Pneumatic haptic interface fuzzy controller for simulation of abdominal palpations during colonoscopy

Abstract

Pneumatic control has been used for armature control of robots with pneumatic air muscles achieving accurate position control of the piston actuator with inexpensive solenoid valves. We describe a pneumatic fuzzy controller associated with a pulse width modulation conversion scheme in a novel haptic device within a colonoscopy simulation system. A rubber bladder was used to simulate forces experienced during abdominal palpation during colonoscopy. The haptic device showed good steady-state response when tested with step inputs. A settling time of 0.41s was achieved on positive control step and 0.52-0.81s for negative steps. Dynamic response was adequate for mimicking interactions during inflation stages while noticeably deficient during deflation periods. Tracking accuracy averaged 94.2% within 300 ms of the reference input while the user was actively applying abdominal palpation and minor repositioning.