An exoskeleton ankle robotic device (10), comprising: a leg brace (12) a foot piece (13) pivotally coupling to the leg brace (12) at or proximal to an ankle position an actuator (16) coupling to the leg brace (12) and the foot piece (13) with an articulated joint (23), the actuator (16) receiving power from a power source (28) and generating torque driving the articulated joint (23) to produce relative rotatory movement between the leg brace (12) and the foot piece (13) a gear transmission system (16,17,18,19) coupling to the articulated joint (23) transmitting rotation axis of the actuator (16) and optimizing it to a place where the device becomes compact and less cumbersome when wearing an unmodified shoe at least one sensor (24,25,26,27) for providing feedback of gait phase of a user and a controller (29) for receiving the feedback of gait phase from at least one sensor (24,25,26,27) and sending command to control the actuator (16) for actively assisting the gait of the user. The exoskeleton ankle robotic device (10) can provide walking assistance in different speed and walking conditions to persons with disability in walking or muscle weakness or joint problem.Linvention concerne un dispositif exosquelette de cheville robotisé (10) qui comporte : une attelle jambière (12) un élément pied (13) se couplant de manière pivotante à lattelle jambière (12) sur ou à proximité dune position de cheville un actionneur (16) se couplant à lattelle jambière (12) et à lélément pied (13) au moyen dun raccord articulé (23), lactionneur (16) recevant de lénergie provenant dune source dalimentation (28) et générant le couple entraînant le raccord articulé (23) afin de produire un mouvement rotatif relatif entre lattelle jambière (12) et lélément pied (13) un système de transmission par engrenages (16,17,18,19) se couplant au raccord articulé (23) transmettant laxe de rotation de lactionneur (16) et permettant de loptimiser à un stade où le dispositif devient compact et moins en
