- Thank you for the introduction.
Again, my name is Brian Mok, I'm from Stanford University
and this work was conducted with my co-authors
Mishel Johns, Stephen Yang,
and also with my advisor Wendy Ju.
Today I'll be talking about
transitions of control and partially
autonomous vehicles and how transforming
steering wheel systems could assist
drivers in those situations.
In the realm of autonomous vehicles
there are classification paradigms
such as SAE's Levels of Automation
which categorize vehicles by what
responsibilities are allocated
to the driver and to the automation.
Vehicles of Level two, Partial Automation,
and Level three, Conditional Automation,
drivers are still expected to take back
control of the vehicle in certain scenarios.
So transitions of control from automation
are important safety-critical aspect
that need to be studied.
In our prior work we looked at
examining how much time drivers need for transition,
particularly how they would perform when
given a certain amount of time.
We did this research utilizing a full-car driving simulator
where we could reliably test driving scenarios
that may be too hazardous for an on-road experiment.
Next, here's an example of what our prior work looked like.
Here the vehicle provides the driver with a audio alert
- [Computer] Emergency automation off.
- And a visual alert on the instrument cluster.
However, sometimes these two things are
not enough to help drivers during the transition.
As you can see, drivers may occasionally
hesitate or respond slowly in a transition
of control of the situation.
After we conducted this study we were interested
in seeing if we could introduce a design intervention
that could help improve
the driver performance after transition.
From the observations of how the drivers behaved
in that study we believe that it would be helpful
to them if we could provide maybe better alert mechanism
and also a clear indicator of which entity was in control.
To accomplish this, we decided to design and test
two Transforming Steering Wheel Systems.
The first was a Mechanically Transforming Steering Wheel
that utilized movement,
something that people are very sensitive to,
and the other was a purely
Visually Transforming Steering Wheel.
For the Mechanically Transforming Steering Wheel
we start out with some initial foamcore prototypes
that we could evaluate and see what types
of motion would be appropriate for a transition scenario.
We had three design requirements for these prototypes
that we believed, if satisfied, would help drivers.
The first is that you need to have distinct physical states.
With shape-changing interfaces they have
the ability to provide dynamic affordances
so by having two distantly different physical states
it can act as a better indicator of who's in control
and show when the driver actually has agency
in controlling the car.
The second is that it needs to have
noticeable movement when transforming
so that it could easily get the attention of the driver
and alert them of the transition.
For example, when we were evaluating these prototypes,
Prototype B had a more noticeable
complex sweeping motion than Prototype A,
so it was favored for this requirement.
Finally, you need to
indicate that a transition was happening,
and what we mean by that is,
when we're evaluating Prototype C, for example,
it looked like a handoff where
the car was giving control back to the driver,
compared to, say, Prototype D, which a lot of our
evaluators found as kind of foreign,
and as having its own agenda
unrelated to transition.
For the final prototype of the Mechanically
Transforming Steering Wheel we combined
the two prototypes that we liked the most
during our initial prototyping sessions
and this design, the upper components
of the steering wheel utilize the four bar linkage movement
that you saw in Prototype B on the previous slide,
while the bottom utilizes the rotating element
in Prototype C that you saw.
When fully deployed, the steering wheel
components dock together.
We believe that, by having two different types of movement
along two planes of motion would make
the transformation even more noticeable.
When we evaluated and developed prototypes
for the Visually Transforming Steering Wheel
we similarly had three design requirements
and again, they needed to have distinct visual states,
they needed to be visually noticeable,
and it had to indicate a transition of control.
We tested out a few different prototypes,
including the display attached
to the center of the steering wheel,
projections onto the steering wheel,
and LEDs embedded along the circumference
of the steering wheel.
With the display prototype we found that
it had a constrained viewing area,
so sometimes it was not as effective
in getting the attention of a driver.
The projection had a different problem,
in that information can occasionally
be obscured by the driver.
Because of that, the LED prototype,
which didn't have some of these drawbacks,
was selected for the final design
of the Visually Transforming Steering Wheel.
Here's a basic system diagram of these steering wheels.
They were designed to be interfaced
with our full-car driving simulator
and the driving simulator would be able
to send commands to a Raspberry Pi via UDP,
and then the Raspberry Pi would relay those commands
to a Arduino on each of these steering wheels
which controls the behavior of
each individual steering wheel.
Next we conducted a
quantitative driving performance study
to see if these steering wheels actually had any effect
on post-transition performance.
To be able to compare these results
with the results of our previous work,
where participants were using
a standard circular steering wheel,
we utilized the same course design and event design.
Participants in this experiment were
not given any secondary tasks,
so when automation was enabled
all that they could do was monitor the car.
We had a two by two design where one factor was
the transition time and the other was the steering wheel.
For the Mechanically Transforming Steering Wheel
we had 28 participants and also for the Visually
Transforming Steering Wheel we also had 28 participants.
The participant's age distribution had a mean of 29.3 years
with a standard deviation of 11.1 years.
This is the course that we used.
Control of the vehicle alternated
between the driver and the automation, as you can see.
At the beginning, the driver goes through
a five minute practice section so that they can become
acclimated to the driving simulator.
After five minutes they're asked to enable the automation.
After driving for 10 minutes along a very straight,
uniform section of road, the car encounters a road hazard
in the form of a curved section of road
that is lacking lane markings.
Participants experience an unstructured transition
of control where they're immediately given back control
two or five seconds before the car enters the curve.
Two sets of pylons bound the area
that the car should stay in,
with one set of pylons closing off
the right lane and another set
indicating where the center divider would be.
Oncoming traffic to the left
and an excavator on the right
discouraged participants from leaving this area.
Here's the example of how the steering wheel
behaves during transition.
For the Mechanically Transforming Steering Wheel,
when the automation is on the steering wheel
retracts back in to indicate that
the automation is in control
and the driver no longer has as much agency.
When the automation is off,
the steering wheel deploys outward
to indicate that the driver needs to take back control.
Here's an example of what that would look like.
- [Computer] Please enable automation.
- So the participant presses a button
and the steering wheel folds back in.
When they get to the event the steering wheel pops back out.
- [Computer] Emergency automation off.
- Oh my god.
- As for the Visually Transforming Steering Wheel,
it had similar behavior, where
when the automation was on
it would glow green to mirror what was on
the instrument cluster.
When the automation is off, it would become unlit.
And so that
the Visually Transforming Steering Wheel
would be able to mimic the Mechanically Transforming
Steering Wheel during the transition back to the driver,
the steering wheel would glow red
for the same amount of time it took
the Mechanically Transforming Steering Wheel to transform.
Here's one of that.
- [Computer] Please enable automation.
- Those transitions look like.
- [Computer] Emergency automation off.
- Oh my god.
Shit.
(audience laughs)
Jesus.
(audience laughs)
- Onto our performance metrics, we had a couple.
The first was Road Excursions.
We had a classification where,
if the participant did not hit any of the pylons
it was considered No Excursion,
if part of the car hits a pylon
it was considered Regular Excursion,
and if the entire car was on the other side
of the pylons it would be a Catastrophic Excursion.
These were the results for the two steering wheel systems
and also for our prior work.
When we conducted Fish's exact tests
we found that for the total number of excursions
that it wasn't a significant difference
between the conditions,
however if you do look at the Catastrophic Excursions
you'll see that the Mechanically Transforming
Steering Wheel doesn't have any,
so it actually did significantly better for that measure.
When we reviewed some of the video we found that
all of those excursions were small grazes against pylons
versus going out into the grass or hitting a car.
Another measure that we used was
the Standard Deviation of Road Offset,
which indicates how far the car is
away from the center of the lane.
This metric looks at how stably
the participant negotiated the event.
We see that the Mechanically Transforming Steering Wheel
performed significantly better than
the Visually Transforming Steering Wheel
and also our standard steering wheel case.
Another measure is the Standard Deviation
of Steering Wheel Position.
And again, this looks at how stably
people negotiated the event.
We found that, again, the Mechanically Transforming
Steering Wheel was better than the Visually Transforming
Steering Wheel,
but there weren't any significant differences between
both steering wheels and the original, prior-work case
with the standard steering wheel.
We have some implications for design from these results.
We saw that the Mechanically Transforming
Steering Wheel was better
for certain metrics,
so we believe that this type of system should be considered
for the development of autonomous vehicles.
We also found that the Visually Transforming Steering Wheel,
although it didn't do very well, was not significantly worse
than the standard steering wheel.
One of those implications is that both steering wheels
could be potentially used for other
applications that are not related to transition of control
without any significant detrimental effects.
I'll just quickly go over
a few of those other applications.
One of them that the Visually Transforming Steering Wheel
could do is to help
with indicating the vehicle's intention.
As you can see there, since the Visually Transforming
Steering Wheel is decoupled from the actual steering wheel
it can show what the car is about to do before it does it,
which could potentially help increase trust.
Another application that we thought of is with the.
(laughs) - That is so cute!
- Mechanically Transforming Steering Wheel.
- It's like a little baby, or a chicken.
- Where it could potentially act
as an interactive robotic avatar.
- Okay. (laughs)
- [Interviewer] Could you tell me how you feel about these?
- That one is like a little foot coming out to kick you.
That would.
For some reason that feels okay
if it's just one of the little legs,
like it's trying to get my attention on this side,
or it's trying to wake me up, or.
(mechanical whirring)
(loud whirring)
(laughs)
The steering wheel has a lot more fun on my drive than I do.
- We actually did a small exploratory study
with a few interaction design experts
looking at different types of animations
and we found a few common threads with our experts'
viewing that directional animations help them
be alerted towards something in that direction.
Just a summary again of the contributions from this paper.
We designed and fabricated two
transforming steering wheel systems,
we tested them for their effectiveness in helping
drivers perform better after a transition of control,
and we also introduced some potential applications
of these two steering wheels outside
of the realm of transition of control.
I'm happy to take any questions.
We have a demo after this session at six o'clock
if you wanna see this
Mechanically Transforming Steering Wheel.
(audience applauding)
- [Daniella] Hello, I am Daniella Briatofacino
from Khartoum University.
I have a question related
to the two different steering wheels.
I wonder what is the influence of the sound,
the noise of the mechanical steering wheels
when it is transforming, and also it's own shape
in terms of the results you got.
- The form factor?
Yeah, the sound was definitely something that we
had not intended for, and actually in our little
follow-up exploratory study a lot of our experts
mentioned that the sound could have been
a potential factor in helping increase performance.
So that's actually, one of the next steps would be
kinda looking at designing this without that sound
or testing it without the sound component
to see if people are still very sensitive to that motion.
As for form factor,
why it is not the conventional circular steering wheel,
in the initial prototyping process
we found that a lot of the kinda circular
steering wheel concepts, it still implied
that there was a lot of agency,
that people could grab and take control.
So we tried to avoid the circular prototypes.
In a paper that we actually had published,
we kinda look at the form factor of this steering wheel
and we found that it did not really have
a significant effect.
We tested this where it remained deployed all the time,
so it would never retract back in
when automation was enabled,
and that didn't have any significant
increases in performance.
So although the form factor is actually
kinda foreign to people,
it didn't factor into the increase in performance.
- [Daniella] Okay, thank you.
- [Man] Great, thanks a lot.