A device for measuring plantar pressures under the sole of the foot

An apparatus is described which gives a rapid and detailed picture of the distribution of pressure under the foot with quantitative information, the pressure distribution being displayed as either a continuous grey scale or a color contour map on a television monitor. A theoretical analysis of the operating principles is given with evidence for its validity, and the practical problems associated with the more detailed aspects of the equipment are discussed. The basic system uses a glass plate illuminated at its edges by strip lights. The top surface of the glass plate is covered with a thin sheet of opaque reflective plastic on which the subject stands. When viewed from below the areas of contact of the foot can be seen with a light intensity related to the applied pressure. The image may be viewed via a mirror with a monochrome television camera and displayed on a monochrome video monitor. An interface has been developed to convert the video information from the monochrome camera into a suitable form to drive a color monitor. The resultant display on the color monitor is a pressure contour map of the pressure distribution underneath the foot.