Soft, Human-Sized Robot Gives Excellent Hugs

Once you get over the awkwardness, receiving a hug from a robot could be as good as the real thing.
Derya Ozdemir
HuggieBot 2.0 in actionAlexis Block et al.

There's a reason why we get the urge to squeeze someone lovingly from time to time, and like most things are, it's got to do with health. From lowering blood pressure and cortisol levels to alleviating stress and anxiety, a hug a day keeps a good job of keeping the doctor away; however, amid a time a casual hug between acquaintances seems so far away, science had got to get creative.

A team of researchers at the Max Planck Institute for Intelligent Systems (MPI-IS) and ETH Zürich have recently come up with a HuggieBot 2.0 that can deliver a loving embrace when requested. 

HuggieBot 2.0 builds on a previous system created by Alexis E. Block, one of the authors, who come up with it after being inspired by her family members who were far away whom she wanted to give a big hug. HuggieBot 1.0, based on a robotic platform created by Willow Garage, was apparently too bulky to be a good hugger, and it couldn't feel the user well because it had only one touch sensor located on its back.

Now, HuggieBot 2.0 is on the road to becoming an excellent hugger.

The robotic anatomy of a hug

"Our new robotic platform was built according to our six design tenets, or 'commandments' for natural and enjoyable robotic hugging," Block said to Tech Explore. "Namely, we felt that a hugging robot should be soft, be warm, be human-sized, visually perceive its user, adjust its embrace to the user's size and position and reliably release when the user wants to end the hug. By following these commandments, HuggieBot 2.0 gives excellent hugs."

The recipe for a robotic hugger is a long yet fun one. The robot has an inflatable, soft torso that can sense a user's contact. Block and her colleagues mounted two Kinova JACO arms, which are robotic arms that are typically attached to wheelchairs, on a custom metal frame. In order to give those warm feelings you get from a hug, the robot's body is covered with heating pads. HuggieBot 2.0 might even look stylish to some with its purple robe and a grey sweatshirt. And the secret ingredient for the perfect hug is of course the padded mittens.

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The robot has a computer for a head and a screen for a face. It has a built-in depth-sensing camera, a speaker, and a micro-controller. It is far from being realistic; however, the screen shows different facial expressions such as smiling and just blinking to make the experience more real-like, or perhaps, creepier.

But how does it move? "For haptic release, we used two different methods," Block explains. "First, we used the torque sensors on the robot's arms to detect when a user wishes to leave the embrace. Then we used the inflatable sensing torso to detect when a user has removed his/her arms from the robot's back, thus indicating their desire to end the hug. These features make HuggieBot 2.0 a more natural and intuitive hugging robot."

By collecting feedback through studies, Block and her colleagues are constantly updating the robot to get the perfect hugger. Now, they have HuggieBot 3.0 which will be presented in a new paper which is yet to be peer-reviewed.

"In addition to showcasing hardware and software improvements, our new paper about HuggieBot 3.0 centers on enabling the robot to detect, classify and respond to intra-hug gestures like rubs, pats, and squeezes," Block said. "Being squeezed by a hugging robot is surprisingly enjoyable!"

The researchers want to explore the physiological effects of receiving hugs from HuggieBot. While receiving hugs from a human is pretty great, Block and her colleagues would like to find out whether a robot's hug can alleviate stress and improve physical wellbeing as much as that of humans or animals. 

The HuggieBot 2.0 and HuggieBot 3.0 are still prototypes, but one day, the researchers want to commercialize the concept. The researchers are also developing HuggieApp which will allow users to remotely send each other customized hugs via the HuggieBot robot. 

This robot will be presented at the ACM/IEEE International Conference on Human-Robot Interaction (HRI) in March.