2.3. Strain gauges and data

Like many sensors, strain gauges transduce strain as a change in resistance. When implemented, this results in a small change in the voltage drop across the sensor. Most ADCs, including the OpenCM’s ADC, cannot read such small signals. A differential operational amplifier (Op-Amp) was employed to amplify the signal by a designated gain of 250 which is enough gain for the ADC to function. This Op-Amp has manually adjustable trimpots to adjust the offset, which can change over time. This is due to a variety of reasons such as the gauges themselves are susceptible to temperature fluctuations.

Strain data was filtered by a moving median filter with a window of 13 timesteps. This filter removed single-step fluctuations in the data due to electrical noise or ADC problems without affecting the strain profile over time. This filter enabled reliable collection of strain data that could be directly run through the CS model to simulate their sensory discharge.