An Improved Zero Potential Circuit for Readout of a Two-Dimensional Resistive Sensor Array.

With one operational amplifier (op-amp) in negative feedback, the traditional zero potential circuit could access one element in the two-dimensional (2-D) resistive sensor array with the shared row-column fashion but it suffered from the crosstalk problem for the non-scanned elements' bypass currents, which were injected into array's non-scanned electrodes from zero potential. Firstly, for suppressing the crosstalk problem, we designed a novel improved zero potential circuit with one more op-amp in negative feedback to sample the total bypass current and calculate the precision resistance of the element being tested (EBT) with it. The improved setting non-scanned-electrode zero potential circuit (S-NSE-ZPC) was given as an example for analyzing and verifying the performance of the improved zero potential circuit. Secondly, in the S-NSE-ZPC and the improved S-NSE-ZPC, the effects of different parameters of the resistive sensor arrays and their readout circuits on the EBT's measurement accuracy were simulated with the NI Multisim 12. Thirdly, part features of the improved circuit were verified with the experiments of a prototype circuit. Followed, the results were discussed and the conclusions were given. The experiment results show that the improved circuit, though it requires one more op-amp, one more resistor and one more sampling channel, can access the EBT in the 2-D resistive sensor array more accurately.

[Short-term memory characteristics of vibration intensity tactile perception on human wrist].

In this study, a recall experiment and a recognition experiment were designed to assess the human wrist's short-term memory characteristics of tactile perception on vibration intensity, by using a novel homemade vibrotactile display device based on the spatiotemporal combination vibration of multiple micro vibration motors as a test device. Based on the obtained experimental data, the short-term memory span, recognition accuracy and reaction time of vibration intensity were analyzed. From the experimental results, some important conclusions can be made: (1) The average short-term memory span of tactile perception on vibration intensity is 3 ± 1 items; (2) The greater difference between two adjacent discrete intensities of vibrotactile stimulation is defined, the better average short-term memory span human wrist gets; (3) There is an obvious difference of the average short-term memory span on vibration intensity between the male and female; (4) The mechanism of information extraction in short-term memory of vibrotactile display is to traverse the scanning process by comparison; (5) The recognition accuracy and reaction time performance of vibrotactile display compares unfavourably with that of visual and auditory. The results from this study are important for designing vibrotactile display coding scheme.

[Remembrance characteristic of softness haptic perception in human fingertips].

Many applications in virtual reality and telerobot call for the implementation of displaying the human softness haptics on the object being touched. Although there are lots of literatures on discrimination threshold for displacement, force magnitude, shape and viscosity, there is still a lack of research on remembrance of softness haptic perception in human fingertips. Such research is needed in designing haptic rendering and display system. In this paper, a novel softness haptic display device based on deformable length of elastic element control was adopted as a test device to study the human fingertip's ability of remembrance of softness haptic perception. According to the recall experiment and recognition experiment, the softness haptic memory span and reaction time were discussed. From the experimental results, some important conclusions have been obtained: (1) human softness haptic memory span is 3 to 4 items, which is smaller than visual memory span and auditory memory span; (2) it is more difficult for people to remember hard objects than soft objects.