SmartArM ARM

Christophe Huchet was the official pilot of the Smart ArM team for the CYBATHLON 2020 Global Edition. He was born with an agenesis of the right arm including the elbow. While studying business, he began a career as a swimmer. Many times, French Champion of 100-meter breaststroke races, in the handisport section, it is however in the valid section that he is the happiest to make finals and podiums. He also obtained to have the FFN rules modified, which regularly disqualified him for not touching the wall with both hands! Over the last 20 years, Christophe has created several restaurants in Paris, that he recently sold in order to resume his studies and become a certified coach. His goal is to guide the managers of small and medium-sized companies, as well as he had been guided as a company manager himself. His participation at the CYBATHLON 2020 Global Edition was for him a new adventure that provided him with a rich and intense year.

SAM (Smart ArM) is an arm prosthesis dedicated to transhumeral (above-elbow) amputees or congenital amputees without a forearm. It offers patients intuitive and efficient control approaches, in order to extend their motor abilities and increase their autonomy when performing Activities of Daily Living.

The goal of SAM is to draw specific attention to the complex case of the “above-the-elbow” amputation level and its particularities. Indeed, transhumeral or congenital amputees who need elbow prostheses have to deal with the complex control of at least two active joints (on which little research is conducted) in addition to hand control. SAM also wants to promote the possibilities offered by non-invasive approaches, in reaction to the recent trends in invasive and surgical techniques (implanted electrodes, muscle reinnervation, etc.).

SAM possesses two motorized degrees of freedom: an active robotised wrist rotator, and an original exoskeletal active elbow especially designed for congenital amputees (missing a forearm and an elbow joint) who usually have long arm residual limb. Moreover, SAM can be fitted with any commercially available prosthetic hand.

The main innovation in SAM is not only in the hardware but rather in the embedded control architecture and the associated sensorimotor control policies that we have been working on for several years. Our innovative control strategy relies on two different control modes:

– a control based on the decoding of myoelectric contraction patterns associated with the voluntary contraction of residual muscles in arm amputees, measured with sEMG electrodes placed within the prosthesis socket.

– a control based on the body and residual limb movements of the user measured with embedded wearable inertial measurement units (IMUs). This control mode essentially relies on body compensatory strategies, in order to coordinate some of the movements of the intermediate prosthetic joints and thus achieve faster reactions and more biomimetic gestures.

These control modes can be coupled together (some joints being controlled by one mode, while some others by the other mode) to enhance the dexterity of its wearer.