A one-dimensional touch panel based on strain sensing

A 1-D touch panel based on strain sensing has been designed and realized as a preliminary test protocol for evaluating smart floor tile design used for indoor localization. By using elementary beam theory, it is possible to inversely compute the location of the force applied based on the outputs of strain gauges attached to each end of the touch panel. Detailed 3D finite element analyses are performed to examine the design concept and to evaluate the effect of boundary conditions and sensor gain differences, as well as possible strain gauge attachment errors. In typical practical applications, the prediction based on 1-D beam mechanics agrees with 3D finite element analysis within 3% error. However, the analytical design approach breaks down near both beam ends, reducing the effective sensing zone. The experimental data also agrees with the analytical results very well. Under an applied force of 1 N, the effective sensing zone is near 70% and the spatial resolution is between ±0.21 and ±0.37 cm. This resolution is sufficient for a finger touch device and is much higher for smart floor applications. The lessons and conclusion learned from this test stage then serve as the basis for more realistic 2D smart floor tile designs currently underway for smart building applications.