Most precise bionic hand controller

The most precise control of a human hand using artificial means was achieved by a team of researchers at the University of Chicago using a system they called DextrEMS. The quality of artificial hand control systems is measured using a metric called the independence index, which compares the movement induced in the target finger with the movement of adjacent fingers. An independence index of 1 is full control of the target finger and no movement in the adjacent fingers, zero is roughly equal movement of both the target and its neighbours, and negative scores indicate more movement of adjacent fingers than the target. A typical human can manage an independence index of 0.84 (we can't move our fingers fully independently), while the DextrEMS system achieved an average independence of 0.6. Typical electrical muscle stimulation techniques, by contrast, can generally only manage an independence of 0.25.

DextrEMS comprises two connected systems. The first is a set of electrical muscle stimulators attached to the skin of the forearm, while the second is a set of electromechanical "brakes" which selectively lock or limit the movement of individual fingers. The EMS sets the fingers in motion, while the brakes refine that broad movement into something more stable and finely controlled.

The system was developed by Pedro Lopes and his team at the University of Chicago's Human-Computer Integration Lab, and first described in a paper presented at the ACM Symposium on User Interface Software and Technology in October 2021.

Several example applications were demonstrated as part of this study. These included allowing someone with no prior knowledge of sign language to fingerspell simple words and phrases using a mobile app to control their hand and using DextrEMS to form the shape of simple guitar chords.