Various advancements have been made in the development of miniature in vivo surgical robots. These robots are designed to perform Laparoendo scopic Single-Site Surgery (LESS). After being inserted through a single incision, these robots can perform surgical procedures in a dexterous workspace. Each robot consists of two halves, and each half is inserted individually through a single incision. Each half can be stepped through preset orientations as it is inserted to overcome the obstacle of limited space. Once both halves are inside the abdominal cavity, control rods protruding through the single incision allow for proper alignment. A central mounting rod is then used to mate the halves together and support the robot. The central mounting rod allows for an endoscope to be inserted through the central mounting rod, between each robot half, to provide visual feedback for surgery. The system allows for three-degree-of-freedom motion of the endoscope. Additionally, an onboard camera can be utilized. The cavity is then sealed and insulated to allow for surgery. The central control rod allows for reorientation of the robot into all four quadrants of the abdominal cavity by external rotation of the rod.

KBl.0 is a five-degree-of-freedom miniature robot. Each arm consists of a torso, upper arm, and forearm segment. The torso provides both yaw and pitch at the shoulder joint of the robot. The upper arm provides for motion of the two-degree-of-freedom elbow joint. The forearm contains an end effector that has both roll and open/close actuation. These specialized end effectors can be interchanged to provide for tissue manipulation, cautery, or suturing capabilities. This robot allows for multiple “angles of attack” for various end point positions of the end effector inside the robot workspace.

RB1.0 is a six-degree-of-freedom robot. Each arm of the robot consists of a torso, upper arm, lower arm, and forearm segment. This robot also utilizes dual end effectors on each arm. The torso utilizes one degree of freedom to provide yaw movement. The upper arm utilizes one degree of freedom to provide roll movement. The lower arm provides two degrees of freedom. One motor orientation provides two degrees of freedom to allow for yaw movement. Finally, the forearm has one-degree-of-freedom pitch capabilities. Additionally, on the forearm, the end effectors have a roll degree of freedom. Various combinations of end effectors can be used on each arm based on the need for surgery.

TB2.0 is a four-degree-of-freedom robot design based on knowledge gained from previous surgical robots. The focus of the design was to develop a simple yet durable robot capable of the forces and speeds required to perform specific surgical tasks. The arms of the robot are 5" long when fully extended, and the largest diameter of the robot is slightly larger than 1". The shoulder joint consists of a 26-mm and a 15-mm coreless permanent magnet direct current motor that actuates the pitch and yaw movements, respectively. The elbow joint is actuated by a 15-mm motor and provides yaw. Each forearm has a 6-mm motor for rotation, and a 15-mm motor for opening and closing the interchangeable specialized end effectors. The torso pieces of the robot can be oriented along any of the Cartesian principle axes (X-Y-Z) in order to allow multiple kinematic configurations. The links of each arm are shaped specifically to maximize joint range and arm workspace. The wiring to the robot will be partially integrated so that it runs though the body of the robot and exits at the back. The arms can be separated for insertion and then remated with a support rod. The support rod can then be used to grossly position the robot.

EBl.0 is a six-degree-of-freedom robot designed for maximum dexterity. The focus of the design was to develop a robot with a large dexterous workspace. The surgical robot has two symmetric halves, a right and a left arm. The two arms are separated when inserted through a single incision and then mated by a single support rod once inside the abdominal cavity. Each arm of the robot is comprised of three sections: a torso, upper arm, and forearm. Each section is responsible for two degrees of freedom. However, the forearm also includes the end effector’s degree of freedom such as open and close of a grasper, hot shear, or Ligasure, giving each arm six degrees of freedom with open and close of the end effector.

These robots can also implement resolvers at the joints. Currently, position is determined through encoders on the motors. When implemented, these resolvers will be attached to the output of the gear train to give a redundant angular position. Additionally, this information will help to determine secondary position and reduce position error.

This work was done by Shane Farritor, Dmitry Oleynikov, Ryan McCormick, Eric Markvicka, and Tyler Wortman of the University of Nebraska for Johnson Space Center. MSC-25620-1


NASA Tech Briefs Magazine

This article first appeared in the January, 2016 issue of NASA Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.