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Drive by wire relies on feedback

-August 30, 2013

With cars getting more "drivers assist" and "in-transit safety" systems, we are getting closer to full drive-by-wire (DBW) vehicles on the open road. While these simple enhancements, such as automated parallel parking, and adaptive cruise control, greatly improve the ownership experience, they impact the driver's experience.

One of the splits in the car buying community is between the use of the car as a simple transportation source from point A to point B, and those who want to have a driving experience. These automated control systems, while in the interest of driving safety, take away from the experience of operating the vehicle. For this reason, cars with something as simple as traction and stability control have an OFF switch for the function, so people can experience the full need to control the car.

It is becoming increasingly more difficult to install the OFF function, as the computers regulating the vehicle operation are expecting a certain amount of sensor input and are the only connections to certain drive operation systems. As these systems put more control in the automation, the driver is doing less and losing touch with the car. Following the line of video game driving games, the solution is to add active haptic feedback to the control systems to let the driver know they are doing something.

Haptics in the car are not new, however the expansion of place of use is new. One of the higher profile and successful uses of haptics is in the "touch feedback" of the BMW iDrive system for center console control (see figure below, courtesy of BMW). This system alerts the driver as to the position of the knob by differentiating the vibration of the knob. This allows for knowing what it is pointing at without requiring the driver to look.

Moving these ideas to driver's control is trickier. One of the places that the haptics are making an entrance is on the accelerator pedal. As the systems have moved away from a direct mechanical linkage between the gas pedal and the engine, getting the sense of pressure, power and force to the driver becomes more important. This is especially true in hybrid systems where the single pedal controls two different drive systems - the electrical one and the gas one.

In order to provide a consistency of feel to the driver, electronically created haptic resistive response feedback is being used to make sure the pedal has the same pressure, requires the same force and has the same road feel under both electric drive and traditional gas drive. A similar trend is happening with shifters for electronic transmission systems - there is a controlled force that varies with the gear change and there is not a direct mechanical connection between the handle/paddles and the gear box.

Turn signals, steering control, brake response, and even seat control are all being considered as areas that can benefit from this sort of feedback. The use of touch allows the driver to be able to assess situations and controls without taking their eyes off the road. They also increase driver awareness and level of alertness.

A challenge with the increasing autonomous driving capabilities of the car is that the driver becomes more of a passive passenger, and is less conscious of what the car is doing. While this adds to some levels of driver's safety, with an operator still in the vehicle there is a chance for an unplanned driver's movement of the car (i.e., a swerve or quick shift in direction). Unless the driver is wide awake, as in a traditional car, these vehicles are adding a threat in addition to safety. One plan is to use haptic feedback to help keep the operator awake and alert.

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