Frequency-Based Temperature Compensation for a Tactile Sensor Using Acoustic Reflection

In minimally invasive surgery, surgeons' tactile sense that contributes to intraoperative palpation and dexterous manipulation is strictly limited. We have previously developed a tactile sensor based on acoustic reflection for laparoscopic tumor detection. There was a major issue of the influence of ambient temperature change on the sensor output. In surgical situations, the temperature of the sensor changes from room temperature to body temperature because the sensor is inserted into the patient's body. In this study, we propose a method of temperature compensation on the basis of frequency characteristics of the sensor. It is advantageous because of no need of any additional elements, such as a temperature sensor. We first investigated the influence of ambient temperature on the sensor output through theoretical analysis and an experiment. On the basis of the results, we developed the method of the compensation, and cross validation was conducted to assess its effectiveness. Moreover, a validation test with a simulated laparoscopic setup, where a temperature gradient along the sensor prove was caused, was conducted. The results showed that the estimation error of the force applied to the sensing area was reduced by applying the proposed temperature compensation.