The New BMW Idrive – Applied Processes and Methods to Assure High Usability

The New BMW iDrive – Applied Processes and Methods to Assure High Usability

Bernhard Niedermaier, Stephan Durach, Lutz Eckstein, and Andreas Keinath

BMW Group, Germany {Bernhard.Niedermaier,Stephan.Durach,Lutz.Eckstein, Andreas.Keinath}@bmw.de

Abstract. With iDrive the BMW Group introduced in 2001 a revolutionary HMI concept, which was firstly able to cope with the constantly increasing number of functions in the automobile. It was designed to optimally support drivers in their various tasks while driving. The basic iDrive concept can be described as separating driving functions from comfort functions as well as separating displays from controls. This basic concept together with a highly mounted display ensures that controls can be reached with no need looking at them and that the central display is easy and quick to access. The trendsetting iDrive idea has been widely adopted in the automotive industry. The following article outlines the iterative design and evaluation process that led to the new generation iDrive introduced in 2008 with the new BMW 7 Series. The basic challenge was to come up with an evolution of the iDrive concept by improving it without loosing the revolutionary approach to automotive HMI design.

Keywords: BMW, iDrive, HMI, automotive, usability.

1 Driver Orientation

One precondition for the design of such a new HMI is to know customer needs worldwide. This is especially true if the HMI is designed to incorporate the latest and upcoming technology without being technology driven. Hence, before starting the actual design process customer requirement clinics in the core markets have been set up and public available reports from numerous sources have been reviewed to understand current user needs and to extrapolate future trends. In cooperation with different universities a number of projects were started with a broad scope for defining new methods for evaluation and conceptual work. As a result of this research it was found that most HMI innovations are coming from consumer electronics industry, however, application to the automotive sector can not be done one to one. Designing a HMI for use while driving has to pay much more attention on installation, information presentation, interaction logic and system behaviour in order to ensure compatibility to the driving task, usability and attractiveness. Therefore, the main focus has to be on designing a driver orientated HMI that is the synapse between driver and vehicle: Driver Orientation means an intuitively understandable HMI, which is efficient in usage and widely accepted. It enables the driver to drive safely while using the vehicles functionality.

V.G. Duffy (Ed.): Digital Human Modeling, HCII 2009, LNCS 5620, pp. 443–452, 2009. © Springer-Verlag Berlin Heidelberg 2009 444 B. Niedermaier et al.

1.1 Competent Interaction through Perfect Ergonomics

An important prerequisite of a driver oriented HMI is an ergonomically perfect layout of the geometry of the driver's working place:

1.2 Optimal Reachability of Controls

All controls are positioned in a way that they can be reached from a comfortable seat- ing position. Therefore the CAD-based man-model RAMSIS has been used to define suitable locations. Fig. 1 shows the area the driver can reach without detaching the right shoulder from the seat. It is obvious that the driver orientated centre stack sig- nificantly improves the reachability of the outer controls for the driver.

Fig. 1. Driver orientation through optimal positioning of controls

1.3 Information Presentation

While controls are positioned primarily in the lower part of the dashboard displays are located basically in the upper part of the dashboard in an accommodation friendly distance relative to the eyes of the driver. Thus displays are very close to the driving- scene and the driver can pick up relevant information with very short glances (Fig. 2). The optional head-up display (HUD) ultimately presents all urgent and driving relevant information in the driver’s primary field of view with no need of refocusing the eyes. In addition to ergonomic installation and well structured information presentation the design of the interaction itself plays a decisive role in enabling the driver to com- petently and confidently interact with the vehicle’s functionality.

1.4 Intuitive and Efficient Interaction

All functions which can be operated need to be prioritized on the basis of typical uses- cases according to their relevance while driving. Important criteria are the frequency The New BMW iDrive – Applied Processes and Methods to Assure High Usability 445 of use and the relevance for driving and comfort. Functions with a high priority can be directly accessed by a hardkey. Medium or low priority functions can be operated menu-driven within the central information display. Controls and displays for high priority functions in the driving area are directly assigned to the driver. Comfort features are positioned in the middle of the vehicle and can be operated by driver and passenger (Fig. 2). The HMI concept should provide an intuitive and easy to learn operation for the driver at first contact. Therefore it is essential to minimize the number of interaction paradigms which the driver needs to understand across all vehicle functions. Regard- ing long-term use the interaction should be efficient and easy to memorize. Since the HMI concept is designed for a safe operation while driving secondary task interaction must be interruptible at anytime with no negative consequences for the driver. This criterion and other important criteria which were applied during the design of interaction can be found in the European Statement of Principles (ESoP) on HMI [1].

Fig. 2. Driver oriented positioning of display and controls

1.5 System Behaviour

In order to achieve high acceptance of the HMI concept, the driver needs to be given an immediate feedback on every control input. Functionality which may attract the driver’s attention like TV, DVD or games should be automatically disabled as soon as the vehicle starts to move. Again a description of the most important design principles is given in the ESoP [1].

1.6 Joy of Use

Beside these scientifically based criteria the interaction concept needs to be attractive. Joy of use is a necessary prerequisite for sheer driving pleasure. Therefore an appeal- ing graphical design as well as high-value and precise controls are indispensable. 446 B. Niedermaier et al.

2 The HMI Concept

2.1 Driving Area

Pressing the start/stop button is all that is required to start the vehicle. The key insert is omitted thanks to the convenience starting function. The instrument cluster is designed using black panel technology, and therefore reveals only the four round in- struments. The cruise control system is controlled on the left-hand side of the multifunctional steering wheel (Fig. 3). The visibility of the controls in combination with their clear labeling enables intuitive operation. In-line with operation, the correspond- ing feedback and displays are shown in the left half of the instrument cluster. The set speed is displayed along the speedometer scale with direct reference to the vehicle‘s current speed. The status displays for the Active Cruise Control system with stop & go function and the lane departure warning system are combined to form an easily understandable schematic portrayal of the current traffic situation. Via the controls on the right-hand steering wheel spoke, the driver can access basic entertainment and telephone functions. To achieve this, a list-based view of the current audio source or the redial list appears in the right area of the instrument cluster. The control for oper- ating the lists is a rotary pushbutton thumbwheel on the right-hand steering wheel spoke. The customer can additionally choose from a range of state-of-the-art driver assistance systems. According to their effect, the systems have been arranged in four groups in the cockpit. The controls for those driver assistance systems which support the driver in perceiving and interpreting the traffic situation are located beneath the central light switch: e.g. the lane change warning system, lane departure warning system, collision warning system, Night Vision with person recognition and the Head- Up Display. Functions which support the driver during parking and maneuvring can be activated in the immediate vicinity of the gear selector lever and the parking brake. The navigation system additionally provides the driver with innovative functions which inform him on the traffic situation ahead of the vehicle. The speed limit display shows the currently applicable speed limit. The Dynamic Drive Control system enables the vehicle‘s handling characteristics to be adjusted.

Fig. 3. Simple access to all information relevant to driving via the multifunctional steering wheel, the instrument cluster and the Head-Up Display

The New BMW iDrive – Applied Processes and Methods to Assure High Usability 447

2.2 Comfort Area

The functions in the comfort area are characterized by the fact that they facilitate direct operation – without any direct reference to the driving task. The controls are positioned in such a way that they make clear, spatial reference to the function and can be comfortably reached from the driving position. Examples of these include the seat adjustment facility on the seat, the window lifter actuators in the door or the slid- ing/tilting sunroof actuator in the roof lining. Further comfort functions such as the audio and air conditioning systems, central information display operation or the USB connection for MP3 players can be comfortably operated by both the driver and the front passenger (Fig. 4). They are therefore located in the center stack or in the area of the center console.

Fig. 4. Audio and air conditioning system controls with direct access

2.3 Screen Operation

Screen operation is also of central importance for the comfort area. The highresolu- tion display, which offers a resolution of 1280 x 480 pixel, enables brilliant and easily legible depiction of the screen contents. Three premises are vital for achieving real driver orientation: 1. Maximum compatibility between operation and visual depiction: The rotary control is depicted and integrated into the design of the screen‘s interface. The seman- tics of the visual representation enables the driver to recognize what interaction is possible at all times. 2. Extremely simple orientation in the system: From the very beginning, the system behaves comprehensibly and enables rapid orientation with short operation routes and transparent menu structures. 3. Attractiveness thanks to an efficient, customer-oriented design: An attractive screen design and high-quality graphics are important prerequisites for a high level of acceptance. However, an attractive system is only created by combining visual quality with individual options for variably configuring the screen‘s subdivision and contents. The screen operation system developed under these premises is characterized by the following features: • Control-element: The design of the controller follows the principle of the previous iDrive controller and extends it with direct selection buttons for the radio, CD/ multimedia, 448 B. Niedermaier et al.

telephone and navigation function areas (Fig. 5). In analogy to an Internet browser, the BACK button enables the driver to walk back along the history of interaction through the menus as often as he wishes. Like a PC‘s right-hand mouse button, the OPTION button offers the driver the possibility to quickly access less frequently required functions. As before, the controller can also be rotated, pressed and, as a further development of the previous pushing movement, tilted.

Fig. 5. Controller with direct access buttons

• Interaction logic and screen layout. The controller´s degrees of freedom are indicated in the design of the menus (Fig. 6; Fig. 7). The central element in the menu design is the image of the controller, which visualizes the valid interaction possibilities. Different menu levels are presented and operated with the aid of the panel principle (Fig. 6). In this case, the branch-off overlaps over the previous panel in the form of a separate panel. Thanks to the panel‘s optical offset, the driver can recognize that he is accessing a lower functional area. By tilting the controller to the left, the driver can run through the entire menu hierarchy up to the main menu. A variable menu layout was developed to meet diverse customer requirements re- garding the desired display contents. To achieve this, the customer can select a split-screen view. The screen area available for operation is dynamically adapted. This creates a second display area for additional information (Fig. 7), which the driver can configure according to his individual requirements.

Fig. 6. Menu level visualization via overlapping panels The New BMW iDrive – Applied Processes and Methods to Assure High Usability 449

Fig. 7. Optimal use of the available screen area with the split-screen active or deactivated

3 Customer Integration in the Whole HMI Design Process

Competent interaction cannot be simply achieved at the drawing board. It is of particular importance to be aware of the real objectives that have to be achieved. To ensure are goal-oriented development customers have been involved already in the early phases of the development process. In the following this approach will be ex- plained.

er om st on u ati C gr nte Functions I HMI Use-Cases HMI Design Concept Requirements

er om ust ion C rat eg Int HMI Evaluation

Fig. 8. Iterative HMI design and evaluation process

As can be seen from Fig. 8, HMI design starts with a set of prerequisites, among which the first is the definition of the functionality. After a clear definition of all functions the next step is to define and prioritize the use-cases in which the functions are expected to be used. These use-cases have been verified and extended to future needs in customer focus groups. Another prerequisite before starting the actual design process is to structure all internal and external requirements. One important example of such requirements is the ESoP [1]. Before starting the actual design and evaluation process customer requirement clinics in the core markets have been set up and public available reports from numerous sources have been reviewed to understand current user needs and to extrapolate future trends. Further, in cooperation with different universities and research institutes a number of projects were started developing new methods for evaluation and carrying out conceptual work. With this necessary input the first iteration of the HMI design can start. The particular challenge is to align these project specific requirements and constraints with the general prerequisites for a driver oriented HMI described in the first part of this paper. The design and evaluation process for the new iDrive has been an iterative process (Fig. 8). Generally, all concept iterations have been evaluated according to usability

450 B. Niedermaier et al. and acceptance criteria as well as to their suitability for use while driving. Therefore, customers have played a central role in defining the necessary prerequisites and in the concept evaluation. .

er er er er tom n tom n tom n tom n us io us io us io us io C rat C rat C rat C rat eg eg eg eg Int Concept 1 Int Int Int Alternative 1 Concept 2 HMI Concept Concept 3 Alternative 2 Customer Clinic Customer Groups Focus Test incl. Usability Simulator Driving Groups Focus Test incl. Usability Simulator Driving Groups Focus Research Market Test incl. Usability Simulator Driving Concept 4

Fig. 9. Reducing variants of the HMI Concept by evaluation and validation using objective and subjective criteria

As Fig. 9 shows, the actual design and evaluation process started initially with four teams in competition. One of the teams was based in the United States (US) to iden- tify and accomplish specific user needs of the US market. Accompanied by ongoing usability-tests each team developed an individual interpretation of the new iDrive. Relying on the basic prerequisites a wide variety of initial iDrive concepts have emerged. Each team built an operational mock-up (Fig. 10) suitable to be connected to the BMW driving simulator. These four iDrive concepts have been evaluated with the involvement of a set of representative customers measuring subjective and objective usability and driver behaviour and performance parameters. It is important to note that customer evaluations have not only been static usability testings or acceptance measurements but also evaluating system use while driving together with driving behaviour and eye tracking data.

Fig. 10. Evaluation in the operational mockups with driving simulation The New BMW iDrive – Applied Processes and Methods to Assure High Usability 451

Based on the results of this competitive customer evaluation of four concept alternatives the best and most promising ideas and features of each concept have been reassembled into two new concept alternatives. Both of them have additionally been detailed within the strong constraints of the complete vehicle development process. The two concept alternatives were again built up in two operational mock-ups and evaluated using driving simulation with customers. The same methods, scenarios and use-cases were used as described above. As a result the two concept alternatives have been synthesized to one concept based on the results of the extensive customer evaluation and including a number of market specific solutions e.g. a Japanese speller. The resulting final concept has been specified in all details and implemented in a prototype vehicle and a final mock-up for ongoing evaluation and usability testing. Additionally a mobile driving simulator was designed capable of all features of the static BMW driving simulation but using three plasma screens displaying the frontal driving scenery instead of a projection. Finally the mock-up and the mobile driving simulation together with the prototype vehicle were used for a worldwide evaluation study in the most important markets. This study was set up to combine traditional methods of market research, investigating customer acceptance and attractiveness as well as formal usability testing with driving behaviour and performance measurement. After incorporating the results of this market study into the final iDrive concept, field testing was done using the prototype vehicle now fully equipped with data loggers and cameras for measuring glance data, interruptability, user behaviour and driving performance. These field tests were used to validate the driving simulator data and finally prove the suitability of the concept for use while driving. New evaluation methods developed with universities and institutes have also been incorporated, namely the occlusion technique [2] to quantify the interruptability of the concept alternatives. Other methods like the Peripheral Detection Task [4] or the Lane Change Task [3] have been developed and used to measure object and event detection in early phases of the ongoing design and evaluation process. The whole set of

Fig. 11. Test methods used in the validation process

452 B. Niedermaier et al. evaluation methods and settings used in the evaluation process from simple usability methods to more advanced methods ranging from field tests to methods incorporating a simulated or abstract driving task are shown in Fig. 11.

4 Conclusion

Developing a new iDrive generation means an evolution of a revolution. Hence, the customer has been the centre of an iterative design and evaluation process. Not only customer satisfaction was taken into account but also objective data on driver behaviour and driving performance reflecting the compatibility between iDrive interaction and the driving task. A wide variety of methods has been applied to ensure that the new iDrive generation is intuitively understood, efficient and accepted, and enables drivers from all relevant markets to drive safely and benefit from the vehicle‘s functionality. The new generation iDrive is designed to enhance and contribute to sheer driving pleasure.

References

1. European Commission, COMMISSION RECOMMENDATION on safe and efficient invehicle information and communication systems: Update of the European Statement of Princi- ples on Human Machine Interaction. Official Journal of the European Communities, Febru- ary 6 (2007) 2. ISO 16673: Road vehicles - Ergonomic aspects of transport information and control systems - Occlusion method to assess visual distraction due to the use of invehicle systems 3. ISO TC22/SC13/WG8 draft, Road vehicles - Ergonomic aspects of transport information and control systems (2008) 4. Jahn, G., Oehme, A., Krems, J.F., Gelau, C.: Peripheral detection as a workload measure in driving: Effects of traffic complexity and route guidance system use in a driving study. Transportation Research Part F 8, 255–275 (2005)