Road Access for Disabled Americans
Links to more Information about Active Suspension
Full-active suspension, NJ Auto Site
. (Short definition)
"...replaces normal springs and shock absorbers
with a double acting hydraulic actuator at each wheel,
driven by a variable-rate hydraulic pump and controlled
by an electronic control unit (computer)."
"Active Suspension ala Infiniti", Bob Freudenberger
. (Detailed Explanation for Laypersons)
"The basic idea is to use a computer, sensors,
a pump, and hydraulic cylinders at each corner to get
the car to do things never before possible, such as
leaning into a curve like a motorcycle, compensating
for the dive of braking and the squat of acceleration,
and raising and lowering its wheels individually to
make pavement imperfections seem to disappear."
"Active Suspension systems ... can store, dissipate
and introduce energy to the system."
Active Suspension, Queens U, Canada
"Improvements to ride quality and handling performance
can be achieved by employing 'active' suspensions. Active
suspensions use servomechanisms to support the dynamic loads.
Arbitrary forces can be applied between the wheels and vehicle
body through the use of actuators. By employing a power source,
these actuators are used continuously to control vehicle movement.
By providing flexible control, active suspensions reduce the
trade-off between handling performance and ride quality that
is present with traditional passive suspensions".
- University of California, Berkeley - ME
Semi-Active Suspension System, Simulation Model, Nagoya University, Japan
"In order to improve the ride comfort and
drivability of cars, the active suspension system
has been developed. The suspension should be soft
for the ride comfort, while it should be stiff for
the drivability. The active suspension systems can
overcome these trade-off, but the systems are more
costly, more complex and less reliable than the
passive ones. The semi-active suspension system
proposed by Karnopp  was based on the passive system
in the structure and aimed to compete with active systems
in achieving the reduction of the body acceleration. The
semi-active system changes only the damping coefficient
by controlling the electromagnetic valve inside the absorber.
All the variables, the deflection, the velocity, the acceleration,
and the jerk of the body must be reduced to achieve better
ride comfort and drivability. Especially the jerk, the
derivative of the acceleration is important to improve
the ride comfort. The conventional control theory based
on state variables cannot handle with all of these variables
in the design procedure. For example, the jerk cannot be
derived in the state equations. On the other hand, in the
GA approach it is easy to implement these variables into
performance index PI, as follows:..."
Analysis of the P.A.W.S. Lorry Suspension, Abstract, University of Cambridge
- Transportation Research Group, Technical Report Archive
"This report compares the theoretical performance of
the Pro-Active World Suspension (PAWS) to (i) a passive suspension,
(ii) an active suspension with `modified skyhook
damping' and (iii) an active suspension with full state
feedback and optimal control."
Active Suspension Systems for Vehicles,
Army Research Laboratory
"... Generates active inputs to cancel motion & vibrations.
Initial efforts are underway in the area of active vehicle suspension
systems via leveraging NASA structural vibration
isolation work. ..."
Drive-by-wire Systems with Active Suspension
"Mercedes are also investigating the combination of
drive-by-wire systems with active suspension (Active Body
Control, ABC) which reduces body movements during
cornering to a minimum and opens up new dimensions in
terms of handling, stability and road-holding."
Motorola / microcontrollers
"Suspension control improves vehicle stability during
high speed manouvers by the use of actuators in the vehicle's ride control
elements. In order to achieve full vehicle dynamic control, information such
as angular speed and direction, vehicle speed, transmission settings, wheel
slip and brake pressure will be required in order to determine proper action.
Motorola is leading the industry in developing microcontrollers for these
Active Cab Suspention, Luleň University of Technology, Sweden
"A number of studies show that operators on forest
machinery are exposed to severe whole-body vibration. At present,
damping of the vibration is incorporated in the cab
seat. The seat however, are primarily designed for road
vehicles, although some modifications have been made to
make them more suitable for off-road operation.
"Another way in which the operator can be isolated
from vibration is to damp the entire cab, in which case the
existing seats are quite suitable. Yet the best solution would be
to equipe the machine with an active cab suspension system;
in other words, to input energy into the suspension system
in order to equalize the vibrations introduced from
the machine. Active suspension systems do already exist for cars..."
This is a bit of a stretch - but it looks like we have
a better chance for a smooth ride on a space launch then
in our neighborhoods.
Another way to avoid the bumps and undulations...
| Fire & EMS
February 7, 2000 / last update: April 21, 2000 (Version 1.b)