Source: gizmag

Bose Corporation is best known for creating high quality audio
products, and if asked to piece together your ideal car, its 11-
speaker sound system would certainly be a contender to feature
within. But the suggestion that Bose's new suspension systems would
feature without begs an explanation.

In an ongoing research project that has spanned over twenty-four
years Bose has created a unique electromagnetic suspension system for
automobiles that is close to commercial release and is set to replace
traditional shocks and springs with electronic actuators.

"This is the first time a suspension system is the same for a sports
car and for a luxury car", said its creator, Dr Amar Bose, chairman
and head of technical design. The result is a ride that is level and
bump free over incredibly rough terrain and when the vehicle turns in
to corners.

The computer-controlled suspension system originated from a research
assignment established by Dr Bosch in 1980. Back then, he conducted a
mathematical study to determine the optimum possible performance of
an automotive suspension, ignoring the limitations of any existing
suspension hardware.

The result of this 5-year study indicated that it was possible to
achieve performance that was much better than anything available.
After evaluating conventional and variable spring/damper systems as
well as hydraulic approaches, it was determined that none had the
combination of speed, strength, and efficiency that was necessary to
provide the desired results.

The study led to electro-magnetics as the one approach that could
realise the desired suspension characteristics. The Bose suspension
concept required significant advancements in four key disciplines:
linear electromagnetic motors, power amplifiers, control algorithms,
and computation speed. Bose took on the challenge of the first three
factors and hedged its bets on Moore's law providing assistance for
the necessary developments needed in computation speeds.

The purpose of an automobile's suspension system is two-fold:
passenger comfort and vehicle control. Comfort is provided by
isolating the vehicle's passengers from road disturbances. Control is
achieved by keeping the car body from rolling and pitching
excessively, and maintaining good contact between the tire and the
road.

Dr. Bose, set out to prove these goals were in conflict and so began
the long road that has led to the revolutionary new system. In a
luxury sedan the suspension is usually designed with an emphasis on
comfort, but the result is a vehicle that rolls and pitches while
driving and during turning and braking. In sports cars, where the
emphasis is on control, the suspension is designed to reduce roll and
pitch, but comfort is sacrificed.

Today, prototypes of the Bose suspension have been installed in
standard production vehicles. These research vehicles have been
tested on a wide variety of roads, on tracks, and on durability
courses with amazing results.

Automobilemag.com experienced the system first hand in a Lexus LS400
on a ride simulator and likened it to sailing along with only the
slightest of cradle rock. All the while via adjacent mirrors the
spectacle of bouncing tyres beneath could be witnessed.

The heart of the system is based upon a linear electromagnetic motor
which is installed at each wheel. Inside the linear electromagnetic
motor are magnets and coils of wire. When electrical power is applied
to the coils, the motor retracts and extends, creating motion between
the wheel and car body. One of the key advantages of an
electromagnetic approach is speed. The linear electromagnetic motor
responds quickly enough to counter the effects of bumps and potholes,
maintaining a comfortable ride. Additionally, the motor has been
designed for maximum strength in a small package, allowing it to put
out enough force to prevent the car from rolling and pitching during
aggressive driving maneuvers.

A power amplifier delivers electrical power to the motor in response
to signals from the control algorithms. The amplifiers are based on
switching amplification technologies pioneered by Dr. Bose at MIT in
the early 1960s - technologies that led to the founding of Bose
Corporation in 1964.

The regenerative power amplifiers allow power to flow into the linear
electromagnetic motor and also allow power to be returned from the
motor. For example, when the Bose suspension encounters a pothole,
power is used to extend the motor and isolate the vehicle's occupants
from the disturbance. On the far side of the pothole, the motor
operates as a generator and returns power back through the amplifier.
In so doing, the Bose suspension requires less than a third of the
power of a typical vehicle's air conditioning system.

The whole system is controlled by a set of mathematical algorithms
developed over the twenty-four years of research. These control
algorithms operate by observing sensor measurements taken from around
the car and sending commands to the power amplifiers installed in
each corner of the vehicle. The goal of the control algorithms is to
allow the car to glide smoothly over roads and to eliminate roll and
pitch during driving.

In many of today's production vehicles, the suspension system is
comprised of front and rear suspension modules that bolt to the
underside of the vehicle. The Bose suspension takes advantage of this
configuration so that a vehicle may be retrofitted with minimal
modifications.

Bose's front suspension modules use a modified MacPherson strut
layout and the rear suspension modules use a double-wishbone linkage
to attach a linear electromagnetic motor between the vehicle body and
each wheel. Torsion springs are used to support the weight of the
vehicle. The suspension also includes a wheel damper at each wheel to
keep the tire from bouncing as it rolls. Unlike conventional dampers,
which transmit vibrations to the vehicle occupants and sacrifice
comfort, the wheel damper in the Bose suspension system operates
without pushing against the car body, maintaining passenger comfort.

Vehicles equipped with the Bose suspension have been tested on a
variety of roads and under many different conditions, demonstrating
the comfort and control benefits drivers will encounter during day to-
day driving. When test drivers execute aggressive cornering maneuvers
like a lane change, the elimination of body roll is felt immediately.
When test drivers take the Bose suspension over bumpy roads, they
report that the reduction in overall body motion and jarring
vibrations results in increased comfort and control.

In bringing the product to market Dr Bose expects that the company
will choose one automaker that is dedicated to performance. When
exactly this will be is laughed off by Dr Bose as he points out the
long past the project already has. It is speculated however that the
system will be commercially available within the next two years.

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