Chassis Dynamics -- Overview (F01/F02): Overview BMW 7 series F01/F02

Operation and display

The driver can select the four main modes using the driving dynamics switch. These main modes are designated as follows

1. Comfort
2. Normal
3. Sport
4. Sport+

After the vehicle is started, the driving dynamics control is always in "Normal" mode. When the driving dynamics switch is moved to the "Sport" position, the driving dynamics control initially changes to "Sport" mode and then to "Sport+" mode if this button is pressed again. If the driver moves the driving dynamics switch to the "Comfort" position, the mode changes in the opposite direction, i. e. from "Sport" to "Normal" mode.

The DTC button provides the driver with two additional modes

1. Traction
2. DSC off

The "Traction" mode can be activated by briefly pressing the DTC button. This works irrespective of which driving dynamics control mode was previously active. "DSC off" is activated by holding the DTC button pressed for longer. The "Traction" and "DSC off" modes can be switched off by pressing the DTC button again. The driving dynamics control subsequently returns to "Normal" mode. If the driver instead presses one of the two rocker switches at the driving dynamics switch to deactivate the "Traction" or "DSC off" modes, the driving dynamics control subsequently enters "Sport" or "Comfort" mode (depending on which rocker switch is pressed).

Each time the driving dynamics switch or DTC button is pressed this immediately prompts a reaction in the instrument cluster display. The changeover to "Sport" mode is shown below.

Scheme 1

After some time, unless the driving dynamics switch is pressed, a more compact version of the display for the driving dynamics control appears.

Scheme 2

Scheme 3

The two modes "Traction" and "DSC off" present a special case in terms of their display requirements. In addition to the text entry, the yellow DSC indicator and warning lamps must be activated.

Scheme 4

Note. New symbols are now used for the yellow DSC indicator and warning lamp and the DTC button. The new DSC symbols used for the first time in the F01/F02 replace the symbols previously used.

Scheme 5

Two different symbols were formerly used for the two states "DTC mode" and "DSC off" and were displayed in the instrument cluster. Since the launch of the F01/F02, only one symbol has been used for both states.

The new symbols are being gradually introduced in all newly developed vehicles. The reason for this are changes to legislation that require automobile manufacturers to produce a uniform display format.

This legislation also specifies that the text message "off" must be displayed as soon as the DSC function is restricted, as is the case in the "Traction" and "Sport+" modes.

When the DTC button or the driving dynamics switch is pressed, an assistance window appears at the same time as the instrument cluster display in the Central Information Display. The name of the newly selected mode appears there together with an explanatory text.

In the "Sport" mode the driver also has the option of configuring this. Assisted by the controller, the driver can choose whether to apply the "Sport" mode to the drive systems, or the dynamic driving systems or both.

SPORT MODE CONFIGURATION

Scheme 6

DRIVE SYSTEM MODE

Design and principle of operation

The angle of a pivoting arm is converted to a voltage signal via the ride-height sensors. The greater the angle (with reference to a defined starting position), the greater the output voltage generated by a Hall sensor element.

Displays and Operation

Note. New symbols are now used for the yellow DSC indicator and warning lamp and the DTC button. The new DSC symbols used for the first time in the F01/F02 replace the symbols previously used.

General Information

Active Roll Stabilization was first fitted on the 7 Series predecessor, the E65/E66, and has been used in similar form since on the E6x and E7x models.

This section only describes the essential details and modifications of the ARS on the F01/F02.

As Vertical Dynamics Control (VDC) is fitted as standard on the F01/F02, the ARS optional extra (now also available in the US markets) is always offered as a combination.

In customer communications, ARS continues to be marketed under the name "Dynamic Drive" on the F01/F02.

The safety concept prevents malfunctioning of the system by monitoring signals and responds in a defined manner to faults caused by external problems on interfacing units or systems. System monitoring essentially comprises of the following monitoring functions

1. Monitoring of the power supply voltage
2. Monitoring of the electrical circuits for the valves and sensors within the system
3. Monitoring of FlexRay bus communication and checking signal plausibility
4. Monitoring hydraulic function when the vehicle is in motion and predrive test

If a fault is detected, a defined response is initiated according to the significance of the fault (function impairment). The VDM control unit records the fault in the fault memory and displays the response on the instrument cluster.

When driven vigorously or on an uneven road surface, a vehicle tends to respond with undesirable body movements. BMW first developed Vertical Dynamics Control for the E70 and was able to effectively reduce such body motion as a result.

VDC improves the following driver-perception related vehicle characteristics according to road surface conditions

1. Body-related ride comfort (primary ride comfort)
2. Roadwheel-related ride comfort (secondary ride comfort)
3. Dynamic handling (transitional response, agility) even with more comfortable suspension setting.

BMW is the first manufacturer to offer a damper adjustment system that is continuously controllable independently of damper compression/extension as is the case with the VDC (2) on the F01/F02.

The essential improvements compared with VDC (1) are

1. 1 EDC control valve for damper extension control
2. 1 EDC control valve for damper compression control
3. "Pre-opening adjustment" for improved body stabilization (has adjustment effect even at low damper rates)
4. Driver-perceptible broad spread in conjunction with the handling setting switch (difference between soft and hard characteristics)
5. Separately adjustable characteristic for roadwheel-related ride comfort (extension characteristic independent of compression characteristic)

Scheme 7

INDEX REFERENCE CHART

VDC DAMPER REFERENCE CHART

In the F01/F02, Dynamic Cruise Control is no longer operated by means of an operating lever. Instead, the driver can operate the function conveniently using a button pad on the multifunction steering wheel.

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INDEX REFERENCE CHART

To prevent accidental activation, the function remains inoperable until the I/0 button has been pressed after the vehicle has started. This switches the function to standby. This state is acknowledged in the instrument cluster by a green indicator light lighting up.

With the function in standby, the driver is now able to activate cruise control. To do this, the driver can press the SET button used to store the vehicle's current road speed as the set speed. An active state is indicated by a green indicator light in the circumference of the speedometer dial lighting up.

There is an alternative way to activate the function if a set speed has already been stored. This is indicated by an orange indicator light in the circumference of the speedometer dial. If the driver wants to use this speed value as the set speed, he simply has to press the RES button. Dynamic Cruise Control then accelerates or decelerates the vehicle to this speed value automatically.

While the function is active, the driver is able to increase or decrease the set speed at any time. There are two adjustment increments available. The rocker switch offers two different increments in either direction. First, the set speed is altered in increments of 1 km/h each time the rocker switch is pressed; second, it is altered in increments of 10 km/h.

Note. In the F01/F02, the adjustment range for the set speed is 30 km/h (18 mph) to 230 km/h (142mph).

If the rocker switch is pressed and held, the system will accelerate/decelerate the vehicle until the rocker switch is released. This is known as a "comfort dynamics" function as featured in the E9x and E6x LCI.

To deactivate the system, the driver can simply operate the brake pedal like before. Or, the driver can deactivate the system by pressing the I/0 button. The system is then returned to standby and keeps the set speed last used stored in its memory.

If the driver then presses the I/0 button once more, the system is completely switched off and the green indicator light in the instrument cluster goes out.

There follows a summary of the most important displays for Dynamic Cruise Control.

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INDEX REFERENCE CHART

In the event of particular operating states, the displays shown here are supplemented by information messages displayed below the speedometer. This is the case, for instance, if the driver attempts to activate the system even though not all the activation criteria have been fulfilled (e. g. speed less than 18 mph).

In the F01/F02, a difference in the way Dynamic Stability Control interacts with Dynamic Cruise Control has been introduced. This is explained by the following example: Using the "Dynamic Performance Control", the driver has selected a mode in which DSC is inactive (e. g. "Sport+" mode). If the driver now activates cruise control, DSC will be activated automatically. This is accompanied by an automatic changeover from "Dynamic Performance Control" to "Normal" mode. In previous vehicles, the driver was unable to activate cruise control without activating DSC manually first.

Scheme 10

The ACC Stop&Go function in the F01/F02 is largely identical to that in the E6x LCI.

ACC Stop&Go extends the operating range of the former ACC system to include low speeds down to a standstill. In other words, speed and distance from the vehicle in front are automatically controlled at those speeds as well.

ACC Stop&Go will automatically stop the car if necessary and then indicate to the driver as soon as it detects that it is possible to start moving again. To pull away again, the driver has to acknowledge this message. The pulling-away process is controlled fully automatically by ACC Stop&Go only if the duration of the standstill is very short.

Thus, ACC Stop&Go provides optimum assistance for the driver not only in moving traffic but also in traffic jams such as are more and more frequently encountered on highways. However, this system (in common with ACC) is not intended for use in urban areas for negotiating junctions or traffic lights.

The functions of ACC Stop&Go in the F01/F02 differ from those in the E6x LCI in the following areas

1. Operation and display
2. Behavior in response to driver's intention to get out.

ACC Stop&Go and DCC are activated/deactivated in a very similar way. The driver is able to activate ACC Stop&Go not only while the vehicle is in motion, but also when the vehicle is stationary, provided the system has detected another vehicle in front. To activate ACC Stop&Go at a standstill, the driver has to depress the brake pedal and press the SET or RES button at the same time. The activation conditions that applied to the E6x LCI similarly apply here

1. Brake pedal must not be depressed
2. Automatic transmission must be in Drive
3. Parking brake must not be activated
4. Radar sensors must be operational and not dirty
5. There must be no system fault present.

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INDEX REFERENCE CHART

If Dynamic Stability Control was inactive before, in the F01/F02 it is activated as soon as ACC Stop&Go is activated. At the same time, the "Dynamic Performance Control" automatically changes to "Normal" mode (same behavior as for DCC).

Similarly, ACC Stop&Go cannot be deactivated by means of the I/0 button while the vehicle is stationary unless the brake pedal is depressed at the same time.

Note. In the F01/F02, the adjustment range for the set speed is 30 km/h (18 mph) to 230 km/h (142mph).

By comparison with DCC, a vehicle with ACC Stop&Go has an MFL button pad that additionally features two buttons for making distance adjustments.

Each (short) button stroke to change the distance increases the desired distance used by ACC Stop&Go for its control process by one increment at a time. A total of four increments are available to the driver.

The most important display functions of ACC Stop&Go in the F01/F02 are illustrated below.

As with DCC, the display symbols for ACC Stop&Go are supplemented by messages displayed below the speedometer as and when necessary.

If the vehicle is equipped with the head-up display option, the ACC displays also appear there, provided the driver has configured them to do so.

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INDEX REFERENCE CHART