Ryan Chin and his colleagues are building the car of the future—a stackable, electric, shared two-passenger city vehicle that rethinks urban mobility. This work, in collaboration with General Motors, takes into account problems of parking, congestion, communication, and energy distribution, and considers the best and most efficient uses of available resources in an urban environment. The project also serves as a platform for investigating Ryan's interests in mass-customization and personalization in product-development processes.
Question: What is the CityCar?
Ryan Chin: CityCar is an electric two-passenger car that’s designed for shared use, meaning that it is not owned by any particular person. It’s a kind of community vehicle, so when you need this city car you swipe a credit card and it unlocks the door for these electric cars. When you’re done with the vehicle you just drop it off at another drop-off point. The CityCar itself is designed specifically for this use case in cities where there is not a lot of parking, a lot of congestion, so the goal of the CityCar is to reduce the number of private automobiles that are on the road. The CityCar itself is designed to fit this need, but also to be very compact, so when it’s being used it doesn’t take very much energy to move it around. It’s very lightweight. It uses in-wheel electric motors meaning that it’s very energy efficient. Each wheel has an electric motor. Each wheel has been given full freedom of 120 degrees of rotation, which means that the vehicle can turn on its own axis. It can part sideways into a parking space, all of the functions and features that you would need in a dense urban environment. The other thing about the city car too is that it can be compacted. It can be folded. It’s designed to be fit into a very small amount of space, so when the car is folded it only takes one-third of the space of a regular parking space, which dramatically changes the need for parking, but also changes the need for servicing and also where the locations are available to place this vehicle, so this vehicle is very, very different both in its use, but also in its design and its sort of layout.
Question: How is the CityCar a total departure from the traditional car?
Ryan Chin: The CityCar is very different than the traditional car. It’s much more lightweight. It only weighs about 1,000 pounds. A traditional car weighs about 3,000 pounds or even more. It uses an electric motor in each wheel. Most vehicles have a gasoline-powered engine. If it’s an electric vehicle it’s usually one electric motor that’s geared to all the wheels. In our case we have direct drive to each wheel, which provides us tremendous energy efficiencies. You don’t have to have a traditional gear box transmission for example and because of that we’re able to then create a new architecture, which allows us to fold and collapse the car. You don’t have to deal with the traditional driveline in the middle of the vehicle anymore. You have direct drive to each of the wheels, which then allows us to change the whole architecture of the vehicle and because of the folding we’re now able to get out through the front instead of the side of the car. Before there was a gasoline-powered engine, you don’t have that in the way anymore, so you get out through the front. When you have that then you have to start thinking about how you get in and out of the vehicle. You know do the seats articulate, which in our case they do. They help you to get out of the vehicle. Do have to have a steering wheel? No, we don’t necessarily have to have a steering wheel. When we’re looking at an omnidirectional vehicle that can go in any direction perhaps a joystick or other kinds of controllers are more useful. The in-wheel drive motors are driven by what we call drive by wire technology, which means that there is no mechanical connection between the steering wheel and the wheels themselves, so you can have by wire or remote control of the wheels themselves, which means that you can look at alternative ways of controlling the vehicle. No steering wheel, no pedals, no buttons, just joystick controls, which allows the freedom to make a very minimal interior. The vehicle now can be very, very compact in its use of components therefore, because the vehicle is very small you can actually have a lot of space because you’re not using those traditional elements, so the vehicle itself has all of these new technologies and in a secondary level you can imagine that the interior perhaps doesn’t even have traditional displays anymore, traditional analogue displays that provide speed and RPMs. It’s something that may not be necessary in cities. You know if you’re in the city you don’t care what your top speed is necessarily. You’re going to be in a traffic jam anyway, so that may not be important to you. The charge level may be more important to you or finding a parking space may be more important to you or finding a friend in an unfamiliar neighborhood may be more important to you. So the display of information will also be very different for the interior and possibly exterior. There are a lot of very interesting new technologies in displays where you can imagine the whole exterior of the vehicle being completely programmable, not only in a superfluous way where you say I want a pink car today and a blue car tomorrow, but perhaps in a very functional pragmatic way where you say it’s a very hot day out, perhaps the car should be white today and tomorrow when it’s very cold perhaps the car should be darker. I think the idea of making the vehicle very personalizable, even though it’s a shared use situation if you can personalize it electronically you’re going to make the car feel, not only feel and look, but also be driven in a way that is very personal to you.
The tires themselves for the city car are an integral part of the wheel unit. The wheel units we’re calling wheel robots, which encapsulate drive motor, suspension, braking, steering all inside the wheel and if you increase the envelope to include the tire you have a complete unit that snaps on and off the vehicle. Just imagine the wheel robot to be almost like a USB stick where you have power and data and some kind of connection to the body of the vehicle. If you can make that a modular unit you can service the vehicle very easily and in fact, we’re even looking at different types of tires that don’t require air and so we can create a completely dry wheel robot that doesn’t need to be serviced with all these fluids that you would see, for cooling perhaps or for braking. We can use the motor for braking. We can use the tires for even suspension. There is new interesting technologies developed in industry today that don’t require any air in the tire, so by removing all that burden of maintaining these elements you can have a very serviceable, maintainable wheel unit, almost like how you would build a computer. You would have all these different units that snap on and snap off for both upgradeability and also for serviceability and over time you can imagine that there could be even a whole economy based on these in-wheel motor units that different manufacturers would produce that can be driven down in price, but driven up in performance based on competition, so it will really change the way you may manufacture vehicles in the future as well.
Question: How safe is the CityCar?
Ryan Chin: The first thing to realize is that we all live already in a society where everyone mixes. You’ll have people walking on the street, people riding bicycles, an 18-wheeler, a kid with a soccer ball all on the street all at the same time, so that… You know we already live in a society where this is lots of different vehicle choices to be made and they’re mixing together. The second thing is that we can design a vehicle that is very safe even though it is smaller and the way to do that is in the architecture of the vehicle itself. The vehicle uses its in-wheel motors, which changes the whole architecture of the vehicle. It shifts a lot of the complexity to the corners of the car, which then means that we have freedom now to design a safety cage around the vehicle in a very different way, meaning that side impact can be taken care of in a much better way because now we don’t have side doors. We get out through the front of the car, so the apertures don’t exist anymore. We can design a safety cage that takes into account different kinds of crumple zones in the front of the vehicle because now there is no engine in the front. Now you can build a safety cage in a much different way. Our car folds, which means that you can utilize the folding as a dampening device during a front and rear collision as well and we’ve started to look at some crash safety simulations of the city car under those conditions and it turns out that when a rigid body crashes often a rigid body like a regular automobile when it crashes it also crumples in a folded manner, so we should utilize the folding to our benefit, not only as a way of compressing the car, but also decelerating the passengers in the cabin itself. So I think there is lots of sort of architectural moves in the design of the vehicle that allow much more safety, but that’s of course actual safety.
There is also perceived safety, which is you know how do people feel about this vehicle? What are the features of the car that make it feel like it’s safe? Part of that of course is the look and feel. The other part of course is active safety, meaning putting sensors into the vehicle, making sure that you avoid and accident and not just you know make the vehicle survivable during an accident. So lane sensing, crash avoidance, active cruise control, all these technologies are being developed currently today. The third factor is the fact that this vehicle is a low speed vehicle. We are living in a sort of very dense and urban world now and this car is designed for metropolitan areas where the speeds are very, very low. In Shanghai today the average speed is nine miles per hour, nine to eleven miles per hour. It’s very, very slow, so that is another thing that you know to put into consideration is that this is not a high-speed vehicle. It’s not a top speed vehicle.
Recorded on January 21, 2010