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Since the beginning of
regular automobile use, the user interface has been evolving. The
first cars had no steering wheels, they had control sticks that
steered and accelerated the car, then came steering wheels, lights,
clutches, brakes, the familiar foot throttle, wipers, and finally
the configuration settled down to what we are all so familiar with
now, with our only choice of interface being automatic or manual
transmissions.
The driver has always been the controller
of all aspects of cars operation through the throttle, brake, and
steering wheel, but with the advent of the Hybrid auto, that has
changed. We were not given the opportunity to chose from a manual
Hybrid drive, or an automatic one. Our only choice, the automatic
hybrid.
In 2000, the Honda Insight Hybrid and then
the Toyota Prius Hybrid cars became available, and to my dismay,
the user interface was left the same as with non hybrid cars. Here
we had a new opportunity for the superior skills that humans could
bring to the control and balancing of the electric gas ratio, for
optimum performance in acceleration or efficiency, depending on the
need. What ever the automakers reasons were, (I am sure there were
many) they chose not to offer us an opportunity to control this
ratio manually. A new control system was forced onto us, the
automatic HHI . The electric to gas ratio was controlled by
supposedly smart algorithms under computer control. Can the
computer see the road ahead ? We can. We have a brain that far
exceeds the power of the on board microcontroller at making subtle
determinations, and we can learn what works best, not fuzzy logic
like the insight likely uses. With MIMA, and the Honda Insight, we
may have our only shot at experiencing this level of user control
of the HHI, as the automakers do not seem to be moving in this
direction in their new hybrid offerings, and the communication
between modules are moving into a networked serial communication
control system which is more difficult to crack, (not
impossible).
Through a collaborative effort of the users
of MIMA, and the programming skills of many of the users, we hope
to show clearly that the human operator needs to be part of the
hybrid control system, at least until cars can see and have
artificial intelligence. MIMA definable manual and automatic
control of the electric drive, should be an option on all hybrid
cars.
Gas priority system (Automatic
HHI)
With the stock Insight IMA system, one must
press down on the gas, lowering the MPG from say 100MPG to 50MPG
before the electric drive fully engages to assist in the
acceleration or hill climb. You have no choice, as the HHI or
Hybrid Human Interface has been strictly defined by the cars
software. The batteries may be fully charged, but you cannot use
just the electric to get over the hill even small ones.
Electric priority system (Manual
HHI)
A careful analysis of the inter-module
signals of the Insight has led to a fairly simple modification that
allows full manual control of both the charging and assist IMA
functions. MIMA can let the driver maintain high mpg, while
manually controlling the electric assist to climb a hill with full
electric assist, or 14,400 watts (144V X 100A). At this rate The
6.5AH capacity cells can not provide climbing power for long before
being depleted. More aggressive assist, means that the charging
must be more aggressive as well. With MIMA, the driver becomes part
of the battery charge maintenance system, either manually by
stopping with the full MIMA recharging of 7200 watts (144V X 50A),
or automatically as he lifts the throttle past the charge
activation set point. The maximum charge is no more aggressive than
if you touched the brakes during an off ramp deceleration, or
braking down a hill, and the assist is no stronger than full
throttle take offs in first or second. The difference is that we
can maintain the full assist or recharging with the MIMA
controller.
The forced recharge of the battery in
normal IMA mode is limited to 10-12 A of charge when the stock
automatic system decides it is time to charge. Once the system
decides it is charge time, it will charge continuously even while
climbing a gentle hill, and therefore puts a constant load on the
engine, when many times it would be better not to. This background
load makes maximum MPG difficult or impossible to achieve . With
MIMA, the charging can be accomplished at up to 50A of charge, when
the situation allows it, at driver discretion, with minimal effect
on MPG. Proportional down hill charging allows maintenance of speed
without using brakes, during deceleration the aggressive charging
can transform more of the kinetic energy into charge before the
mechanical brakes are needed for the final stop. When climbing
hills the background 10-12A charge can be switched off to maximize
MPG. Only time will tell how far the MIMA system will be developed,
meanwhile lets enjoy the possibilities.
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