The Theoretical Analysis And Design Of A Cervical Exoskeleton Based On Spherical Parallel Mechanism For Patients With ALS

This paper aims to design an ALS(amyotrophic lateral sclerosis) cervical exoskeleton.The prototype of the mechanism is a kind of spherical parallel mechanism. The theoretical research and optimization design were studied.First, by analyzing the research status of ALS treatment and cervical care, we found that the treatment of ALS is in favor of a variety of treatment strategies, and there is no special design of cervical exoskeleton for patients with ALS. Therefore, the cervical exoskeleton which can realize three degree-of-freedom rotation of ALS patients, not only fill the cervical exoskeleton technology gaps, but also provides a new combined treatment strategy for the patients with ALS, which is of great significance.As the ALS cervical exoskeleton is research object, spherical parallel mechanism was comprehensive analysed. In order to realize three degree-of-freedom rotation of ALS patients, the 3-RRS spherical parallel mechanism ultimately used as ALS cervical exoskeleton structure prototype. The cervical exoskeleton mechanism prototype coordinate system was established, and four main design parameters were identified. On the basis of these, the position analysis of the cervical exoskeleton is performed by using the spherical analytic theory. The correctness of the position analysis is verified by drawing the curve of the relationship between the input and output.Based on the position analysis, the velocity input and output equations of the ALS cervical exoskeleton were established, and the velocity Jacobi matrix was obtained. Because of the special characteristic of the cervical exoskeleton, the virtual work principle can be directly obtained by the relationship between the driving torque and the external torque of the moving platform, thus the force Jacobi matrix of the mechanism is obtained. Based on the global performance index which is proposed by Gosselin, four kinds of performance evaluation indicators were used to judge the performance of ALS cervical exoskeleton. The performance atlases of cervical exoskeleton under different structural parameters were analyzed. In addition, through the analysis of the constraints and the boundary search method, the section working space of the cervical exoskeleton which use different design parameters was analyzed.According to the performance index, the working space and the cervical movement, the ALS cervical exoskeleton was designed for meeting the needs of patients with ALS. In the ADAMS environment, the structure model of ALS cervical exoskeleton was established. According to the actual needs, the specific parameters of ALS cervical exoskeleton were designed. A control system model was established. The Simulink and Adams co simulation verify whether the control strategy meets the needs of ALS cervical exoskeleton, and ensure the feasibility of the ALS cervical exoskeleton.