A Brief Review of the Electronics, Control System Architecture, and Human Interface for Commercial Lower Limb Medical Exoskeletons Stabilized by Aid of Crutches

Research in the field of the powered orthoses or exoskeletons has expanded tremendously over the past years. Lower limb exoskeletons are widely used in robotic rehabilitation and are showing benefits in the patients quality of life. Many engineering reviews have been published about these devices and addressed general aspects. To the best of our knowledge, no review has minutely discussed specifically the control of the most common used devices, particularly the algorithms used to define the function state of the exoskeleton, such as walking, sit-to-stand, etc. In this contribution, the control hardware and software, as well as the integrated sensors for the feedback are thoroughly analyzed. We will also discuss the importance of user-specific state definition and customized control architecture. Although there are many prototypes developed nowadays, we chose to target medical lower limb exoskeletons that uses crutches to keep balance, and that are minimally actuated. These are the most common system that are now being commercialized and used worldwide. Therefore, the outcome of such a review helps to have a practical insight in all of: the mechatronics design, system architecture, and control technology.