A knowledge-based controller for an autonomous mobile robot is realized as a hierarchy of production systems. The hierarchical structure is achieved following the information hierarchy of the system. A high level path planning is possible by utilizing the incomplete world description. More detailed linguistic information, obtained from sensors that cover the close surroundings, enables the lower level planning and control of the robot motion. A linguistic model is developed by describing the relationships among the entities of the world description. This model is then transformed into the form of rules of motion control. The inexactness of the world description is modeled using the tools of fuzzy set theory, leading to a production system with a fuzzy database and a redundant rule base.