DRIVER ADVICE SYSTEM FOR A VEHICLE
Field of invention
The present invention relates to a driver advice system for a vehicle and to a method of
advising a driver on vehicle operation. Aspects of the invention relate to a system, to a
method and to a vehicle.
Background to the invention
It is known in vehicles to provide various different subsystems which can operate in different
configurations so as to suit different driving conditions. By way of example, automatic
transmissions can be controlled in a variety of modes (e.g. sport, manual, winter or
economy) in which changes between gear ratios and other subsystem control parameters
are modified so as to suit the conditions of the terrain or driving style of the driver, it is also
known to provide air suspensions with on-road and off-road modes. Stability control systems
can be operated at reduced activity so as to give the driver more direct control, and power
steering systems can be operated in different modes to provide a varying level of assistance
depending on driving conditions.
The Applicant has recognised previously that the high level of choice for drivers poses a
complicated and confusing scenario for an effective, safe and enjoyable driving experience.
Our granted US patent US 7,349,776 describes a vehicle control system in which the driver
can implement improved control over a broad range of driving conditions, and in particular
over a number of different terrains which may be encountered when driving off-road. In
response to a driver input command relating to the terrain, the vehicle control system is
selected to operate in one of a number of different driving modes. For each driving mode,
the various vehicle subsystems are operated in a manner appropriate to the corresponding
terrain.
It has now been recognised that further improvements to the vehicle control system would
provide a more effective and enjoyable driving experience for a range of driving styles and
driver abilities. It is therefore an object of the present invention to provide an improvement to
systems generally of the aforementioned type. Other aims and advantages of the invention
will become apparent from the following description, claims and drawings.

By way of background to the present invention, WO2009/066143 describes a presentation
device for a vehicle in which a recommended control state for a driver-selected mode of
travel is compared with a recommended control state for the actual mode of travel. If there is
a deviation between the recommended control state and the actual control state, the driver is
presented with a recommendation to change the control state. The method therefore
involves a comparison between a control state appropriate for a driver-defined mode of
travel and an actual control state in generating advice for the driver.
Summary of the invention
Aspects of the invention provide a system, a method and a vehicle as claimed in the
appended claims.
According to another aspect of the invention, there is provided a driver advice system for a
vehicle having at least one vehicle subsystem; the driver advice system comprising selection
means.for receiving at least one driving condition indicator for the vehicle and for selecting,
from a plurality of settings, a preferred setting for the at least one vehicle subsystem. The
preferred setting may be selected in response to the at least one driving condition indicator.
The driver advice system may further include an indication means for providing to the driver,
an indication of the preferred setting for at least one of the vehicle subsystems. In response
to receiving the indication of the preferred setting, the driver can then act on the advice to
select the preferred setting for the at least one vehicle subsystem.
In one embodiment, therefore, the driver advice system further includes means for receiving,
from the driver acting in response to the indication, an input indicative of the preferred
setting.
The system may further include control means responsive to the driver-input and being
arranged to select the preferred setting for the at least one vehicle subsystem.
The driver may be advised on the most appropriate setting for any one of the vehicle
subsystems, for example a transfer box system, a braking system, a steering system or an
accelerator system, or may be advised on two or more of the vehicle subsystems, depending
on the required level of sophistication of the vehicle.
Embodiments of the invention therefore provide a driver advice system that is operable in
response to one or more driving condition indicators to provide advisory instruction to the

driver regarding at least one vehicle setting. The at least one vehicle setting may include, for
example, a transfer box status and/or a ride height status. On receipt of the advice, the.
driver can then act to select the vehicle setting that has been determined to be the most
appropriate for the particular driving conditions.
The system may further comprise means for generating a signal from which the at least one
driving condition indicators is derived. For example, the means for generating may include
one or more of a vehicle detection system and a vehicle sensor system.
At least one of the driving condition indicators may be derived from a signal indicative of the
terrain in the immediate vicinity of the vehicle over which it is travelling (e.g. the terrain
immediately beneath the vehicle wheels). Alternatively, at least one of the driving condition
indicators/may be derived from a signal indicative of the terrain in the surrounding vicinity of
the vehicle over which it is about to travel. In another embodiment, at least one of the driving
condition indicators is derived from a signal indicative of a style of driving of the vehicle (e.g.
sport mode, economy mode).
For example, said means for generating may include one or more of a vehicle detection
systerry and a vehicle sensor system. The vehicle detection system may include one or more
of a camera system, a RADAR system and a LIDAR system. The vehicle sensor system
may include one or more of a wheel speed sensor, a temperature sensor, a pressure sensor,
a gyroscopic sensor for measuring yaw, roll or pitch of the vehicle, a vehicle speed sensor
an engine torque sensor, a longitudinal acceleration sensor, a steering angle sensor, a
steering wheel speed sensor, a gradient sensor, a lateral acceleration sensor, a brake pedal
position sensor, an acceleration pedal position sensor and longitudinal, lateral and/or vertical
motion sensors.
Importantly, in some embodiments of the invention, the driving condition indicators are
derived from a system or systems provided on the vehicle. This differs from the
aforementioned prior art system in which a user-defined input is used as the basis for the
comparison on which advice to the driver is provided.
In other embodiments of the invention, the driving condition indicators may correspond to the
status of a control system of the vehicle, which may be a status selected by the user of the
vehicle.

The driving condition indicators may include one or more of vehicle speed, road roughness,
distance travelled with road roughness, surface friction at the vehicle wheels, vehicle
gradient or attitude, engine torque of the vehicle engine and ambient temperature.
By way. of example, one of the vehicle subsystems may be a transfer box and wherein
settings for the transfer box from which the preferred setting is selected include high and low
range settings. In another example the vehicle subsystem may be a driving style mode
selector which enables selection between, for example, sport mode, standard mode or
economy mode. The settings for the driving style mode selector from which the preferred
setting is selected may therefore include at least one or more of sport mode, economy more
and standard mode.
The driver advice system may further include means for receiving a signal indicative of
vehicle speed; means for comparing the signal indicative of vehicle speed with a
predetermined threshold vehicle speed above which the low range setting is inappropriate;
and means for inhibiting the indication means in circumstances in which the preferred setting
is determined to be the low range setting and the vehicle speed exceeds the predetermined
threshold vehicle speed.
In another example, one of the vehicle subsystems may be an air suspension system and
wherein settings for the air suspension system from which the preferred setting is selected
include off-road, intermediate and on-road ride height settings. The driver advice system
may further include means for receiving a signal indicative of vehicle speed; means for
comparing the signal indicative of vehicle speed with a predetermined threshold vehicle
speed above which the off-road ride height setting is inappropriate; and means for inhibiting
the indication means in circumstances in which the preferred setting is determined to be the
off-road ride-height setting and the vehicle speed exceeds the predetermined threshold
vehicle speed.
In an embodiment, the selection means also receives a trailer-attached status signal, and
wherein the preferred setting for the or each of the vehicle subsystems is also determined in
response to the trailer-attached status signal.
The indication means may include a visual display device (device (e.g. LCD screen or head
up display) and/or an audio device and/or a kinaesthetic device, by which means information
relating to the preferred setting is relayed to the driver of the vehicle.

According to a further aspect of the invention, there is provided a vehicle control system for
at least one vehicle subsystem of a vehicle, the vehicle control system comprising the driver
advice system in accordance with a preceding aspect of the invention. The vehicle control
system may further include a subsystem controller for controlling at least one vehicle
subsystem in a plurality of subsystem control modes, each of which corresponds to one or
more different driving conditions for the vehicle, and evaluation means for evaluating at least
one of the driving condition indicators to determine the extent to which each of the
subsystem control modes is appropriate and for providing an output indicative of the
subsystem control mode that is most appropriate.
The vehicle control system may further comprise an automatic control means operable in an
automatic response mode to select a subsystem control mode in dependence on the output.
The evaluation means may preferably take the form of a software-implemented evaluation
means in the form of a processor located within a vehicle control unit of the vehicle control
system.
In one embodiment, the evaluation means is arranged to determine the probability that each
of the. subsystem control modes is appropriate and wherein the output provided by the
evaluation means is indicative of the subsystem control mode with the highest probability.
The or each vehicle subsystem that the driver is advised upon by the driver advice system
may, but need not, be the same as the or each of the vehicle subsystems which is selected
in the automatic response mode.
Each of the driving conditions to which each of the subsystem control modes corresponds is
representative of at least one terrain type, or of a style of driving of the vehicle (e.g. sport
mode, economy mode).
In an embodiment of this aspect of the invention, the driver advice system is further operable
in response to the output indicative of the subsystem control mode that is most appropriate
e.g. with the highest probability of being appropriate.
The vehicle control system may further include switching means for enabling switching
between the automatic response mode in which the automatic control means controls the
vehicle subsystems in dependence on the output automatically, and a manual response
mode in which the appropriate subsystem control mode is selected by the driver manually.

The driver advice system may be further operable to provide an indication to the driver to
switch to the automatic response mode if a subsystem control mode has been selected by
the driver in the manual response mode which is inconsistent with the subsystem control
mode selected in dependence on the output.
The at feast one vehicle subsystem may include one or more of: an engine management
system, a steering controller, a brakes controller, transmission controller and a suspension
controller.
According to a still further aspect of the invention, there is provided a method for advising a
driver of a vehicle comprising one or more vehicle subsystems, the method comprising:
receiving at least one driving condition indicator for the vehicle; selecting, from a plurality of
settings, a preferred setting for one or more of the vehicle subsystems in response to the at
least one driving condition indicator; and providing to the driver an indication of the preferred
setting for one or more of the vehicle subsystems.
According to yet another aspect of the invention, there is provided a vehicle having a driver
advice system of a preceding aspect of the invention.
Within the scope of this application it is envisaged that the various aspects, embodiments,
examples and alternatives, and in particular the features thereof, set out in the preceding
paragraphs, in the claims and/or in the following description and drawings, may be taken
independently or in any combination thereof. For example, features described in connection
with one embodiment are applicable to all embodiments, unless such features are
incompatible.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example only, with reference
to the accompanying figures in which:
Figure 1 is a block diagram to illustrate a vehicle control system including various vehicle
subsystems under the control of the vehicle control system; and
Figure 2 is a block diagram of human machine interface (HM1) elements forming part of the
vehicle control system in Figure 1 in more detail.

Detailed description of the invention
Figures 1 and 2 show a vehicle control unit (VCU) 10 for a vehicle intended to be suitable for
off-road use, that is for use on terrain other than regular tarmac road surfaces. The VCU 10
controls a plurality of vehicle subsystems 12 including, but not limited to, an engine
management system 12a, a transmission system 12b, a steering system 12c, a brakes
system 12d and a suspension system 12e. Although five subsystems are illustrated as being
under the control of the VCU 10, in practice a greater number of vehicle subsystems may be
included on the vehicle and may be under the control of the VCU 10. The VCU 10 includes a
subsystem control module 14 (ATCM), which provides control signals via line 13 to each of
the vehicle subsystems to control the subsystems in a manner appropriate to the driving
condition, such as the terrain, on which the vehicle is travelling (referred to as the terrain
condition). The subsystems 12 also communicate with the subsystems control module 14 via
signal line 13 to feedback information on subsystem status.
The VCU 10 receives a plurality of signals, represented generally at 16 and 17, which are
received from a plurality of vehicle sensors and are representative of a variety of different
parameters associated with vehicle motion and status. As described in further detail below,
the signals 16, 17 provide, or are used to calculate, a plurality of driving condition indicators
(also referred to as terrain indicators) which are indicative of the nature of the condition in
which the vehicle is travelling. One advantageous feature of the invention is that the VCU 10
determines the most appropriate control mode for the various subsystems on the basis of
the terrain indicators, and automatically controls the subsystems accordingly.
The sensors (not shown) on the vehicle include, but are not limited to, sensors which provide
continuous sensor outputs 16 to the VCU 10, including wheel speed sensors, an ambient
temperature sensor, an atmospheric pressure sensor, tyre pressure sensors, sensors, such
as gyroscopic sensors, for measuring yaw, roll and pitch of the vehicle, a vehicle speed
sensor, a longitudinal acceleration sensor, an engine torque sensor (or engine torque
estimator), a steering angle sensor, a steering wheel speed sensor, a gradient sensor (or
gradient estimator), a lateral acceleration sensor on the stability control system (SCS), a
brake pedal position sensor, an acceleration pedal position sensor and longitudinal, lateral,
vertical motion sensors.
In other embodiments, only a selection of the aforementioned sensors may be used.

The VCU 10 also receives a signal from the electronic power assisted steering unit (ePAS
unit) of the vehicle to indicate the steering force that is applied to the wheels (steering force
applied by the driver combined with steering force applied by the ePAS system).
The vehicle is also provided with a plurality of sensors which provide discrete sensor outputs
17 to the VCU 10, including a cruise control status signal (ON/OFF), a transfer box status
signal (whether the gear ratio is set to a HIGH range or a LOW range), a Hill Descent
Control (HDC) status signal (ON/OFF), a trailer connect status signal (ON/OFF), a signal to
indicate that the Stability Control System (SCS) has been activated (ON/OFF), a windscreen
wiper signal (ON/OFF), air suspension status (Raised/High, Normal, or Low), and a Dynamic
Stability Control (DSC) signal (ON/OFF).
The vehicle may also be provided with one or more detection systems (not shown in the
accompanying figures) in the form of a camera system, a RADAR system or a LIDAR
system. The camera system may, for example, include one or more camera sensors that
form a part of a parking aid system on the vehicle. Alternatively, the cameras may be
provided to give an indication of the nature of the terrain in the surrounding vicinity of the
vehicle, but not necessarily the terrain immediately beneath the vehicle wheels. Further
examples of the use of camera data in the present invention will be described in further
detail below.
The VCU 10 includes an evaluation means in the form of an estimator module 18 and a
calculation and selection means in the form of a selector module 20. Initially the continuous
outputs 16 from the sensors are provided to the estimator module 18 whereas the discrete
signals 17 are provided to the selector module 20.
The estimator module 18 comprises a plurality of estimator modules dedicated to specific
aspects of vehicle and vehicle sub-system behaviour. In the'example shown, these modules
comprise: wheel acceleration 18a; wheel inertia torque estimator 18b; vehicle longitudinal
force 18c; aerodynamic drag estimator 18d; wheel longitudinal force estimator 18e; wheel
slip detection 18f; lateral acceleration estimator 18g; vehicle yaw estimator 18h; wheel speed
variation and corrugation detection 18i; surface rolling resistance 18j; wheel longitudinal slip
or 'breakaway torque' 18k; surface friction or 'mu' plausibility check 181; lateral surface
friction or 'mu' estimation / rut detection 18m; steering force estimator 18n; and corrugation
detection estimation 18o.

Within a first stage of the estimator module 18, various ones of the sensor outputs 16 are
used to derive a number of terrain indicators. In a first stage of the estimator module 18, a
vehicle speed is derived from the wheel speed sensors, wheel acceleration is derived from
the wheel speed sensors, the longitudinal force on the wheels is derived from the vehicle
longitudinal acceleration sensor, and the torque at which wheel slip occurs (if wheel slip
occurs) is derived from the motion sensors to detect yaw, pitch and roll. Other calculations
performed within the first stage of the estimator module 18 include the wheel inertia torque
(the torque associated with accelerating or decelerating the rotating mass of the wheels),
"continuity of progress" (the assessment of whether the vehicle is starting and stopping, for
example as may be the case when the vehicle is travelling over rocky terrain), aerodynamic
drag, yaw, and lateral vehicle acceleration.
The estimator module 18 also includes a second stage in which the following terrain
indicators are calculated: surface rolling resistance (based on the wheel inertia torque, the
longitudinal force on the vehicle, aerodynamic drag, and the longitudinal force on the
wheels), the steering force on the steering wheel (based on the lateral acceleration and the
output from the steering wheel sensor), the wheel longitudinal slip (based on the longitudinal
force on the wheels, the wheel acceleration, SCS activity and a signal indicative of whether
wheel slip has occurred), lateral friction (calculated from the measured lateral acceleration
and the yaw versus the predicted lateral acceleration and yaw), and corrugation detection
(high frequency, low amplitude wheel height excitement indicative of a washboard type
surface).
The SCS activity signal is derived from several outputs from a Stability Control Systems
(SCS) ECU (not shown), which contains the DSC (Dynamic Stability Control) function, the
TC (Traction Control) function, ABS (anti-lock braking system) and HDC (hili descent control)
algorithms, indicating DSC activity, TC activity, ABS activity, brake interventions on
individual wheels, and engine torque reduction requests from the SCS ECU to the engine.
All these indicate a slip event has occurred and the SCS ECU has taken action to control it.
The estimator module 18 also uses the outputs from the wheel speed sensors to determine
a wheel speed variation and corrugation detection signal.
On the basis of the windscreen wiper signal (ON/OFF), the estimator module 18 also
calculates how long the windscreen wipers have been in an ON state (i.e. a rain duration
signal).

The VCU 10 also includes a road roughness module 24 for calculating the terrain
roughness/corrugation based on the air suspension sensors (the ride height sensors) and
the wheel accelerometers. A terrain indicator signal in the form of a roughness output signal
26 is output from the road roughness module 24. Additionally or alternatively, wheel
articulation data may be provided to the road roughness module 24 by appropriate sensing
means, such as suspension stroke transducers, such as continuously variable damping
(CVD) sensors.
The estimates for the wheel longitudinal slip and the lateral friction estimation are compared
with one another within the estimator module 18 as a plausibility check.
Calculations for wheel speed variation and corrugation output, the surface rolling resistance
estimation, the wheel longitudinal slip and the corrugation detection, together with the friction
plausibility check, are output from the estimator module 18 and provide terrain indicator
output signals 22, indicative of the nature of the terrain in which the vehicle is travelling, for
further processing within the VCU 10.
The terrain indicator signals 22 from the estimator module 18 are provided to the selector
module 20 for determining which of a plurality of vehicle subsystem control modes is most
appropriate based on the indicators of the type of terrain in which the vehicle is travelling.
The selector module 20 serves as an automatic special program selector (ASPS) and
comprises an automatic special program selector (ASPS) algorithm, or probability algorithm
20a. The most appropriate control mode is determined by analysing the probability that each
of the different control modes is appropriate on the basis of the terrain indicator signals 22,
26 from the estimator module 18 and the road roughness module 24.
The vehicle subsystems 12 may be controlled automatically (referred to as the "automatic
mode") in response to a control output signal 30 from the selector module 20 and without the
need for driver input. Alternatively, the vehicle subsystems 12 may be operated in response
to a manual driver input (referred to as "manual mode") via a Human Machine Interface
(HMl) module (not shown in Figure 1).
When-operating in the automatic mode, the selection of the most appropriate subsystem
control mode is achieved by means of a three phase process:

(1) for each type of control mode, a calculation is performed of the probability that the control
mode is suitable for the terrain over which the vehicle is travelling, based on the terrain
indicators;
(2) the integration of "positive differences" between the probability for the current control
mode^and the other control modes; and
(3) the program request to the control module 14 when the integration value exceeds a pre-
determined threshold or the current terrain control mode probability is zero.
The specific steps for phases (1), (2) and (3) will now be described in more detail.
In phase (1), the continuous terrain indicator signals in the form of the road surface
roughness output 26 and the outputs 22 from the estimator module 18 are provided to the
selector module 20. The selector module 20 also receives the discrete terrain indicators 17
directly from various sensors on the vehicle, including the transfer box status signal (whether
the gear ratio is set to a HIGH range or a LOW range), the DSC status signal, cruise control
status (whether the vehicle's cruise control system is ON or OFF), and trailer connect status
(whether or not a trailer is connected to the vehicle). Terrain indicator signals indicative of
ambient temperature and atmospheric pressure are also provided to the selector module 20.
The probability algorithm 20a for calculating the most suitable control mode for the vehicle
subsystems based on the discrete terrain indicator signals 17 received directly from the
sensors and the continuous terrain indicators 22, 26 calculated by the estimator module 18
and the road surface roughness module 24, respectively.
The control modes typically include a grass/gravel/snow control mode (GGS mode) that is
suitable for when the vehicle is travelling in grass, gravel or snow terrain, a mud/ruts control
mode (MR mode) which is suitable for when the vehicle is travelling in mud and/or rutted
terrain, a rock crawl/boulder mode (RB mode) which is suitable for when the vehicle is
travelling across rocky terrain such as a boulder field, a sand mode (Sand mode) which is
suitable for when the vehicle is travelling in sand terrain (or deep soft snow) and a special
programs OFF mode (SP OFF mode) which is a suitable compromise mode, or general
mode, for all terrain conditions and especially vehicle travel on motorways and regular
roadways.

The different terrain types are grouped according to the friction of the terrain and the
roughness of the terrain. For example, it is appropriate to: group grass, gravel and snow
together as terrains that provide a low friction and a relatively smooth surface, and it is
appropriate to group rock and boulder terrains together as they tend to be characterised by
relatively high friction and very high roughness.
For each subsystem control mode, the algorithm 20a within the selector module 20 performs
a probability calculation, based on the terrain indicators, to determine a probability that each
of the different control modes is appropriate. The selector module 20 includes a tuneable
data map which relates the continuous terrain indicators 22, 26 (e.g. vehicle speed, road
roughness, steering angle) to a probability that a particular control mode is appropriate. Each
probability value typically takes a value of between 0 and 1. So, for example, the vehicle
speed calculation may return a probability of 0.7 for the RB mode if the vehicle speed is
relatively slow, whereas if the vehicle speed is relatively high the probability for the RB mode
will be much lower (e.g. 0.2). This is because it is much less likely that a high vehicle speed
is indicative that the vehicle is travelling over a rock or boulder terrain.
In addition, for each subsystem control mode, each of the discrete terrain indicators 17 (e.g.
trailer connection status ON/OFF, cruise control status ON/OFF) is also used to calculate an
associated probability for each of the control modes, GGS, RB, Sand, MR or SP OFF. So,
for example, if cruise control is switched on by the driver of the vehicle, the probability that
the SP OFF mode is appropriate is relatively high, whereas the probability that the MR
control mode is appropriate will be lower.
For each of the different sub system control modes, a combined probability value, Pb, is
calculated based on the individual probabilities for that control mode, as described above, as
derived from each of the continuous or discrete terrain indicators 17, 22, 26. In the following
equation, for each control mode the individual probability as determined for each terrain
indicator is represented by a, b, c, d...n. The combined probability value, Pb, for each control
mode is then calculated as follows:
Pb = (a.b.c.d....n)/ ((a.b.c.d...n) + (1-a). (1-b). (1-c). (1-d)....(1-n))
Any number of individual probabilities may be input to the probability algorithm 20a and any
one probability value input to the probability algorithm may itself be the output of a
combinational probability function.

Once the combined probability value for each control mode has been calculated, the
subsystem control program corresponding to the control mode with the highest probability is
selected within the selector module 20 and an output signal 30 providing an indication of this
is provided to the subsystem control module 14. The benefit of using a combined probability
function based on multiple terrain indicators is that certain indicators may make a control
mode (e.g. GGS or MR) more or less likely when combined together, compared with basing
the selection on just a single terrain indicator alone.
A further control signal 31 from the selector module 20 is provided to a driver advice system
in the form of a driver tutoring (DT) or driver advice module 34, to initiate driver tutoring
routines, as described in further detail below. The driver advice module 34 is fed with data
from multiple vehicle sus-systems pertaining to the status and behaviour of the vehicle and
comprises a plurality of elements dedicated to key features for example: auto response 34a;
suspension ride height and/or pressure settings 34b; and transfer box ration setting 34c.
In phase (2), an integration process is implemented continually within the selector module
(20) to determine whether it is necessary to change from the current control mode to one of
the alternative control modes.
The first step of the integration process is to determine whether there is a positive difference
between the combined probability value for each of the alternative control modes compared
with the combined probability value for the current control mode.
By way of example, assume the current control mode is GGS with a combined probability
value of 0.5. If a combined probability value for the sand control mode is 0.7, a positive
difference is calculated between the two probabilities (i.e. a positive difference value of 0.2).
The positive difference value is integrated with respect to time. If the difference remains
positive and the integrated value reaches a predetermined change threshold (referred to as
the change threshold), or one of a plurality of predetermined change thresholds, the selector
module 20 determines that the current terrain control mode (for GGS) is to be updated to. a
new, alternative control mode (in this example, the sand control mode). A control output
signal 30 is then output from the selector module 20 to the subsystem control module 14 to
initiate the sand control mode for the vehicle subsystems.
In phase (3), the probability difference is monitored and if, at any point during the integration
process, the probability difference changes from a positive value to a negative value, the
integration process is cancelled and reset to zero. Similarly, if the integrated value for one of

the other alternative control modes (i.e. other than sand), reaches the predetermined change
threshold before the probability result for the sand control mode, the integration process for
the sand control mode is cancelled and reset to zero and the other alternative control mode,
with a higher probability difference, is selected.
If a high speed of response is required, one consequence may be that a high and frequent
number of control mode changes are implemented. In some circumstances, the high number
of changes may be inappropriate or excessive. The rate of change of the control mode is
affected by two elements of the calibration process: the combined probability values of each
of the control modes and the integrated positive difference threshold for change (the change
threshold). The problem of frequent control mode changes can be countered in one of two
ways. If the change threshold is set to a relatively large value, it will take longer for any one
control mode to switch to another. This strategy will have an affect on all control mode
selections. Alternatively, by ensuring there is only a small difference between the data map
probability values for the different control modes, for example by setting all values to be
close to 0.5, it will take longer for a change in the control mode to be implemented compared
with the situation where there is a large difference. If desired, this strategy can be used to
affect the speed of response in relation to only selected ones of the terrain indicators and
control modes.
The probability difference between the current control mode and all other control modes is
monitored continually and the integrated value for each control mode is continually
compared with the predetermined change threshold. The predetermined change threshold is
calibrated offline, prior to vehicle running, and is stored in a memory of the selector module
20.
It is beneficial for the predetermined change threshold to be variable with the terrain indicator
for surface roughness. In this way the frequency with which the subsystem control mode is
changed can be altered, depending on the nature of the terrain roughness in which the
vehicle is travelling. For example, if the vehicle is travelling on-road (e.g. on a regular
smooth road surface), where the surface roughness is low, the change threshold is set to a
relatively high value so that it takes longer for the integrated difference value to reach the
threshold and so the control mode is changed less frequently. This avoids a control mode
change if, for example, a vehicle mounts a curb for a short period of time on an otherwise
straightforward journey on a regular road. Conversely, if the vehicle is travelling off-road,
where the surface roughness is high, the change threshold is set to a lower value so that the

control mode is changed more frequently to accommodate the genuine changes in terrain
that warrant an adjustment to the control mode.
In a preferred embodiment, one or more additional change thresholds may also be
implemented for comparison with the integrated difference value, each of which is based on
a different one of the terrain indicators. For example, another change threshold may be set
dependent on vehicle rolling resistance. In this case the integrated difference value is
compared with both thresholds (one for surface roughness and one for rolling resistance),
and when a first one of the thresholds is crossed a change to the control mode is initiated.
If it is determined that the combined probability of the current control mode becomes zero, a
control output signal 30 from the selector module 20 is sent to the control module 14 to
implement one of the other control modes corresponding to that with the highest combined
probability. Primarily, this mode of change will be implemented to handle discrete terrain
indicators which are indicative that it is no longer acceptable to remain in the current control
mode. For example, if the driver selects cruise control, the subsystem control module will
automatically set the probability for the MR mode and sand mode to zero. This is because
the GGS mode and the SP OFF mode are the only suitable modes for the vehicle
subsystems if the vehicle is in a cruise control mode. If the RB mode is selected at the time
the driver selects cruise control, the probability for the RB mode is immediately set to zero
and the subsystem controller immediately selects one of the other control modes with the
highest probability.
Other indicators that may be used to apply constraints to the number of control modes that
are "available" for selection include DSC ON/OF status (e.g. if the DSC status is turned OFF,
the automatic mode of operation is not available), trailer status and transfer box status
(HIGH/LOW range).
There are a number of circumstances in which the integration process will be paused and
the current integration value is stored in memory, rather than resetting to zero, as follows: (a)
when the vehicle is travelling in reverse; (b)fora predetermined distance travelling forwards
after a reverse motion; (c) when the vehicle is in park mode; (d) when the vehicle is travelling
below a certain speed; (e) when the vehicle is changing gear; (f) when the vehicle is braking
with zero.throttle being applied; and (g) when active braking is taking place. For example, for
option (b) above, the selector module 20 may be programmed so that, if it is determined that
the RB mode has the highest combined probability value, the integration process is started

as soon as the vehicle starts to move forwards after a reverse motion, rather than waiting for
a predetermined distance.
The subsystem control module 14 will now be described in further detail. The module 14
includes three functions; a validation, fault management and check function 14a, an
algorithm 14b to allow switching between automatic operation and manual operation (as
described in further detail below), and an interface algorithm 14c for the (HMl) module to
support the automatic response mode of operation. The HMl module 32 is shown in more
detail in Figure 2.
The subsystem control module 14 provides three output signals to the HMl module 32. A first
output signal 35 provides a notification to the HMl module 32 of whether the automatic mode
or the manual mode is active. If the automatic mode is active then a second output signal 36
is provided to notify the driver when the system is "optimising" and a change in the control
mode is taking place. A third output signal 37 is provided to the HMl module 32 for the
purpose of driver tutoring, as described further below.
Referring to Figure 2, the HMl module 32 provides an interface between the selector module
20 and the driver of the vehicle and includes a selector switch 32a, a messaging module 32b
and a High Level Display Function (HLDF) module 32c. In the example shown in Figure 2, .
the selector switch 32a includes a dedicated hardware switch 32aa and switchgear
comprising or arranged to support an existing vehicle system 32ab. The messaging module
32b comprises: display communication means 32ba, arranged to manage and generate
messages to an instrument pack display and communicate with other related vehicle sub-
systems; and a driver advice generator 32bb, arranged to provide appropriate messages to
the driver via the instrument pack display. The HLDF module 32c comprises modules for
driver information feedback 32ca and for supporting existing vehicle based HLDF systems
and functionality 32cb.
The HMl module 32 is arranged to allow the driver of the vehicle to override the automatic
mode and select the manual mode of operation, if preferred, via the selector switch 32a. The
HMl module 32 also provides advice to the driver regarding various vehicle configurations,
including the transfer box setting (HI or LO range), the air suspension off-road ride height
(Raised/High, Normal, or Low)' and a notification of when it is desirable to select the
automatic mode of operation. The HLDF module 32c includes a plurality of graphical
indicators (not shown) to indicate to the driver when there has been a change in the selected
subsystem control mode when the system is operating in the automatic response mode (i.e.

derived from the second output signal 36). Typically, for example, the HLDF module 32c
may display a textual indication to the driver along the lines of "CONTROL MODE
UPDATING".
On start-up of the vehicle, the control system is in the automatic mode and selector module
20 continually performs the probability analysis described above to deduce which of the
various control modes is most appropriate. The selector module 20 automatically adjusts the
control mode so that the mode which is most appropriate is used to control the vehicle
subsystems. At any time the driver can deliberately override the automatic mode by
switching the system into the manual mode via the selector switch 32a of the HMI module
32.
A further feature of the invention is that it includes the driver tutoring module, or driver advice
module 34, which serves to provide instruction to the driver regarding various vehicle
configurations or settings. The driver advice module 34 provides an interface between the
selector module 20 and the HMI module 32 and provides instruction or advice messages to
the driver relating to the air suspension setting (vehicle ride height) and the transfer box
setting (HIGH/LOW gearratio). The driver advice module 34 receives inputs from the air
suspension system (not shown) and from the transfer box (also not shown) to indicate
current status, and also receives the roughness output signal 26 from the road roughness
module 24. Other driving-condition indicators (not shown in the figures) may also be
provided to the module 34, for example the distance travelled at a particular road roughness,
vehicle speed, surface friction (using SCS slip event detection), vehicle gradient, engine
torque and ambient temperature. These indicators influence vehicle performance within the
external environment of the vehicle, and as such will be referred to as "external driving
condition.indicators".
A trailer-attached status signal (ON/OFF) may also be provided to the module 34.
In addition, the module receives the output signal 31 from the selector module 20 to indicate
which is the most appropriate one of the control system modes, based on the various terrain
indicators. The driver advice module 34 includes a means for storing pre-stored look-up
tables or data maps and for determining the most appropriate vehicle settings (referred to as
the preferred settings), from a plurality of suitable vehicle settings, depending on the various
external driving condition indicators it receives and, optionally, the trailer-attached status
signal. The appropriate vehicle settings are then provided via three outputs 50, 52, 54 to the
subsystem control module 14 and, from there, to the HMI module 32.

The outputs from the driver advice module 34 to the subsystem control module 14 include a
transfer.box setting signal 54, an air suspension setting signal 52 and an automatic mode
advice signal 50. In the sub-system control module 14 a validation check or fault detection
process 14a is carried out. The validation and fault detection process 14a operates so as to
ensure that if one of the subsystems cannot support a selected control mode, for example
because of a fault, appropriate action is taken (e.g. in the form of a warning). If validation is
completed successfully, an indication is provided to the HMI module 32, via output 36, of the
appropriate transfer box setting (high/low gear ratio) and the appropriate air suspension
setting (Raised, Normal, or Low ride height) based on the control mode that is determined to
be the most appropriate for current conditions and on the various indicators that the module
34 receives. The driver can then act, via the selector switchgear 32a, on the indication
provided by the HMI module 32 to adjust the ride height (High, Normal, or Low) and/or the
transfer box (HIGH/LOW) in accordance with the advice. It is a particular benefit of this
feature .of the invention that the driver is provided with prompt advice on optimal vehicle
settings which are determined oh the basis of indicators of the current terrain conditions.
The automatic mode advice signal 50 is also sent to the subsystem control module 14 so
that, if the system is operating in manual mode and it is determined that one or more of the
vehicle configurations for the ride height and the transfer box setting is inappropriate (as
discussed further below), an indication is provided to the driver via the HMI module 32 that it
would be advisable to select the' automatic mode of operation. On receiving this indication,
the driver can then, via the selector switchgear 32a, select the automatic mode of operation.
There now follows a series of examples of how the driver advice module 34 may operate.
Example 1
The driver advice module 34 advises the driver to select the transfer box low range setting if
the vehicle is continually driven on a rough road. This advice is referred to as "transfer box
low range for vehicle control". The advice is based on a function of the road roughness index
(as indicated by signal 26) and the distance travelled with that road roughness index. The
advice is inhibited if low range js already selected, low surface friction is detected, the
vehicle is above a predetermined threshold speed above which the low range setting is not
appropriate, the ambient temperature is below a threshold where low surface friction may
occur or a fault is set for any critical input to this component of the system. The rationale for
this operation is that on very rough tracks, or when overcoming large obstacles and terrain

features, it is easier to control vehicle speed when in low range to enable a steady, low
speed to be maintained without constant use of the brake pedal.
Example 2
The driver advice module 34 advises the driver to select the transfer box low range setting if
the vehicle is driven on an intermittently rough road. This advice is based on a function of
road roughness and distance travelled with the road roughness index. The advice is inhibited
if low range is already selected, the vehicle is above a predetermined threshold speed above
which low range is not appropriate, low surface friction is detected, the ambient temperature
is below a threshold where low surface friction may occur or a fault is set for any critical input
to this component of the system. The term "intermittent" in this context means that the road
roughness is not sustained for long enough to activate the "transfer box low range for vehicle
control" advice, as referred to previously in Example 1.The rationale for this operation is that
on intermittently rough tracks it is easier to control vehicle speed over the rougher sections
when in low range to enable a steady speed to be maintained, without constant use of the
brake pedal. These conditions are typical of rough farm tracks, for example.
Example 3
The driver advice module may operate to advise a transfer box low range setting to increase
the torque available at the wheels and so to protect against transmission abuse. This advise
is based on a function of engine torque and torque converter slip, signals for which are both
supplied to the module 34. The advice is inhibited if low range is already selected, the
vehicle is above a predetermined threshold speed above which the low range setting is
inappropriate, low surface friction is detected, the ambient temperature is below a threshold
where low surface friction may occur or a fault is set for any critical input to this component
of the system. The rationale for this operation is that when a vehicle is, for example, towing
another vehicle out of a ditch, ascending a steep slope, pulling a fallen tree out of the way,
pulling a high load for an extended period or a long steep ascent, more torque can be
provided by selecting a low range setting. Continuous periods of high engine torque and
torque converter slip cause oil temperatures to rise and potential transmission abuse may
occur, and selecting low range can protect the transmission against this.
Example 4

/The driver advice module 34 may operate to advise a transfer box low range setting when
the vehicle is on steep gradients. For example, the driver advice module 34 advises the
driver to select the transfer box low range to pull away on gradients that are too steep to
begin the ascent in high range. The advice is based on a function of the gradient when the
vehicle is at a standstill and uses alternate thresholds if a trailer is hitched and detected by
the vehicle (trailer status ON). The advice is inhibited if low range is already selected, the
vehicle is not at a standstill, low surface friction is detected, the ambient temperature is
below a threshold where low surface friction may occur or a fault is set for any critical input
to this component of the system. The rationale for this operation is that when insufficient
torque is available at the wheels to pull away on a gradient in high range, selecting low
range before pulling away again will give greater control.
Example 5
The drive advice module 34 may operate to advise the driver to select the air suspension off-
road ride height if the vehicle is driven on a continually rough road. The advice is based on a
function of road roughness index and distance travelled with that road roughness index. The
advice is inhibited if the air suspension is already at off-road ride height, the suspension is at
intermediate ride height, the vehicle is being driven at speeds outside the speed range for
off-road ride height selection (e.g. above a predetermined threshold speed above which off-
road ride height is inappropriate), the vehicle has a trailer attached (trailer status ON) or a
fault is.set for any critical input to the system. The rationale for this operation is that for very
rough tracks or when overcoming large obstacles and terrain features, increasing ground
clearance will protect against damage to the underside of the vehicle or grounding of the
vehicle. This mode of operation is therefore referred to as "off-road ride height for underside
protection" advice.
Example 6
The driver advice module may operate to advise the driver to select the air suspension off-
road ride height if the vehicle is driven on an intermittently rough road. The vehicle is
therefore provided with hardware to receive an input from the driver of the appropriate air
suspension setting, in response to the advice that the driver receives. The advice is based
on a function of road roughness index and distance travelled with that road roughness. The
advice is inhibited if the air suspension is already at off-road ride height, the suspension is at
intermediate ride height, the vehicle is being driven at speeds outside the speed range for
off-road ride height selection (e.g. above a predetermined threshold speed above which off-
road ride-height is inappropriate), the vehicle has a trailer detected (trailer status ON) or a

fault is set for any critical input to the system. The term "intermittent" in this context means
that the road roughness is not sustained for long enough to activate "off-road ride height for
underside protection" advice, as referred to above in Example 5. The rationale for this
operation is that on intermittently rough tracks increasing ground clearance will protect
against damage to the underside or grounding of the vehicle.
Example 7
The driver advice module 34 may operate to advise the driver to select transfer box high
range for the prevailing driving conditions. The vehicle is therefore provided with hardware to
receive an input from the driver of the appropriate transfer box range, in response to the
advice that the driver receives. The advice is based on a function of vehicle speed and time
and that vehicle speed. The advice is inhibited if the high range is already selected or a fault
is set for any critical input to the system. The rationale for this operation is that if transfer box
low range is selected and the vehicle is driven at speeds approaching the limit for low range
for an extended period, transmission abuse could occur. Also, there may be cases where the
driver has inadvertently selected low range, advice to select high range in this case reduces
the likelihood of driver irritation.
Example 8
The driver advice module 34 may operate to advise the driver to select the automatic control
mode if the vehicle is being driven on-road for an extended period of time in manually-
selected MR mode, GGS mode, Sand mode or RB mode. The advice is inhibited if Dynamic
Stability Control is off (DSC OFF), the vehicle has a trailer detected (trailer status ON) or a
fault is set for any critical input to the system. The rationale behind this is operation is that if
an inappropriate control mode has been selected by the driver, the vehicle performance is
not optimised for on-road performance. Advice to select the automatic control mode reduces
the likelihood of driver annoyance as the most appropriate control mode for the conditions
will then be selected for the driver automatically.
Example 9
In another embodiment of the invention the driver advice module may advise the driver to
select from a plurality of different driving style modes, such as standard mode, economy
mode (often referred to as. Eco mode) and sport mode, using a driving style mode selector
system. For example, if the driver has selected sport mode but it is determined from the

driving condition indicators that the vehicle has moved from a high speed, sporty
environment (e.g. motorway) to a low speed, economy style driving environment (e.g.
urban), the driver advice module will advise the driver that Eco mode should be selected by
the driving style mode selector system as the most appropriate driving style mode.
For each driving style mode that can be selected various ones of the vehicle subsystems will
have preferred settings, or a range settings, which are suitable for that particular driving
style. For example, in selecting Eco mode or sport mode (or any other driving style mode),
the vehicle subsystems which may be adjusted to a preferred setting (or range of settings)
include the gearbox, the part of the engine control system which includes throttle maps that
determine fuel delivery, and the part of the engine control system which includes calibration
maps.
Example 10
In another embodiment of the invention, if the vehicle is provided with a gearbox that has
high number of gear ratios (e.g. gears 1 to 10), the driver advice module advises the driver
to select from a selected group of the gear ratios only (e.g. the low gear ratios 1 to 4) in
response to the driving condition indicators.
Example 11
Other vehicle subsystems about which the driver may be advised of the preferred setting
include the vehicle braking system, the vehicle steering system or the vehicle accelerator.
For example, on the basis of the driving condition indicators, for example on a steep hill, a
signal may be provided to the driver regarding the preferred setting of the vehicle handbrake
of the braking system i.e. that the handbrake should be applied. Other settings provided to
the driver may be indicators that the angle of steer is too great for the terrain conditions, that
acceleration is too great for the terrain conditions, or that braking is too hard for the terrain
conditions. For example, the driver may be provided with an indication that the angle of steer
is too great for terrain conditions if it is determined that this is the case, and if the angle of
steer is determined to be appropriate for the terrain conditions then no indicator is provided
to the driver or an indicator is provided that the angle of steer is appropriate (e.g. by the
visual display of a light, or not).
Example 12

In another embodiment, driving condition indicators may be provided to the selector module
20 which are derived from another control system of the vehicle, for example to indicate the
status of the control system (e.g. ON or OFF). The status of the control system may have
been selected automatically by a vehicle system or may be a user-defined status. In
response to the status signal, a preferred setting (e.g. ON or OFF) is determined and the
output is provided to the driver advice module 34 to provide an advisory instruction to the
driver regarding the preferred setting. By way of example, a driving condition indicator may
be provided to the selector module regarding the status of the cruise control system of the
vehicle, and in response to which it may be determined that a particular subsystem control
mode is appropriate. The preferred setting for the subsystem control mode is then advised to
the driver.
Other examples
The HMI module 32 may also be provided with a further selector switch (not shown) which
may be operable by the driver to implement the advisory vehicle settings displayed or
otherwise conveyed via the driver advice module 34. For example, the further selector switch
may be a manually operable push-button switch which, when depressed by the driver,
initiates control signals to the vehicle subsystems which implement the advisory vehicle
settings.
It will be appreciated that the indications provided to the driver by the driver advice module
may be provided by means other than visual, for example by audio instruction if appropriate
audio hardware is incorporated into the vehicle. A head up display may also interface with
the driver advice module 34 to convey the driver advice.
The vehicle control system may, in other embodiments, take signals from one or more
camera or other detection systems provided on the vehicle to determine which of the
subsystem control modes is most appropriate. Use of camera or other detection systems in
this way provides a means of anticipating in advance a change in terrain or obstructions in
the vehicle pathway, for example, and enables the driver to be warned in advance about the
most appropriate subsystem control mode to be selected to traverse such conditions. It will
be appreciated that the driver need not be advised only on the local terrain in the immediate
vicinity of the vehicle (for example, immediately beneath the vehicle wheels), but may be
advised on the most appropriate control mode to navigate over the terrain in the surrounding
vicinity in the forthcoming vehicle pathway.

lt is a.particular benefit of the invention that inputs from the brake and accelerator pedal
sensors are provided to the estimator module 18 and are used as terrain indicators in the
probability calculations to determine the most appropriate control mode. An indication from
the pedal sensors that there is simultaneous use of the brake and the throttle pedal provides
an indication of the nature of the terrain over which the vehicle is travelling.
It is a further benefit of the invention that the signals output from the ePAS to indicate the
steering force applied to the wheels (steering force applied by the driver combined with
steering force applied by the ePAS system) are used to determine the most appropriate
control mode by inputting the steering force signal to the estimator module 18.
A still.further novel aspect of the invention is that the status of the windscreen or headlamp
wipers and the. duration for which they are operational is used as a terrain indicator for input
to the estimator module 18 and/or the selector module 20.
The wiper signal, the steering wheel force applied signal, and the pedal position signals are
all input to the VCU 10 so as to contribute to the determination of the most appropriate
control mode based on the combined probability calculation within the selector module 20.
It will be understood that the embodiments described above are given by way of example
only and are not intended to limit the invention, the scope of which is defined in the
appended claims. It will also be understood that the embodiments described may be used
individually or in combination.

We Claim:
1. A system for a vehicle having at least one vehicle subsystem (12a-12e), the system
comprising:
selection means (20) for receiving at least one driving condition indicator (17, 22, 26)
for the vehicle and for selecting, from a plurality of settings, a preferred setting for the at
least one vehicle subsystem (12a-12e) in response to the at least one driving condition
indicator (17, 22, 26); and
indication means for providing to the driver an indication of the preferred setting for at
least one of the vehicle subsystems.
2. A system as claimed in claim 1, further comprising means for receiving a driver input
indicative of the preferred setting.
3. A system as claimed in claim 2, further comprising control means responsive to the
driver input and being arranged to select the preferred setting for the at least one vehicle
subsystem.
4.. A system as claimed in any one of claims 1 to 3, further comprising means for
generating a signal from which the at least one driving condition indicator is derived.
5. . A system as claimed in claim 4, wherein said means for generating includes one or
more of a vehicle detection system and a vehicle sensor system.
6. A system as claimed in any one of claims 1 to 5, further comprising a detection
system, wherein at least one of the driving condition indicators is derived from a signal
indicative of the terrain in the immediate vicinity of the vehicle over which it is travelling.
7. A system as claimed in any one of claims 1 to 6, wherein at least one of the driving
condition indicators is derived from a signal indicative of the terrain in the surrounding vicinity
of the vehicle over which it is about to travel.
8. A vehicle control system as claimed in claim 6 or claim 7, wherein each of the driving
conditions to which each of the subsystem control modes corresponds is representative of at
least one terrain type.

9. A system as claimed in any one of claims 1 to 5, wherein at least one of the driving
condition indicators is derived from a signal indicative of a style of driving of the vehicle.
10. A system as claimed in any one of claims 1 to 9, wherein the at least one driving
condition indicator includes one or more of: vehicle speed, road roughness, distance
travelled with road roughness, surface friction at the vehicle wheels, vehicle gradient,
engine torque of the vehicle engine and ambient temperature.
11. A system as claimed in any one of claims 1 to 10, wherein one of the vehicle
subsystems (12a-12e) includes a transfer box and wherein settings for the transfer box from
which the preferred setting is selected include high and low range settings.
12. A system as claimed in claim 11, comprising:
means for receiving a signal indicative of vehicle speed;
means for comparing the signal indicative of vehicle speed with a predetermined
threshold vehicle speed above which the low range setting is inappropriate; and
means for inhibiting the indication means in circumstances in which the preferred
setting is determined to be the low range setting and the vehicle speed exceeds the
predetermined threshold vehicle speed.
13. A system as claimed in any one of claims 1 to 12, wherein one of the vehicle
subsystems (12a-12e) includes an air suspension system and wherein settings for the air
suspension system from which the preferred setting is selected include off-road,
intermediate and on-road ride height settings.
14. A system as claimed in claim 13, comprising:
means for receiving a signal indicative of vehicle speed;
means for comparing the signal indicative of vehicle speed with a predetermined
threshold vehicle speed above which the off-road ride height setting is inappropriate, and
means for inhibiting the indication means in circumstances in which the preferred
setting is determined to be the off-road ride-height setting and the vehicle speed exceeds the
predetermined threshold vehicle speed.
15. A system as claimed in any one of claims 1 to 14, wherein the selection means also
receives a trailer-attached status signal, and wherein the preferred setting for the or each of
the vehicle subsystems is also determined in response to the trailer-attached status signal.

16. A system as claimed in any one of claims 1 to 15, wherein the indication means
includes a visual display device and/or an audio device and/or a kinaesthetic device.
17. . A system as claimed in any one of claims 1 to 16, wherein one of the vehicle
subsystems (12a-12e) includes a driving style mode selector system and wherein the
settings for the driving style mode selector system from which the preferred setting is
selected include at least one or more of sport mode, economy more and standard mode.
18. A vehicle control system for at least one vehicle subsystem (12a-12e) of a vehicle,
the vehicle control system comprising the system as claimed in any one of claims 1 to 17,
and further comprising:
a subsystem controller (14) for controlling at least one vehicle subsystem in a
plurality of subsystem control modes, each of which corresponds to one or more different
driving conditions for the vehicle; and
. evaluation means (20) for evaluating at least one of the driving condition indicators to
determine.the extent to which each of the subsystem control modes is appropriate and for
providing.an output (31) indicative of the subsystem control mode which is most appropriate.
19. A vehicle control system as claimed in claim 18, wherein the evaluation means (20)
is arranged to determine the probability that each of the subsystem control modes is
appropriate and wherein the output (31) provided by the evaluation means is indicative of the
subsystem control mode with the highest probability.
20. A vehicle control system as claimed in claim 18 or claim 19, further comprising;
automatic control means operable in an automatic response mode to select a
subsystem control mode in dependence on the output.
21. . A vehicle control system as claimed in claim 20, wherein the system is operable in
response to the output (31) indicative of the subsystem control mode with the highest
probability of being appropriate.
22. A vehicle control system as claimed in claim 20 or claim 21, including switching
means for enabling switching between the automatic response mode in which the automatic
control means controls the vehicle subsystems in dependence on the output automatically,
and a manual response mode in which the appropriate subsystem control mode is selected
by the driver manually.

23. A vehicle control system as claimed in claim 22, wherein the system is operable to
provide an indication to the driver to switch to the automatic response mode if a subsystem
control mode has been selected by the driver in the manual response mode which is not
consistent with the subsystem control mode selected in dependence on the output.
24. A vehicle control system as claimed any one of claims 1 to 23, wherein the at least
one vehicle subsystem (12a-12e) includes one or more of: an engine management system,
a steering controller, a brakes controller, a transmission controller and a suspension
controller.
25. A method for advising a driver of a vehicle comprising one or more vehicle
subsystems, the method comprising:
receiving at least one driving condition indicator (17, 22,26) for the vehicle;
selecting, from a plurality of settings, a preferred setting for the or each vehicle
subsystem (12a-12e) in response to the at least one driving condition indicator; and
providing to the driver an indication of the preferred setting for at least one of the
vehicle: subsystems.
26. A method as claimed in claim 25, wherein the at least one driving condition indicator
is derived from a signal indicative of the terrain in the surrounding vicinity of the vehicle over.
which it is about to travel.
27. A rhethod as claimed in claim 25, wherein the at least one driving condition indicator
is derived from a signal indicative of the terrain in the immediate vicinity of the vehicle over
which it is travelling.
28. A system, a vehicle or a method constructed and/or arranged substantially as herein
described with reference to the accompanying figures.