The firing activities of place cells in the rat hippocampus exhibit strong correlations to the animal's location. External (e.g. visual) as well as internal (proprioceptive and vestibular) sensory information take part in controlling hippocampal place fields. Previously it has been observed that when rats shuttle between a movable origin and a fixed target the hippocampus encodes position in two different frames of reference. This paper presents a new model of hippocampal place cells that explains place coding in multiple reference frames by continuous interaction between visual and self-motion information. The model is tested using a simulated mobile robot in a real-world experimental paradigm.