First multi-channel armband that conveys artificial
touch
Science and Technology Daily (Reporter Zhang Mengran) With the current myoelectric prosthetic hand, even if all 5 fingers can be individually controlled, the user can only perform one grasping motion at a time.
In a paper published in Scientific Reports, U.S. researchers say they have pioneered a wearable, multi-channel haptic feedback soft robotic armband that conveys artificial touch to the robotic user, allowing them to dexterously use a prosthetic hand while grasping and moving two objects without breaking or falling, even if their view of both objects is obstructed.
Researchers at Florida Atlantic University have investigated whether people can precisely control the grip force exerted on two different objects, simultaneously grasping them with a dexterous artificial hand.
In the study, they also explored the role of visual feedback in this complex multitasking model by systematically blocking both visual and haptic feedback.
They found that, even when vision was available, subjects qualitatively rated tactile feedback as much more important than visual feedback, as there was often little or no visually perceptible warning before the grasped object was broken or dropped.
Compared to previous studies, the synchronous control method shortened the time required to move and deliver both objects, and subjects with limb loss did not differ significantly from other subjects on key performance indicators of the task.
The new armband non-invasively integrates multiple channels of tactile feedback with soft actuators, including vibrotactile stimulators, to indicate if the grasped object has been damaged.
The armband is designed for tactile feedback in three locations corresponding to the thumb, index and little fingers to communicate the magnitude of the force applied to the two objects in the hand.
The armband is also equipped with three co-located vibrotactile actuators that vibrate to alert subjects if an object in the grip is disrupted.
In the multifunctional control example shown in the study, subjects held a card between their index and middle fingers while unscrewing the cap of a water bottle with their thumb and pinky.
Another demonstration is to grab a ball with three fingers, while the pinky is used to toggle the light switch at the same time.
Achieving fine-grained dexterous control requires not only interpretation of grasp control intent, but also supplemental haptic feedback, the researchers say.
The research aims to address the loss of touch, which is currently a major barrier to multitasking or getting the most out of a prosthetic hand in people with missing upper limbs.
Research contributes to future highly complex bimanual robotic frameworks, with the goal of enabling people with missing upper limbs to achieve work and play goals that are currently inaccessible.