One of the innovative features of that vehicle was its in-wheel motors that powered the front wheels. These motors were run on lead-acid batteries that were recharged by a pair of combustion engines.
While an in-wheel engine offers advantages in reducing weight and moving components, why carmakers have been reluctant to embrace it.
First, an in-wheel motor’s electrical components aren’t shielded from damaging elements such as dirt, water, corrosion and potholes. This means they have to be more resilient and more resistant to the elements—including sometimes being submerged in water—all while handling the high voltage needed to turn the wheels. It has been traditionally easier and safer to house those components further inside the chassis and away from the wheels.
Second, adding weight to the wheels increases the vehicle’s “unsprung” weight—that is, the weight of the vehicle that isn’t supported by its suspension. The heavier the unsprung mass, the more difficult it is to maneuver the vehicle and the bumpier the ride, since more of the vehicle will be jostled about by an uneven road surface.
Indigo Technologies has proposed an innovative solution: its own in-wheel drive system called the T1. This system places a module that consists of brakes, steering and active suspension—as well as a battery-operated motor—right at the wheel itself rather than in middle of the chassis.
A lower voltage means a smaller battery and engine needed to create an electrical current—which in turn reduces the unsprung weight of the vehicle. Indeed, the lighter the vehicle as a whole makes the unsprung weight less of a concern—and by eliminating the need for driveshafts, transmission components and suspension, the weight is reduced even more. This makes it easier for a 48-volt battery to power the car—meaning the battery itself can be smaller, cutting out even more mass! A bumpy ride and motion sickness are further reduced thanks to each T1’s active suspension and the ability to control each wheel independently, boosting the vehicle’s grip and making it more stable when changing speed or direction.
“We addressed the unsprung mass issue by ensuring that the vehicle itself can be lower in mass,” said Brian Hemond, CEO at Indigo Technologies. “We're not trying to power SUVs or even conventional passenger sedans but smaller vehicles, and that makes the unsprung mass issue less of a problem."
Indigo is “reinventing the wheel” for electric autonomous vehicles.
The technology behind the T1 also has the potential to fundamentally alter the way vehicles are made. Moving the motor inside the wheel means you can dramatically reduce the size of the vehicle by eliminating the space formerly taken up by the in-chassis engine, drivetrain and suspension components. As a result, you can build a smaller and lighter car that is maximized for passenger comfort and aerodynamic efficiency.
Reduced vehicle weight means also that the propulsive motors do not need to be as powerful as those of conventional electric cars—especially as the task of propulsion is divided four ways between them
And the lighter the car, the lighter the load on the battery and motor, which don’t have to work as hard to move the car—especially if the task is divided among the four motors. In addition, with active suspension you can recreate the smooth and safe ride of a larger vehicle.
As a result, with an in-wheel motor and active suspension, a carmaker can produce vehicles 10 times more efficient than current ones.
This could be especially significant for the growing rideshare market. The average rideshare trip is 1.1 passengers, plus the driver—meaning the majority of Uber or Lyft rides don’t exceed two passengers. And as automated driving technologies continue to improve, the ridesharing sector could eventually remove the need for a driver—leaving only one or two passengers per ride. Instead of using a conventional four- or five-passenger capacity vehicle, rideshare operators could opt for a cheaper, more efficient autonomous two-seater—exactly the kind of vehicle that would use an in-wheel engine such as Indigo’s T1. In fact, Indigo has created a concept two-seater electric commuter car called the Draco that showcases this potential.
As innovative as electric vehicles are, they still use drivetrains that closely resemble their internal-combustion predecessors: a motor at the front and/or back that uses shafts and gears to turn the wheels. All this machinery takes up space and adds to the weight of the vehicle—as do axles, steering and suspension systems.
Indigo foresees a paradigm shift in the way vehicles are designed, powered and manufactured—with its T1 technology at the center of that change. The company is talking to carmakers and component manufacturers about producing the T1—an important next step in bringing the technology to market.
Over a century later, Ferdinand Porsche’s innovative design could once again revolutionize the way cars are built.
Read more about developments in electric vehicle technology at Nanoparticles Pave the Way for a Million-Mile EV Battery.