Studies in the US have shown that approximately 12% of the population aged 12-65 has trouble executing ambulant activities. Additionally muscle degeneration with age poses extra difficulties for people aged 65 and older. The latter age category is expected to expand to 34% of the population by 2050. All these people would benefit from the design of an assistive exoskeleton.
Several research groups are working on the development of assistive devices. Some are passive and can only provide limited assistance to the wearer. Others are active and actuated in the conventional way: one actuator on every joint, providing all torque requirements. This is an energy consuming way of actuation and makes that their autonomy remains rather limited. The current challenge is to combine the advantages of the above two categories of assistive devices: delivering the required amount of assistance in an energy-efficient way.
Goal of the project
The main goal of this project is to succeed in developing an actuation system that delivers sufficient assistance to the wearer in an energy-efficient way.
Human walking is an energy-efficient task: in order to lose weight one has to go for a run rather than a walk. This energy-efficiency is partly due to storage of energy in the elastic components of the muscles such as the tendons. For example when humans jump or run, energy is stored in the Achilles tendon during ground impact. Another contribution to the energy-efficiency of human walking is the presence of bi-articular muscles. These muscles span two joints and allow for energy transfer between the joints.
These mechanisms are to be mimiced in the actuation system in order to make it energy-efficient. The use of compliant actuators allows for energy storage in the elastic element and release afterwards. Elastic bi-articular elements will allow the transfer of energy between the hip, knee and ankle joint.