Joint Rotation Angle Research Articles

Development and Evaluation of an Adaptive Multi-DOF Finger with Mechanical-Sensor Integrated for Prosthetic Hand.

To realize the adaptive grasping of objects with diverse shapes and to capture the joint angles of the finger, a multi degree of freedom (DOF) adaptive finger for prosthetic hand is proposed in this paper. The fingers are designed with three joints. The maximum rotation angle of the finger joints is 90°. The angle at which the finger joints bend can be captured. Firstly, the prototype design, forward kinematics and force analysis of phalanges are described in detail. In order to achieve an adaptive motion pattern similar to that of the human hand, this paper investigates the optimization of the torsion spring stiffness coefficient so that the metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and distal interphalangeal (DIP) joints of the bionic finger meet a motion ratio of approximately 3:3:1. Then, in order to realize the joint angle measurement in the process of grasping an object, the mechanical-sensor integrated finger joint is designed, and the composition, angle measurement principle and measurement circuit are introduced in detail. Finally, joint angle measurement, movement law evaluation and object grasping experiments are performed to verify the validity of the designed finger. The experimental results show that the root-mean-square (RMS) of the DIP, PIP and MCP angle measurement errors are 0.36°, 0.59° and 0.32°, respectively. The designed finger is able to grasp objects with different shapes stably.

Mechanical responses of bell‐and‐spigot joints in buried prestressed concrete cylinder pipe under coupled service and surcharge loads

AbstractPrestressed concrete cylinder pipe (PCCP) is widely used in hydraulic engineering. The bell‐and‐spigot joint is a weak point along a PCCP pipeline, since damage of joint can affect the operation of the whole pipeline. In this paper, a three‐dimensional numerical model of buried PCCP, considering the simulation of rubber gasket in bell‐and‐spigot joint is established. The fluid–structure coupling of PCCP is accomplished using the Mesh‐based parallel Code Coupling Interface (MpCCI), where the pipe and the surrounding soil are characterized in the software ABAQUS, and the pressurized water is modeled in the software FLUENT. The force and rotation angle at joints of PCCP under different conditions, including surcharge load, loading location, cover depth, and internal pressure, are analyzed. It is shown that the rotation angle of joint exceeds the allowable value, when the surcharge load is greater than 180 kPa. Compared with the effect of surcharge load, the offset distance (i.e., distance between the loading position and the pipe axis) has a greater influence on the development of horizontal displacement and rotation angle. As the offset distance increases, both the horizontal displacement and rotation angle at joints increase first, and they decrease after the peak.

The Path Planning of Synchronous Cooperative Motion Control between Robot and Positioner for Complex Space Curve Processing

In this paper, we propose a synchronous cooperative path planning (SCPP) algorithm for the robot and the positioner to process complex space curve workpieces. The specific algorithm design is illustrated by using the intersecting line welding as an example. The robot and positioner are regarded as an 8-degree-of-freedom (DOF) system to plan the whole synchronous cooperative motion path, and the constraint for the Y-axis of the welding torch coordination system is added for solving the intersecting line orientation information. SCPP is used to process the intersecting line. The changes of welding torch orientation and robot joint rotation angles during welding of the intersecting line by using the improved method and compared to the traditional method. The experimental results show that 8-DOF keeps synchronous cooperative in the whole movement. There is no interference happening during the entire cooperative movement and the welding torch’s orientation remains basically unchanged during the welding intersecting line.

The Acute Influence of Running-Induced Fatigue on the Performance and Biomechanics of a Countermovement Jump

Lower limb kinematics and kinetics during the landing phase of jumping might change because of localized muscle fatigue. This study aimed to investigate the acute influence of running-induced fatigue on the performance and lower limb kinematics and kinetics of a countermovement jump. A running-induced fatigue protocol was applied to fifteen male subjects. Participants were asked to perform three successful countermovement jumps before and after fatigue. Kinematic and kinetic data were collected to compare any fatigue influences. Wilcoxon signed-rank tests and paired-sample t-tests were used to analyze the data. Running-induced fatigue did not significantly change vertical jump height and peak vertical ground reaction forces (GRF) during the push-off and landing phases. Lower limb biomechanics significantly changed, especially kinematic parameters. During the push-off phase, fatigue resulted in an increased ankle peak inversion angle, knee minimal flexion angle, knee peak abduction angle, and hip peak flexion moment. In addition, the range of motion (ROM) of the ankle and knee joints in the frontal plane was also increased. Certain parameters decreased as a result of fatigue, such as the ankle peak internal rotation angle, hip peak abduction angle, the ROM of the ankle joint in the sagittal plane, and ROM of the hip joint in the frontal plane. During the landing phase, the peak inversion angle and peak external rotation angle of the ankle joint, peak abduction angle of the knee and hip joint, ROM of the ankle joint in the horizontal plane, ROM of the ankle and knee joint in the frontal plane were all increased as a result of fatigue. The knee peak flexion moment and hip peak extension moment, however, were decreased. Under fatigue conditions, lower limb kinetics and kinematics were changed during both the push-off and landing phases. More attention should be focused on the landing phase and the last period of the push-off phase due to potentially higher risks of injury. The findings of the current study may be beneficial to athletes and coaches in preventing jumping related injuries.

Numerical and Dynamic Errors Analysis of Planar Multibody Mechanical Systems With Adjustable Clearance Joints Based on Lagrange Equations and Experiment.

For theoretical study and engineering application, it is necessary to provide an accurate and simple dynamical model to simulate the multibody mechanical systems with clearance joints and it is also the subject of this article. Based on Lagrange equations of the first kind, a different numerical methodology, the length and rotation angle of the clearance joints are looked as independent coordinates for the first time, is presented in detail. The slider-crank mechanism, with a single or double adjustable revolute clearance joints, is used as a numerical model. A test rig and a simulink model, fully in accordance with the numerical model, are used to measure the velocity, displacement, and acceleration. The numerical results tally with experimental and simulink results reveal that the new methodology, presented in this paper, provides a correct approach to build the dynamical equations of mechanism with clearance joints. Lyapunov exponent is used to analyze the motion status, chaotic or periodic, of the slider. Based on data points, mean absolute deviation (MAD) is applied to judge the dynamical errors, displacement, velocity, and acceleration, of the slider due to clearance joints. With the help of Lyapunov exponent and MAD, the results indicated that various clearance sizes and drive speeds can change the dynamical behaviors of the slider, which is complex but can be predicted in some way.

Evaluation of physical workload during work behavior for work environment design from biomechanical perspective: a case study in initial orientation selection of work object for manual handling tasks

To improve workability, designing the work environment by considering physical workload can be effective. This paper proposes a new quantitative evaluation method of physical workload during work behavior, which uses quaternion and joint torque ratio. As an indicator of physical workload, the proposed method calculated a dimensionless value based on joint rotation angle, joint rotation axis angle, and joint torque ratio. Joint rotation angle and joint rotation axis angle are angle changes in the joint and its rotational axis from those in the previous sampling, respectively. These angles were calculated using quaternions. Joint torque ratio was calculated using a three-dimensional rigid link model that simulates the human body. The applicability of the proposed method was examined in several conditions of manual handling tasks set by varying the initial pose of the work object. In the experiments, posture and electromyogram (EMG) of the upper limb were measured. The results showed that the proposed method can evaluate workability of initial orientation of work objects on biomechanical perspective, whereas EMG could not.

Association of meniscal flounce in the knee with the pattern and location of meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles: a magnetic resonance evaluation.

To determine the association of meniscal flounce with the pattern and location of the meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles. A total of 283 knees of 280 patients were retrospectively reviewed over a 9-month period. Thirty-one magnetic resonance images of patients with meniscal flounce were compared with those of age- and sex-matched control group (n = 62) without meniscal flounce. The presence of meniscal tear was evaluated and, if present, its location and pattern were recorded. The amount of joint effusion was graded, and the joint angle was measured. The Fisher's exact, Cochran-Armitage trend, and t tests were performed to compare the findings between the two groups. The decision tree analysis was employed to determine the most significant factor of meniscal flounce. Meniscal flounce was present in 11.0% (31/283) of the adult population. Approximately 80.6% of meniscal flounce occurred in the torn medial menisci. The presence of meniscal flounce was significantly associated with tears at the body (p = 0.007), posterior horn (p = 0.001), and meniscocapsular junction (p = 0.002) of the medial meniscus. The decision tree analysis revealed that the posterior horn tear of the medial meniscus was the most significant predictor of meniscal flounce. The most significant factor associated with meniscal flounce is tear at the posterior horn of the medial meniscus, followed by tear at the meniscocapsular junction.

Dynamical mechanics behavior and safety analysis of deep water riser considering the normal drilling condition and hang-off condition

A dynamic analysis model for the drilling riser was established and applied under normal drilling and hang-off conditions by distinguishing the boundary condition. This model was discretized by the FEM and solved by Newmark β method. The correctness of this model was verified through an experiment. Results indicate that the lateral displacement distribution and riser stress increase with the current speed and platform drift distance. A platform that drifts along the current is conducive to counteract the rotation of the upper joint but promotes the rotation of the bottom joint of the riser. A riser that is approximately 2,000 m long under normal drilling condition can withstand the current loads for a 10-year return period. The hang-off riser should be evacuated after being disconnected from the bottom along with the current as soon as possible. In addition, the riser that evacuated under soft hang-off condition can significantly reduce stress but enlarge the rotation angle of the upper flexible joint.

Assessment of the talar deformity and alignment in congenital clubfoot using three-dimensional MRI after Ponseti method

BackgroundPonseti method have been widely accepted as the initial treatment of congenital idiopathic clubfoot because its excellent primary result. On the other hand, relapses after Ponseti method are not uncommon and the cause of relapses have not been fully elucidated. We investigated detailed morphology and alignment of tarsal bones in clubfoot after Ponseti method using three-dimensional MRI analysis. MethodsWe performed MRI with 10 patients of unilateral clubfoot at three months after Achilles tenotomy. Based on the MRI volume data, we reconstructed three-dimensional bone surface model using the marching cubes method. We evaluated the volume of the talus and navicular bone, medial and planter deviation of the talar head and neck, medial deviation of the navicular bone, and internal rotation angle of the distal tibiofibular joint. ResultsIn clubfoot, the volume of talus and navicular bone were significantly smaller compared with the contralateral side. Deviation of the talar head and neck varied from medially to almost the same as that on the contralateral side. The degree of deformity of the talus and alignment of the navicular bone and distal tibiofibular joint showed correlations. ConclusionsPatients with the medial deviated talar neck might have the alignment change of navicular bone and distal tibiofibular joint. Deformity of talar neck might to be compensated by talonavicular joint and distal tibiofibular joint through the manipulation of Ponseti method.

RETRACTED: Reducing energy consumption via trajectory planning method for delta high-speed parallel manipulator

This paper selects delta high-speed parallel robot with three degrees of freedom as the research object. The trajectory planning strategies of Cartesian space and angular displacement, angular velocity and angular acceleration of three joints in high-speed handling are studied. Firstly, the critical trajectory points starting point and end point, and points for obstacle avoidance height are set up, and then according to the inverse kinematics model of the robot, a point-to-point “door” type moving trajectory is established, and the mapping relationship between the motion characteristics of the operating space and the motion characteristics of the joint space is established by using the 4-3-4 degree polynomial motion law in the operating space. However, aiming at the higher energy consumption of 4-3-4 degree polynomial interpolation caused by longer the trajectory, and difficult control of obstacle avoidance height, one key point is added. Thereby, the motion rules are interpolated by 4-3-3-4 degree polynomial interpolation, and the mapping relationship between the motion characteristics of the operating space and the motion characteristics of the joint space is established. Two trajectory planning methods are simultaneously simulated under the same keys points and the same trajectory time range. The motion characteristics of the joint rotation angle of the parallel robot between polynomial interpolations are respectively compared. The results show that the trajectory planning method based on 4-3-3-4 degree polynomial interpolation in joint space has obvious advantages in improving the running state of the delta parallel robot and reducing the energy consumption of the system.

Assessment of lower limb rotational profile and its correlation with the tibial tuberosity-trochlea groove distance: A radiological study.

The purpose of our study was to determine whether there is a correlation between the lower limb rotational profile and tibial tuberosity-trochlea groove (TT-TG) distance. The computed tomography cross-sectional imaging on 50 patients' lower limbs (100 limbs) was investigated at our institution. The TT-TG distance was measured along with rotational measurements including femoral version (FV), tibial torsion and knee joint rotation angle (KJRA). Patients were divided into two groups. Group 1 had a TT-TG ≥ 20 mm which was considered pathological and group 2 with a non-pathological TT-TG (≤19 mm). Rotational angles were compared between groups. Statistical analysis was performed using the t-test and Mann-Whitney U analysis. Our results demonstrated a statistically significant difference in the mean KJRA (p = 0.026) between the pathological (mean = 10.6, standard deviation (SD) = 7.79°) and the non-pathological TT-TG groups (mean = 6.99, SD = 5.06°). A higher mean value for FV and tibial torsion was also demonstrated in patients with a pathological TT-TG (18.2 vs. 13.7, 32.8 vs. 30.9, p > 0.05, respectively). In conclusion, there was a statistically significant higher mean value for the KJRA in patients with a pathological TT-TG. Hence, a lateralized tibial tubercle as demonstrated by an increase in the TT-TG distance may be associated with a coexisting lower limb rotational malalignment.

Assembly dynamics of a large space modular satellite antenna

The autonomous assembly technology can be used to construct large space structures such as space telescopes, satellite antennas and space stations. A novel computation methodology to study the assembly dynamics of a large space modular satellite antenna is proposed. The system rigid body and flexible body are respectively described by the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). A parameterized inverse kinematics resolution method is used to evaluate the arm joint rotation angles of a rigid assembly manipulator with 7 degree-of-freedom (DOF). To minimize the disturbance of the floating satellite base attitude, an efficient particle swarm optimization (PSO) algorithm with Latin hypercube sampling skill (LHS-PSO) is used to find the optimized arm joint trajectories of the assembly manipulator arms. In the optimization process the oriented bounding box (OBB) contact detection method is also embedded to eliminate the trajectories which may lead to the arm-satellite or arm-arm impact problems. Finally, two numerical examples are provided to validate the proposed computation methodology. The results show that the satellite base attitude almost return back to its initial state after completing the assembly process by using the optimized joint trajectories.

A Moment Approach to Positioning Accuracy Reliability Analysis for Industrial Robots

The uncertain variables of the link dimensions and joint clearances, whose deviation is caused by manufacturing and assembling errors, have a considerable influence on the positioning accuracy of industrial robots. Understanding how these uncertain variables affect the positioning accuracy of industrial robots is very important to select appropriate parameters during design process. In this paper, the positioning accuracy reliability of industrial robots is analyzed considering the influence of uncertain variables. First, the kinematic models of industrial robots are established based on the Denavit–Hartenberg method, in which the link lengths and joint rotation angles are treated as uncertain variables. Second, the Sobol’ method is used to analyze the sensitivity of uncertain variables for the positioning accuracy of industrial robots, by which the sensitive variables are determined to perform the reliability analysis. Finally, in view of the sensitive variables, the first-four order moments and probability density function of the manipulator's positioning point are assessed by the point estimation method (PEM) in three examples. The Monte Carlo simulation method, the maximum entropy problem with fractional order moments (maximum entropy problem with fractional order moments method (ME-FM) method), and the experimental method are also performed as comparative methods. All the results demonstrate that the proposed PEM has a higher accuracy and efficiency to assess the positioning accuracy reliability of industrial robots.

Measurement of small rotation angle of flange joints by a novel flexure magnifying mechanism

Bolted flange joints are indispensable components in process industries due to the good sealing, assemble and disassemble capacities. Generally, the flange rigidity characterized by the rotation angle is a key index to evaluate the sealing tightness of flange joints. However, the rotation angle of flange is usually too small (less than 1°) to monitor during the assemble and operation stages. Accordingly, a novel flexure magnifying mechanism is designed to measure the small rotation angle of flange joints under internal pressure and external bending moment. The magnification factor and calculation approach of the flexure amplification mechanism are deduced and verified by experimental data and finite element simulation. Results indicate that the proposed measuring apparatus has good performance to monitor the maximum rotation angle. It is of great interest that the measured location of the maximum rotation angle is in good agreement with that in the experiment, and the average error is 7.3%, which is acceptable for practical application. Additionally, the leakage rate at the top of flange joints slowly and almost linearly increases with the increment of external bending moment ascribing to the decrease the gasket stress near the top of flange joints.

An FBG-Based Sensing Glove to Measure Dynamic Finger Flexure With an Angular Resolution of 0.1$^{\circ }$ up to Speeds of 80$\mathrm{^{\circ }\text{/s}}$

We demonstrate a fiber Bragg grating (FBG) sensor-based highly accurate instrumented glove that can measure finger flexure with an angular resolution of 0.1 $^{\circ }$ . The sensing unit consists of an FBG that is very sensitive to axial strain induced by the flexing of fingers. The spectral shift of the reflection spectrum of the FBG varies linearly with the joint rotation angle. The sensor offers a very high angular resolution of 0.1 $^{\circ }$ with a very high sensitivity of 18.45 pm/degree. The accuracy evaluated using a mechanical setup, and the human hand is 0.13 $^{\circ }$ and 0.67 $^{\circ }$ , respectively. This is much better than many other reported sensors. The sensor showed excellent repeatability with a maximum standard deviation of 0.30 $^{\circ }$ and 0.79 $^{\circ }$ on a mechanical setup and the human hand, respectively. The results are validated using a precalibrated inertial measurement unit (IMU) sensor. The sensor also exhibited much better dynamic response compared to the IMU upto a rotation speed of 80 $^{\circ }$ /s. These results demonstrate that our sensor is a strong potential candidate for the development of high-accuracy instrumented gloves that could be used to monitor the progress in the rehabilitation of stroke survivors. This paper focuses on the careful characterization of the sensor to establish it as a sensitive and practical approach. The accuracy, repeatability, and dynamic response were evaluated using a motorized mechanical model of a finger joint and also on the hands of two human subjects.

Position/force control of master–slave antagonistic joint actuated by water hydraulic artificial muscles

Because of the high force–weight ratio of water hydraulic artificial muscle and its high compatibility with an underwater environment, the water hydraulic artificial muscle has received increasing attention due to its potential uses in marine engineering applications. The master–slave anthropopathic joint actuated by water hydraulic artificial muscles is light and small, and it has good maneuverability for underwater manipulators. However, the control methodologies for water hydraulic artificial muscle joint have not been thoroughly explored to date. This article introduces a master–slave control system of isomorphic artificial muscle joints. The water hydraulic artificial muscle joint acts as a slave joint working under the sea, and the pneumatic artificial muscle joint acts as a master joint that is operated by people. The rotation angle signal of the pneumatic artificial muscle joint is fed back as the input to regulate the rotation angle of the water hydraulic artificial muscle joint through a proportional–integral–derivative control. Meanwhile, the torque of the pneumatic artificial muscle joint is controlled by a proportional–integral–derivative controller based on the feedback of a two-force-transducer system in the water hydraulic artificial muscle joint as input. Therefore, the operator can control the movement and feel the load of the water hydraulic artificial muscle slave joint. Master–slave control experiments were performed, and the position/torque control results were analyzed using various loads and torque gains. This study contributes to the design and control of an anthropopathic underwater manipulator.

Optimizing method of mechanism angle of upper limb rehabilitation robot at glenohumeral joint

At present, there are seventy million stroke patients in China and annual death toll of stroke is 1 million 650 thousand people. The survivors about 75% become disabled persons and lose the ability to move. To address this issue, a kind of rehabilitation exoskeleton robot called YANARM is proposed which for training of shoulder complex. This paper, a kind of method for optimizing the angle parameters of series dynamic axes under given workspace conditions is presented. The forward and inverse kinematics solutions of glenohumeral mechanism are solved based on the exponential product formula (POE) and the Paden-Kahan sub-problem. The range of joint rotation angle can be inversely solved according to the end of the arm position at the borderline of the workspace. A curve between the angle and the CP which equal mean variance of joint rotation range plus sum of all joint rotation ranges is solved. The mechanism angle of glenohumeral joint is optimized by this method.

Sensitivity analysis of beam–column joint rotation angles with respect to the stiffnesses of the columns of frame structures

Purpose Damage detection of frame structures is important for guaranteeing the safety of people’s lives and property. Sensitivity analysis is an effective method for damage identification. The purpose of this paper is to conduct a sensitivity analysis of beam–column joint rotation angles for frame structures with limited flexural stiffness beams. Design/methodology/approach First, based on the D-value method and the assumption of inflection points, statically indeterminate frames were transformed to statically determinate structures, and the expressions of beam–column joint rotation angles were derived. Next, the sensitivity coefficients of beam–column joint rotation angles were obtained by taking the derivative of the expressions of beam–column joint rotation angles with respect to the linear stiffness of column. Finally, the expressions of the sensitivity coefficients were verified by a numerical example. Findings The analytical solutions of the sensitivity coefficients are in good agreement with finite element results. The results show that the beam–column joint rotation angles of damaged column decrease and those of intact columns within the same story increase when damage occurs. Originality/value In this study, the sensitivity coefficients of beam–column joint rotation angles with respect to the linear stiffnesses of columns were derived for frame structures. Based on the result of the sensitivity analysis, the relationship between the changes of beam–column joint rotation angles and damaged columns is revealed. The findings provide an important base to further detect damage of frame structures.

Reconstructing Human Joint Motion with Computational Fabrics

Accurate and continuous monitoring of joint rotational motion is crucial for a wide range of applications such as physical rehabilitation [6, 85] and motion training [22, 54, 68]. Existing motion capture systems, however, either need instrumentation of the environment, or fail to track arbitrary joint motion, or impose wearing discomfort by requiring rigid electrical sensors right around the joint area. This work studies the use of everyday fabrics as a flexible and soft sensing medium to monitor joint angular motion accurately and reliably. Specifically we focus on the primary use of conductive stretchable fabrics to sense the skin deformation during joint motion and infer the joint rotational angle. We tackle challenges of fabric sensing originated by the inherent properties of elastic materials by leveraging two types of sensing fabric and characterizing their properties based on models in material science. We apply models from bio-mechanics to infer joint angles and propose the use of dual strain sensing to enhance sensing robustness against user diversity and fabric position offsets. We fabricate prototypes using off-the-shelf fabrics and micro-controller. Experiments with ten participants show 9.69° median angular error in tracking joint angle and its sensing robustness across various users and activities.

A novel testing setup for determining the flexural properties of tunnel segmental joints: Development and application

A novel testing setup is developed for structural tests on segmental joints of shield tunnels. It lies on the ground and is a self-balanced system. The applied axial force and bending moment are coupled, and the combination of target axial force and bending moment at the joint can be achieved by adjusting the horizontally-applied forces. It is more economic and flexible than the traditional two-point bending testing setups. The effectiveness of internal force/moment transmission of the testing setup was verified by comparing the experimental data with theoretically-determined values and numerical simulation results. It was then applied to investigate the flexural behaviour of longitudinal joint of a deeply-buried tunnel subjected to both sagging and hogging moments. The rotational stiffnesses of the testing joint were determined. The influences of bending moment and axial force on joint deformation were unified through eccentricity. In both the sagging moment and hogging moment cases, the joint deformation varied with eccentricity following a bilinear trend composed of an axial-force-dominant stage and a bending-moment-dominant stage. The slopes of the relationships between eccentricity and joint rotation angle are steeper in the hogging moment case than in the sagging moment case due to the absence of bolts at the extrados.