Touch and go - Design - BMW's iDrive system

Automotive Design & Production, June, 2002 by Kermit Whitfield

Automakers currently face the dilemma of how to give customers the increased in-car functionality they demand without creating a corresponding rise in driver distraction. One answer is to better utilize the sense of touch. BMW has done is with its controversial new iDrive system, but will other follow?

Whenever it debuts a new car, BMW usually receives plaudits, not brickbats. But when it recently unveiled its new flagship 7-Series it faced a chorus of criticism about certain aspects of the vehicle, ranging from the exterior styling to the instruction cards included for parking valets so they could learn the complex maneuver of, ah, parking it. But the area that was singled out for the most derision was the iDrive user interface that consolidates control over 700 functions in one large knob. Ironically, the iDrive system has drawn criticism for being too complicated though its chief premise is simplification.

Two major areas are placed under iDrive's control: a driving zone, which centers on functions like steering and shifting, and a comfort zone. The comfort zone includes the navigation system, the telephone book for the on-board phone, audio equipment settings, customized climate control, and more. To use iDrive, the driver (or passenger) manipulates a large silver knob (the "controller") located atop the center console in order to navigate and select functions displayed on a screen in the center of the instrument panel.

TOUCH CONTROL

Key to the functionality is tactile feedback, which is said to allow people to gather information through the sense of touch, while simultaneously allowing them to focus on other tasks-like keeping their eyes on the road. It provides complex sensations that let practiced users tunnel through multiple menus without looking at the display. For example, when scrolling down a phone list the knob will emit a tactile "bump" whenever a name is passed to give the operator a sense of speed and location.

To help develop the tactile feedback aspect of iDrive, BMW turned to Immersion Corp. (San Jose, CA), a small Silicon Valley company that previously worked primarily on enhancing the feel of gaming joysticks and computer mice. Immersion developed the software that assigns unique sensations through the control knob to corresponding images on the system's monitor. It also designed the control unit and oversaw prototype production. (Mass production is being handled by Alps Electric.)

Immersion uses some programming sleight of hand to achieve its effects, but the hardware is pretty straightforward. The compact unit is essentially made up of an off-the-shelf motor and actuators. A high-resolution position sensor determines the relative position of the knob, and drives the motor against the motion of the operator the exact amount necessary to create the desired force feedback sensation. The motor itself has a skewed rotor like those found in inkjet printers which eliminates the detent torque that would coarsen the feel.

The feedback system has the capability of creating a wide array of tactile sensations, but BMW and Immersion chose to stick to familiar ones, lest people be overwhelmed and-ultimately-turned off. So, adjusting the bass or treble with the iDrive control knob feels just like it does on a conventional sound system. And zooming in on a navigation map simulates the feel of the zoom function on a camera.

Although the number of things the iDrive can do is vast (some think too vast), during development a question being asked was how much was enough. "We don't think functions that are highly immediate or have a high frequency of use make sense to fold into a graphical or contact-sensitive user interface," says Steve Vassallo, senior director of mechanical engineering at Immersion. "If the kids are screaming and you need to turn the volume down quickly, you don't want to have to tunnel through a menu to get to that." Therefore, some functions like temperature, fan speed and audio volume maintain their dedicated controls on the instrument panel, but almost everything else is selected and adjusted via the iDrive knob.

DISTRACTION REDUCTION

One of the chief aims of iDrive--as well as a number of other systems with tactile feedback components that are beginning to emerge--is the reduction of driver distraction through the transfer of some informational load from the visual to the tactile. Immersion claims their system can shave tenths of a second off emergency response times by keeping a driver's eyes on the road. It also promises to reduce the overall amount of time needed to make adjustments. As Vassallo points out, "Touch is really the only bi-directional sense. That is, you can manipulate something and immediately feel the results of that manipulation. So you can close the loop that much faster."

Instrument panel design stands to benefit as well. The recent explosion of in-car functions has turned some automotive cockpits into a dog's breakfast of knobs and switches. But as the 7-Series cockpit illustrates, with a single knob controlling most functions, the number of single-purpose controls can be kept to a minimum.