Moratuwa University develops “Compatible Joint Ankle Exoskeleton Robot”

The Bionics Laboratory of the Department of Mechanical Engineering of the University of Moratuwa has begun research to develop an ankle exoskeleton robot, named “C-JAE.”

The robot is a wearable device which combines human intelligence with mechanism to perform human ankle motions. The mechanism and drive units are placed at the foot and shank segments to carry out robotic rehabilitation and/or to provide locomotion assistance for humans having mobility impairments, the researchers said in a media release.

Currently several researches and organisations around the world are working on evolving similar kind of technologies to win back the ability to perform activities of daily living (ADL) for such physically weakened people. But in Sri Lanka, there is a lack of trend in using exoskeletons and carrying out such types of research.

C-JAE is derived from the terms ‘ Compat i ble Joint Ankle Exoskeleton’, meaning articulated robotic ankle exoskeleton with compatible joint axes to generate human ankle motions. A human ankle has three major degrees of freedom (DoF) per limb. From a kinematic point-of view, the most existent ankle exoskeletons support only one DoF. However it is vital to facilitate the ankle joint complex to generate triplanar motions. The axes of rotation of the ankle joint also have oblique angles with respect to anatomical planes of the human body. If an ankle exoskeleton supports only one motion, the natural motion patterns of the wearer can be inhibited. This will eventually have a negative influence on the overall energetic cost of transportation and prolonged exposure may lead to damages to the musculoskeletal system.

C-JAE supports all three DoF at the ankle joint using novel mechanism, while ensuring joint axes mapping for full ranges of motion. It means, with the intention of maximising user compatibility and performance, the proposed mechanism has compatible joint axes for each DOF. The robot weighs 2.6 kg without battery pack, which is comparably lightweight and user friendly than the existent devices. The highlight of C-JAE is its ability to comply with functional and ergonomics requirements of human ankle joint.

The feasibility and performance of C-JAE was evaluated using a healthy male subject, in the first stage of development. In the second stage, rehabilitation capability will be clinically tested with a suitable patient.

The project has been carried out by final year undergraduates from the Department of Mechanical Engineering - Amashi Weerasingha, Kasun Harshana and Kesara Withanage under the supervision of Prof. Ruwan Gopura and Eng. Pubudu Ranaweera, senior lecturer, Department of Mechanical Engineering, University of Moratuwa. The developers has a plan to further customise the device for commercial purposes in the perspective of improving its functionality.