Joint Rotation Angle Research Articles

Experimental testing on ductile-iron joint panels for high-stiffness segmental joints of deep-buried drainage shield tunnels

Because of the large earth pressure and high inner water pressure, high-stiffness segmental joints with ductile-iron joint panels (DIJPs) are needed to improve the bearing capacity of segmental joints for deep-buried drainage shield tunnels. DIJPs are always mounted in high-stiffness segmental joints to restrain deformation and reduce the joint rotation angle, thus improving the bearing capacity of segmental joints. Full-scale tensile experiments on the performance of DIJPs with different structural styles, in terms of deformation characteristic, anchorage property, and failure mode, were carried out to evaluate the applicability of DIJPs for deep-buried drainage shield tunnels. The test results show that bending deflection appears in DIJPs if the flexural rigidity of DIJPs is insufficient, which will cause bending-tensile failure for the DIJP anchor bars. The failure position is in the weak interface: the screw thread position of the anchor bars, which is the connection position between the anchor bars and DIJPs; connecting the anchor bars with the main reinforcing bars by stirrups or filling the hand hole can restrain the bending deflection of the DIJP and improve the bearing capacity of the anchor bars. When the anchor bars are connected with the main reinforcing bars, the deformation of the DIJP decreases by 5.6%, and the bearing capacity of the anchor bars increases by 31.1%; further, if the hand hole are filled with cement, the deformation of the DIJP decreases by 22.2% and the bearing capacity of the anchor bars increases by 34.1%. Considering the failure modes of the specimens, it is believed that increasing the flexural rigidity of the DIJP and improving the connection performance between the DIJP and anchor bars can improve the behavior of the DIJP and anchor bars.

Estimating the Effects of Tunnelling on Preexisting Jointed Pipelines

Tunnel excavation inevitably results in ground movements and changes in soil stress, leading to additional stress on and settlement of nearby buried pipelines. This article focuses on the response of jointed pipelines to twin tunnelling. The relationship between the relative pipe‐soil displacement and the relative pipe‐soil stiffness was first determined. Based on this analysis, a series of numerical parametric studies encompassing 7776 conditions were performed to investigate the responses of a jointed pipeline to twin tunnelling. The results are used to estimate a regression equation for the relationship between the relative pipe‐soil stiffness and the normalized maximum joint rotation angle. This equation can be used for the direct calculation of the maximum joint rotation angle that will result from single or twin tunnelling and for the assessment of the tunnelling‐induced risk to jointed pipelines. The applicability and reliability of the regression equation are validated by comparing the calculated values with the results of earlier centrifuge tests.

Kinetic analysis of tandem gait on a sine-wave-shaped walkway.

[Purpose] The purpose of this study was to ascertain the kinetic characteristics on a horizontal plane, including knee joint rotation, when performing tandem gait on a sine-wave walkway. [Participants and Methods] The participants were 10 healthy adults. The movement task included tandem gait on a sine-wave walkway. The instruments used were an electromyograph and a three-dimensional motion analysis system. Regarding data analysis, we determined the knee joint rotation angle and muscle activity of the biceps femoris and semitendinosus muscle. [Results] The knee joint rotation angle range was 48.1 ± 6.7°. Two strategies were confirmed with regard to the direction of knee joint rotation: a case in which the agonist muscle acts actively and a case in which the antagonist muscle acts passively. [Conclusion] It has been suggested that the knee joint rotational angle and muscular activity of the rotator muscle group are important for tandem gait on a sine-wave-shaped walking path.

Gimbaled Tiltrotor Conversion Flight Loads Prediction Using Three-Dimensional Structural Analysis

This paper presents a method for modeling gimbaled rotor aeromechanics in Experimental 3D structural dynamics solver, which is a next-generation three-dimensional finite-element-based rotor structural dynamics solver. The rotor is modeled using a single blade with a free flap hinge at the hub, the motion of which is suppressed at integer multiples of the blade passage frequency by introducing harmonics of the joint rotation angle as additional trim variables, efficiently simulating gimbal kinematics. Rotor frequencies are examined for a three-bladed gimbaled rotor model and are found to combine the modes of both free flap hinge and fixed flap hinge (cantilevered) one-bladed models, similar to a teetering rotor, justifying the gimbal modeling methodology. Gimbal flapping is examined for a proprotor in edgewise flight: successful suppression of steady and 3/rev flapping indicates the gimbal model accurately represents the rotor kinematics. Air loads and blade loads are examined with and without with the gimbal model, revealing an increase in 3/rev sectional normal aerodynamic force on the blade but a decrease in the 3/rev flap and lag bending moment when the gimbal is added. Three-dimensional axial stress distribution at the blade root is examined, revealing only minor differences with and without the gimbal model, primarily in the flex beam.

Analysis of the biomechanical characteristics of the knee joint with a meniscus injury.

The knee joint is one of the most important joints in the human body. The meniscus is a half-moon cartilage which locates between the medial and lateral condyle of the thighbone and the medial and lateral condyle of the shin in the knee joint, and it has multiple functions such as bearing load, cushioning and stabilising joints. It is easy to be injured because of its complex structure and functions. In this study, the physical fitness of patients with meniscus injury was tested using kinematic measurement, and the data were collected for biomechanical analysis on the parameters such as the angle and stress when the patient's bent knees during sports. The results demonstrated that the average values of bending angle, the rotation angle of the knee joint and intensity of pressure of the patients with meniscus injury were remarkably different with those of people without meniscus injury. Biomechanical characteristics are of extensive values to the treatment of meniscus injury.

Effects of the material of running shoes on biomechanical characteristics during running

Running as a sport is beneficial to the enhancement of cardiovascular function and body health. Running shoes play an assisting role during running. Running shoes which are made of different materials and have different sole rigidity can produce different counterforces to the sole of the foot and, moreover, have influences on running. In this study, running shoes with different rigidity of soles were manufactured using natural rubber and ehylene-vinyl acetate foaming composite material. The tracks of all the reflection points were captured using an infrared camera, and then the kinetic data of the subjects were recorded. The influence of the rigidity of sole on sport dynamics and biomechanics of lower limbs was analyzed and compared through kinetic test. The results demonstrated that the hardness of the sole had no influence on the first peak force, but had influence on the appearance time, maximum loading rate, and 50-ms passive impulse. When the hardness of the sole was 10°, the first peak force appeared the earliest, and the loading rate and passive impulse were the largest. The hardness of the sole had no influence on the motion of knee joints and abduction exercise of ankle joints, but had influence on the flexion and extension and internal rotation motion. When the hardness of the sole was 10°, the maximum flexion angle and internal rotation angle of the ankle joints were the largest.

A novel hexapod and its prototype for secondary mirror alignment in telescopes

This paper presents a novel hexapod as the adjustment mechanism for a telescope to actively align its secondary mirror. The special hexapod provides six degrees of freedom (6-DOFs) with decoupled translation and rotation. The decoupled kinematic motions are analyzed and commented on as the alignment mechanism of a secondary mirror from an optical alignment point of view. In terms of performance of the adjustment generally required by the secondary mirror in a telescope, we developed a prototype that uses a novel hexapod design with linear micro-displacement actuators. Especially, in order to achieve high precision, flexures were used to build joints for the hexapod to minimize frictions and eliminate backlashes. Based on the specific configuration and dimension of the prototype hexapod, an analytical model of the reachable workspace was built with the constraints defined by limited rotation angles of the flexure-based joints. We used a laser tracker to verify that the hexapod can reach a spherical translation workspace of ϕ6 mm and a rotation workspace of ± 1°. The translational repeatability was tested to be around half a by laser displacement sensors. In addition, we also measured the axial and lateral stiffnesses of the hexapod to be around 5500 N mm−1 and 1750 N mm−1, respectively. The kinematic analyses and convincing test results jointly encourage implementing the novel hexapod design with decoupled translation and rotation as a favorable alignment mechanism for secondary mirrors in astronomical telescopes.

Mechanical design and trajectory planning of a lower limb rehabilitation robot with a variable workspace

The early phase of extremity rehabilitation training has high potential impact for stroke patients. However, most of the lower limb rehabilitation robots in hospitals are proposed just suitable for patients at the middle or later recovery stage. This article investigates a new sitting/lying multi-joint lower limb rehabilitation robot. It can be used at all recovery stages, including the initial stage. Based on man–machine engineering and the innovative design for mechanism, the leg length of the lower limb rehabilitation robot is automatically adjusted to fit patients with different heights. The lower limb rehabilitation robot is a typical human–machine system, and the limb safety of the patient is the most important principle to be considered in its design. The hip joint rotation ranges are different in people’s sitting and lying postures. Different training postures cannot make the training workspace unique. Besides the leg lengths and joint rotation angles varied with different patients, the idea of variable workspace of the lower limb rehabilitation robot is first proposed. Based on the variable workspace, three trajectory planning methods are developed. In order to verify the trajectory planning methods, an experimental study has been conducted. Theoretical and actual curves of the hip rotation, knee rotation, and leg mechanism end point motion trajectories are obtained for three unimpaired subjects. Most importantly, a clinical trial demonstrated the safety and feasibility of the proposed lower limb rehabilitation robot.

Investigation of Occupant Lower Extremity Injures under Various Overlap Frontal Crashes

With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments. A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance. Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle. Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.

Biohybrid robot with an antagonistic pair of skeletal muscle tissues

We propose a biohybrid robot with an antagonistic pair of skeletal muscle tissues. In the biohybrid robot, two skeletal muscle tissues are arranged in plane symmetry and their ends are connected to a joint via flexible ribbons working like tendons. Since bending of the flexible ribbons prevent the skeletal muscle tissues from deformation, the skeletal muscle tissues achieve linear actuations, inducing smooth rotation of the joint (rotation angle: ~90 degree), comparable to that of our finger. Due to controllability for contractions of skeletal muscle tissues, the biohybrid robot allow pick-and-place manipulation of a ring as an example of its operations. Therefore, we believe that the biohybrid robot will become a platform to replicate various lifelike movements.

Dimensional synthesis of a 3UPS-PRU parallel robot

SUMMARYThis paper introduces the methodology of the dimensional synthesis for a 3UPS-PRU parallel robot. The dimensional synthesis of the 3UPS-PRU parallel robot is proposed considering the maximum input velocity of actuating joints as the objective function and constraints on the installation dimension, robot dimension, joint rotation angle and interference. The objective of the dimensional synthesis is to minimize the maximum input velocity of actuating joints when the moving platform translates along the z-axis in the maximum linear velocity and rotates about an arbitrary axis in the maximum angular velocity in the desired workspace. The constraint on the robot dimension is included in the dimensional synthesis of the 3UPS-PRU parallel robot when pursuing the kinematic property to meet the miniaturization principle with the reduced building cost. An example of the dimensional synthesis of a 3UPS-PRU parallel robot is presented with the maximum linear velocity and angular velocity required for the moving platform in the desired workspace.

An MR-compatible gyroscope-based arm movement tracking system

BackgroundFunctional magnetic resonance imaging is well suited to link neural population activation with movement parameters of complex natural arm movements. However, currently existing MR-compatible arm tracking devices are not constructed to measure arm joint movement parameters of unrestricted movements. Therefore, to date most research focuses on simple arm movements or includes very little knowledge about the actual movement kinematics. New methodWe developed a low cost gyroscope-based arm movement tracking system (GAMTS) that features MR-compatibility. The system consists of dual-axis analogue gyroscopes that measure rotations of upper and lower arm joints. After MR artifact reduction, the rotation angles of the individual arm joints are calculated and used to animate a realistic arm model that is implemented in the OpenSim platform. The OpenSim platform can then provide the kinematics of any point on the arm model. ResultsIn order to demonstrate the capabilities of the system, we first assessed the quality of reconstructed wrist movements in a low-noise environment where typical MR-related problems are absent and finally, we validated the reconstruction in the MR environment. Comparison with existing methodsThe system provides the kinematics of the whole arm when natural unrestricted arm movements are performed inside the MR-scanner. ConclusionThe GAMTS is reliably capable of reconstructing the kinematics of trajectories and the reconstruction error is small in comparison with the movement induced variation of speed, displacement, and rotation. Moreover, the system can be used to probe brain areas for their correlation with movement kinematics.

Numerical parametric study of tunneling-induced joint rotation angle in jointed pipelines

Pipeline–tunnel interaction has attracted increasing research attention recently. Previous studies focused mainly on tunneling-induced deformation in continuous pipelines. In this paper, an extensive numerical parametric study is conducted to investigate the response of jointed pipelines (where joints are simulated as hinges) to tunnel excavation. Prior to the numerical parametric study, the numerical model was verified by centrifuge test results. Parameters considered include ground settlement profile, pipe dimensions, pipe segment length, and soil properties. The maximum and minimum joint rotation angles occur when the tunnel centerline is located directly beneath a joint and a pipe segment center, respectively. When pipe segments are relatively flexible, the joint rotation angle increases rapidly as pipe segment flexural stiffness increases. In contrast, negligible changes are observed in the joint rotation angle for relatively stiff pipe segments when pipe segment flexural stiffness changes. A dimensionless parameter, called relative pipe segment–soil stiffness, is defined to differentiate the response of flexible and stiff jointed pipelines. The relative pipe–soil stiffness and normalized pipe segment length are adopted to predict jointed rotation angles for relatively flexible and stiff pipelines, respectively. Dimensionless plots are developed for directly estimating upper and lower bounds on joint rotation angles due to tunneling.

Dynamic optimum design of a 3UPS-PRU parallel robot

This article deals with the methodology of the dynamic optimum design of the one translational and three rotational degrees of freedom parallel robots while considering the rigid-body dynamic property. The dynamic optimum design of the 3UPS-PRU (underlined P denotes an active prismatic joint driven by a servomotor) parallel robot is presented while considering the constraints on the installation dimension, joint rotation angle, and the interference. The maximum driving torque and the maximum driving power of the actuating joints are taken as the objective functions in the dynamic optimum design, respectively. The physical meanings of the objective functions are the maximum driving torque and the maximum driving power of the actuating joints when the moving platform translates along the z-axis in the maximum linear acceleration amax, rotates about an arbitrary axis in the maximum angular acceleration αmax, translates along the z-axis in the maximum linear velocity vmax, and rotates about an arbitrary axis in the maximum angular velocity ωmax at the same time. The object of the dynamic optimum design is to minimize the maximum driving torque or the maximum driving power by employing worst case criterion. In the predefined design task, the results of the dynamic optimum design of the 3UPS-PRU parallel robot are the same when taking the maximum driving torque and the maximum driving power as the objective functions. The phenomenon can be verified by the fact that the distributions of the maximum driving torque and the maximum driving power are very similar to each other. The robot dimension has also been taken into account in the dynamic optimum design of the 3UPS-PRU parallel robot due to the consideration of the building cost and the miniaturization. The example of the dynamic optimum design of the 3UPS-PRU parallel robot is presented in the simulation. The conclusions are provided at the end of the article.

A torsional MRE joint for a C-shaped robotic leg

Serving to improve stability and energy efficiency during locomotion, in nature, animals modulate their leg stiffness to adapt to their terrain. Now incorporated into many locomotive robot designs, such compliance control can enable disturbance rejection and improved transition between changing ground conditions. This paper presents a novel design of a variable stiffness leg utilizing a magnetorheological elastomer joint in a literal rolling spring loaded inverted pendulum (R-SLIP) morphology. Through the semi-active control of this hybrid permanent-magnet and coil design, variable stiffness is realized, offering a design which is capable of both softening and stiffening in an adaptive sort of way, with a maximum stiffness change of 48.0%. Experimental characterization first serves to assess the stiffness variation capacity of the torsional joint, and through later comparison with force testing of the leg, the linear stiffness is characterized with the R-SLIP-like behavior of the leg being demonstrated. Through the force relationships applied, a generalized relationship for determining linear stiffness based on joint rotation angle is also proposed, further aiding experimental validation.

Comparison of the Achilles tendon moment arms determined using the tendon excursion and three-dimensional methods

The moment arm of muscle‐tendon force is a key parameter for calculating muscle and tendon properties. The tendon excursion method was used for determining the Achilles tendon moment arm (ATMA). However, the accuracy of this method remains unclear. This study aimed to investigate the magnitude of error introduced in determining the ATMA using the tendon excursion method by comparing it with the reference three‐dimensional (3D) method. The tendon excursion method determined the ATMA as the ratio between the Achilles tendon displacement during foot rotation from 15° of dorsiflexion to 15° of plantarflexion and the joint rotation angle. A series of foot images was obtained at 15° of dorsiflexion, the neutral position, and 15° of plantarflexion. The 3D value of the ATMA was determined as the shortest distance between the talocrural joint axis and the line of action of the Achilles tendon force. The ATMA determined by the tendon excursion method was smaller by 3.8 mm than that determined using the 3D method. This error may be explained mainly by the length change in the Achilles tendon due to the change in the force applied to it, as passive plantarflexion torque was different by 11 Nm between 15° of dorsiflexion and 15° of plantarflexion. Furthermore, the ATMAs determined using the 3D and tendon excursion methods were significantly correlated but the coefficient of determination was not large (R 2 = 0.352). This result suggests that the tendon excursion method may not be feasible to evaluate the individual variability of the ATMA.

Measurement and Analysis of Lower Limb Kinematics for the Female Chinese Population During Squatting

AbstractThe study investigates three-dimensional kinematics of lower limb for female Chinese population during normal squatting activity. 25 young female and 25 elder female Chinese subjects were recruited. With each subject's data collected, the means of three-dimensional rotation angles of knee, hip, and ankle joints of those two groups were calculated and analyzed. Measured results showed that the maximal eccentric range of hip flexion/extension of 128.6° for the young female group (P < 0.05) was compared with that of 158.8° for the elder female group. Thus, the elder female undergoes more hip flexion/extension angles than the young female in the posture of squatting. The mean range of motion (ROM) of knee flexion/extension was 140.2° for the young female group and 138.7° (significant level P > 0.05) for the elder female group. The mean ROM of ankle flexion/extension was 47.90° for the young female group and 31.9° (P > 0.05) for the elder female group. The ROMs obtained in the experiment during squatting were greater than the reported ones achieved after joint arthroplasty. These data may be invaluable in providing designers of lower limb prosthesis with basic mechanical parameters, and assessing the effect of kinematics of low limb on rehabilitation for the Chinese population.

관절의 회전각을 이용한 자세 매칭률 획득 방법

Recently, in rehabilitation treatment, the situation that requires a measure of the accuracy of the pose and movement of joints is being increased due to the habits and lifestyle of modern people and the environment. In particular, there is a need for active automated system that can determine itself for the matching rate of pose Basically, a method for measuring the matching rate of pose is used by extracting an image using the Kinect or extracting a silhouette using the imaging device. However, in the case of extracting a silhouette, it is difficult to set the comparison, and in the case of using the Kinect sensor, there is a disadvantages that high accumulated error rate according to movement. Therefore, In this paper, we propose a method to reduce the accumulated error of matching rate of pose getting the rotation angle of joint by measuring the real-time amount of change of 9-axis sensor. In particular, it can be measured same conditions that unrelated of the physical condition and unaffected by the data for the back and forth movement, because of it compares the current rotation angle of the joint. Finally, we show a comparative advantage results by compared with traditional method of extracting a silhouette and a method using a Kinect sensor.

Biomechanical analysis of lower limbs in adolescents patients with idiopathic scoliosis

Objective To analyze the biomechanical properties of the lower limb in patients with adolescent idiopathic scoliosis (AIS), and to explore the relationship between the biomechanical anomaly of lower limbs and AIS. Methods A total of 116 AIS patients were recruited as the observation group, and another 116 healthy counterparts were selected as the control group. The biomechanical properties of the lower limbs including the torsion angle of the tibia, forefoot-rearfoot angle, rotation angle of the hip joint, leg length difference, and pronation of the ankle were measured and compared between the 2 groups. Then multiple factors regression analysis was conducted to reveal the risking factors for AIS. Results Significant differences were observed between the AIS group and the control group in the leg length difference [(5.94±6.07) mm vs (0.74±2.20)mm]and forefoot-rearfoot angle [(0.17±4.72)° vs (-0.46±3.60)°](P<0.01). In the AIS group, significant differences were found in the rotation amplitude of the left and right ankle, with a difference of -1.27° at standard deviation of 3.28 (P<0.01). Multi-factor regression analysis indicated that the leg length difference and forefoot-rearfoot angle were risk factors for AIS. The odds ratio of the leg length difference and forefoot-rearfoot angle were 1.45 and 0.97, respectively. Conclusions The leg length difference and forefoot-rearfoot angle are risk factors for AIS. Key words: Adolescent; Idiopathic scoliosis; Lower limb; Biomechanics

AR技術を用いた３次元足部挙動の計測評価システムの開発

Running form with pronation characteristic is an important key to choose suitable footwear and running gear. This paper describes development of a three-dimensional foot behavior measurement system with low-cost and small-footprint, and formulation of an evaluation parameter to identify runner's pronation characteristic accurately. The measurement system has SngleCamera3D (Photron Co., Ltd.) based on AR technology. In this system, subjects run on a treadmill with four AR markers attached on their heels and calves, while their running forms are recorded from behind by a single video camera. From a sequence of 2D images, three-dimensional orientation matrices of the heel and the calf during running are obtained by modified OpenCV image processing. We also proposed “pronation score” which took into account subtalar joint, heel inclination and tibial rotation angles during stance phase. As a result, the score showed good agreement with runner's pronation type evaluated by specialists. By using the proposed system, we evaluated 216 recreational runners in a major marathon event in Japan, and found that 22%, 40% and 38% of runners were underpronators, neutral pronators and overpronators, respectively.