An exoskeleton device in accordance with the present disclosure may generally include a series elastic actuator (SEA), a slider-crank mechanism and a four bar linkage mechanism. The SEA includes a motor and a ball screw coupled to a shaft of the motor via a shaft coupler, which transfers rotational motion of the shaft directly to the ball screw. The slider-crank mechanism includes a ball nut and a crank. As the ball screw rotates, the ball nut converts rotational motion of the ball screw into linear motion of the ball nut to drive the crank. The crank converts linear motion of the ball nut back into rotational motion at the input of the four bar linkage mechanism. The four bar linkage mechanism is coupled to an output of the crank and configured to provide a complex motion profile that emulates kinematics of a wearer's joint.