In this paper, a portable ankle robot with the design consideration of reducing the burden exerted on wearers and self-adjustable posture is presented. Firstly, by deriving the burden, namely the extra energy consumption of the wearer caused by the inertia of an ankle foot orthosis (AFO), the ideal position of the AFO’s gravity centre that reduces the burden is investigated. Secondly, according to the ideal location, the structural layout of the ankle robot is determined, and its detailed configuration is introduced. Following that, based on a 2-degree-of-freedom (DOF) foot model, the robot-human system is set up and analysed. On one aspect, the mechanism of self-adjustment of the device’s posture is illustrated. On the other aspect, the torque assistance of the device is verified by the kinetic analysis of the system. Finally, a portable robotic control system is set up and tested on a healthy subject. Results indicated the effectiveness of the system in generating adaptive reference joint trajectories and making the subject well track them.
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