Esophageal Peristaltic Control of a Soft-Bodied Swallowing Robot by the Central Pattern Generator

Dysphagia, the medical term for swallowing disorders, is a major problem for the elderly, leading to low quality of life, high cost of care, and at times, to death. One approach to improving the safety and efficiency of the swallowing process in dysphagic patients is to provide foods with modified viscosities. In this study, a bioinspired swallowing robot with an embedded stretchable deformation sensor matrix has been developed as an in vitro simulator to simulate the human swallowing process, with the control of a central pattern generator (CPG) model to generate peristaltic wave signals. The robot is soft bodied and pneumatically actuated, constructed from silicon rubber with layers of inflatable chambers. The CPG generated oscillations are taken as electrical signals to prescribe the pressure in the inflatable chambers. The prescribed pressure is regulated through proportional valves. The CPG is designed according to the principle of harmonic balance, and the design procedure is implemented in a graphical user interface. Based on the experimental data, a lookup table is developed to relate the input voltages for the pressure in the chambers to the robot's conduit surface deformation. A nanocomposite-based stretchable deformation sensor matrix is embedded into the swallowing robot to determine the deformation based on changes in resistance. Pressure trajectories are generated by the CPG for a desired peristaltic waveform. Three sensing pads are used to determine the conduit deformation. Conduit deformation is converted from sensors resistance changes and the results show that the CPG is able to produce the oscillatory signals needed to achieve the peristaltic wave movement in the soft-bodied swallowing robot.