A robot navigation system based on combined two fuzzy logic controllers is developed for a mobile robot. Eight ultrasonic sensors, a GPS sensor and two fuzzy logic controllers with separate 81 rules were used to realize this navigation system. The data from sensors are used to the input of each fuzzy controller. The outputs of fuzzy controllers control the speed of two servo motors. The robot with this navigation system chooses one of two controllers based on the information from the sensors while navigating for the targets. Fuzzy controllerl has functions which are target steering, avoiding obstacles and following the edge of obstacles. Fuzzy controlle2 has a function which makes the robot keeps following the edge of obstacles. Simulation results show that a mobile robot's escaping ability from U-shaped obstacle was improved and steering ability for a target by avoiding obstacles was also improved with this combined fuzzy logic controller.