A Miniature Continuum Robot with Integrated Piezoelectric Beacon Transducers and its Ultrasonic Shape Detection in Robot-Assisted Minimally Invasive Surgeries

Minimally invasive surgeries (MIS) or natural orifice transluminal endoscopic surgeries (NOTES) such as the transurethral resection of bladder tumor (TURBT) require the surgical robot to be miniaturized to perform surgical procedures in confined spaces. However, the surgical robot's tiny size poses problems in its fabrication and shape sensing. In this paper, a miniature continuum surgical robot is proposed with a unique laminated structure which can be fabricated through a 2D lamination process and converted into 3D through folding. This multi-material laminated structure also facilitates the integration of tiny piezoelectric transducers on the robot's surface as beacons to generate ultrasonic waves for shape detection. A novel beacon total focusing method (b-TFM) algorithm is developed to process the received ultrasonic data and create a high-quality ultrasonic image from which the shape of the continuum robot can be extracted. The proposed robot and the ultrasonic shape detection method are validated through simulations and experiments. The error in the open-loop trajectory control is less than 4 mm without compensation, and the error in the ultrasonic shape detection is less than 1 mm. This confirms the possibility of improving the trajectory control accuracy by using the detected shape as a feedback for closed-loop control.