Motion Measurement Method Research Articles

Assessing the 3D accuracy of consumer grade distance camera measurement of respiratory motion

Recently range imagers or distance camera systems have garnered interest for measuring respiratory motion without using markers, which can then be used as a surrogate in diagnosis and treatment for example in diagnostic imaging or radiotherapy. However, their use may have limitations, especially among lower cost systems, whereby their accuracy decrease greatly with the distance of the patient from the camera. This is considering the fact that the motion amplitude of the anterior surface of the body in normal breathing is typically around 1 cm or less, which is at the limit of accuracy of these systems. This accuracy limitation is even more pertinent when the fact that the 1 cm accuracy is desired over the whole anterior surface that is image and not just an average measurement of distance. We study this limitation in a low cost system i.e. the Microsoft KinectTM, using both version 1 and version 2 of the sensor. The 3D accuracy of both versions is compared with an alternative method of respiratory motion measurement i.e. a respiratory belt, at a distance of around 1.35 m. This study can be a guide for the design and application of range imaging systems in the clinical setting.

Easy measuring instrument for analyzing the radial and tilt error motions of a rotating shaft

In this study, a real-time measurement system to easily apply multi-probe error separation method for error motion measurement of a shaft was designed and developed. An arrangement condition of sensing probes for accurate multi-probe error separation method was examined and verified by a simulation test. By following the examined arrangement condition for multi-probe method, a measurement system to measure radial and tilt error motions of a shaft was designed and developed. The efficiency of the multi-probe method with the examined arrangement condition was checked by comparing the error motion results for a rotary stage with the error motions in the specifications of the guarantee. It is expected to apply this system to a real-time monitoring system of failure diagnosis for rotating shafts in ships and plants.

A six-direction absolute displacement sensor for time-delayed control based on quasi-zero-stiffness property

A novel six-direction sensor for absolute vibration motion is proposed in this study for the measurement of absolute motions by employing multi-direction quasi-zero-stiffness property. Scissor-like structures with pre-deformed springs are applied symmetrically in the proposed sensor. Based on the mathematical modeling of the proposed six-direction sensor, it is shown that the stiffness and damping properties of the sensor are adjustable nonlinear functions which are dependent on the structural parameters of scissor-like structures. And then, by utilizing bifurcation theory and perturbation method, the structural parameters are optimized for the improvement of measurement accuracy. For the realization of the approximate fixed point for a moving vibration object, the vibration from measurement object to the sensor is isolated, and thus the sensor could obtain the absolute motions. Utilizing the signals obtained by the proposed sensor directly, better vibration/suppression effectiveness is achieved. The results provide a novel and significant six-direction absolute motion measurement method by utilizing multi-direction quasi-zero-stiffness property with noticeable isolation performance only with passive elements.

Precise planar motion measurement of a swimming multi-joint robotic fish

This paper presents a method for planar motion measurement of a swimming multi-joint robotic fish. The motion of the robotic fish is captured via image sequences and a proposed tracking scheme is employed to continuously detect and track the robotic fish. The tracking scheme initially acquires a rough scope of the robotic fish and thereafter precisely locates it. Historical motion information is utilized to determine the rough scope, which can speed up the tracking process and avoid possible ambient interference. A combination of adaptive bilateral filtering and k-means clustering is then applied to segment out color markers accurately. The pose of the robotic fish is calculated in accordance with the centers of these markers. Further, we address the problem of time synchronization between the on-board motion control system of the robotic fish and the motion measurement system. To the best of our knowledge, this problem has not been tackled in previous research on robotic fish. With information about both the multi-link structure and motion law of the robotic fish, we convert the problem to a nonlinear optimization problem, which we then solve using the particle swarm optimization (PSO) algorithm. Further, smoothing splines are adopted to fit curves of poses versus time, in order to obtain a continuous motion state and alleviate the impact of noise. Velocity is acquired via a temporal derivative operation. The results of experiments conducted verify the efficacy of the proposed method.

ウェアラブルセンサシステムを用いた身体パラメータ推定に関する研究

The aim of this study is to establish the estimation method of body parameter using wearable sensor system. The wearable motion sensor installs gyro sensor, acceleration sensor and magnetic field sensor, and this sensor outputs angular velocity, acceleration and magnetic field. The output of acceleration sensor attached to body segment includes the centrifugal and tangential acceleration components, and these components include the position vector from the joint to the sensor. The proposed method estimates the position vector from the joint to the sensor by using the output of wearable motion sensor. Furthermore, the position vector is focused the component of 1-axis direction. We conducted the measurement experiment of bending exercises by a subject attaching the wearable motion sensors. The position vector from foot joint to the motion sensor attaching to lower thigh is estimated. The position vector indicated the similar result against the length measured using other method. We indicated that the proposed method can use in actual body motion measurement. Therefore, the method can be used for the development of more simply motion measurement method in the motion analysis using wearable motion sensor.

Development of Wearable Training Device with Multiple Degrees of Freedom: Wearable Parallel-Link Measuring Device

The authors propose a wrist joint motion measuring device that can be applied to training devices. This study, the authors described developed a wrist motion measurement method that uses wearable p...

Foot Motion Measurement for Home based Rehabilitation Using Distributed Wearable Sensor

This paper presents a wearable sensors based foot motion measurement method for rehabilitation applications. Two commercial wearable sensors were adopted with three measurement units fixed on feet. Quaternions were employed to represent three-dimensional orientation and an proportional-integral-filter (PIF) algorithm was used to calculate the quaternion derivative. Foot position and orientation were estimated and the effectiveness of the proposed method was validated on healthy subjects. Experimental results demonstrated that the proposed method is capable of providing consistent tracking of human foot without significant drift, with less than 0.5% position error, which matches that of Kalman based methods. The aim of this work is to allow therapists to make use of the biofeedback information to create biofeedback rehabilitation protocols, which can be used to monitor and evaluate rehabilitation progresses by the performance of patients doing prescribe corrective body movement and gesture. Moreover, this method could be applied to other cyclical activity monitoring.

The reliability of novel multiregional spinal motion measurement device

Background: Current spinal range of motion (ROM) measurement methods have limitations ranging from the amount of detail obtained to environmental costs and complexity. In particular, limited regional spinal motion is obtained using the current methods. However, a new portable ‘string’ of accelerometers is proposed to overcome these limitations. Objectives: This study seeks to determine the reliability of this sensor string in measuring three-dimensional spinal ROM and to investigate the relative motions across six different regions. Methods: Two procedures were undertaken on 18 healthy participants. Protocol one: two sensors were placed on the forehead and T1 to measure cervical ROM; and protocol two: six sensors were placed on the spinous processes of T1, T4, T8, T12, L3 and S1 to measure thoraco-lumbar regional ROM. Results: The ICC values for all regions were found to be high, ranging from ICC=0.88–0.99 for all movements and regions of the spine, demonstrating that the proposed methods were highly reliable for repeated measures. The standard error of the means (SEMs) were small, ranging from 0.7–5.2°. The flexion/extension motion demonstrated a mean SEM of 1.9° and 1.1° for lateral bending motions. Slightly larger SEMs were observed for rotation, especially for the upper thoracic (UT) and mid thoracic (MT) region with an overall mean SEM of 3.1°. Minimum detectable change (MDC) values ranged from 1.9–14.4°. The flexion/extension motion demonstrated a mean MDC of 5.2° with 3.1° for lateral bending motions. Slightly larger MDCs were observed for rotation (mean MDC=8.4°), especially for the UT and MT region. Implications: This method was able to quantify the relative contribution of differing regions to the overall motion. The method described represents a reliable method of assessing spinal ROM across multiple spinal regions.

基于空间相机时间延迟积分传感器拼接区图像的像移测量

In order to measure the wide-frequency-range image motion caused by spacecraft attitude instability or residual vibration of the vibration isolation devices, image motion measurement method using images taken from time delayed integration (TDI) sensors, overlapped area is proposed. Offset coefficient is defined to measure the mismatch between image motion velocity and integration time. The relationship between mismatch and image quality using modulation transfer function (MTF) as image quality evaluation index is analyzed. The image motion measuring accuracy range is determined. By taking full advantage of features of the images taken from TDI sensors, overlapped area that have the same content but are taken at the different time, the theory of image motion measurement method based on images taken from TDI sensors, overlapped area is elaborated. Experimental results show that the measurement precision can reach 0.2377 pixel, and the measurement bandwidth can reach 228 Hz, proving that this method can effectively achieve wide-frequency-range, high-precision measurement of image motion.

동적원심모형 시험을 이용한 부지응답해석 검증시 입력 지진의 결정

In order to verify the reliability of numerical site response analysis program, both soil free-field and base rock input motions should be provided. Beside the field earthquake motion records, the most effective testing method for obtaining the above motions is the dynamic geotechnical centrifuge test. However, need is to verify if the motion recorded at the base of the soil model container in the centrifuge facility is the true base rock input motion or not. In this paper, the appropriate input motion measurement method for the verification of seismic response analysis is examined by dynamic geotechnical centrifuge test and using three-dimensional finite difference analysis results. From the results, it appears that the ESB (equivalent shear beam) model container distorts downward the propagating wave with larger magnitude of centrifugal acceleration and base rock input motion. Thus, the distortion makes the measurement of the base rock outcrop motion difficult which is essential for extracting the base rock incident motion. However, the base rock outcrop motion generated by using deconvolution method is free from the distortion effect of centrifugal acceleration.

Novel horseback riding simulator based on 6-DOF motion measurement, a motion base, and interactive control of gaits

This article describes the development process of a horseback riding simulator capable of generating a close to natural riding sensation. The development process started with 6-DOF motion measurement of the dynamics of the rider’s saddle during riding. Six-dimensional measurements during riding are required to fully understand the character of the saddle dynamics during different gaits. The measured quantities, i.e. translation accelerations and angular velocities, were transformed and filtered to form position references for a hydraulic Gough–Stewart platform. The presented novel motion measurement method is easy to use and makes it possible to measure gaits of several individual horses in a short time. It also provides a straightforward approach to produce motion data for the motion platform. In the second phase of the study, an artificial horse body made of glass fiber was mounted on the motion platform. The developed simulator realizes all three basic gaits walk, trot, and gallop. The rider is able to control the behavior of the simulator via sensors and an interactive interface. The control aids sensed by the interface are reins tension, calf pressure, and stirrup angle. A novel intelligent algorithm mimicking the real rider–horse interaction to vary the gaits and their frequencies was developed and tested.

2A1-G02 装着型パラレルリンク機構を用いた手首関節運動計測装置の開発(感覚・運動・計測(1))

We propose a wrist joint measuring device that can be applied to the training device. In this study, we have developed a wrist motion measurement method using wearable parallel link mechanisms to measure body exercise continuously. The proposed method is non-invasive and simple mechanism which uses compact linear encoders. Equipment is attached to the human hand and lower arm via a glove and belts. Measurement experiments of wrist motion were conducted for 12 subjects, and the obtained results were compared with previous anatomical results. Finally, the validity of the proposed method was demonstrated.

Motion Analysis and Joint Angle Measurement of Skier Gliding on the Actual Snow Field Using Inertial Sensors

This paper deals with the motion analysis of skier gliding on the actual snow field using inertial sensors. It is difficult to measure the motion of skier gliding on the actual snow field since the gliding velocity is fast and the measurement area is large. Therefore, few studies have analyzed ski turns in gliding on the actual snow field. It is necessary to analyze the skier gliding on the actual snow field in resolving the mechanism of ski turns. In our previous study, we developed the motion measurement method of skier using inertial and magnetic field sensors. The 3D posture is estimated by applying the sensor fusion method, and the method can estimate the 3D posture compensating the drift error of gyro sensor and reducing the effect of dynamic acceleration of accelerometer. Furthermore, we developed the sensor fusion method estimating the 3D posture in local coordinate by the information of inertial sensors attaching the body segments. The joint angle of skier in gliding on the actual snow field can be estimated by this method and inverse kinematics. We conducted the measurement experiment by skier gliding on the actual snow field. The inertial sensors and the GPS receiver were attached to the body segments and the top of skier, respectively. Skier conducted carving and skidding turns in this experiment. We calculated the joint angles of skier by the information of inertial sensors, and the switchovers of turns are estimated by the GPS receiver output. The results of motion analysis indicated the major feature of skier's motion and the difference between carving and skidding turns. Therefore, the analysis results can be used to the skill rating, the clarification of the mechanism of ski turns and the suggestion of more ideal turning form.

Measurement of lumbar spine range of movement and coupled motion using inertial sensors – A protocol validity study

Measurement of spinal lumbar range of movement is useful in clinical examination of the spine and for monitoring changes in spinal movement characteristics of individuals over time, particularly in the research context. As the spine exhibits six degrees of movement, three dimensional measurements provide additional information that could benefit the study of spinal conditions. Inertial measurement systems present an innovative method of spinal motion measurement. These systems are small and portable, and of low cost compared to laboratory based three dimensional measurement systems such as electromagnetic and opto-electronic systems. The present study aimed to validate the use of inertial measurement systems in three dimensional spinal range of movement measurement using an electromagnetic tracking system as a reference. Twenty-six healthy participants had their lumbar spine range of movement measured using both an inertial measurement system and an electromagnetic tracking system. Measurements taken by the inertial measurement system were found to be highly correlated with the electromagnetic tracking system (overall regression R2 0.999, p < 0.005). Measurements showed strong agreement (mean differences between −0.81° and 1.26°) and produced no significant difference from the electromagnetic tracking system (paired t-test p > 0.05). The ranges of movement measured were also highly comparable to those reported in the literature. Inertial measurement systems that consist of triaxial gyroscopes, accelerometers and magnetometers are concluded to be valid tools for three dimensional spinal range of movement measurement within or outside of the laboratory settings due to their cost, size and portability.

101 慣性センサ・地磁気センサを用いたスポーツにおける運動計測法に関する研究(運動計測(1))

101 慣性センサ・地磁気センサを用いたスポーツにおける運動計測法に関する研究(運動計測(1))

An attempt of a new motion measurement method for alpine ski turns using inertial sensors

This paper proposes the motion measurement method of skiing turn using inertial sensor. This method calculates the joint angle of the skier gliding on the actual snow field using the information from the inertial sensor units. The sensor fusion estimates the 3D posture (Roll-Pitch-Yaw angle) of local coordinate system compensated drift error of gyro sensor output using acceleration sensor output. The unscented Kalman filter is used to apply the sensor fusion. The joint angle is calculated by applying inverse kinematics to the 3D posture. In this study, the measurement experiment was conducted by the skier gliding on the actual snow field. The inertial sensor units were attached to body segments of skier. We obtained the joint angle of skier (Lumber, hip, knee and ankle). The results of motion analysis represented the major features of skiing turn, and the effectiveness of our proposed method was indicated.

210 身体動作計測のためのサンプリング同期式無線慣性センサ(学生賞II,一般講演)

210 身体動作計測のためのサンプリング同期式無線慣性センサ(学生賞II,一般講演)

Monocular trajectory intersection method for 3D motion measurement of a point target

This article proposes a monocular trajectory intersection method, a videometrics measurement with a mature theoretical system to solve the 3D motion parameters of a point target. It determines the target’s motion parameters including its 3D trajectory and velocity by intersecting the parametric trajectory of a motion target and series of sight-rays by which a motion camera observes the target, in contrast with the regular intersection method for 3D measurement by which the sight-rays intersect at one point. The method offers an approach to overcome the technical failure of traditional monocular measurements for the 3D motion of a point target and thus extends the application fields of photogrammetry and computer vision. Wide application is expected in passive observations of motion targets on various mobile beds.

B-34 慣性センサ・地磁気センサを用いたスポーツにおける運動計測に関する研究(計測・システム1)

This paper proposes the new motion measurement method in sports using the motion measurement system installed inertial and magnetic field sensors. This system provides tri-axis angular velocity, tri-axis acceleration and tri-axis magnetic field. Introducing the sensor fusion algorithm using adaptive Kalman filter, the effect of magnetic disturbance is compensated. Furthermore, the advanced sensor fusion algorithm is constructed using quaternion to enable motion measurement in wide range of motion. In order to confirm the accuracy of proposed measurement methods, we compared the value obtained by the proposed methods with the value of encoder. It is found that these methods provide the accurate value in the motion analysis in the space with magnetic disturbance and in wide range of motion. Consequently, the proposed methods in this paper can be used to the motion analysis in various sports.

Study of the motion artefacts of skin-mounted inertial sensors under different attachment conditions

A common problem shared by accelerometers, inertial sensors and any motion measurement method based on skin-mounted sensors is the movement of the soft tissues covering the bones. The aim of this work is to propose a method for the validation of the attachment of skin-mounted sensors. A second-order (mass–spring–damper) model was proposed to characterize the behaviour of the soft tissue between the bone and the sensor. Three sets of experiments were performed. In the first one, different procedures to excite the system were evaluated to select an adequate excitation stimulus. In the second one, the selected stimulus was applied under varying attachment conditions while the third experiment was used to test the model. The heel drop was chosen as the excitation method because it showed lower variability and could discriminate between different attachment conditions. There was, in agreement with the model, a trend to increase the natural frequency of the system with decreasing accelerometer mass. An important result is the development of a standard procedure to test the bandwidth of skin-mounted inertial sensors, such as accelerometers mounted on the skin or markers heavier than a few grams.