Biomechatronic design criteria of systems for robot-mediated rehabilitation therapy

Systems for delivering robot-mediated rehabilitation therapy are useful tools to support clinicians in providing high-intensity, repetitive, and task-specific treatment, in order to maximize the efficacy of the recovery process, especially for neurologically injured patients. Such systems are typically conceived to constantly work in constrained motion with the human body. This is a quite challenging situation for designers: physical human-robot interaction should be properly exploited and optimized, starting from the definition of adequate functional and technical specifications of the overall system up to the integration of some level of real-time, adaptive behavior of the robot that should feature an effective performance while dealing with uncertainty and complexity associated with physiopathologic conditions of human subjects. A top-down, biomechatronic design approach is consequently required to develop systems for robot-mediated therapy: in-depth modeling of the human agent, that is, the patient, must be the first step that provides basic guidance for subsequently running a typical concurrent, iterative mechatronic design cycle of mechanical, electronic, and multilayered control subsystems of the robotic therapeutic machine. The present chapter has the aim to provide an overview on biomechatronic design criteria of generic systems for robot-mediated rehabilitation therapy focused on both the upper and lower extremities. First, basic guidelines on how to build an appropriate model of the human component instrumental for robot design are briefly discussed. Then, criteria for the identification of functional and technical specifications and the selection of key components of the robotic system as a result of the application of a truly biomechatronic approach are introduced. Finally, two design case studies are presented: (a) the CBM-Motus, a planar robot for upper-limb poststroke rehabilitation, and (b) LENAR, a nonanthropomorphic wearable robot for walking assistance.