Toshikazu Kawai

Free allocation of actuator against end-effector by using flexible actuator

A new actuator system, flexible actuator (FA) is proposed in this paper. FA consists of direct drive motor and thrust wire. Thrust wire is composed of polyethylene tube and stainless-steel stranded wire. The stainless-steel stranded wire moves back and forth in the tube, and force is transmitted from actuator to end-effector. Since thrust wire has flexibility with high performance of force transferability, the physical relationship between actuator and end-effector can be decided freely. Furthermore, since this actuator has low friction, reproduction of force sensation is conducted accurately. FA is one of the fundamental device for evolution of robotics. The experimental results show the validity of the proposed mechanism

Use of a micromanipulator system (NeuRobot) in endoscopic neurosurgery

NeuRobot, a micromanipulator system with a rigid neuroendoscope and three micromanipulators, was developed for less invasive and telecontrolled neurosurgery. This system can be used to perform sophisticated surgical procedures through a small, 10-mm-diameter, window. The present study was performed to evaluate the feasibility of using NeuRobot in neuroendoscopy. Four different intraventricular neurosurgical procedures were simulated in three fixed cadaver heads using NeuRobot: (1) fenestration of the floor of the third ventricle; (2) fenestration of the septum pellucidum; (3) biopsy of the thalamus; and (4) biopsy of the choroid plexus of the lateral ventricle. Each procedure required less than 2 min, and all procedures were performed accurately. After these surgical simulations, a third ventriculostomy was carried out safely and adequately in a patient with obstructive hydrocephalus due to a midbrain venous angioma. Our results confirmed that NeuRobot is applicable to lesions in which conventional endoscopic neurosurgery is indicated. Furthermore, NeuRobot can perform more complex surgical procedures than a conventional neuroendoscope because of its maneuverability and stability. NeuRobot will become a useful neurosurgical tool for dealing with lesions that are difficult to treat by conventional neuroendoscopic surgery.

Micromanipulator system (NeuRobot): clinical application in neurosurgery

Abstract The NeuRobot, telecontrolled micromanipulator system, having a rigid neuroendoscope and three robot arms, has been developed for less invasive and telecontrolled neurosurgery. It has a capability of sophisticated surgical procedures through a small window of 10-mm width. In this paper, bipolar coagulator system, sterilization, and experience of clinical application are reported. The NeuRobot will become a promising neurosurgical tool for less invasive neurosurgery.

Development of exchangeable microforceps for a micromanipulator system

TOSHIKAZU KAWAI 1;¤, KOUJI NISHIZAWA , FUJIO TAJIMA , KAZUTOSHI KAN 1, MASAKATSU FUJIE 1, KINTOMO TAKAKURA2, SHIGEAKI KOBAYASHI 3 and TAKEYOSHI DOHI 4 1 Mechanical Engineering Research Laboratory, Hitachi, Ltd., 502, Kandatsu, Tsuchiura, Ibaraki 300-0013, Japan 2 Tokyo Women’s Medical College, 8 Kawada-cho, Shinjuku-ku,Tokyo 162-8666, Japan 3 Shinshu University, School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan 4 Faculty of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Bilateral Control in Multi DOF Haptic Surgical Robotic System Utilizing FPGA

Minimally invasive surgery is an important issue from the point of view of patients quality of life (QoL). An endoscopic surgery is one of the minimally invasive surgeries. With the endoscopic surgery, pain could be less. This operation, however, has difficulty, and surgeons have to be well trained. To solve this problem, an endoscopic surgery system based on haptic teleoperation was proposed. The characteristic of the system is position and force information is transmitted bilaterally between master and slave robots. This means that a teleoperation with haptic information can be achieved, and surgeons can perform a telesurgery safely and smoothly. The system, however, does not have enough degrees of freedom for an actual operation. In this paper, a multi degrees of freedom endoscopic robotic system is proposed. This system has 6 degrees of freedom on each master and slave robot. A haptic control system implemented in the proposed system is based on acceleration control. Due to control in acceleration dimension, robust and ideal position and force control are able to be attained simultaneously. The control system requires a short sampling period for attainment of wide bandwidth to transmit keen force sensation. To ensure the short sampling period in a multi degrees of freedom system, this paper proposes the multi degrees of freedom tele-robotic system utilizing FPGA as a controller. Finally the validity of the proposed system is shown by experimental results.

Bipolar coagulation - capable microforceps

Microforceps that can be used with the hyper utility mechatronic assistant system (HUMAN) for bipolar coagulation in minimally invasive neurosurgery were developed. A method of using two sets of those forceps for bipolar coagulation was developed, in which electrical current is passed through the drive wires to the forceps tips to form an electrical circuit. A prototype mechanism that employs a torque tube to achieve an opening and closing speed of 138/spl deg//s was fabricated. A forceps drive system that has a delay time of 0.06 s was constructed by using a fast control algorithm. In vivo experiments on rat abdomen and rat brain blood vessels confirmed that the bipolar coagulation function is of a practical level. Three neurosurgical clinicians confirmed the good operability and practicality of the gripping function in experiments on a human cadaveric brain. Furthermore, both doctors and engineers confirmed that the microforceps described here can be used in their present form in tumor removal and other such procedures. Following these basic engineering experiments, basic medical experiments (including experiments on the optimum distance between the lens of the endoscope and, the object of manipulation), various surgical procedures performed on living rat brain, surgical simulations performed on a human cadaver, and experiments on safety in ethylene oxide gas sterilization were performed. They lead to the conclusion that clinical use of the HUMAN system is feasible.

Development of HUMAN system with three micromanipulators for minimally invasive neurosurgery

Abstract A microsurgery assisting system for minimally invasive neurosurgery has been developed. Three sets of micromanipulators and a rigid endoscope are integrated together in a thin tubular insertion part. Each manipulator has three degrees of freedom and controlled through the control levers on the console. The manipulator has tubular structure, which allows a thin operating device to travel through it. It has been verified that the device can take up in-vivo tissue and the laser knife works well with the manipulator.