Researchers at Florida Atlantic University have carried out a new and innovative study with haptic/touch sensation feedback, electromyogram (EMG) control, and a wearable soft robotic armband that can dramatically help users of prosthetic hands. The new findings could change the way future artificial hands are controlled by users.
The researchers at the university’s College of Engineering and Computer Science worked alongside FAU’s Charles E. Schmidt College of Science to investigate whether people could precisely control the grip forces applied to two different objects grasped simultaneously with an artificial hand.
The team also explored how visual feedback could assist the complex multitasking model by systematically blocking visual and haptic feedback. They also studied how a simultaneous object transportation experiment could save time and set out to design a multichannel wearable soft robotic armband that could convey artificial sensations of touch to the robotic hand users.
The results of the research were published in the journal Scientific Reports.
Uses Multiple Channels of Haptic Feedback
The research demonstrated that multiple channels of haptic feedback enabled users to grasp and transport two objects simultaneously with the dexterous artificial hand. They could carry out these tasks without breaking or dropping the objects, which held true even when the users had their vision obstructed.
The new approach also improved the time required to transport and deliver both objects, and users qualitatively rated haptic feedback as considerably more important than visual feedback.
Erik Engeberg, Ph.D., is corresponding author, a professor, and member of FAU’s 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 simultaneous control task while integrating multiple channels of haptic feedback noninvasively,” said Engeberg. “None of our study participants had significant prior use of EMG-controlled artificial hands, yet they were able to learn to harness this multitasking functionality after two short training sessions.”
Designing Custom Fabricated Robotic Armband
The research team provided haptic feedback by working on the EMG control and design of the custom fabricated soft robotic armband. They collaborated with Emmanuelle Tognoli, Ph.D., who is co-author and a research professor at FAU Department of Psychology and Center for Complex Systems and Brain Sciences.
The team fitted the armband with soft actuators, which helped convey a proportional sense of contact forces. They also included vibrotactile stimulators to indicate if the grasped objects had been broken.
Three locations on the armband were designed for haptic feedback: the thumb, index, and little finger. These three areas are sufficient to convey the force applied to both objects grasped by the hand. The armband aslo has three air chambers that each proportionately correspond to one of the three BioTacs, which are fitted on the fingertips of the hand. Besides all of this, the armband has three vibrotactile actuators that indicate to the user if the objects had been broken.
Moaed A. Abd is first author and a Ph.D. student in FAU’s Department of Ocean and Mechanical Engineering.
“Examples of multifunction control demonstrated in our study included the proportional control of a card being pinched between the index and middle fingers at the same time that the thumb and little finger were used to unscrew the lid of a water bottle. Another simultaneous control demonstration was with a ball that was grasped with three fingers while the little finger was simultaneously used to toggle a light switch,” Abd said.
The new innovative study could be used to enable upper limb-absent individuals to pursue career paths and other recreational pursuits.
Stella Batalama, Ph.D., is dean at FAU College of Engineering and Computer Science.
“Enabling refined dexterous control is a highly complex problem to solve and continues to be an active area of research because it necessitates not only the interpretation of human grasp control intentions, but also complementary haptic feedback of tactile sensations,” said Batalama. “With this innovative study, our researchers are addressing the loss of tactile sensations, which is currently a major roadblock in preventing upper limb-absent people from multitasking or using the full dexterity of their prosthetic hands.”
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