Development of a three-dimensional tactile sensor for minimally invasive instruments

This paper proposes a three-dimensional tactile sensor that can be attached to the tip of an endoscope or catheter to detect the tip contact conditions. Because conventional minimally invasive instruments (MIIs) without a sensor cannot detect the posture and applied force at the tip, operators cannot obtain accurate information during minimally invasive surgery (MIS). The sensor consists of an elastic cylinder and three strain gauges. The gauges, located on the surface of the cylinder at intervals of 120°, are used to detect deformation of the cylinder caused by contact with the inner walls of the patient's organs. The output voltage signals of the gauges are approximated by a sinusoidal function with a phase difference of 120°. The three-dimensional contact angle and applied force at the tip of the sensor can be estimated accurately from the three sinusoidal functions and measured output voltage signal from the gauges. The operating principle of the sensor is examined through several experimental conditions.