Presently, most virtual reality systems use upper body parts to interact with objects in the virtual environment. This situation is caused by technological limitations of current interface devices. Starting from this viewpoint we developed a new interface for detecting ankle motions relative to the knee. We believe that hands-free navigation, unlike the majority of navigation techniques based on hand motions, has the greatest potential for maximizing the interactivity of virtual environments since navigation modes are more direct motion of the feet. We Therefore, created a simple device to detect ankle movements with rotary encoders sensors. These sensors rotate according to the amount and direction of the movement of the foot. The sensors are attached to a sandal and can be used for many purposes including virtual games. Validation of our approach is given by discussion and ilustration of some experimental results.