A team at University of California, Santa Barbara created a device that simulates the forces felt by the hand when touching an object. Information from the UCSB study will be used to provide prosthetic hand wearers with more natural touch feedback and a greater range of functionality.
The engineers' study used a specialized array of tiny accelerometers, or vibration sensors, worn on the sides and backs of the fingers and hands. Using the device, the researchers were able, for the first time, to capture, catalog, and analyze patterns of vibration in the skin of the whole hand that were produced during active touch.
Actions such as tapping and sliding one or several fingers over different types of material, as well grasping, gripping, and indirect tapping (using an object to tap on a surface) all gave rise to distinctive vibration signatures.
“We can liken this to the different ways that a bell will sound if it is struck by a metal hammer or a rubber mallet,” said UC Santa Barbara faculty member Yon Visell, an assistant professor in the Department of Electrical and Computer Engineering, in the Department of Mechanical Engineering and in the campus’s Media Arts and Technology graduate program.
According to the study, the vibrations generated through touch, and the distribution of vibrations in the hand, depend very closely on the type of action and the object being manipulated. For instance, vibration patterns produced by tapping a single finger were stronger than those made by grasping, gripping or sliding, but were much more localized in the finger. The patterns of vibration throughout the skin of the hand also varied according to the number of fingers used, the object being manipulated, and the action being performed.
