Simulation of Codman's paradox reveals a general law of motion

Characterisation of gestural units in light of human-avatar interaction

“…This order emerges from the difference in the range of motion of each DOF involved in the schema according to its range of motion. Motion is transferred through moments of inertia attached to each DOF and as a function of (involuntary) conjoint movement of the longitudinal axis (exterior/interior rotation or pronation/supination) associated with any joint with two DOF [9,10,35]. Thus, for the GU "refuse", for example (Fig.…”

Is Codman's paradox really a paradox?

“…The Codman's paradox refers to a specific pattern of motion at the shoulder joint (Cheng, 2006). If the arm performs three consecutive rotations that result in a closedloop motion of the arm's end, its axial rotation will be different from the axial rotation in the original posture.…”

“…A possibility of clinical use in motion range diagnostics has been suggested (Cheng, 2006). Certainly measuring the swing of the arm would be easier than measuring arm's axial rotation.…”

“…A phenomenon called Codman's paradox has long been described in context of shoulder (arm) motion study and has again been discussed (Cheng, 2006). We want to dedicate this paper to Codman's paradox.…”

Conjunct rotation: Codman’s paradox revisited

“…However, the valuable aspect of conjunct rotation as described by Codman is not fully accounted for by what they call pseudo rotation. Cheng formalized his concept of two-step rotation introduced earlier [3] to explain these two aspects of rotation [2] but without explicitly referring to terms of 2D motion as done by the AAOS [1].…”