Abstract
One of the most suitable ways of distributing a resistive sensor array for reading is an array with M rows and N columns. This allows reduced wiring and a certain degree of parallelism in the implementation, although it also introduces crosstalk effects. Several types of circuits can carry out the analogue-digital conversion of this type of sensors. This article focuses on the use of operational amplifiers with capacitive feedback and FPGAs for this task. Specifically, modifications of a previously reported circuit are proposed to reduce the errors due to the non-idealities of the amplifiers and the I/O drivers of the FPGA. Moreover, calibration algorithms are derived from the analysis of the proposed circuitry to reduce the crosstalk error and improve the accuracy. Finally, the performances of the proposals is evaluated experimentally on an array of resistors and for different ranges.
Highlights
There is a large range of applications which use resistive sensor arrays to obtain information about a specific system, such as temperature sensing [1,2], gas detection [3,4], tactile sensing [5,6,7,8] and others.The complexity of the electronic system necessary to read the information of the array depends on the number of sensors, the number of connections necessary to extract the information, the resistance values of each sensor, and the speed necessary to obtain this information
For circuits with maximum parallelism, if the sensors are distributed in a 2 dimensional array with lengths M for rows and N for columns, the number of wires may reach 2 ˆ M N
Each of these wires should be connected to a circuit to scan the information of a specific sensor in which the resistance value is translated into a voltage value and subsequently a digital number, meaning M N of these circuits would be required
Summary
There is a large range of applications which use resistive sensor arrays to obtain information about a specific system, such as temperature sensing [1,2], gas detection [3,4], tactile sensing [5,6,7,8] and others. An improved version of this type of circuits is the one known as improved isolated drive feedback circuit (IIDFC), proposed in [10] This solution is slower since it involves multiplying by M N the scanning time of a single sensor in order to obtain the information from all the array, to which the time necessary for multiplexing must be added. In systems such as these, the tactile sensor arrays are medium-size (in our case M = 8 and N = 6) and a scanning frequency of 250 frames per second is sufficient to correctly detect slippage [12] For this reason, a trade-off between speed and wiring complexity of the system has been chosen, meaning the information contained in all the sensors connected to a single sensor row is accessed simultaneously using six equal circuits (one per column) to obtain a digital scan of the information.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call