The effect of walking with elastic ankle exoskeletons on the internal force of knee and ankle

Using the passive ankle exoskeleton to reduce the energy consumption of human walking has been proposed by many researchers; however, limited knowledge of the impact of walking with the PAE on the human body has been reported. This study was to quantify the changes in the joints’ internal forces (JIFs) during assisted walking. The joint kinematic patterns must be studied as a priority, and then it was used as the input of dynamic analysis to obtain the changes of JIFs. Firstly, based on the developed human-PAE system, we simulated the PAE assisting humans walking over a series of ankle angles, and the simulation result was consistent with the experimental data that the walking angle of the ankle joint kept invariable during walking with the PAE. Furthermore, we found that the JIFs of the knee and ankle, calculated by the biomechanical modeling, decreased at different degrees. The changes in the JIFs indicated that while reducing the ankle moment of normal walking by PAE, it also brought lower JIFs. The results provided a new perspective for using the elastic elements to assist human body movement, which reduces the JIFs of humans when assisting humans walking with an elastic ankle exoskeleton.