A deforming sensing surface for evaluation of contact conditions

Presents a novel tactile sensing surface that can be used to measure the position and magnitude of point contact forces and to identify the size of contact shapes. The surface is of simple construction, applies a low number of sensing positions and a computational interpretation scheme. Experimental demonstration devices have been manufactured and use a polypropylene surface with non-contact infra-red sensors incorporated to detect the deflection of the surface. Interpretation methods described are based on simple algorithms such as neural networks and a ratio function. Accuracy is within 5% of full positional range. The method can determine force levels to within a tolerance of 0.5 N. Position and force measurement are possible with a minimum of four infra-red transducers strategically placed to reflect light from the deflecting surface. This provides a basis for low cost data entry interfaces in applications, such as keypads for control surfaces where sterility is important, and surgical operating theatre applications are an example. Safety-critical applications may benefit from the capabilities of this technology to include redundancy by incorporation of additional transducers for measuring deflection.