Posture estimation of mobile robots: observers-sensors

In this paper the state estimation from sensors measurements for control of mobile robots is discussed. This problem is very important when in the practice many parts of the system state are inaccessible. An observer capable of estimating the state of nonlinear systems with unknown inputs can also be of tremendous use when dealing with the problem of fault detection measurement instruments, since in such systems most actuator failures can be generally modeled as unknown inputs (control) to the system. The necessary condition for observer existence is the system observability. We relate observability of states to the concept of sensors choice with respect to the control. An aspect of the concept such as observer is discussed, (known as the rank condition) observability condition is derived, and we present some simulation for wall-following in the paper