RESUMEN
Objective To develop a method for localizing a detecting capsule in the gastrointestinal tract.Methods A three-axis magnetic sensor was sealed in the detecting capsule.Three flat coils were fixed on patients' back.The coils were excited one by one to generate electromagnetic fields.The position and the orientation of the capsule could be determined by telemetering the signals from the magnetic sensor incorporated in the capsule.Results The telemetric localization system worked successfully.A localization model describing the relationship between the magnetic field strength and the position and orientation of the capsule,was correctly established basing on the principle of magnetic dipoles,and neural network algorithm was employed to solve a non-linear equation set.Conclusion The results showed that the localization method is feasible and the precision is higher than existing methods.The localization device can perform consecutive tracking and can be made into a portable type.After putting into practice,the device can also be used in food selection for astronauts by monitoring their gastrointestinal parameters in space.