Accurate modeling of low-cost piezoresistive force sensors for haptic interfaces

In this paper we present a new method for measuring forces using piezoresistive sensors. This method dramatically increases the accuracy and repeatability of the readings compared with traditional methods. These improvements will allow the common use of piezoresistive sensors in robotic applications, where only expensive and sophisticated force sensors such as load cells are currently used. We also present a sketch of a haptic interface under development, consisting of a data glove in which these force sensors are integrated. This interface is intended to control an Intelligent Assist Device by measuring operator-applied forces to the load. The new method proposed for measuring forces in piezoresistive sensors consists of reading conductance and capacitance by applying DC and sinusoidal waveforms to the sensors, thereby allow us to determine a multivariable estimation of force, instead of using the traditional, purely resistive model that has been used up to now.