Hideyuki Hirata

Design and experimental evaluation of a teleoperated haptic robot–assisted catheter operating system

Minimally invasive surgery and therapy is popularly used both for diagnosis and for surgery. Teleoperation, a promising surgery, is used to protect the surgeon from X-ray radiation as well as to address the problem of lacking experienced surgeons in remote rural areas. However, surgery success ratio should be considered because the surgeon was separated from the patient remotely. A most effective addressing method to improve success ratio is design of a haptic interface as a master console, which can provide the “immersive” operation to the surgeon. In this study, a haptic catheter operation system for teleoperation through exploiting magnetorheological fluids is proposed to solve the safety problem. The haptic sensation is provided by varying the viscosity of the magnetorheological fluids by adjusting the magnetic field, which is dependent on the force measured in the slave manipulator. Therefore, three parts of the haptic interface were designed and fabricated: magnetic field, magnetorheological fluids container and haptic performance calibration mechanism. Some preliminary experiments have been done to verify the effectiveness of this kind of haptic interface. Experimental results illustrated that the designed haptic catheter operation system can be used for teleoperation and for training the surgeon for the non-experience.

Design and performance evaluation of an amphibious spherical robot

This paper presents an amphibious spherical robot that consists of a sealed upper hemispheroid, two quarter spherical shells, and a plastic circular plate. It has a plastic shelf for carrying the micro-robots, and four actuating units for movement. Each unit is composed of a water-jet propeller and two servomotors, each of which can rotate 90? in the horizontal and vertical directions. The robot is capable of motion on land, as well as underwater. The robot is capable of three walking gaits; therefore, we describe experiments on various terrains to evaluate the walking motion performance, including stability and velocity. Additionally, plenty of underwater experiments are conducted to evaluate the underwater performance, containing horizontal and vertical motions, and to verify the fixture and deployment mechanism for the micro-robot. We describe an amphibious spherical robot, which is capable of motion on land, as well as underwater.The amphibious robot has two actuation systems: a quadruped walking actuation system and a water-jet actuation system.The amphibious robot can move with a relatively high velocity and for a relatively long period of time on land and underwater.The amphibious robot can carry the micro-robot, which is used as a manipulator underwater.

Safety Operation Consciousness Realization of a MR Fluids-Based Novel Haptic Interface for Teleoperated Catheter Minimally Invasive Neurosurgery

In catheter minimally invasive neurosurgery (CMINS), catheter tip collision with the blood vessel detection during the surgery practice is important. Moreover, successful CMINS is dependent on the discrimination of collision by a skilled surgeon in direct operation. However, in the context of teleoperated scenario, the surgeon was physically separated. Therefore, the lack of haptic sensation is a major challenge for a telesurgery scenario. A human operator-centered haptic interface is adopted to address this problem. In this paper, a teleoperated robotic-assisted surgery and psychophysics-based safety operation consciousness theory was presented. Moreover, a human operator-centered haptic interface design concept is first introduced into actuator choice and design. A semiactive haptic interface was designed and fabricated through taking full advantage of MR fluids. Furthermore, a mechanical model (force/torque model) was established. In addition, in case of no collision, transparency of a teleoperated system was realized; in case of collision, psychophysics-based collision discrimination control scheme was first presented to provide safety operation consciousness. Experiments demonstrate the usability of the designed haptic interface and correctness of the safety operation consciousness control scheme.

Comparison of sEMG-Based Feature Extraction and Motion Classification Methods for Upper-Limb Movement

The surface electromyography (sEMG) technique is proposed for muscle activation detection and intuitive control of prostheses or robot arms. Motion recognition is widely used to map sEMG signals to the target motions. One of the main factors preventing the implementation of this kind of method for real-time applications is the unsatisfactory motion recognition rate and time consumption. The purpose of this paper is to compare eight combinations of four feature extraction methods (Root Mean Square (RMS), Detrended Fluctuation Analysis (DFA), Weight Peaks (WP), and Muscular Model (MM)) and two classifiers (Neural Networks (NN) and Support Vector Machine (SVM)), for the task of mapping sEMG signals to eight upper-limb motions, to find out the relation between these methods and propose a proper combination to solve this issue. Seven subjects participated in the experiment and six muscles of the upper-limb were selected to record sEMG signals. The experimental results showed that NN classifier obtained the highest recognition accuracy rate (88.7%) during the training process while SVM performed better in real-time experiments (85.9%). For time consumption, SVM took less time than NN during the training process but needed more time for real-time computation. Among the four feature extraction methods, WP had the highest recognition rate for the training process (97.7%) while MM performed the best during real-time tests (94.3%). The combination of MM and NN is recommended for strict real-time applications while a combination of MM and SVM will be more suitable when time consumption is not a key requirement.

Design of a Novel Telerehabilitation System with a Force-Sensing Mechanism

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist–patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist’s motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients’ safety is guaranteed by monitoring the motor’s current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients’ safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

A virtual‐reality simulator and force sensation combined catheter operation training system and its preliminary evaluation

Endovascular surgery benefits patients because of its superior short convalescence and lack of damage to healthy tissue. However, such advantages require the operator to be equipped with dexterous skills for catheter manipulation without resulting in collateral damage. To achieve this goal, a training system is in high demand.

A virtual reality-based method of decreasing transmission time of visual feedback for a tele-operative robotic catheter operating system.

An Internet‐based tele‐operative robotic catheter operating system was designed for vascular interventional surgery, to afford unskilled surgeons the opportunity to learn basic catheter/guidewire skills, while allowing experienced physicians to perform surgeries cooperatively. Remote surgical procedures, limited by variable transmission times for visual feedback, have been associated with deterioration in operability and vascular wall damage during surgery.

A novel hybrid microrobot using rotational magnetic field for medical applications

Magnetically actuated microrobots for such tools have potential accomplish procedures in biological and medical applications. In this paper, a novel magnetically actuated hybrid microrobot with hybrid motion driven by an electromagnetic actuation system has been proposed. An o-ring type permanent magnet is embedded in the hybrid microrobot as an actuator driven by rotational magnetic field which is generated by a 3 axes Helmholtz coils. It is composed by two motion mechanisms. One is the spiral jet motion moved by rotating its body. The other one is fin motion moved by vibrating its body. Because only one permanent magnet is used inside the hybrid microrobot, two motions can be controlled separately without any interference. The hybrid microrobot can change its two motions to realize multi-DOFs movement and flexibility motion. The verified experiments are conducted in the pipe. The experimental results indicate that the moving speed can be controlled by adjusting the magnetic field changing frequency and the direction of motion can be controlled by changing the magnetic field direction.

Electromyography-Based Quantitative Representation Method for Upper-Limb Elbow Joint Angle in Sagittal Plane.

This paper presents a quantitative representation method for the upper-limb elbow joint angle using only electromyography (EMG) signals for continuous elbow joint voluntary flexion and extension in the sagittal plane. The dynamics relation between the musculotendon force exerted by the biceps brachii muscle and the elbow joint angle is developed for a modified musculoskeletal model. Based on the dynamics model, a quadratic-like quantitative relationship between EMG signals and the elbow joint angle is built using a Hill-type-based muscular model. Furthermore, a state switching model is designed to stabilize the transition of EMG signals between different muscle contraction motions during the whole movement. To evaluate the efficiency of the method, ten subjects performed continuous experiments during a 4-day period and five of them performed a subsequent consecutive stepping test. The results were calculated in real-time and used as control reference to drive an exoskeleton device bilaterally. The experimental results indicate that the proposed method can provide suitable prediction results with root-mean-square (RMS) errors of below 10° in continuous motion and RMS errors of below 10° in stepping motion with 20° and 30° increments. It is also easier to calibrate and implement.

Mechatronic System and Experiments of a Spherical Underwater Robot: SUR-II

This paper describes the structural design of the SUR-II spherical underwater robot. A spherical shape was adopted due to its outstanding shock resistance and flexibility. We designed and developed vectored water-jet thrusters to implement 4-degrees-of-freedom (4-DOF) underwater motion while saving energy. Because each thruster provided 2-DOF motion, three were sufficient for 4-DOF motion. Therefore, the propulsion system was composed of three vectored water-jet thrusters mounted on an equilateral triangular support. A master–slave structure was employed for the electrical design to realize data collection and motion control. The master side was used for the sensor data collection and control algorithm, and the slave side was used to control the propulsion system. After examining the performance of a first-generation electrical system, we chose a more powerful master processor to allow for a more complicated control algorithm. A microelectromechanical system (MEMS) inertial measurement unit replaced the original gyroscope to collect the attitude angle for the three axes. A Kalman filter was used to calibrate the data output and reduce the noise of the MEMS sensor. A series of underwater motion experiments were carried out to test the performance of the spherical underwater robot; these included surge motion, yaw motion, depth control, and multiple-depth control tests. A proportional–derivative (PD) controller was used to control the direction of the vectored water-jet thrusters for underwater motion. The experimental results demonstrated that the spherical underwater robot could realize underwater motion by controlling the direction of the thrusters. However, the robot was not very stable because the change in the propulsive force was nonlinear.