PRODUCT PROFILE 55
A leap in steering control
Sentient has introduced Blueprint Steering, a leap in steering fidelity. Will the system
also challenge how we think about optimal suspension design?
November/December 2019 • VehicleDynamicsInternational.com
ABOVE LEFT:
Sentient’s annual
winter test in 2019
took place 120 miles
north of the Arctic
Circle in Sweden
ABOVE RIGHT: The
Sentient in-house
developed powercontrol
module
executes Blueprint
Steering
BELOW: Sentient
is celebrating 10
years as a company
and its Blueprint
Steering has
been proven in
production for more
than six years
READER INQUIRY SERVICE
To learn more from Sentient, visit
www.magupdate.co.uk/pvdi
››The hydraulic boost-curve
assisted steering gear was a
very successful technology for
more than half a century, until electric
power steering (EPS) finally matured
enough to become the system of choice.
Surprisingly, since electronic control
gives so many new opportunities, EPS
typically still relies on a boost-curve
with all its limitations and drawbacks.
Sentient has abandoned the boostcurve
concept altogether for its Blueprint
Steering system, which features
sophisticated control algorithms and
the use of available signals. The system
provides high-fidelity feedback true to
lateral acceleration, rather than the sum
of wanted and unwanted forces around
the steering axis. Blueprint Steering is
therefore inherently disturbance free –
bid farewell to torque steer, sensitivity
to wide tyres, road disturbances, poor
self-aligning and other phenomena that
can impair steering feel and precision.
Through the innovative use of vehicle
state information, Blueprint Steering has
brought back intuitive and even tuneable
understeer and oversteer feedback, a
beloved attribute once taken almost for
granted, but unfortunately lost in many
modern cars with EPS.
Key attributes and features of
Blueprint Steering include high-fidelity
feedback, superior on-centre precision,
a disturbance-free experience, limit
handling feedback, excellent integration
with ADAS/AD, and steering feel
that is ready for steer by wire.
Blueprint Steering can also be
a new optimisation opportunity for
the complete front suspension and
steering system.
An interesting prospect is to reduce
the forces needed to turn the wheels,
which would allow the steering gear to
be downsized, creating benefits in terms
of cost, weight and energy. Reducing
the required steering forces also reduces
compliance, which can help to improve
steering feel.
When researching this possibility,
Sentient cooperated with CAE Value,
a company that specialises in suspension
design optimisation. CAE Value
performed a design exploration on
an elastokinematic suspension model
representative of a FWD compact luxury
crossover car.
The steering rack forces during
parking (i.e. zero vehicle speed) were
selected as the object to minimise. The
optimisation process resulted in a 14%
reduction of maximum required steering
rack forces. Equally important is that all
other performance parameters remained
unaffected or even improved. This force
reduction can enable higher front axle
loads on the same platform, which is
a welcome advantage, especially in the
electrification era, with heavy hybrid
and battery systems.
With the engineers less constrained
by very narrow targets for elements
such as scrub radius, caster trail and
king-pin inclination, other specific
parameters could be prioritised. A
performance car maker could use the
newly acquired advantage to optimise
camber control for maximising cornering
performance.
With Blueprint Steering, Sentient
brings a powerful and novel method to
realise premium steering feel. In the
future, vehicle-dynamics engineers can
rethink optimal suspension design, as
steering feel is already inherently given.
The exploration has just started.
/VehicleDynamicsInternational.com
/pvdi