Wearable robots improve coordination between pairs of violin players

In some settings and when completing some collaborative tasks, humans are required to coordinate their movements or actions with those of others. A clear example of this is musical performance, particularly instances in which two or more musicians play their instruments together.

To coordinate their movements and play in sync, musicians typically focus on different types of sensory information, including sound signals and visual cues. The same type of information is also used by other people who are required to coordinate their actions with those of others, including athletes, dancers, and some skilled laborers who work in teams.

Researchers at Università Campus Bio-Medico di Roma, Scuola Superiore Sant'Anna di Pisa, and other institutes recently developed a new wearable robotic system that could help musicians to play in sync. This system, presented in a paper published in Science Robotics, is essentially an exoskeleton that can be attached to a person's upper limbs and provides haptic feedback, allowing them to feel the movements of the partner.

"This work stems from the European project CONBOTS (CONnected through roBOTS), which aimed to explore how robots can enhance human-human interaction in real-world tasks by creating a physical connection between people," Francesco Di Tommaso, co-first author of the paper, told Tech Xplore.

"The key idea is to leverage haptic communication, the sense of touch and physical forces, as a channel to exchange movement information. Violin duo performance offers a fascinating example of sensorimotor interactions, as musicians are highly trained to coordinate through hearing and vision, yet they cannot rely on physical contact."

A wearable robotic system that leverages haptic feedback

The main objective of the recent work by Di Tommaso and his colleagues was to explore the potential of robot-mediated haptic feedback for enhancing coordination in collaborative tasks that involve two people. To do this, they developed two exoskeletons and then tested them on pairs of violinists who were performing together.

"We developed a pair of wearable robotic devices, or exoskeletons, that connect the movements of two violinists," explained Di Tommaso. "Each device measures the motion of one musician and delivers forces to the other based on the difference between their movements. In this way, musicians can 'feel' each other's actions in real time, as if they were physically connected, while preserving their natural expressivity."

The key advantage of the new robotic system introduced by the researchers is that it rapidly provides intuitive signals that can aid coordination. Typically, musicians primarily adjust their movements by looking at what other musicians are doing, which requires their conscious attention. The team showed that haptic feedback can be significantly more helpful for coordination, as it is processed directly by the human body and requires minimal conscious effort.

"We tested our approach by asking 20 pairs of musicians (10 amateurs and 10 professionals) to perform under different sensory feedback conditions: hearing only, hearing and seeing, hearing and feeling (with our exoskeleton), and all three combined," said Di Tommaso. "Strikingly, we found that robot-mediated haptic feedback was more effective than vision in improving coordination during violin duo performance."

Improving pair coordination in different settings

In the team's experiments involving pairs of violinists, the exoskeletons led to more coordinated movements and thus a greater musical synchronicity. This was somewhat surprising, as violinists do not typically rely on haptic feedback for coordination and the team's system was entirely new to them.

"Violinists are trained to rely on visual cues, yet we found that they benefited from a completely unfamiliar type of feedback with forces whose origin they were not even aware of," said Di Tommaso.

"Interestingly, the combination of all sensory modalities produced the highest level of coordination, highlighting the importance of multisensory integration. Our study shows that exoskeletons can introduce a new channel for human communication, one that is embodied, immediate, and largely implicit, without interfering with natural movement, even in highly skilled tasks."

In the future, the team's newly developed system could be tested in further experiments with musicians and adapted for other applications. For example, it might also prove useful for athletic training, education, and rehabilitation.

"For example, a teacher and a student, or a physical therapist and a patient, could be physically coupled through these exoskeletons, allowing movement corrections to be conveyed directly through touch," explained Di Tommaso.

"This could make learning more intuitive, as the less experienced partner can feel the correct movement, while the more experienced one can directly perceive the error. In the longer term, this concept could even enable remote physical interaction, allowing people to collaborate or train together across distances while still sharing a sense of touch."

Written for you by our author Ingrid Fadelli, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.