The central nervous system (CNS) exploits anticipatory (APAs) and compensatory (CPAs) postural adjustments to maintain the balance. The postural adjustments comprising stability of the center of mass (CoM) and the pressure distribution of the body influence each other if there is a lack of performance in either of them. Any predictable or sudden perturbation may pave the way for the divergence of CoM from equilibrium and inhomogeneous pressure distribution of the body. Such a situation is often observed in the daily lives of Multiple Sclerosis (MS) patients due to their poor APAs and CPAs and induces their falls. The way of minimizing the risk of falls in neurological patients is by utilizing perturbation-based rehabilitation, as it is efficient in the recovery of the balance disorder. In light of the findings, we present the design, implementation, and experimental evaluation of a novel 3 DoF parallel manipulator to treat the balance disorder of MS. The robotic platform allows angular motion of the ankle based on its anthropomorphic freedom. Moreover, the end-effector endowed with upper and lower platforms is designed to evaluate both the pressure distribution of each foot and the CoM of the body, respectively. Data gathered from the platforms are utilized to both evaluate the performance of the patients and used in high-level control of the robotic platform to regulate the difficulty level of tasks. In this study, kinematic and dynamic analyses of the robot are derived and validated in the simulation environment. Low-level control of the first prototype is also successfully implemented through the PID controller. The capacity of each platform is evaluated with a set of experiments considering the assessment of pressure distribution and CoM of the foot-like objects on the end-effector. The experimental results indicate that such a system well-address the need for balance skill training and assessment through the APAs and CPAs.

We present the design, implementation, and experimental evaluation of a 3 DOF robotic platform to treat the balance disorder of the patients with MS. The robotic platform is designed to allow angular motion of the ankle based on the anthropomorphic freedom in the space. That being said, such a robot forces patients to keep their balance by changing the angular position of the platform in three directions. The difficulty level of the tasks are determined based on the data gathered from the upper and lower platforms responsible for patients' reaction time against the unexpected perturbations. The upper platform instantaneously provides pressure distribution of each foot, whereas the lower platform simultaneously shares the center of mass of the patient. In this study, the kinematic and dynamic analyses, and simulation of the 3 DOF parallel manipulator is successfully implemented. The control of the proof of concept design is carried out by means of PID control. The working principle of the upper and lower platforms are verified by set of experiments.