Omnidirectional camera and head-mount display contribute to the safety of laparoscopic surgery.

BACKGROUND: We focused on the availability of an omnidirectional camera and head-mount display (HMD). If the laparoscope is an omnidirectional camera, captured images are sent to the HMD worn by the operator in real time. The operator can thus view the image as they like without moving the camera and obtain a 360° view intuitively. However, the surgical system that can be used for actual laparoscopic operations has not yet been developed. In this study, we aimed to show that an omnidirectional camera and HMD would be useful in laparoscopic surgery. MATERIAL AND METHODS: Eleven medical students and twelve surgical residents (Surgeons group) participated in this study. We created an experimental box with five marks randomly attached inside the box, and the inside cannot be seen from the outside. We measured the time it took to identify all marks between conventional laparoscope and substitute system in each group. RESULTS: In the substitute system, the time required for the task was significantly shorter than with conventional laparoscopy in each group. CONCLUSION: An omnidirectional camera and HMD may be a useful new device for laparoscopic surgery. This system may help improve the safety of laparoscopic surgery.

Accuracy of Temporo-Spatial and Lower Limb Joint Kinematics Parameters Using OpenPose for Various Gait Patterns With Orthosis.

A cost-effective gait analysis system without attachments and specialized large environments can provide useful information to determine effective treatment in clinical sites. This study investigates the capability of a single camera-based pose estimation system using OpenPose (OP) to measure the temporo-spatial and joint kinematics parameters during gait with orthosis. Eleven healthy adult males walked under different conditions of speed and foot progression angle (FPA). Temporo-spatial and joint kinematics parameters were measured using a single camera-based system with OP and a three-dimensional motion capture system. The limit of agreement, mean absolute error, absolute agreement (ICC2, 1), and relative consistency (ICC3, 1) between the systems under each condition were assessed for reliability and validity. The results demonstrated that most of the ICC for temporo-spatial parameters and hip and knee kinematics parameters were good to excellent (0.60 - 0.98). Conversely, most of the ICC for ankle kinematics in all conditions were poor to fair (< 0.60). Thus, the gait analysis using OP can be used as a clinical assessment tool for determining the temporo-spatial, hip, and knee sagittal plane angles during gait.

Feature Selection and Validation of a Machine Learning-Based Lower Limb Risk Assessment Tool: A Feasibility Study.

Early and self-identification of locomotive degradation facilitates us with awareness and motivation to prevent further deterioration. We propose the usage of nine squat and four one-leg standing exercise features as input parameters to Machine Learning (ML) classifiers in order to perform lower limb skill assessment. The significance of this approach is that it does not demand manpower and infrastructure, unlike traditional methods. We base the output layer of the classifiers on the Short Test Battery Locomotive Syndrome (STBLS) test used to detect Locomotive Syndrome (LS) approved by the Japanese Orthopedic Association (JOA). We obtained three assessment scores by using this test, namely sit-stand, 2-stride, and Geriatric Locomotive Function Scale (GLFS-25). We tested two ML methods, namely an Artificial Neural Network (ANN) comprised of two hidden layers with six nodes per layer configured with Rectified-Linear-Unit (ReLU) activation function and a Random Forest (RF) regressor with number of estimators varied from 5 to 100. We could predict the stand-up and 2-stride scores of the STBLS test with correlation of 0.59 and 0.76 between the real and predicted data, respectively, by using the ANN. The best accuracies (R-squared values) obtained through the RF regressor were 0.86, 0.79, and 0.73 for stand-up, 2-stride, and GLFS-25 scores, respectively.

Effect of Varying Soft Actuator Band Positions of a Wearable Assist Device on Gait Simulation of Lower Limb Muscle Force.

The purpose of this study is to investigate the effect of changing the application points and directions of the soft actuator band of a wearable hip assist device on muscle force and joint kinematics during gait. Healthy adult participants walked under four conditions with varying band positions of a soft wearable hip assist device. The three-dimensional coordinates of markers and ground reaction force data were measured during gait. Lower limb muscle forces and joint angles were calculated using a musculoskeletal model. Our results showed that the position and running direction of the soft actuator band decreased the forces of the iliopsoas and hamstring muscles.

Effects of Varying Plantarflexion Stiffness of Ankle-Foot Orthosis on Achilles Tendon and Propulsion Force During Gait.

An ankle-foot orthosis (AFO) with a plantarflexion resistance function, improves post-stroke gait. An AFO with a plantarflexion resistance function not only affects the first rocker function and the weight acceptance but also the late stance phase. Achilles tendon extension is important for ankle joint function and for forward propulsion during the late stance phase; however, the effect of an AFO with a plantarflexion resistance function on the Achilles tendon is unclear. The purpose of this study was to investigate the effect of plantarflexion resistance on the extension of the Achilles tendon and the forward-propulsive force. Herein, 10 healthy adult males participated who walked under three different conditions: a no-AFO condition and two AFO conditions that had different levels of plantarflexion resistance (P1 and P2). The stiffness value of the P1 and P2 conditions was 0.56 and 1.47 Nm/°, respectively. A three-dimensional (3D) motion analysis system and a musculoskeletal model were used to assess the tendon-length change, the ground reaction force, kinematics, and kinetics data. The change in Achilles tendon length was significantly lower in the P1 and P2 conditions than the no-AFO condition. Furthermore, changes in the length of the Achilles tendon significantly decreased in the P2 condition when compared with that in the P1 condition. The peak anterior ground reaction force was significantly lower in the P2 condition than the no-AFO condition. These results suggest that excessive assist provided by an AFO prevents efficient gait by decreasing both the forward-propulsive force and tendon function.

Force perceptual bias caused by muscle activity in unimanual steering.

This study sought to investigate whether force perceptual bias was affected by differences in posture while steering an automobile using a psychophysical experiment to examine the relationship with muscle activity. The human perceptual characteristics of weight and force are known to be nonlinear, and a perceptual bias can occur, that is, bias that causes a perception of something that is larger or smaller than the actual scale. This is considered to be caused by physical and/or psychological conditions. Sense of effort is believed to be one influential factor. It is known to correlate with muscle activity intensity, and bias may be caused by muscle activity changes. In the current study, we hypothesized that force perceptual bias would depend on posture due to the intensity of muscle activity changes caused by changing postures during steering operation. By investigating this hypothesis, we can clarify the relationship between sense of effort and muscle activity. To investigate this issue, we conducted a psychophysical experiment to confirm postural dependence, and estimated muscle activity using a three-dimensional musculoskeletal model simulation with postural and arm force data during the experiment. In addition, prediction of bias was conducted based on a simulation in the psychophysical experiment using these data. The results revealed that bias existed, as measured by differences in postures. Additionally, a significant moderate correlation was found between the predicted bias and the actual bias, indicating the existence of a relationship between muscle activity and bias.

Effects of altering plantar flexion resistance of an ankle-foot orthosis on muscle force and kinematics during gait training.

Ankle-foot orthosis (AFO) can improve gait in stroke patients. Addition of plantar flexion resistance (PFR) can improve the first foot rocker function. However, the effect of changing the PFR on the ankle muscle force during gait training is unclear. This study aimed to determine the effect of changing the PFR of an AFO on spatiotemporal parameters (speed, bilateral step length, and cadence), peak angle of ankle plantar flexion and knee flexion, and muscle force (tibialis anterior [TA], medial head of the gastrocnemius [MGAS], and soleus) during early stance using a musculoskeletal model. Ten healthy adult men walked under five conditions: a no-AFO condition and PFR conditions 1-4. Spatiotemporal parameters and peak joint angles during the early stance phase were measured from experimental data, with muscle force estimated from simulations of a musculoskeletal model. Increasing the PFR of the AFO decreased TA muscle force and increased MGAS muscle force but had no influence on spatiotemporal parameters and joint angles. Adjustment of the PFR modifies the muscle force around the ankle, which can maximize the effect of AFO during gait training.

A prospective study of the safety and usefulness of a new miniature wide-angle camera: the "BirdView camera system".

BACKGROUND: The performance of endoscopic surgery has quickly become widespread as a minimally invasive therapy. However, complications still occur due to technical difficulties. In the present study, we focused on the problem of blind spots, which is one of the several problems that occur during endoscopic surgery and developed "BirdView," a camera system with a wide field of view, with SHARP Corporation. METHODS: In the present study, we conducted a clinical trial (Phase I) to confirm the safety and usefulness of the BirdView camera system. We herein report the results. RESULTS: In this study, surgical adverse events were reported in 2 cases (problems with ileus and urination). There were no cases of device failure, damage to the surrounding organs, or mortality. CONCLUSIONS: We evaluated the safety of the BirdView camera system. We believe that this camera system will contribute to the performance safe endoscopic surgery and the execution of robotic surgery, in which operators do not have the benefit of tactile feedback.

System to Evaluate the Skill of Operating Hydraulic Excavators Using a Remote Controlled Excavator and Virtual Reality.

We developed a system to evaluate the skill of operating a hydraulic excavator. The system employs a remotely controlled (RC) excavator and virtual reality (VR) technology. We remodeled the RC excavator so that it can be operated in the same manner as a real excavator and proceeded to measure the excavator's state. To evaluate the skill of operating this system, we calculated several indices from the data recorded during excavation work and compared the indices obtained for expert and non-expert operators. The results revealed that it is possible to distinguish whether an expert or non-expert is operating the RC excavator. We calculated the same indices from the data recorded during excavation with a real excavator and verified that there exists a high correlation between the indices of the RC excavator and those of the real excavator. Thus, we confirmed that the indices of the real excavator and those of the simulator exhibited similar trends. This suggests that it is possible to partly evaluate the operation characteristics of a real excavator by using an RC excavator with different dynamics compared with a real excavator.

Development of a Lightweight Flexible Construction Work Assist Suit Using Pneumatic Rubber Artificial Muscles.

We developed an assist suit with lightweight, flexible artificial muscles of pneumatic rubber for reducing muscle load in the lumbar region. We designed two assist forces to control the artificial muscles with pulse width modulation based on the measured EMG of the spinal column muscle and estimated the torque of the hip joint. The experimental results confirmed the developed work assist suit could unload muscle activity during bending and stretching exercises. We also proposed to use an EMG measurement device at the wearer's temple to control the assist timing and confirmed the feasibility of detecting the intention of the wearer.

Estimation of compressive tibiofemoral force using over resistance of ankle-foot orthosis on gait.

The purpose of this study was to investigate the effect of changing the plantar flexion resistance (PFR) of an ankle-foot orthosis (AFO) on the compressive tibiofemoral force, knee muscle forces, and knee joint angle. We measured and estimated knee flexion angle, knee muscle force, and the compressive tibiofemoral force in healthy adult males. The results showed that the first peak compressive tibiofemoral force, peak knee flexion angle, and peak quadriceps muscle force increased in the strong PFR condition compared with the no-AFO condition. These results suggest that over-PFR caused various knee troubles.

Estimation of knee joint reaction force based on the plantar flexion resistance of an ankle-foot orthosis during gait.

[Purpose] The purpose of this study was to investigate the effect of changing the plantar flexion resistance of an ankle-foot orthosis on knee joint reaction and knee muscle forces. Furthermore, the influence of an ankle-foot orthosis with an over-plantar flexion resistance function on knee joint reaction force was verified. [Participants and Methods] Ten healthy adult males walked under the following three conditions: (1) no ankle-foot orthosis, and with ankle-foot orthoses with (2) a strong and (3) a weak plantar flexion resistance (ankle-foot orthosis conditions). The knee flexion angle, quadricep muscle force, hamstring muscle force, and knee joint reaction force during the stance phase were measured using a motion analysis system, musculoskeletal model, and ankle-foot orthosis model. [Results] The peak knee joint reaction force, knee flexion angle, and quadricep muscle force in the early stance phase significantly increased in the strong plantar flexion resistance condition in comparison with the "no ankle-foot orthosis" condition. [Conclusion] Increased knee joint reaction force with over-plantar flexion resistance suggests that over-plantar flexion resistance causes various knee problems such as knee pain and knee osteoarthritis.

Prediction of Perceived Steering Wheel Operation Force by Muscle Activity.

Humans feel forces or weights while grasping and manipulating an object. There is a difference between the physical and perceived forces because the physical characteristics of an object and/or human psychophysical characteristics affect perceived force. Sense of effort plays an important role in deciding the movement made by humans. In this study, we propose a computational method to predict the perceived force by evaluating the muscle activity as a function of effort in the operation of a steering wheel based on a 3D-musculoskeletal model simulation. We found that the perceived-force characteristics depend on the driving posture, though the applied force is the same. We evaluated the results, and showed that the mean of the absolute error is 1.78 N for the experiments conducted on four different vehicles in commercially available.

Variance distribution analysis of surface EMG signals based on marginal maximum likelihood estimation.

This paper describes the estimation and analysis of variance distribution of surface electromyogram (EMG) signals based on a stochastic EMG model. With the assumption that EMG signals at a certain time follow Gaussian distribution, their variance is handled as a random variable that follows inverse gamma distribution, and noise superimposed onto this variance can be expressed accordingly. The paper proposes variance distribution estimation based on marginal likelihood maximization of EMG signals. A simulation experiment using artificially generated signals to verify its accuracy indicated that the method can estimate variance distribution with high accuracy for a wide range of variance distribution shaping. Analysis of variance distribution using measured EMG signals revealed the relationship between muscle force and variance distribution involving signal-dependent noise.

A Variance Distribution Model of Surface EMG Signals Based on Inverse Gamma Distribution.

Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this variance. Variance distribution estimation based on marginal likelihood maximization is also outlined in this paper. The procedure can be approximated using rectified and smoothed EMG signals, thereby allowing the determination of distribution parameters in real time at low computational cost. Results: A simulation experiment was performed to evaluate the accuracy of distribution estimation using artificially generated EMG signals, with results demonstrating that the proposed model's accuracy is higher than that of maximum-likelihood-based estimation. Analysis of variance distribution using real EMG data also suggested a relationship between variance distribution and signal-dependent noise. Conclusion: The study reported here was conducted to examine the performance of a proposed surface EMG model capable of representing variance distribution and a related distribution parameter estimation method. Experiments using artificial and real EMG data demonstrated the validity of the model. Significance: Variance distribution estimated using the proposed model exhibits potential in the estimation of muscle force.Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this variance. Variance distribution estimation based on marginal likelihood maximization is also outlined in this paper. The procedure can be approximated using rectified and smoothed EMG signals, thereby allowing the determination of distribution parameters in real time at low computational cost. Results: A simulation experiment was performed to evaluate the accuracy of distribution estimation using artificially generated EMG signals, with results demonstrating that the proposed model's accuracy is higher than that of maximum-likelihood-based estimation. Analysis of variance distribution using real EMG data also suggested a relationship between variance distribution and signal-dependent noise. Conclusion: The study reported here was conducted to examine the performance of a proposed surface EMG model capable of representing variance distribution and a related distribution parameter estimation method. Experiments using artificial and real EMG data demonstrated the validity of the model. Significance: Variance distribution estimated using the proposed model exhibits potential in the estimation of muscle force.

A Mathematical Model of the Olfactory Bulb for the Selective Adaptation Mechanism in the Rodent Olfactory System.

To predict the odor quality of an odorant mixture, the interaction between odorants must be taken into account. Previously, an experiment in which mice discriminated between odorant mixtures identified a selective adaptation mechanism in the olfactory system. This paper proposes an olfactory model for odorant mixtures that can account for selective adaptation in terms of neural activity. The proposed model uses the spatial activity pattern of the mitral layer obtained from model simulations to predict the perceptual similarity between odors. Measured glomerular activity patterns are used as input to the model. The neural interaction between mitral cells and granular cells is then simulated, and a dissimilarity index between odors is defined using the activity patterns of the mitral layer. An odor set composed of three odorants is used to test the ability of the model. Simulations are performed based on the odor discrimination experiment on mice. As a result, we observe that part of the neural activity in the glomerular layer is enhanced in the mitral layer, whereas another part is suppressed. We find that the dissimilarity index strongly correlates with the odor discrimination rate of mice: r = 0.88 (p = 0.019). We conclude that our model has the ability to predict the perceptual similarity of odorant mixtures. In addition, the model also accounts for selective adaptation via the odor discrimination rate, and the enhancement and inhibition in the mitral layer may be related to this selective adaptation.

The usefulness of 3-dimensional endoscope systems in endoscopic surgery.

BACKGROUND: The image quality and performance of 3-dimensional video image systems has improved along with improvements in technology. However, objective evaluation on the usefulness of 3-dimensional video image systems is insufficient. Therefore, we decided to investigate the usefulness of 3-dimensional video image systems using the objective endoscopic surgery technology evaluating apparatus that we have developed, the Hiroshima University Endoscopic Surgical Assessment Device (HUESAD). METHODS: The participants were 28 student volunteers enrolled in Hiroshima University (17 men and 11 women, age: median 22.5, range 20-25), with no one having experienced endoscopic surgery training. Testing was carried out by dividing the subjects into two groups to initially carry out HUESAD with 2-dimensional video imaging (N = 14) and with 3-dimensional video imaging (N = 14). Questionnaires were carried out along with the investigation regarding both 2-dimensional and 3-dimensional video imaging. The task was carried out for approximately 15 min regarding both 2-dimensional and 3-dimensional video imaging. Lastly, the Mental Rotation Test, which is a standard space perception ability test, was used to evaluate the space perception ability. RESULTS: No difference was observed in the nauseous and uncomfortable feeling of practitioners between the two groups. Regarding smoothness, no difference was observed between 2-dimensional and 3-dimensional video imaging (p = 0.8665). Deviation (space perception ability) and approaching time (accuracy) were significantly lower with 3-dimensional video imaging compared to 2-dimensional video imaging. Moreover, the approaching time (accuracy) significantly improved in 3-dimensional video imaging compared to 2-dimensional video imaging in the group with low space perception ability (p = 0.0085). CONCLUSION: Objective evaluation using HUESAD and subjective evaluation by questionnaire revealed that endoscopic surgery techniques significantly improved in 3-dimensional video imaging compared to 2-dimensional video imaging. Moreover, it is believed that this effect is more effective in people with low space perception ability and beginner students.

Prediction of posture-dependent tremor by the calculation of the endpoint compliance.

This paper proposes to use the analysis of human mechanical impedance to predict spatial behavior of tremor. Traditional studies have revealed that the variability in force is proportional to the mean level of force generated, which is described as signal dependent noise. The variability in force sometimes generates unintentional and uncontrollable rhythmic muscle movements, called tremor. Tremor appears most commonly on arms and hands due to not only a symptom of a neurological disorder, but also when we tighten our muscles. This study hypothesizes that the posture-dependent tremor at the hand is affected by the mechanical impedance of the arm, which is represented as the endpoint compliance ellipsoid. To verify this hypothesis, we measured the trajectory of the endpoint of the arm by human experiments, and compared the results with the endpoint compliance ellipsoid computationally obtained. The human experiment where the oscillations at the hand are measured revealed that the simulation results well correspond with the human experiments. This suggests that the posture-dependent motion noise is affected by the mechanical impedance of human body.

Stochastic resonance enhanced tactile feedback in laparoscopic surgery.

BACKGROUND: One of the disadvantages of laparoscopic surgery is its decreased tactile feedback. Surgical experience compensates for the decline in the sense of touch due to an improved ability to process visual information. Stochastic resonance (SR) is known to improve tactile sensation. In this study, we sought to improve the tactile feedback in laparoscopic surgery using SR to safely perform laparoscopic surgery. METHODS: Ten surgeons (nine males and one female, age: 30-44 years, median age: 34) with the experiences of >50 laparoscopic surgeries volunteered to participate in this study. We tested the hypothesis that low-level noise applied to the hand can enhance the tactile sensation during surgery. We performed this experiment under three hand conditions (bare-handed conditions, gloved conditions and using the laparoscopic instrument with gloved hands). A piezoelectric actuator that generates vibrations was attached on the radial side of the participant's index finger or to the grip of the laparoscopic instrument. Fine-touch tests were performed using the Semmes-Weinstein test kit. Moreover, we planned laparoscopic suturing and knot-tying tasks in the dry box and using an animal model under controlled vibrations. RESULTS: In the touch tests using bare hands, gloved hands and the laparoscopic instrument, the mean correct ratio was significantly lower than that observed in the test with no vibrations. Moreover, the OSATS scores for the laparoscopic suturing and knot-tying tasks showed significantly better scores with vibrations. CONCLUSIONS: This technique has a potential to be a great help in establishing safer and high-quality laparoscopic procedures.

A Recurrent Probabilistic Neural Network with Dimensionality Reduction Based on Time-series Discriminant Component Analysis.

This paper proposes a probabilistic neural network (NN) developed on the basis of time-series discriminant component analysis (TSDCA) that can be used to classify high-dimensional time-series patterns. TSDCA involves the compression of high-dimensional time series into a lower dimensional space using a set of orthogonal transformations and the calculation of posterior probabilities based on a continuous-density hidden Markov model with a Gaussian mixture model expressed in the reduced-dimensional space. The analysis can be incorporated into an NN, which is named a time-series discriminant component network (TSDCN), so that parameters of dimensionality reduction and classification can be obtained simultaneously as network coefficients according to a backpropagation through time-based learning algorithm with the Lagrange multiplier method. The TSDCN is considered to enable high-accuracy classification of high-dimensional time-series patterns and to reduce the computation time taken for network training. The validity of the TSDCN is demonstrated for high-dimensional artificial data and electroencephalogram signals in the experiments conducted during the study.