# Lower- Limb Exosuits for Rehabilitation or Assistance of Human Movement: A Systematic Review
## 4 Conclusions
### What Technologies Are Used in Lower-Limb Exosuits? It was found that active lower-limb exosuits used electric and pneumatic actuators to control movement, while passive exosuits used elastic materials for energy storage and release. The need for external power of active exosuits led to three out of nine active exosuits being tethered, limiting their range of mobility. For increasing autonomy and range of mobility, battery-powered systems were used in the remaining six active exosuits. The force transmission from actuator to human body joint was provided mostly by Bowden cables, permitting a light mechanical system with the motors being apart from the site of actuation. We suggested other materials, such as shape memory alloys or active mechanical metamaterials, as suitable materials for actuation and force transmission in future exosuits. For the control of active exosuits, sensors are used to provide input. These sensors were commercially available force, pressure or strain sensors and inertial measurement units. Biological signals, as measured by EMG or EEG, were not used to control the exosuits. We suggest the use of EMG feedback as a viable input for the control scheme. The control schemes were automatic in active exosuits, detecting the intended movement cycle and adjusted actuators accordingly, while passive exosuits did not have an active control. Weight and power consumption were deemed important, but not all studies reported these parameters. Particularly power consumption was not reported in any study, even though it is an important parameter for the dimensioning of the power supply system of the exosuit. What Are the Outcomes of Clinical Evaluations of Lower-limb Exosuits with Users Suffering from Mobility Impairment? The reported clinical outcomes of lower-limb exosuit use were overall positive. Most lower-limb exosuits addressed one articulation, with the ankle being the prevalent joint. The exosuits were mainly used by post-stroke individuals, but also to a lesser extent by osteoarthritis and trauma patients. As future fields of application, we suggested multiple sclerosis and cerebral palsy. The used test protocols were mostly focused on gait analysis using motion tracking or direct gait measurement with specific commercial systems. Additionally, balance was assessed with balance scales and muscle activity via surface EMG. Only few studies employed questionnaires to assess subjective parameters. To gather data for the design and everyday use of exosuits, it was suggested to include activity-specific tests, the evaluation of exosuit ergonomics and analysis of the intended environment for the exosuit in the test protocol. In all fields of application, the use of passive exosuits resulted in improved gait spa-tio-temporal parameters such as velocity, cadence, step length, stride length and single-limb support. Moreover, a diminished knee abduction moment was reported, which is important to prevent the progression of osteoarthritis. The use of active exosuits induced a more symmetrical body movement and reduced metabolic energy consumption during gait. Of all clinical studies reviewed, no studies about the long-term effects on impaired users were found. While short-term evaluations have been conducted, the future study of clinical long-term effects of exosuit use on an impaired user is important for the development of rehabilitation and assistive exosuit technology. Finally, a direct comparison between exoskeletons and exosuits is encouraged. This comparison might yield a list of technical advantages and issues of both systems and could lead to an implementation of improvements to replace a found issue of one system with a better solution found in the other. Conceptualization: M.A.K. and J.M.F.-L.; Data curation: M.A.K. ; Formal analysis: M.A.K. ; Funding acquisition: M.A.K. and J.M.F.-L.; Investigation: M.A.K. ; Methodology: M.A.K. and J.M.F.-L.; Project administration: J.M.F.-L.; Resources: M.A.K. and J.M.F.-L.; Software: M.A.K. ; Supervision: J.M.F.-L.; Validation: J.M.F.-L.; Visualization: M.A.K.