THE MYOKINETIC CONTROL INTERFACE: HOW MANY MAGNETS CAN BE IMPLANTED IN AN AMPUTATED FOREARM? EVIDENCES FROM A SIMULATED ENVIRONMENT

Abstract

The displacement of residual muscles during voluntary contraction in a transradial amputee could be effectively exploited to control multiple degrees of freedom in a hand prosthesis. We recently introduced a new human-machine interface (the myokinetic control interface) which aims at tracking muscles contraction through implanted permanent magnets and magnetic field sensors located inside the socket. Magnetic markers (MM) tracking systems have been widely investigated in the past, especially for controlling and guiding medical tools for intra-body applications. However, specific design rules for a multiarticulate robotic hand control system have not been defined yet. Here, we studied the tracking accuracy of multiple implanted magnets by simulating different levels of trans-radial amputation using a 3D CAD model of the forearm. A magnets placing procedure was developed to position the MMs in the available muscles, following general guidelines derived in our previous study. The localizer was able to accurately track up to 9, 13 and 18 MMs, in a proximal, middle and distal representative amputation, respectively. Localization errors below ~3% the length of the trajectories travelled by the MMs during muscles contraction were achieved for all amputation levels. Not only this work answers the question: “how many magnets could be implanted in a forearm and successfully tracked with a myokinetic control approach?”, but also provides interesting insights for a wide range of bioengineering applications exploiting remote tracking.