At Teague, we’ve had the opportunity to work on the development of autonomous vehicles and the plethora of new experiences and interactions that will happen because of them. A lot of this effort here and elsewhere has been focused on the features that passengers or pedestrians will have direct interaction with, such as exterior size and shape, interior layout, hardware interface, and so on. Working through so many of these features has made us curious about how one of the most fundamental features of the car—the wheel itself—could be challenged in order to better serve a vehicle of the future.
Traffic flow in future dense urban areas will reassemble current warehouses where vehicles move slower, yet more fluid, allowing for mixed human and vehicle traffic at the same time. We can likely expect vehicles to evolve similarly to warehouse-based autonomous and semi-autonomous platforms: aware, connected, omnidirectional, and changing purposes depending on the current need. Serving humans where and when they are needed, but disappearing when not in use.
Traditional wheels limit freedom of movement outside.
Ideally, the vehicle could be entered or loaded from any side, which is perfect for when space is really at a premium and also creates better options for the ingress and egress of differently-abled individuals. What this requires is a wheel that takes up minimal space for wheel arches, wheel wells, or any feature that would obstruct a flat, clean base floor.
While the traditional car wheel is a tried and true device, it does present a few limitations to car design and overall mobility. In this exploration, we are looking at how we might be able to re-think the wheel by taking a quick look at what the limitations of conventional wheels are, and exploring a few ways that we might re-imagine the wheel to overcome those limitations.
A quick look around in areas both inside and outside of automotive transportation shows that freedom of movement is a real challenge today in many wheeled vehicle applications, and that more than a few people are looking to solve it.
Usually, the more freedom of movement that the wheels provide, the more space, or complexity they require.
Four-wheel steering.
In this solution, each wheel can swivel 45 degrees, and up to 90 degrees. Coordinating the speed, direction, and angle of all four wheels gives the car greater freedom of movement, while also providing the speed and ride quality of conventional wheels and tires. However, a drawback of this design is the increased mechanical complexity around each wheel needed to enable this functionality; in practice, packaging this complexity into a vehicle is more intrusive on interior space than the traditional design.
Spherical tires.
In 2016, Goodyear brought the concept of a spherical tire to “reality” with the introduction of its Eagle 360 tire —a future-forward magnetic levitating sphere solution designed for autonomous vehicles. Although the design has many benefits, a spherical tire occupies the same—or even more—space as a traditional round wheel. There’s also no telling how much complexity will be required to magnetically levitate a car above four independently-controlled spheres.
Omnidirectional wheels.
Found in more and more factories and warehouses today, omnidirectional and Mecanum wheels provide 360-degree freedom of movement and zero-point turning capability—perfect for maneuverability in tight grid-based layouts. The drawbacks of this design for potential urban vehicle use come from the complexity and speed limitations of the wheel itself.
Tilted wheels.
A compromise between wheel simplicity and omnidirectional drive, the “Max” wheel seeks to provide omnidirectional mobility but with a simpler design than most of the other concepts. But the wheel assembly still takes up a large volume, resulting in a lot of interior encroachment.
The FlatWheel – a concept somewhere in between.
None of the aforementioned solutions are exactly what we were looking for when it comes to our goals of both increasing interior space and providing a vehicle with omnidirectional mobility.
The FlatWheel is a concept somewhere in between the tilted wheel and the four-wheel steering systems. The basic idea is that you start with a normal wheel, then angle it on its side until it’s almost flat. This approach retains a lot of the straightforward simplicity of the classic wheel, but because of its flattish orientation, gives back internal usable space and offers a not-too-complex way to gain omnidirectional mobility. For this exploration, we assumed use of hub motors integrated within the wheel.
Of course, the vehicle’s chassis involves more than just wheels. In addition to the wheels and the steering mechanism, we need to consider some type of motors, batteries, suspension system, sensors, control electronics, and so on. Improving one on the cost of another would be a vain effort.
Without some kind of test of the FlatWheel powertrain, it’s hard to say exactly how feasible it might be, so in Part II of this Labs post we’ll talk about how we evaluated and tested the system to get a sense of how it might perform in real life.
