02-08-2014, 10:52 AM
An approach to Adaptive cruise control system
[attachment=66490]
Abstract
Speed control is one of the measure issues in
automobiles. With varying terrains the driver has to
frequently speedup and slow down the vehicle.
Manually doing this work is tedious and needs a lot of
concentration. Fuel efficiency introduces another
bottleneck. Cruise control system is a system that
automatically controls the speed of a vehicle, even in
varying terrain. The system takes over the throttle of
the car to maintain a steady speed as set by the driver.
In classical process control, the corresponding signal
would be a change in the throttle setting; this avoids
calibration and wears problems with sensors and
engine. One of the conventional cruise control
requirement is thus to specify control of the current
speed of the vehicle [1]. The proposed system ACC
“Adaptive Cruise Control” system is an improvement
over conventional cruise control system.(ACC)’
automatically adjusts vehicle speed to maintain a
driver-selected safe distance from the vehicle ahead in
the same lane. Keywords—cruise control, throttle,
Introduction
Speed control with a centrifugal
governor was used in automobiles as
early as the 1910s, notably by Peerless.
A centrifugal governor is a specific type
of governor that controls the speed of an
engine by regulating the amount of fuel
(or working fluid) admitted, so as to
maintain a near constant speed whatever
the load or fuel supply conditions. It uses
the principle of proportional control. The
governor adjusts the throttle position as
the speed of the engine changes with
different loads. Peerless advertised that
their system would "maintain speed
whether up hill or down".Modern cruise
control (also known as a Speedo stat)
was invented in 1945 by the blind
inventor and mechanical engineer Ralph
Teetor. His idea was born out of the
frustration of riding in a car driven by
his lawyer, who kept speeding up and
slowing down as he talked. The cruise
control system controls the speed of your
car the same way you do, by adjusting
the throttle position. But cruise control
actuates the throttle valve by a cable
connected to an actuator, instead of by
pressing a pedal. The throttle valve
controls the power and speed of the
engine by limiting how much air the
engine takes in. Many cars use actuators
powered by engine vacuum to open and
close the throttle. These systems use a
small, electronically controlled valve to
regulate the vacuum in a diaphragm.
This works in a similar way to the brake
booster, which provides power to your
brake system.
Control interface
The driver operates the system via a set
of switches on the steering wheel. The
switches have in addition two switches
to control the time gap between the ACC
vehicle and the target vehicle. In
addition there are a series of text
messages that can be displayed on the
instrument cluster to inform the driver of
the state of the ACC system and to
provide any necessary warnings. The
driver engages the ACC system by first
pressing the ON switch which places the
system into the 'ACC standby' state. The
driver then presses the Set switch to
enter the 'ACC active' state at which
point the ACC system attempts to
control the vehicle to the driver's set
speed dependent upon the traffic
environment[2].
Transitioning Between Speed
Control and Follow Modes
The ACC system automatically
transitions between Speed Control and
Time Gap (Follow) Modes. The mode of
operation is determined by the lower of
the set speed for Speed Control Mode
and the target speed to maintain the gap
between the ACC vehicle and a forward
vehicle. Basically, if no vehicle is
present within the clearance distance, the
system will operate in Speed Control
mode, else, it will operate in Time Gap
mode.
G. Canceling Cruise Control
Operation
Cruise Control operation may be
cancelled by the operator or
automatically via the ACC system.
Either of the following conditions will
deactivate ACC: Brake pedal is pressed
'Off' button is pressed Vehicle Speed <
25 mph An ACC system fault is
detected.
Conclusion
With traffic continually increasing, basic
cruise control is becoming less useful, but instead of becoming obsolete,
cruise control systems are adapting to
this new reality -- soon, cars will be
equipped with adaptive cruise control,
which will allow your car to follow the
car in front of it while continually
adjusting speed to maintain a safe
distance. The evolution of these comfort
systems is logically going towards
implementing new additional functions
and safety strategies in order to detect
and actuate in case of emergency. This
transition has to be done in clear and
precise steps to assure an easy adaptation
to each improvement.
[attachment=66490]
Abstract
Speed control is one of the measure issues in
automobiles. With varying terrains the driver has to
frequently speedup and slow down the vehicle.
Manually doing this work is tedious and needs a lot of
concentration. Fuel efficiency introduces another
bottleneck. Cruise control system is a system that
automatically controls the speed of a vehicle, even in
varying terrain. The system takes over the throttle of
the car to maintain a steady speed as set by the driver.
In classical process control, the corresponding signal
would be a change in the throttle setting; this avoids
calibration and wears problems with sensors and
engine. One of the conventional cruise control
requirement is thus to specify control of the current
speed of the vehicle [1]. The proposed system ACC
“Adaptive Cruise Control” system is an improvement
over conventional cruise control system.(ACC)’
automatically adjusts vehicle speed to maintain a
driver-selected safe distance from the vehicle ahead in
the same lane. Keywords—cruise control, throttle,
Introduction
Speed control with a centrifugal
governor was used in automobiles as
early as the 1910s, notably by Peerless.
A centrifugal governor is a specific type
of governor that controls the speed of an
engine by regulating the amount of fuel
(or working fluid) admitted, so as to
maintain a near constant speed whatever
the load or fuel supply conditions. It uses
the principle of proportional control. The
governor adjusts the throttle position as
the speed of the engine changes with
different loads. Peerless advertised that
their system would "maintain speed
whether up hill or down".Modern cruise
control (also known as a Speedo stat)
was invented in 1945 by the blind
inventor and mechanical engineer Ralph
Teetor. His idea was born out of the
frustration of riding in a car driven by
his lawyer, who kept speeding up and
slowing down as he talked. The cruise
control system controls the speed of your
car the same way you do, by adjusting
the throttle position. But cruise control
actuates the throttle valve by a cable
connected to an actuator, instead of by
pressing a pedal. The throttle valve
controls the power and speed of the
engine by limiting how much air the
engine takes in. Many cars use actuators
powered by engine vacuum to open and
close the throttle. These systems use a
small, electronically controlled valve to
regulate the vacuum in a diaphragm.
This works in a similar way to the brake
booster, which provides power to your
brake system.
Control interface
The driver operates the system via a set
of switches on the steering wheel. The
switches have in addition two switches
to control the time gap between the ACC
vehicle and the target vehicle. In
addition there are a series of text
messages that can be displayed on the
instrument cluster to inform the driver of
the state of the ACC system and to
provide any necessary warnings. The
driver engages the ACC system by first
pressing the ON switch which places the
system into the 'ACC standby' state. The
driver then presses the Set switch to
enter the 'ACC active' state at which
point the ACC system attempts to
control the vehicle to the driver's set
speed dependent upon the traffic
environment[2].
Transitioning Between Speed
Control and Follow Modes
The ACC system automatically
transitions between Speed Control and
Time Gap (Follow) Modes. The mode of
operation is determined by the lower of
the set speed for Speed Control Mode
and the target speed to maintain the gap
between the ACC vehicle and a forward
vehicle. Basically, if no vehicle is
present within the clearance distance, the
system will operate in Speed Control
mode, else, it will operate in Time Gap
mode.
G. Canceling Cruise Control
Operation
Cruise Control operation may be
cancelled by the operator or
automatically via the ACC system.
Either of the following conditions will
deactivate ACC: Brake pedal is pressed
'Off' button is pressed Vehicle Speed <
25 mph An ACC system fault is
detected.
Conclusion
With traffic continually increasing, basic
cruise control is becoming less useful, but instead of becoming obsolete,
cruise control systems are adapting to
this new reality -- soon, cars will be
equipped with adaptive cruise control,
which will allow your car to follow the
car in front of it while continually
adjusting speed to maintain a safe
distance. The evolution of these comfort
systems is logically going towards
implementing new additional functions
and safety strategies in order to detect
and actuate in case of emergency. This
transition has to be done in clear and
precise steps to assure an easy adaptation
to each improvement.