Florida Atlantic University researchers have conducted an innovative new study with haptic/tactile sensation feedback, electromyogram (EMG) monitoring, and a wearable soft robotic armband that can significantly help users of prosthetic hands. The new findings could change how future artificial hands are controlled by users.
Researchers from the university’s College of Engineering and Computer Science worked alongside FAU’s Charles E. Schmidt College of Science to determine if people could precisely control the gripping forces applied to two different objects grasped simultaneously with a artificial hand.
The team also explored how visual feedback could help the complex multitasking pattern by systematically blocking visual and haptic feedback. They also investigated how a simultaneous object-carrying experiment could save time and set out to design a multi-channel wearable soft robotic armband that could impart artificial sensations of touch to users of the robotic hand.
The research results have been published in the journal Scientific reports.
Uses multiple channels of haptic feedback
The research demonstrated that multiple haptic feedback channels allowed users to grasp and carry two objects simultaneously with the dexterous artificial hand. They could perform these tasks without breaking or dropping objects, which was true even when users had obstructed vision.
The new approach also improved the time it takes to transport and deliver both objects, and users qualitatively rated haptic feedback as significantly more important than visual feedback.
Erik Engeberg, Ph.D., is a corresponding author, professor, and member of the FAU Center for Complex Systems and Brain Sciences, I-SENSE, and the FAU Stiles-Nicholson Brain Institute.
“Our study is the first to demonstrate the feasibility of this complex task of simultaneous control while integrating multiple haptic feedback channels in a non-invasive way,” Engeberg said. “None of the participants in our study had previously used EMG-controlled artificial hands to any significant extent, but they were able to learn how to use this multitasking feature after two short training sessions.”
Design a custom made robotic armband
The research team provided haptic feedback while working on EMG control and the design of the custom-made soft robotic armband. They collaborated with Emmanuelle Tognoli, Ph.D., who is co-author and research professor in FAU’s Department of Psychology and the Center for Complex Systems and Brain Sciences.
The team fitted the cuff with soft actuators, which helped convey a proportional feel of the contact forces. They also included vibrotactile stimulators to indicate if grabbed objects had been broken.
Three locations on the cuff have been designed for haptic feedback: thumb, index and little finger. These three zones are sufficient to transmit the force applied to the two objects grasped by the hand. The armband also has three air chambers that each correspond proportionally to one of the three BioTacs, which are mounted on the fingertips of the hand. Besides all this, the armband has three vibrotactile actuators that tell the user if the objects have been broken.
Moaed A. Abd is the first author and holds a Ph.D. student in the Department of Oceanic and Mechanical Engineering at FAU.
“Examples of multi-function control demonstrated in our study included proportional control of a card pinched between the index and middle fingers at the same time as the thumb and little finger were used to unscrew the lid of a water bottle. Another demonstration of simultaneous control was with a ball that was gripped with three fingers while the little finger was simultaneously used to flip a light switch,” Abd said.
The innovative new study could be used to enable people with upper limb absence to pursue career paths and other recreational pursuits.
Stella Batalama, Ph.D., is Dean of the FAU College of Engineering and Computer Science.
“Enabling refined dexterous control is a very complex problem to solve and continues to be an active area of research as it requires not only the interpretation of human grip control intentions but also complementary haptic feedback of tactile sensations” , said Batalama. “With this innovative study, our researchers are tackling the loss of tactile sensations, which is currently a major obstacle to preventing people with upper limb absence from multi-tasking or using their full dexterity. prosthetics.”