Runaway unintended acceleration is alarming enough but if the brakes also fail to respond you have a combination
to be avoided at all cost. The episode on I-8 to San Diego, where James Sikes could not stop his runaway Toyota Prius
hybrid may have been a hoax, although the California Highway Patrol Officer, Jonathon Neibert, who drove alongside at
over 90 miles per hour giving instructions, did not seem to think so. Hoax or not, Mr. Sikes’s declaration,
made on camera beside his then stationary Toyota Prius, and broadcast on national TV channels, that he would never ride
in it again, has created anxiety and concern—such as that of a man now getting rid of his new Prius. Delays in reporting
previous episodes of runaway acceleration have resulted in Mr. Toyoda’s apology before Congress and a fine of $16 million
(the maximum allowed). Toyota’s ability to track down the problem has been made even more questionable by NASA’s receiving
instructions to lend a hand.
Toyota’s future depends on restoration of public trust. A car that unexpectedly accelerates and whose brakes fail to stop
it is terrifying. A key question to be asked is whether there is something about the brakes in a Prius, compared to a standard car,
which might cause them not to respond? If there is, it would help a great deal to restore public trust if that something were
removed so that Toyota could at least say that the brakes on the Prius function as they do in a conventional gasoline car. Of
course, brakes can fail in non-hybrid cars, too, and unexpected acceleration was a problem with the early cruise controls, but
we’re not going to give up driving cars with cruise control and conventional brakes.
A clue to the “something” we’re looking for appears in the Prius brochure that refers to “integrated regenerative braking.”
Regenerative braking converts the energy of motion into electricity to be stored in the battery instead of converting it into
heat generated by friction in the car’s disc brakes. This is desirable because the less friction brakes are used, the greater
the economy. Regeneration is easy in an electric-drive car because the same electric motor that drives the car can work as a
generator and slow the car down.
Regenerative and friction brakes are two distinct systems and each could be operated by its own pedal without in any way affecting
the friction brakes but, instead, they are integrated or “blended” so that they can use the same brake pedal. The blending is so
smooth that the driver would not normally suspect that the brakes differ from those in a gasoline car and a computer is interposed
to do the blending. Obviously, the computer must go between the brake pedal and the rest of the friction braking system and could,
therefore, be responsible for a failure to respond to pedal pressure. Defective or not, this is a definite “something” that raises
doubts and removing the “something” would make it easier to restore confidence. At least we should be able stop the car,
especially if the brake pedal also disengages the engine, as it does in a gasoline car running on cruise control.
Steve Wozniak has commented on the fallibility of computers in this context and David W. Gilbert testifying before a Congressional
sub-committee has criticized Toyota’s electric throttle control fail-safe systems.
If the brake pedal operates only the friction brakes what happens to regenerative braking? Although it is not an essential
feature—earlier electric-drive cars did not have it—it is too valuable to abandon. Instead of adding a third pedal
for regenerative braking, the accelerator pedal can be replaced by a rocking pedal that rocks left and right.2 To the
right it accelerates while to the left it decelerates regeneratively. When the foot is removed, the rocking pedal returns
to its default mid-position. Note that the left/right movements of the rocking pedal are mutually exclusive, like its
acceleration/deceleration functions. Transferring from rocking right to rocking left, and vice versa, is easier than moving
the right foot from the accelerator to the brake pedal. In normal driving with a rocking pedal, the brake pedal is used very
little. The driver can feel right away whether he is rocking the pedal to the left or the right because of the associated
internal or external rotation of his ankle. Therefore, accidents arising from the driver mistakenly pressing the accelerator,
in the belief that it was the brake, should be less likely than they are with a conventional, non-rocking pedal system.
In practice this works beautifully and intuitively in a prototype known as Ridek III.
3 The problem is solved
in a solution that does not require the extensive testing that any correction of an existing mechanical or software problem
would need because the advantage is intrinsic to the solution, like the installation of a handrail to a steep and difficult staircase.
Not only that, the distinctive appearance of the rocking pedal informs prospective passengers that, in this car,
there is no brake blending and the brakes are no less trustworthy than in any gasoline car.
1 President, The Ridek Corp., 2266 Sunrise Dr. Point Roberts, WA 98281, USA. Phone: 360-945-5242, dower@whidbey.com
2 Patent pending. The rocking pedal and other ideas are described in A Better Plan for a Better Place, a book by Gordon Dower, available from Ridek Inc., 2260 Sunrise Drive, Point Roberts, WA 98281, $ 19.95
3 www.ridek.com, Ridek III is a quick-change modular car, basic features of which were patented in 2000 in the USA and subsequently in Europe and Canada. Ridek is composed of a motorized deck, or Modek, and a Ridon body that rides upon it. Its quick-change modularity has many advantages, including reduced overall motoring cost and increased convenience.
4 Motor controller and programming supplied by Rinehart Motion Systems, Portland OR.