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Sensors: Touch, Force, and Torque
Published in Richard L. Shell, Ernest L. Hall, Handbook of Industrial Automation, 2000
A force-sensing resistor is a piezoresistive conductive polymer, which changes resistance in a predictable manner following application of force to its surface. It is normally supplied as a polymer sheet which has had the sensing film applied by screen printing. The sensing film consists of both electrically conducting and nonconducting particles suspended in a matrix. The particle sizes are of the order of fractions of microns, and are formulated to reduce the temperature dependence, improve mechanical properties and increase surface durability. Applying a force to the surface of a sensing film causes particles to touch the conducting electrodes, changing the resistance of the film. As with all resistive-based sensors the force-sensitive resistor requires a relatively simple interface and can operate satisfactorily in moderately hostile environments.
Robot’s Sensors and Instrumentation
Published in Jitendra R. Raol, Ajith K. Gopal, Mobile Intelligent Autonomous Systems, 2016
Force-sensing resistor (FSR) responds to the physical pressure applied on its surface. When no force is applied, the FSR depicts maximum resistance, and when force is applied, its resistance becomes less. The FSR is basically made of two layers: (i) the resistive (semi-conductive polymer) top layer and (ii) the ‘inter-digitating’ conductive electrodes on the bottom layer upon which the top layer rests. When no force is applied, the digitating area makes very little contact with each other and hence resistance is high. But when the force is applied, the top and bottom layers get squashed together, causing an increase in conductance and hence a decrease in resistance (conductance is inversely proportional to resistance).
Assessment of children’s writing features: A pilot method study of pen-grip kinetics and writing surface pressure
Published in Assistive Technology, 2023
Michal Hochhauser, Michael Wagner, Nir Shvalb
To match the sampling rates of the grip sensors (250 samples) and of the tablet’s pressure sensor, pressure data were up-sampled by linear interpolation. The force-sensing resistors’ measurement output correlates to the applied force. That is, the applied forces and the force sensitive resistor (FSR) conductance reading are linearly correlated within the defined force range of the sensor. To extract a precise estimation for the force applied, given only a limited number of correlation estimations, we used simple linear interpolation. To convert the nonscaled tablet scores and FSR scores to pressure values (i.e., Newtons), we followed the calibration procedure provided in MovAlyzeR® (NeuroScript, 2018) and the Adafruit website (lady ada, 2012), respectively. Subsequently, we tested the tool with one student to examine the feasibility of measuring additional properties, including time to write a single letter, total time of the writing task, time between letters and words (in-air), and spacing (mm) between letters and words. These variables will be explored and analyzed in a future controlled study to discriminate between children with and without handwriting difficulties.