Why teaching robots to blink is hard but important – 5/9/2023 – Tech

It’s the first time I play drums with a robot.

I’m sitting at a table facing an adorable humanoid robot called an iCub.

We each have our own stick and drum box, and we must hit the box with the stick in sync with a light pattern.

But of course I’m also watching the robot — and I’m aware that it’s watching me.

This percussion experiment was designed to test how the presence of a robot doing the same task affects the behavior of a human being.

It is one of many human-robot interaction experiments carried out by the research group Contact (which stands for Cognitive Architecture for Collaborative Technologies) at the Italian Institute of Technology in Genoa.

Although I am aware of the lights and other people in the room, my gaze continues to be drawn to the iCub’s heavy white lids.

For starters, there’s a noticeable noise as the robot blinks every few seconds.

And because this baby-faced robot has big, expressive eyes, it locks you in with its gaze.

This is important because there is much more to blinking, as with other aspects of looking, than what our eyes actually see.

“Although it is often assumed that blinking is just a reflexive physiological function associated with protective functions and ocular lubrication, it also plays an important role in the reciprocal interaction,” notes Helena Kiilavuori, a psychology researcher at the University of Tampere in Finland.

The human blink conveys attention and emotion. As a means of non-verbal communication, this act expresses a number of things that we are not consciously aware of, as a cue to enter into a conversation.

Thus, it is just one of many social signals that humans constantly exchange without being aware of them, although we derive a great deal of information and comfort from them.

So social roboticists have studied both the physical and psychological properties of human blinking to understand why it might be useful to have a robot equivalent.

“Due to the many important functions of blinking in human behavior, it can be assumed that having robots blink their eyes can significantly improve their human appearance. This can, in turn, facilitate interaction between humans and robots,” explains Kiilavuori.

In other words, “when the robot is blinking well, people are moved by the character,” says David Hanson, who leads Hanson Robotics.

subtle movements

The Contact survey, conducted with 13-year-olds and adults in Italy, shows that both groups simply like blinking robots more.

A robot that doesn’t blink can give someone the unpleasant impression of being watched, explains Alessandra Sciutti, who leads the Contact unit.

Humans also see robots that blink more naturally as more intelligent. And intelligence is important in situations where humans rely on robots to provide information, such as at transit stations.

Despite the benefits of “natural” blinking, offering this ability to robots (apart from avatars and robots with screen monitors for faces) is technically challenging.

“Blinking is one of the most subtle human movements, so designing mechanisms that can mimic these movements requires advanced technology, such as high-precision motors,” explains Kiilavuori. The roboticists at Engineered Arts, for example, use expensive aerospace-grade motors, in addition to designing their own electronic controls.

Specifically, says Hanson of Hanson Robotics, “The speed of the motors that move the skin material when blinking is really challenging, and getting the eye shape to look natural while blinking is also challenging. In addition to reducing friction between the eyelids, artificial and the surface of the eye itself”.

Another issue is the balance between speed and sound of the motorized blink. Francesco Rea, senior technician at the Contact unit, explains that in the iCub robot a quieter motor could attenuate the blinking sound.

But slower movement would make the robot appear sleepy.

If it blinks too slowly, it also risks losing visual information, as the iCub’s camera is located behind the eyes.

“In vision, missing two frames isn’t that big of an issue,” says Rea.

“Losing ten frames starts to be a problem.”

Another challenge is timing and duration of blinks, explains Kiilavuori.

The different functions that the blink performs — how a person changes the speed at which they blink when telling a lie — involve different eyelid dynamics, as well as different emotional states.

“Any deviation from the timing and natural and appropriate duration of the blink, in a given context, can make the robot appear strange and distracting,” she says.

The Contact team uses a software program that partially randomizes the intervals between single and double blinks. After all, steady blinking wouldn’t look very natural either.

At Disney Research, robotics experts joined forces with character animators to develop a research prototype for a realistic robotic look.

The goal is to design an expressive gaze system that is easy for animators to control in order to convey subtle emotions.

With things like eyelid movement curves, “we can isolate these individual behaviors, which makes it really easy to really focus on correcting small aspects and small details,” says James Kennedy, researcher at Disney Research.

They patented their robotic detection and gaze control system. This includes software to process images captured by a camera on the robot’s chest and generate control signals for movements such as opening and closing the eyelids.

Kennedy says the research remains more in the experimental realm and is not yet being applied to Disney theme parks.

“The goal here was really to take a single social cue that we were interested in and take it as far as possible to create believable, realistic movements and behaviors that we felt would provide a foundation for engaging with people.”

The technology would need to be refined so that, for example, the gaze system would remain believable in closer interactions with humans for longer.

Another general challenge would be getting the humanoid robots to start synchronizing their blink patterns with humans, like humans do during conversation.

And unlike the exaggerated representations in pop culture of androids that are indistinguishable from humans, blinking is a small example of the many complexities that still keep robotic interactions from feeling completely natural.

By trying to reproduce such a tiny and sometimes underappreciated mechanism as blinking, “you actually reveal how complex this mechanism is and thus how much subtle motion there is,” notes Kennedy.

“And that’s where we have this great opportunity for exploration and invention.”

This text was originally published here.