This paper presents two different approaches for developing the residual generation module of a model-based sensor fault detection (FD) system applied to the robot navigation problem. The first approach is based on the structural analysis. The second one exploits the structure of nonlinear geometric control theory to derive the nonlinear analytical redundancy (NLAR) tests for sensor navigation purposes. The robot sensor suite includes at least a Global Positioning System (GPS) antenna, an Inertial Measurement Unit (IMU), and two incremental optical encoders. Analysis of the residuals generated by these two presented methods shown that the structural analysis is the feasible way to treat the navigation sensor fault detection problem, as confirmed by the developed experimental results.