistance systems, which help take control of the vehicle in emergency situations, each of the techniques was found to reduce the reaction time as compared to manual braking. However, the mind-reading system that used EEG was found to be quicker than the EMG-based system.

The results were arrived at using 18 able-bodied volunteers of both sexes and a driving simulator that had conventional driving controls. The volunteers, who used the driving simulator one by one, were asked to follow a computer-controlled vehicle, travelling at a speed of 100 km/h, while staying within a 20-metre distance of the lead vehicle. In order to make the driving task both realistic and demanding, the scientists included winding roads and heavy oncoming traffic as features in the simulator.

Emergency-braking situations were created at random intervals by decreasing the speed of the vehicle in front, forcing the participants to press the brake pedal when they saw the flashing brake lights of the lead vehicle. At this point, the scientists gathered data using EEG and EMG. For comparison, the researchers also recorded information on the time each subject took to release the accelerator pedal and press the brake pedal, deceleration of both the vehicles and the distance between the two vehicles.

The researchers also used the initial EEG readings to determine which parts of the brain are more active in a braking scenario and accordingly tweaked the signal detection system so that it reduced the response time further. Comparing the two systems, the scientists said that they found brain tapping more useful. “The EEG signals would be of more help, since they can predict [the decision to brake] much earlier,” Haufe told KnowHow. He said they would soon test the system under real conditions. This is absolutely necessary as in the real world there is a much higher variability of possible situations.

However, to take the system to the market they would first have to develop suitable EEG sensors. “Current EEG sensors are uncomfortable as they require a lot of time to prepare and need to be filled with gel which has to be washed out later. There are already dry electrode systems which work without gel, microelectrodes which are barely noticeable, and wireless systems, but there is no system which would combine the advantages of all these approaches,” Haufe said.

Till then we will have to apply the brakes ourselves and pray for the best.

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