Takayuki Tsuji

Multi-DOF Forceps Manipulator System for Laparoscopic Surgery - Mechanism Miniaturized & Evaluation of New Interface

The Multi-DOF forceps manipulator we developed has two additional DOF of bending on the tip of forceps, and provides new surgical fields and techniques for surgeons. The most remarkable characteristics of the prototype described in this paper are: 1) the small diameter and the small radius of curvature of bending; 2) the confirmation of perfect cleanness and sterilization of this manipulator. In this paper, we will show some new mechanisms of the forceps manipulator. Firstly, we made new mechanism of bending forceps. Using the mechanism, we made new prototype of forceps manipulator which diameter is 5mm. Secondly, we developed new concept of man-machine interface for the system. It will show the new control method and surgeons can operate surgeries with more dexterity and without confusion. We evaluated the system including new interface on typical laparosurgical procedure using simulator, and confirmed the effectiveness of this concepts.

Multi-DOF Forceps Manipulator System for Laparoscopic Surgery

Many problems in laparoscopic surgery are due to the poor degrees of freedom of movement (DOF) in controlling forceps and laparoscopes. The Multi-DOF forceps manipulator we have newly developed has two additional DOF of bending on the tip of forceps, and provides new surgical fields and techniques for surgeons. The most remarkable characteristics of the prototype described in this paper are: 1) the small diameter (∅ 6 mm) and the small radius of curvature of bending; 2) the large force generated on each bending and grasping axis; 3) the confirmation of perfect cleanness and sterilization of this manipulator. The effectiveness of these characteristics was confirmed in actual testing by surgeons. This manipulator can solve problems met with in laparoscopic surgery, and will establish new standards for laparoscopic surgery with higher effectiveness and safety.

Analysis of Forces during Robotic Needle Insertion to Human Vertebra

The purpose of this study is assessment of forces and torques required for robotic needle insertion to human vertebra. Axial forces during robotic insertion to human vertebrae fixed with formalin (water solution of formaldehyde(FA)) did not exceed 25 N when the feed rate was no more than 0.5 mm/s. There was relatively strong correlation between the axial force variation during insertion and the distribution of bone local CT-value along the needle path. This result shows the importance of preoperative X-ray CT image guidance for robotic needle insertion with safely small axial forces. There was no significant influence of FA-fixation on axial forces during robotic needle insertion to human femoral heads. The forces during robotic insertion to human femoral head were as small as less than 50% of those during manual insertion, and which indicates that the robot can contribute to the safe needle insertion to human vertebra in percutaneous vertebroplasty.

Micro-grasping Forceps Manipulator for MR-Guided Neurosurgery

Mechanical support system is needed for minimally invasive surgery, since it enables precise manipulation of surgical instruments beyond human ability in a small operation space. Furthermore, a robot available for intraoperative MRI guided neurosurgical procedures could allow less invasive and more accurate image guided surgery. By combination of precise positioning to the target by intra-operative MRI guided surgery and dexterity by the multi function micromanipulator, safe and smooth operation is expected to be performed. In this approach, we have developed MR-compatible micro-forceps manipulator of the multi-function micromanipulator system for neurosurgery. By a new cam mechanism for two degrees of bending freedom, we achieved these excellent characteristics for the micro forceps. 1) Simple mechanism suitable for a micromanipulator, 2) Precise positioning, 3) Suitable mechanism for MR compatible manipulator. By evaluation experiments, we confirmed precise positioning of the manipulator and MR compatibility of the manipulator.

Forces and torques during robotic needle insertion to human vertebra

Abstract The purpose of this study is assessment of forces and torques required for robotic needle insertion to human vertebra. Axial forces during robotic insertion to human vertebrae fixed with formalin (4% solution of formaldehyde (FA)) did not exceed 25 N when the feed rate was no more than 0.5 mm/s. There were no significant differences between mechanical properties of the bones conserved under FA-fixation and under freezing. The forces during robotic insertion to using human femoral head were as small as less than 50% of those in case of manual insertion, which indicates the safety of robotic needle insertion to human vertebra.

Automated handling system for excretion

The new automated system for excretion was developed. The system consisted of a diaper cup and control unit. The diaper cup is composed of a resin-molded cup and exchangeable diaper made of cotton cloth. The diaper cup is connected to the control unit with a suction hose, a hose for heated air, a tube for warm water and an electric lead for the sensors. The control unit is composed of a suction motor unit for excreta, a tank of warm water for washing the area surrounding the excretory organs, a collection tank for the excreta, valves and a control board for the whole unit. A reflecting light sensor for detecting faeces and an impedance sensor for detecting moisture are set in the internal part of the diaper cup. The experiments were performed for seven elderly patients and results showed that the sensor successfully detected urination. We found that the system is effective and increases the quality of life of people requiring diapers.

Development of a Robotic Laser Surgical Tool with an Integrated Video Endoscope

Integration of new surgical devices with surgery assisting robots is required by surgeons. We have developed a novel robotic laser coagulator with a charge coupled device (CCD) video endoscope and a bending joint. The endoscope visualizes the detail of the target, and bending joint realizes the irradiation in a selected direction. We adopted two laser diodes for this purpose: an infrared semiconductor laser (λ = 980 nm) for coagulation, and a visible wavelength laser (λ = 635 nm) acting as a pointer for the target. The technical originality of this work is the mounting of a laser module on the forceps without using an optical fiber or mirror guide. This reduces the danger of laser leakage at the bending joint, and realizes miniaturization in the multiarticular robot. The clinical significance is the precise positioning and intuitive operation of the laser coagulator through future integration of this tool with a master–slave robotic system. An in vivo study achieved necrosis of liver tissue, and demonstrated the feasibility of the robotic laser coagulator using a CCD video endoscope.

DEVELOPMENT OF MASTER-SLAVE ROBOTIC SYSTEM FOR LAPAROSCOPIC SURGERY

ABSTRACT Laparoscopic surgery is widely performed as a less traumatic minimally invasive surgery. It, however, requires experiences and skills for surgeons. For realizing high quality and preciseness of surgical operation, we developed a new compact slave robot in a master-slave system. It consisted of manipulator positioning arm, forceps manipulator, and bending forceps. We integrated them into a slave robot with seven DOFs. In vivo experiment was conducted to evaluate the basic motion and the feasibility.

A new compact robot for manipulating forceps using friction wheel and gimbals mechanism

We developed a compact robot for manipulating forceps using a friction wheel and a gimbals mechanism. This robot works as a small slave robot in master-slave robotic system. Rotation and translation (back and forth) of forceps was realized with “friction wheel mechanism”. This mechanism does not have limitation in transnational motion of forceps. Determination of forceps insertion direction was realized by a small gimbals mechanism with two degrees of freedom (DOF). Friction wheels had the function of both holding and driving forceps, so we succeeded in making the system compact. The size was 42mm diameter and 89mm long and 250g in weight. Gimbals mechanism realized the two DOF for determining the direction of the forceps. The size was 39mm × 54mm × 70mm and 330g in weight. We integrated the two mechanisms into a new compact robot for manipulating forceps. This manipulator is enough small to use three sets without occupying the operating space above the abdomen.

A high-speed optical mapping system to record cardiac action potential

Reentry is irregular, abnormal electrophysiological activity of a heart and is thought of major cause of electrical instability leading to cardiac sudden death. A new digital video imaging system was developed and its performance was evaluated to analyze the spiral wave dynamics during polymorphic ventricular tachycardia with high spatio-temporal resolution (1 ms, 0.1 mm).