A system comprising means for filtering IMU data and calculating physical parameter related to movement data; a portable device for quantifying movements of pronation and/or supination of a person, and intended to be used when the person has the elbow on a horizontal support, said portable device comprising: • a solid armature with: - means for attaching, configured to secure one hand of the person in the device, during the movements of pronation and/or supination; - a central pivot element intended to be in contact with the horizontal support, during angular oscillations of the hand, between two opposed identical "first block angles" relative to a vertical position called "neutral position", which are defined between the solid armature and the horizontal support, the "first block angles" defining a "small amplitude", - first means for blocking the movement of pronation and the movement of supination of the elbow, at the two "first block angles"; - second means for blocking the movement of pronation and the movement of supination, at two identical opposed "second block angles" relative to the neutral position, between the solid armature relative to the horizontal support, the "second block angles" defining a "large amplitude" greater than the "small amplitude"; • an IMU configured to measure movement data among: the acceleration and/or speed, and/or angular orientation, and/or frequency of the device, at least at the two "first block angles" and at the two "second block angles"; wherein the solid armature consists of a frame with: two parallel principal parts with rigid bars mounted perpendicularly to two parallel transversal parts with transversal rods, the attaching means being mounted on the parallel transversal rods. wherein the second means for blocking are the parallel principal parts. • a solid armature with: - means for attaching, configured to secure one hand of the person in the device, during the movements of pronation and/or supination; - a central pivot element intended to be in contact with the horizontal support, during angular oscillations of the hand, between two opposed identical "first block angles" relative to a vertical position called "neutral position", which are defined between the solid armature and the horizontal support, the "first block angles" defining a "small amplitude", - first means for blocking the movement of pronation and the movement of supination of the elbow, at the two "first block angles"; - second means for blocking the movement of pronation and the movement of supination, at two identical opposed "second block angles" relative to the neutral position, between the solid armature relative to the horizontal support, the "second block angles" defining a "large amplitude" greater than the "small amplitude"; - means for attaching, configured to secure one hand of the person in the device, during the movements of pronation and/or supination; - a central pivot element intended to be in contact with the horizontal support, during angular oscillations of the hand, between two opposed identical "first block angles" relative to a vertical position called "neutral position", which are defined between the solid armature and the horizontal support, the "first block angles" defining a "small amplitude", between two opposed identical "first block angles" relative to a vertical position called "neutral position", which are defined between the solid armature and the horizontal support, the "first block angles" defining a "small amplitude", - first means for blocking the movement of pronation and the movement of supination of the elbow, at the two "first block angles"; - second means for blocking the movement of pronation and the movement of supination, at two identical opposed "second block angles" relative to the neutral position, between the solid armature relative to the horizontal support, the "second block angles" defining a "large amplitude" greater than the "small amplitude"; at two identical opposed "second block angles" relative to the neutral position, between the solid armature relative to the horizontal support, the "second block angles" defining a "large amplitude" greater than the "small amplitude"; • an IMU configured to measure movement data among: the acceleration and/or speed, and/or angular orientation, and/or frequency of the device, at least at the two "first block angles" and at the two "second block angles"; wherein the solid armature consists of a frame with: two parallel principal parts with rigid bars mounted perpendicularly to two parallel transversal parts with transversal rods, the attaching means being mounted on the parallel transversal rods. wherein the second means for blocking are the parallel principal parts.