Postural balance, which has a big role in daily life, is generally known as one’s strength to retain stability. Balance takes advantage of the integration of multisensory inputs that work together to stabilize one’s standing. For the unable ones, it may be harder to obtain stability in postural balance. Hence, it is noteworthy to design and evaluate devices, such as orthosis, which can help these subjects experience postural balance independently and without the use of crutches. The orthosis used by these subjects should be easy-to-use, reliable and with high safety. In this research, a mathematical framework is presented which can be used to redesign the physical parameters of a Hip-Knee-Ankle-Foot-Orthosis (HKAFO) to support a better body curvature and also guarantee a more stable arm free stance. Also, since vertical vibrations is a rehabilitation method for the paraplegic subjects, an analysis is done to understand how these vibrations could be added to avoid instability in the paraplegic subjects. And finally, an approach is presented to show the hip joint torque limits which keep the body in stable stance if the hip joint of the orthosis is activated. The results of this research can be the starting point in designing an exoskeleton for the postural balance of the paraplegic subjects. Keywords Postural balance, stability, vestibular system, paraplegic subjects, passive orthosis, vertical vibrations.
