The mechanism of balance assistance for lower limb exoskeleton: review and perspectives

One of the current research hotspots in lower limb exoskeletons (LLEs) is balance assistance. However, there is no systematic review to integrate the solutions and to highlight the challenges for balance and stabilization of LLEs that have been provided in previous studies. Therefore, this paper aims to integrate the approaches and identify the balance assistance/recovery strategy in various movement situations. We found that the balance strategies of LLEs are mainly focused on walking on level ground, with low coverage of most basic movement situations. Based on the available balance assistance methods, some possible future trends are presented, such as rethinking the role of humans in human-exoskeleton systems. This paper also provides a corresponding overview of the application of the stability criterion, which researchers can use as a reference to develop methods for further maintaining the balance and stability of LLEs.