川村 和也

BACKGROUND: Respiratory rehabilitation reduces breathlessness from patient with respiratory dysfunction. Chest expansion score, which represents the circumference magnitude of the thoracic cage, is used for a target when treating patients with respiratory disease. However, it is often difficult for patients to understand the changes in the respiratory status and be motivated for therapy continuously. We developed a new measurement system with biofeedback named BREATH which shows chest expansion scores in real time. The purpose of this study was to determine the reliability and validity of the novel system in advance of clinical application. METHODS: Three evaluators measured chest expansion in 33 healthy individuals using tape measure, which is used for the measurement traditionally, and BREATH. The wire for BREATH system was threaded over the thoracic continuously and the data was recorded automatically; whereas the tape was winded and measured each maximal expiration and inspiration timing by evaluator. All participants were performed both measurement simultaneously for three times during deep breath. In this study, we studied chest expansion score without using biofeedback data of BREATH to check the validity of the result. To confirm intra- and inter-evaluator reliability, we computed intra-class correlations (ICCs). We used Pearson's correlation coefficient to evaluate the validity of measurement result by BREATH with reference to the tape measure results. RESULTS: The average (standard deviation) chest expansion scores for all, men and women by the tape measure were 5.53 (1.88), 6.40 (1.69) and 5.22 (1.39) cm, respectively, and those by BREATH were 3.89 (2.04), 4.36 (1.83) and 2.89 (1.66) cm, respectively. ICC within and among the three evaluators for BREATH and the tape measure were 0.90-0.94 and 0.85-0.94 and 0.85 and 0.82, respectively. The correlation coefficient between the two methods was 0.76-0.87. CONCLUSION: The novel measurement system, BREATH, has high intra- and inter-evaluator reliabilities and validity; therefore it can lead us more effective respiratory exercise. Using its biofeedback data, this system may help patients with respiratory disease to do exercises more efficiently and clinicians to assess the respiratory exercise more accurately.

In this study, we developed a robotic heartbeat simulator which is able to simulate a heartbeat for quantitative evaluation of availability and safety of the master-slave surgical robot system with heartbeat synchronization mechanism. We got a design specification of the robotic heartbeat simulator from in vivo measurement by using an experimental animal (pig). Based on the specification, we fixed a parallel mechanism link parameter of the robotic heartbeat simulator by genetic algorithm (GA). We measured the working space of the robotic heartbeat simulator and we confirmed that the robotic heartbeat simulator has the desired operating range. Furthermore, we conducted heartbeat simulation experiment by the developed robot. The results showed that a maximum value of cross-correlation function between desired trajectory and measured trajectory was 0.98-0.99 in x, y, z, roll and yaw axis, 0.89 in pitch axis. By this result, we revealed that the robotic heartbeat simulator has a high performance to simulate a heartbeat.

We have been developing the Orthopaedic physical examination assisting system using magnetic position tracker to quantitate knee laxity diagnosis. In this study, to investigate the influence of anatomical landmark sampling error for bone coordinate registration, reproducibility verification simulation was done. Firstly, the motion data of imitation bones was acquired using the system and set as a reference data. To get the error motion data, virtual error vectors were added on the reference sampling points and new motion data was recomputed. Evaluation was executed by comparison with the reference data and recomputed data. The evaluation results lead improvement methods of measurement reproducibility as follows. 1. It is important to point the landmarks proximal to the knee carefully because the contribution of the motion error is higher than the distal landmarks. 2. To reduce the registration error, thigh and shank receivers should be set close to the knee as possible. 3. If the allowance area of the sampling error is in 2.0 mm diameter circle, Diagnosis error using IKDC Knee examination form is approximately 20 %.

Our research is focused on the home healthcare support system for motor function impaired persons (MIPs) whose motor function should be closely monitored during either in-hospital or at-home training therapy process. Especially, for the at-home monitoring, the demand of which is increasing, not only close observation, but also accurate behavior recognition of daily living activity, as well as motor function evaluation, are necessary. In this study, such a system was established by developing a cost-effective, safe and easy to use mobile robot. With such a robotic monitoring system, the in-hospital time for most MIPs and the burden to therapists can be significantly decreased. In order to realize the robotic monitoring system, we proposed several algorithms to solve the difficulties arising from the mobile sensing for moving MIPs, and recognize several frequent daily living activities, including impaired walking. Concretely, algorithms to use both color images and depth images was proposed to improve the accuracy of MIPs measurement, and a Hidden Markov Model (HMM) was implemented to deal with the uncertainty on time sequence data and relate the state transitions over time for daily living activity recognition. Experiments have demonstrated promising results on joint trajectory measurement, and recognition of daily living activities. © 2013 Springer-Verlag Berlin Heidelberg.

The objective of this study is building the systems which can prescript desirable leg orthosis for leg paralyzed patients. In this paper we build leg muscular estimate model by using Bayesian network. Our method can estimate activity level of muscle using only two kinds of parameter. Sole pressure distribution and Joint angle. And this method has three advantages. Our use of 10% increments in the levels of the measured factors enabled changes in these factors during gait to be reflected in the model. Variations in the influence of factors that differ between low and high muscle activity are represented. It is easier to use than physical models; three- dimensional motion analysis is not necessary and the method is convenient for clinical use. We estimate healthy person's leg muscular activity, and leg paralyzed person's leg muscular activity by using our model. The accuracy of healthy person model estimation is over 90%. And the accuracy of leg paralyzed model estimation is over 85%.

Surgical robots have undergone considerable improvement in recent years. But intuitive operability, which represents user interoperability, has not been quantitatively evaluated. With the aim of designing a robot with intuitive operability, we thus propose a method for measuring brain activity to determine intuitive operability. The purpose of this paper is to clarify the master configuration against the position of the monitor that best allows user to perceive the manipulator as part of his own body. We assume that the master configuration provides immersive reality to user as if he puts own arm into the monitor. In our experiments, subjects controlled the hand controller to position the tip of the virtual slave manipulator on a target in the surgical simulator and we measured brain activity using brain imaging devices. We carried out experiments a number of times with the master manipulator configured in a variety of ways and the position of the monitor fixed. We found that the brain was significantly activated in all subjects when the master manipulator was located behind the monitor. We concluded that the master configuration produces immersive reality through body images related to visual and somatic sensory feedback.

The mobility-aid is important for the people with severe disability, especially, the child with sever cerebral palsy. In this article, interactive learning system between human and robot is applied for an electric powered wheelchair of the person with severe cerebral palsy. The user, that is, human, understands how to control wheelchair whose input signal is an acceleration data attached at right foot with feeling wheelchair' movement. The robot, that is, wheelchair, understands user's obscure foot movement using a self organizing map. The effectiveness of proposed interactive learning system was evaluated by the experiments with 10 healthy subjects and a child with severe cerebral palsy.

Recently, increased attention has been focused on single port endoscopic surgery (SPS). We have developed a robotic system for SPS with two surgical manipulators: an endoscopic manipulator and a positioning manipulator that moves the endoscope. The robot can manipulate both the position and orientation of the endoscope to achieve the desirable endoscopic field of view. Two methods can be used to operate the endoscopic view: "control corresponding to position" mode and "control corresponding to velocity" mode. Although both are widely used for moving the visual field, the operability of each method has not been examined quantitatively. Thus, we compare the operability of the two methods for adjusting the endoscopic view, and present the results and suitable applications of each method. The results of the quantitative evaluation experiments show that the "control corresponding to position" mode is suitable for short-distance or precise adjustment of the endoscope, whereas the "control corresponding to velocity" mode is better suited to long-distance movement.

In this paper, by means of a statistical method, we use sole pressure on each part, angle of joint, femoral and crural muscle activities to produce a new foot muscle activity model for use in the design of ankle-foot orthoses. We built a Bayesian network model[1] by examining the normal gait of a nondisabled subject. We measured the activity of the lower foot muscles using electromyography, joint angles and the pressure on different parts of the sole. From these data, we built three models, representing the stance phase, the control phase and the propulsive phase. The accuracy of these models was confirmed. The largest feature of this model is making every 10% level nodes of each measurement data. Normal Bayesian network can estimate only muscle active or not active. But this method can estimate activity level of muscle. From this feature this method has three advantages. First, our use of 10% increments in the levels of the measured factors enabled changes in these factors during gait to be reflected in the model. Second, variations in the influence of factors that differ between low and high muscle activity are represented. Third, it is easier to use than physical models; three-dimensional motion analysis is not required and the method is convenient for clinical use. In an evaluation of this model, we confirmed that this model can estimate all muscular activity level with an accuracy rate greater than 95%.

In the present paper, we examine the appropriateness of a new model to examine the activity of the foot in gait. We developed an estimation model for foot-ankle muscular activity in the design of an ankle-foot orthosis by means of a statistical method. We chose three muscles for measuring muscular activity and built a Bayesian network model to confirm the appropriateness of the estimation model. We experimentally examined the normal gait of a non-disabled subject. We measured the muscular activity of the lower foot muscles using electromyography, the joint angles, and the pressure on each part of the sole. From these data, we obtained the causal relationship at every 10% level for these factors and built models for the stance phase, control term, and propulsive term. Our model has three advantages. First, it can express the influences that change during gait because we use 10% level nodes for each factor. Second, it can express the influences of factors that differ for low and high muscular-activity levels. Third, we created divided models that are able to reflect the actual features of gait. In evaluating the new model, we confirmed it is able to estimate all muscular activity level with an accuracy of over 90%.

Surgical robots have improved considerably in recent years, but intuitive operability, which represents user inter-operability, has not been quantitatively evaluated. Therefore, for design of a robot with intuitive operability, we propose a method to measure brain activity to determine intuitive operability. The objective of this paper is to determine the master configuration against the monitor that allows users to perceive the manipulator as part of their own body. We assume that the master configuration produces an immersive reality experience for the user of putting his own arm into the monitor. In our experiments, as subjects controlled the hand controller to position the tip of the virtual slave manipulator on a target in a surgical simulator, we measured brain activity through brain-imaging devices. We performed our experiments for a variety of master manipulator configurations with the monitor position fixed. For all test subjects, we found that brain activity was stimulated significantly when the master manipulator was located behind the monitor. We conclude that this master configuration produces immersive reality through the body image, which is related to visual and somatic sense feedback.

The objective of this study is to develop an estimation model of foot-ankle muscular activity for designing an ankle-foot orthosis with a training function. We built a Bayesian network model [1] and chose three muscles to confirm its effectiveness. Such a model needs to include all factors affecting the gait, for example, speed reflex movements, joint angles and so forth. In an experiment, we examined the normal gait of a non-disabled subject. We measured the muscular activity of the lower foot muscles by electromyography, the joint angles by using statistical methods, and the sole pressure on each part of the sole. From this data, we obtained the causal relationship at every 10% level of these factors. Our model has three advantages. First, it can express the influences, which change throughout the gait, because we use 10% level nodes of each factor. Second, it can express the influences of factors, which are different for low and high muscular activity levels. Last, the model can compensate the missed estimations by estimating every 10% level muscle activity. In an evaluation of this model, we confirmed that this model can estimate all muscular activity level with an accuracy rate greater than 90%. © 2012 IEEE.

Surgical robot has been considerable improvement in recent years, but their intuitive operability, representing user interoperability, has yet to be quantitatively evaluated. Thus, we propose a method for measuring brain activity to determine intuitive operability so as to design a robot with intuitive operability. The objective of this paper is to determine the angle and radius between the endoscope and the manipulator that allows users to perceive the manipulator as part of their body. In the experiments, subjects moved the hand controller to position the tip of the virtual slave manipulator on the target in the surgical simulator, measured the brain activity through brain imaging devices. The experiment was carried out a number of times with the virtual slave manipulator configured in a variety of ways. The results show that brain activation is significantly greater with a particular slave manipulator configuration. It concludes that the hand-eye coordination between the body image and the robot should be closely matched in the design of a robot with intuitive operability.

Needle insertion treatments for liver tumors require accurate placement of the needle tip into the target tissue. However, it is difficult to insert the needle into the tissue because of tissue displacement due to organ deformation. Thus, path planning using numerical simulation to analyze organ deformation is important for accurate needle insertion. The objective of our work was to develop and validate a viscoelastic and nonlinear physical liver model. First, we present a material model to represent the viscoelastic and material, nonlinear properties of liver tissue for needle insertion simulation. Material properties of liver tissue were measured using a rheometer and modeled from the measured data. The liver viscoelastic characteristics were represented by differential equations, including the fractional derivative term. Next, nonlinearity with respect to the fractional derivative was measured, and the stress–strain relationship using a cubic function was modeled. Second, the experimental method to validate the model is explained. In vitro experiments that made use of porcine liver were conducted for comparison with the simulation using the model. Results of the in vitro experiment showed that the liver model reproduced with high accuracy (1) the relationship between needle displacement and force during needle insertion, (2) the velocity dependence of needle displacement and force when a puncture occurred and (3) the nonlinear and viscoelastic responses of displacement at an internally located point.

We present a material model to represent the viscoelastic and material, nonlinear properties of liver tissue for needle insertion simulation. Material properties of liver tissue were measured using a rheometer and modeled from the measured data. The liver viscoelastic characteristics were represented by differential equations, including the fractional derivative term. Next, nonlinearity with respect to the fractional derivative was measured, and the stress-strain relationship using a cubic function was modeled. The material properties of liver tissue were represented by a simple equation with only a few parameters. We evaluated the variety of each stiffness parameter from measurements of 50 samples. The results showed a high degree of variation in each stiffness parameter, especially with respect to nonlinearity. Moreover, each parameter had a low correlation coefficient. We also modeled the probability of variation in material properties from these results to provide a basis for deformation simulations considering individual patient differences. © 2012 by JSME.

Improvement of thoracic mobility is important for patients with diseases such as chronic obstructive pulmonary disease (COPD). Chest expansion training is often conducted to increase the thoracic excursion. However, it is difficult for the patients to keep the motivation for rehabilitation, because the chest excursion is only measured. In this paper, we analyze the effect of real-time biofeedback on thoracic excursion. In 30 healthy subjects, thoracic excursion was increased by 6 mm (17%) when using the biofeedback system. Our results confirmed that we have developed an effective system for rehabilitation of respiratory function. © 2012 by JSME.

The objective of this study is to develop an estimation model of foot-ankle muscular activity for designing an ankle-foot orthosis with a training function. We built a Bayesian network model [1] and chose three muscles to confirm its effectiveness. Such a model needs to include all factors affecting the gait, for example, speed reflex movements, joint angles and so forth. In an experiment, we examined the normal gait of a non-disabled subject. We measured the muscular activity of the lower foot muscles by electromyography, the joint angles by using statistical methods, and the sole pressure on each part of the sole. From this data, we obtained the causal relationship at every 10% level of these factors. Our model has three advantages. First, it can express the influences, which change throughout the gait, because we use 10% level nodes of each factor. Second, it can express the influences of factors, which are different for low and high muscular activity levels. Last, the model can compensate the missed estimations by estimating every 10% level muscle activity. In an evaluation of this model, we confirmed that this model can estimate all muscular activity level with an accuracy rate greater than 90%.

Recent design methods for surgical robots suffer from an inherent problem. In these methods, the surgeon's operation manner is not considered when designing the robotic mechanism. As such, it is possible that a non-user-friendly robot is developed for surgeons to operate. To solve this problem, we developed a system that takes into consideration the surgeon's operation manner during the design phase of the robot. Using this system, we can operate a simulated robot with any mechanisms and can search a mechanism that is user-friendly in terms of the surgeon's operation manner. In the experiments, we investigated the need for considering the surgeon's operation manner when designing a surgical robot. The results clearly show there is indeed such a need.

In this paper we develop an estimation model of foot-ankle muscular activity for designing an ankle-foot orthosis. We used Baysian network for building the model and evaluate the model. Especially we talk about conformity with actual muscle activity. Our model has three advantages. First, it can express the influences, which change throughout the gait, because we use 10% level nodes of each factor. Second, it can express the influences of factors, which are different for low and high muscular activity legels. Last, the model can compensate the missed estimations by estimating every 10% level muscle activity. In an evaluation of this model, we confirmed that this model can estimate all muscular activity level with an accuracy rate greater than 90%.

In gait rehabilitation, achieving a gait analysis method using a simple system during long-distance walking is important. This method is required to measure all gait parameters in a single measurement. In addition, it is required that the measurement system is not spatially constrained. Therefore, we have been developing a gait tracking system with acceleration sensors for long-distance gait rehabilitation. In this paper, we describe a gait phase detection method using foot acceleration data for estimating ground reaction force during long-distance gait rehabilitation. To develop this method, we focused on the jerk of each foot in vertical axis direction. Using two accelerometers mounted on the left and right feet, we carried out three experiments. First, we measured the jerk of each foot during a free gait to verify the relation with the walking speed. Second, we measured the jerk of each foot during walking faster than normal for each subject. We then compared these results with the results of first experiments. Finally, we measured the jerk of each foot during left-right asymmetrical walking. The results confirmed that gait phase could be detected using the jerk of each leg, calculated from acceleration data in vertical axis direction. In particular, the timing of Heel-contact / Toe-off could be obtained with an average error of 0.03 s. And as a preliminary study, we estimated the ground reaction force using the one of the results.

Patients with diseases such as chronic obstructive pulmonary disease (COPD) need to improve their thorax mobility. Thoracic ROM is one of the simplest and most useful indexes to evaluate the respiratory function. In this paper, we have proposed the prototype of a simple thoracic ROM measurement system with real-time visual bio-feedback in the chest expansion test. In this system, the thoracic ROM is measured using a wire-type linear encoder whose wire is wrapped around the thorax. In this paper, firstly, the repeatability and reliability of measured thoracic ROM was confirmed as a first report of the developed prototype. Secondly, we analyzed the effect of the bio-feedback system on the respiratory function. The result of the experiment showed that it was easier to maintain a large and stable thoracic ROM during deep breathing by using the real-time visual biofeedback system of the thoracic ROM.

A number of upper limb amputees experience difficulty in picking up a food bowl during a meal, because grip force estimation using EMG currently does not provide sufficient accuracy for this task. In this paper, we propose a grip force estimation system that allows amputees to pick up a bowl with a prosthetic hand by using the properties of muscle stiffness in addition to EMG. We have chosen a tray holding task to evaluate the proposed system. A weight is dropped on the tray and the subjects are expected to control the tray's attitude during the task. Actual grip force, EMG, and muscle stiffness are measured, and the actual measured grip force is compared with the estimated grip force for evaluation. As a result, the proposed algorithm is found to be able to estimate grip force with an error of just 18[N], which is 30% smaller than in the method that uses only EMG. From the result that the response time estimated by proposed system is even less than a human's mechanical reaction time, the effectiveness of the proposed method has been validated.

Medical technology has advanced with the introduction of robot technology, which facilitates some traditional medical treatments that previously were very difficult. However, at present, surgical robots are used in limited medical domains because these robots are designed using only data obtained from adult patients and are not suitable for targets having different properties, such as children. Therefore, surgical robots are required to perform specific functions for each clinical case. In addition, the robots must exhibit sufficiently high movability and operability for each case. In the present study, we focused on evaluation of the mechanism and configuration of a surgical robot by a simulation based on movability and operability during an operation. We previously proposed the development of a simulator system that reproduces the conditions of a robot and a target in a virtual patient body to evaluate the operability of the surgeon during an operation. In the present paper, we describe a simple experiment to verify the condition of the surgical assisting robot during an operation. In this experiment, the operation imitating suturing motion was carried out in a virtual workspace, and the surgical robot was evaluated based on manipulability as an indicator of movability. As the result, it was confirmed that the robot was controlled with low manipulability of the left side manipulator during the suturing. This simulation system can verify the less movable condition of a robot before developing an actual robot. Our results show the effectiveness of this proposed simulation system.

Recent development methods for surgical robots have an inherent problem. The user-friendliness of operating robot cannot be revealed until completion of the robot. To assist the design of a surgical robot that is user-friendly in terms of surgeon's operation, we propose a system that considers the operation manner of surgeon during the design phase of the robot. This system includes the following functionality: 1) a master manipulator that measures the operation manner of the surgeon (operator), and 2) a slave simulator in which the mechanical parameters can be configured freely. The operator can use the master manipulator to operate the slave simulator. Using this system, we investigate the necessity of considering the operator's manner when developing a surgical robot. In the experiment, we used three instruments with mechanisms that differed with respect to the length between bending joints and measured the trajectory of each instrument tip position during the surgical task. The results show that there are differences in the trajectories of each mechanism. Based on the results, changes in the mechanism of the surgical robot influenced the operator's manner. Therefore, when designing the mechanism for a surgical robot, there is a need to consider how this influences the operator's manner.

The objective of this study is to develop a 3D ankle-foot model containing toe expression for designing an AFO (ankle-foot orthosis) with a training function. Two experiments were conducted to (1) show the influence of toes by comparing walking with and without an AFO, and (2) clarify the functions of toes during walking by correlating the activity of the major muscles controlling the ankle and the toes to the sole pressure data during walking. By analyzing the results of these two experiments, the necessary components and conditions of a detailed 3D foot-ankle model for developing an AFO with a training effect were clarified. A model was built and examined with empirical facts, and data were collected from the AFO simulation.

In this paper, a master-slave surgical robot system with heartbeat synchronization mechanism for off-pump CABG suturing operation is developed. This robot system is composed of a master manipulator, a slave manipulator, a heartbeat sensing system and a compact flexible endoscope system. The heartbeat sensing system measures 6 DOF heartbeat motion in real-time. The position of the slave manipulator is controlled as synchronizing with heartbeat. The compact flexible endoscope is fixed to a heart using a soft coupling which is used in medical case, so that the relative position between a heart and the compact flexible endoscope is maintained constant. Moreover, the surgical robot system is controlled in master-slave control method for surgeon's tele-operation. Therefore this system is able to perform surgical procedure while the system synchronizes with the heartbeat. In order to evaluate the performance of the system, the synchronization ability test, the master-slave operation test in vivo, and the performance of suturing operation under synchronization were conducted. In the result of the first test, it was showed that the maximum error between desired position and experimental position in the synchronization control was less than 1mm. In the second test, it was confirmed that the system was able to suture a pericardia, which was not beating. In the third test, it became clear that the maximum error between the desired position and experimental position was less than 1.24 to 2mm and the system was able to suture an isolated tissue which was driven by a robotic heartbeat phantom in 1Hz.

We have been developing the Orthopaedic physical examination assisting system using magnetic position tracker to quantitate knee laxity diagnosis. In this study, to investigate the influence of anatomical landmark sampling error for bone coordinate registration, reproducibility verification simulation was done. Firstly, the motion data of imitation bones was acquired using the system and set as a reference data. To get the error motion data, virtual error vectors were added on the reference sampling points and new motion data was recomputed. Evaluation was executed by comparison with the reference data and recomputed data. The evaluation results lead improvement methods of measurement reproducibility as follows. 1. It is important to point the landmarks proximal to the knee carefully because the contribution of the motion error is higher than the distal landmarks. 2. To reduce the registration error, thigh and shank receivers should be set close to the knee as possible. 3. If the allowance area of the sampling error is in 2.0 mm diameter circle, Diagnosis error using IKDC Knee examination form is approximately 20 %.

In this study, to improve accuracy and reproducibility of knee laxity diagnosis, Orthopaedic physical examination assisting system was developed. The system enables the surgeon to monitor the force vector added by himself and the posture of the knee in real-time. The advantage of the developed system is to quantify the normal orthopaedic physical examination, without any modification, which is accustomed to general orthopaedic surgeons. The force vector added to the shank by a surgeon is measured with 3 axis force sensor and 6DOF magnetic tracker FASTRAK, and 6DOF knee joint motion of the patient is measured with two FASTRAK receivers which are attached on its thigh and shank. In this system, to describe the 6DOF knee motion, Femoral and tibial coordinate systems are defined with bony landmark which is easily palpated and are registered to the thigh or shank receiver coordinate system by homogeneous transformation matrix which is acquired by the special stylus. To evaluate the effectiveness of the system, the posterior drawer test with the system was done by 5 young healthy people. The evaluation parameters were knee posture, load magnitude and load position during the experiment. The result showed examination accuracy was significantly improved in all evaluation parameters.

In this study, to improve accuracy and reproducibility of knee laxity diagnosis, Orthopaedic physical examination assisting system was developed. The system enables the surgeon to monitor the force vector added by himself and the posture of the knee in real-time. The advantage of the developed system is to quantify the normal orthopaedic physical examination, without any modification, which is accustomed to general orthopaedic surgeons. The force vector added to the shank by a surgeon is measured with 3 axis force sensor and 6DOF magnetic tracker FASTRAK, and 6DOF knee joint motion of the patient is measured with two FASTRAK receivers which are attached on its thigh and shank. In this system, to describe the 6DOF knee motion, Femoral and tibial coordinate systems are defined with bony landmark which is easily palpated and are registered to the thigh or shank receiver coordinate system by homogeneous transformation matrix which is acquired by the special stylus. To evaluate the effectiveness of the system, the posterior drawer test with the system was done by 5 young healthy people. The evaluation parameters were knee posture, load magnitude and load position during the experiment. The result showed examination accuracy was significantly improved in all evaluation parameters.

OBJECTIVE: The purpose of our work was to develop an integrated system with image guidance and deformation simulation for the purpose of accurate needle insertion. METHODS: We designed an ultrasound-guided needle insertion manipulator and physical model to simulate liver deformation. We carried out an in vivo experiment using a porcine liver to verify the effectiveness of our manipulator and model. RESULTS: The results of the in vivo experiment showed that the needle insertion manipulator accurately positions the needle tip into the target. The experimental results also showed that the liver model accurately reproduces the nonlinear increase of force upon the needle during insertion. DISCUSSION: Based on these results, it is suggested that the needle insertion manipulator and the physical liver model developed and validated in this work are effective for accurate needle insertion.

Tele-surgery enables medical care even in remote regions, and has been accomplished in clinical cases by means of dedicated communication lines. To make tele-surgery a more widespread method of providing medical care, a surgical environment needs to be made available using public lines of communication, such as the Internet. Moreover, a support system during surgery is required, as the use of surgical tools is performed in an environment subject to delay. In our research, we focus on the operability of specific tasks conducted by surgeons during a medical procedure, with the aim of clarifying, by means of a simulation, the optimum environment for robotic tele-surgery. In the study, we set up experimental systems using our proposed simulation system. In addition, we investigate the mental workloads on subjects and verify the effect of visual-assistance information as a pilot study. The operability of the task of gripping soft tissue was evaluated using a subjective workload assessment tool, the NASA Task Load Index. Results show that the tasks were completed, but the workload did not improve to less than 300ms and 400ms in the simulated environment. Verifying the effect of the support system was an important task under a more-than 200ms delay using this experiment, and future studies will evaluate the operability of the system under varying conditions of comfort. In addition, an intra-operative assistance system will be constructed using a simulation.

A reconfigurable master device has been proposed for a reconfigurable modular surgical robot. A simulation-based experimental setup was developed to evaluate the feasibility of the master device. The time spent to perform a given task, the workload evaluated by the NASA TLX questionnaire, and the preference of the topology indicated by the subjects were used as evaluation items. The preliminary results suggested that the preferred topology may vary depending on the user, and the reconfigurable master device would let each surgeon customize the master device according to his/her own preferences. © 2010 IEEE.

OBJECTIVE: The objective of our work is to develop and validate a viscoelastic and nonlinear physical liver model for organ model-based needle insertion, in which the deformation of an organ is estimated and predicted, and the needle path is determined with organ deformation taken into consideration. MATERIALS AND METHODS: First, an overview is given of the development of the physical liver model. The material properties of the liver considering viscoelasticity and nonlinearity are modeled based on the measured data collected from a pig's liver. The method to develop the liver model using FEM is also shown. Second, the experimental method to validate the model is explained. Both in vitro and in vivo experiments that made use of a pig's liver were conducted for comparison with the simulation using the model. RESULTS: Results of the in vitro experiment showed that the model reproduces nonlinear and viscoelastic response of displacement at an internally located point with high accuracy. For a force up to 0.45 N, the maximum error is below 1 mm. Results of the in vivo experiment showed that the model reproduces the nonlinear increase of load upon the needle during insertion. DISCUSSION: Based on these results, the liver model developed and validated in this work reproduces the physical response of a liver in both in vitro and in vivo situations.

We describe a control method, for a surgical robot, which prevents the overload at fragile tissues. In particular, we focused on the control parameter setting method to ensure the robustness of the performance relative to the variation of the organ stiffness parameter. Firstly, we present Position/Limited Stress control to achieving both precise positioning and prevention of overload. FEM based organ model was used to estimate the stress in this control method. Secondly, we describe the control parameter setting method. The control parameter was set to realize sufficient performance within the range of stiffness variation. Finally, we carried out a numerical simulation and an in vitro experiment. The simulation result suggests that our control method and parameter setting method helps prevent stress overload, not depending on the stiffness of organ model. The in vitro experimental result suggests that our method helps prevent stress overload of the in vitro-liver, the stiffness parameter of which is unknown.

Tele-surgery enables medical care even in remote regions and has been accomplished in clinical cases by means of special communication lines. To make tele-surgery a more common method of medical care, the surgical environment must be made available using public lines of communication, such as the Internet. Moreover, a support system during operation is required as the use of surgical tools occurs in a delayed environment. In our research, we focus on the operability of certain tasks conducted by surgeons during a medical procedure, and aim to clarify the optimum environment for robotic tele-surgery using a simulation. In the present study, we conducted an experiment to evaluate this operability using a simulation system consisting of a virtual slave manipulator, network simulator and an organ deformation calculator. The operability of a task to grip soft tissue was evaluated using a subjective workload assessment tool, NASA Task Load Index (NASA-TLX). Results indicate that operability changed over a delay of 200 ms in the environment during the experiment. Future studies will focus on clarifying a comfortable tele-surgical environment using the present evaluation of operability. In addition, an intra-operative assistance system will be constructed using a simulation.

Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle accurately because of cancer displacement caused by organ deformation. Therefore, a path planning using numerical simulation to analyze the deformation of the organ is important for accurate needle insertion. The problem in developing a planning method is that puncture conditions, such as the force applied to the needle, is difficult to be decided deterministically, because the experimental data of puncture conditions have variations. Therefore, the purpose of this research was to develop a novel planning method to decide the robust paths of straight needle insertion for various puncture points. The basic idea of this planning method is to consider the puncture condition probabilistic and to evaluate the expected value of needle placement accuracy. First, a probability-based puncture condition was introduced, and then the expected value of needle placement accuracy was defined. Next, the optimization method was developed to search the insertion path in a way that minimizes the expected values of needle placement accuracy. Then, a numerical simulation and evaluation of the planning method was conducted, using a liver-shaped 2D model. Furthermore, an in-vitro experiment was carried out to measure needle placement accuracy from the optimized path. Experimental results show that the planning method realizes needle insertion with a mean accuracy of 13 mm.

We are developing integrated robotic system with needle insertion robot and biomechanical simulator to realize localized RFA therapy. In this paper, we introduce the following three key systems: Needle insertion robot, biomechanical physical liver model for deformation simulation and temperature distribution simulation. ©2009 IEEE.

Medical technology has advanced with the introduction of robot technology, making previous medical treatments that were very difficult far more possible. However, operation of a surgical robot demands substantial training and continual practice on the part of the surgeon because it requires difficult techniques that are different from those of traditional Surgical procedures. So we focused on a simulation technology based on the physical characteristics of organs as an intra-operative assistance for a surgeon. In this research, we proposed the development of surgical simulation, using a physical model, for intra-operative navigation. In this paper, we describe the design of our proposed system, in particular our organ deformation calculator. We performed two experiments with pig liver and silicone model to evaluate the accuracy of the calculator. We obtained adequate experimental results of a target node at a nearby point of interaction, because this point ensures better accuracy for our simulation model.

Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle into the cancer because of cancer displacement due to the organ deformation. Then, a path planning using numerical simulation to analyze the deformation of the organ and the timing of puncture is important for the accurate needle insertion. In this study, we have explained the modeling of conditions where the puncture occurs. Firstly, this paper shows needle insertion experiments for the hog liver in order to measure the needle force and displacement where the puncture occurs. According to the experimental results, significant variations in puncture force were observed. Accordingly, we proposed a novel condition of the force causing a puncture considering probability distribution. We summarized variations of the puncture force in the experimental data and represented conditions where a puncture occurs with probability distribution models where the force is random variable. In addition, the boundary conditions and liver shapes are considered by analyzing the stress status near the needle. Then, we derived the conditions of the puncture with probability distribution models where the stress is random variable.