Curvisensors for inside and outside robot arms

When long robot arms are considered, or when improvements to their poor payload-to-weight ratio are sought, there is a need to take arrays of measurements of deflections or strains within solid members. Methods have been proposed which use interferometry with embedded optical fibres, but these are costly and have not met with successful implementation. Resistive strain gauges, on the other hand, are not particularly suited for applications on/in composite materials which one may want to consider in this case. A new fibre optic sensor is proposed with the fibre transmissivity sensitive to deflection. This transmissivity can be read using a linear optical array which gives ease of interfacing to a computer; the total system is inexpensive. The sensor gives preferential sensitivity about a chosen axis, so that vector measurements can be made with an array of such sensors