Maximum Rotation Angle Research Articles

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.

The effect of the change of football turf on knee kinematics of adolescent male football players.

The aim of this study was to investigate the effect of the change of football turf on knee kinematics of adolescent male football players. Thirteen adolescent male football players were tested by a portable infrared motion analysis system based on markers. The angular displacements of flexion/extension,valgus/varus and internal/external rotation were calculated respectively when players performed 90° shuttle running on artificial turf and natural turf. The maximum valgus angle and range of valgus/varus were larger when they were changed from artificial turf to natural turf (P<0.05). There were no significant differences in the maximum flexion angle, maximum extension angle, range of flexion/extension, maximum varus angle, maximum internal rotation angle, maximum external rotation angle and range of internal/external rotation (P>0.05). The change of football turf has a significant effect on knee kinematics of adolescent male football players. The risk of noncontact anterior cruciate ligament (ACL) injury is increased when players who are changed from artificial turf to natural turf.

Initial stability of one-stage anterior debridement and cage implantation combined with anterior-lateral fixation by a dual screw-rod construct in the treatment of lumbosacral tuberculosis: a cadaveric biomechanical study

BackgroundAlthough various surgical methods are used to treat lumbosacral tuberculosis, no unified surgical approach exists. Thus, exploring an optimal operation method has substantial clinical importance. Evaluate the initial stability of a new surgical method, a one-stage anterior debridement and cage implantation combined with anterior-lateral fixation by a dual screw-rod construct, in the treatment of lumbosacral tuberculosis and provide biomechanical support for its further promotion in clinical applications.MethodsFifteen fresh human lumbosacral spine specimens without fractures, deformities or osteoporosis were randomly divided into intact (I), anterior fixation (AF) and posterior fixation (PF) groups. All AF and PF group specimens had subtotal resections of the L5 vertebra and adjacent discs, while the I group specimens were kept intact. Then, titanium cages were implanted in the surgical site and a dual screw-rod construct was fixed anterior-laterally in the AF group, while the PF group specimens were fixed posteriorly with only the dual screw-rod construct. Mechanical tests were conducted for initial stability evaluations.ResultsThe load at the maximum displacement (5 mm) or rotation angle (5 °) was less for the I group specimens than for the AF and PF group specimens in all directions (P < 0.05). The load at the maximum displacement (5 mm) was greater for the AF group specimens than for the PF group specimens in flexion, lateral bending and axial compression (P < 0.05) and lower than in the PF group specimens in extension (P < 0.05). In torsion, there was no difference between the loads in the AF and PF groups at the maximum rotation angle (5 °) (P > 0.05).Conclusions: The proposed surgical approach can provide better immediate stability than anterior debridement with posterior dual screw-rod fixation in the treatment of lumbosacral tuberculosis in flexion, lateral bending and axial compression.

Landing Kinematics, Sports Performance, and Isokinetic Strength in Adolescent Male Volleyball Athletes: Influence of Core Training.

Core control and strength are important for reducing the risk of lower-extremity injury. Current evidence on the effect of core training in male adolescent athletes is limited, and other investigations into the effects of core training often emphasized core strength only. To examine whether core training emphasizing both control and strength of the trunk and hip would improve joint kinematics during landing, sports performance, and lower-extremity muscle strength in adolescent male volleyball athletes. Single group pretest and posttest design. University laboratory. Sixteen male participants (age: 13.4 [1]y, height: 167.8 [8.6]cm, mass: 58.6 [13.9]kg, and volleyball experience: 3.8 [1.5]y) from a Division I volleyball team at a junior high school. Kinematics of the trunk and lower-extremity during box landing and spike jump landing tasks, volleyball-related sports performance, and isokinetic strength of hip and knee muscles were assessed before and after a 6-week core training program. After training, the participants demonstrated decreased trunk flexion angle (P = .01, Cohen's d = 0.78) during the box landing task and reduced the maximum knee internal rotation angle (P = .04, Cohen's d = 0.56) during the spike jump landing task. The average isokinetic strength of hip flexors and external rotators, and knee flexors and extensors also significantly increased (P = .001, Cohen's d = 0.98; P = .04, Cohen's d = 0.57; P = .02, Cohen's d = 0.66; P = .003, Cohen's d = 0.87, respectively); however, sports performance did not show significant changes. A more erect landing posture following training suggests that the core training program may be beneficial for improving core stability. The long-term effect of core training for knee injury prevention needs further investigation.

Increment Dynamic Analysis for One-Story Asymmetric Plan Systems under Hard Soil Site

Considering the multi-dimensional feature of earthquake motions and the torsion response can aggravate destroying of structure, the one-storey asymmetric plan system with three degree of freedom is established. The yield rule of this asymmetric system is determined by two-dimensional yield-surface plasticity function. Bi-directional Earthquake motion records for hard soil site are selected as the excitations of this asymmetric system. The increment dynamic analysis for this system is conducted, and increment dynamic analysis capacity curves are given in which peak ground acceleration is used as earthquake intensity parameter, the ductility factor and the maximum rotation angle are used as performance parameters, respectively. The effect of eccentricity, frequency ratio on responses of the one-storey asymmetric plan system, are analyzed based on the two types of capacity curves.

Efficient Hybrid Method of FEA-Based RSM and PSO Algorithm for Multi-Objective Optimization Design for a Compliant Rotary Joint for Upper Limb Assistive Device

This paper proposes an efficient hybrid methodology for multi-objective optimization design of a compliant rotary joint (CRJ). A combination of the Taguchi method (TM), finite element analysis (FEA), the response surface method (RSM), and particle swarm optimization (PSO) algorithm is developed to solving the optimization problem. Firstly, the TM is applied to determine the number of numerical experiments. And then, 3D models of the CRJ is built for FEA simulation, and mathematical models are formed using the RSM. Subsequently, the suitability of the regression equation is assessed. At the same time, the calculation of weight factors is identified based on the series of statistical equations. Based on the well-established equations, a minimum mass and a maximum rotational angle are simultaneously optimized through the PSO algorithm. Analysis of variance is used to analyze the contribution of design variables. The behavior of the proposed method is compared to the adaptive elitist differential evolution and cuckoo search algorithm through the Wilcoxon signed rank test and Friedman test. The results determined the weight factors of the mass and rotational angle are about 0.4983 and 0.5017, respectively. The results found that the optimum the mass and rotational angle are 0.0368 grams and 59.1928 degrees, respectively. It revealed that the maximum stress of 335 MPa can guarantee a long working time. The results showed that the proposed hybrid method outperforms compared to other evolutionary algorithms. The predicted results are close to the validation results. The proposed method is useful for related engineering fields.

Design of flexure revolute joint based on double compliant curved beam

In view of the problems of low accuracy and large impact caused by flexure joints during the deployable process, design of an integrated flexure revolute joint for folding mechanisms is important. Using a double compliant curved beam as a flexible unit of a joint, the revolute joint is designed based on the method of compliance and stiffness ellipsoids. The geometrical constraints model of the curved beam is established to define the design range of the unit. The total error model, which is obtained by the analysis of single-parameter errors, is used to choose the size of the unit with the smallest error. The finite element models of the flexure joints are established to analyze the rotational stiffness, translational stiffness, and the maximum rotational angle of the joints. The rotational angle of one flexure revolute joint in one direction can reach 35.7°. The rotational angle of the series flexure revolute joint in one direction can achieve 51°. The experiments of single and series flexure joints are carried out to verify the correctness of the design and for the analysis of the flexure joint.

A novel ring-beam piezoelectric actuator for small-size and high-precision manipulator

A new type of ring (joint)-beam (arm) element based on piezoelectric actuator is designed in this paper. By using piezoelectric ceramics, the vibration modes of two parallel beams are excited and coupled to form in-plane waves on the ring. As the piezoelectric actuator has the dual effect of acting as the power source and the main body structure of the arm joint, compared with the rotating joint using DC motor as the power source, the actuator does not need additional space to install the motor, which makes joint mechanism have the advantages of simple structure and small volume. Furthermore, the micro-displacement control of joints can be achieved by the characteristics of fast response and power self-locking based on the friction driving principle. A two-degree-of-freedom three-arm prototype of the joint mechanism is designed to obtain the parameters of the piezoelectric actuator and carry out related experiments. The prototype of the mechanism is 72 g in weight and 105 mm in length, and the maximum rotation angle of each joint is 210 deg. The experimental results indicate that, when driving frequency is 58.6 kHz and the driving voltage is 300 Vpp, the angular speed of the prototype reaches 45.9 deg/s, the resolution is 0.015 deg and the startup and shutdown response time are 35 ms and 21 ms, respectively. Due to its simple and compact structure, the manipulator have strong growth potential for meeting the requirements of wet hyperbaric environment. The characteristics of fast response time and high resolution enable good mobility and high precision.

Features of dynamics of the load-carrying body of the belt tubular conveyor

The problems of researching the dynamics of the load-carrying body of a belt tubular conveyor (BTC) are formulated. It is noted that for BTC, at which the flat belt is rolled into a pipe with the help of special roller supports, the main danger is torsional vibrations. The factors causing torsional vibrations of the tubular belt are analyzed. An estimate of the maximum angle of rotation of the belt from the suddenly applied moment is given. A comparison of the angular turns of the tubular belt of the closed and open profiles is made. The relations of the main belt’s parameters, which exclude the possibility of its significant rotation and load spills are obtained.

Aerodynamic Analysis and Simulation of Flapping Wing Aerial Vehicles on Hovering

In order to design and verify control algorithms for flapping wing aerial vehicles(FWAVs), calculation models of the translational force, rotational force and virtual mass force were established with the basis on the modified quasi-steady aerodynamic theory and high lift mechanisms of insect flight. The simulation results show that the rotational force and virtual mass force can be ignored in the hovering FWAVs with simple harmonic motions in a cycle. The effects of the wing deformation on aerodynamic forces were investigated by regarding the maximum rotational angle of wingtip as a reference variable. The simulation results also show that the average lift coefficient increases and drag coefficient decreases with the increase of the maximum rotational angle of wingtip in the range of 0-90°.

Design of flexible hinges in electromagnetically driven artificial flapping-wing insects for improved lift force

This paper presents a design approach to determine the bending stiffness of the flexible hinge in electromagnetically driven artificial flapping-wing insects for improved lift force. The prototype insects are fabricated by laser cutting technique and have a wingspan of 3.6 cm and a total mass of 84 mg. To induce effective wing rotational movements for improved aerodynamic performances, the geometric parameters of the flexible hinge in the wing rotation mechanism are optimized based on lift force simulations and bending stiffness tests on the enlarged flexible hinges. With an applied AC current of 420 mA (AC voltage of 0.5 V), the prototype #4 with optimized flexible hinge can produce effective wing rotational movements with a maximum rotation angle of 50° and a flapping amplitude of ±50.6° at 65 Hz. Such wing movements can generate a measured average lift force of 384.5 µN to produce a total lift force to weight ratio of 0.47. With this magnitude of lift force, the prototype can slide on a tilted guide rail with an inclined angle of 7°. Such results validate the feasibility of the design approach of the flexible hinge in the artificial insects for improved lift force.

Simultaneous control of polarization and amplitude over broad bandwidth using multi-layered anisotropic metasurfaces.

In this paper, the broadband transmissive modulation of polarization and amplitude is demonstrated with high efficiency and tunability using multi-layered aluminum metasurfaces. Broadband and nondispersive optical rotation in the optical frequency region is realized by using Fabry-Pérot-like cavity and phase compensation. Simultaneously, the transmission amplitude can be independently controlled by adjusting the twist angle of the anisotropic metasurfaces. The proposed polarization-amplitude modulators are numerically demonstrated to achieve large tunability with an amplitude modulation depth of 0.95 and maximum rotation angle of 180°.

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.

Electrostatic flapping-wing actuator with improved lift force by the pivot-spar bracket design

Appropriate wing rotational movements in flapping wing flight are essential to generate aerodynamic lift force. This paper presents the usage of a pair of “pivot-spar” brackets to guide rotational movements of an electrostatic flapping-wing actuator for enhanced lift force. The wing rotation pattern is guided by the bracket design with the help of numerical simulations. Wing movements with desired rotation pattern are recorded by a high speed camera and the instantaneous lift force generated by the flapping-wing actuator is measured by a test platform using a lever and a high-precision force sensor. Experimentally, the flapping-wing actuator using the “pivot-spar” brackets with a diverging angle of 40° can achieve a maximum wing rotation angle of 29° and generate an aerodynamic lift force at 79.2 μN. Besides, this work also uses advanced micro fabrication methods based on laser cutting technique and the mass of the flapping-wing actuator can be reduced to 50 mg. With 2.5 times higher lift force at 79.2 μN and 20 times lower overall system mass at 50 mg as compared with the earlier report, 50 times higher efficiency is achieved by calculating the total lift force/weight ratio for the presented electrostatic flapping-wing actuator with “pivot-spar” design. This result advances the field of electrostatic flapping-wing actuator toward its possible takeoff in the future.

Double stage FPCB scanning micromirror for laser line generator

This paper presents a laser line generator consisting of an electrostatic scanning micromirror utilizing a Double-Stage Flexible Printed Circuit Board (DS-FPCB). It consists of two stages with the rotating electrode in the 1st stage, and the mirror plate in the 2nd stage. Due to both rotating electrode being much closer to the rotational axis and the rotational amplification effect between the two stages, the DS-FPCB micromirror can have a 90% higher maximum rotation angle, in comparison to previously developed single stage FPCB micromirrors, while retaining benefits of low cost (a few dollars) and high surface quality (high flatness, radius of curvature (ROC) >10 m, good roughness of nanometers). The DS-FPCB micromirror is modeled and prototypes are fabricated and tested, achieving a 3.25° optical rotation at 100 V (sinusoidal wave driving signal) and 10.87° at 150 V (square wave driving signal), both at 117 Hz. A laser line generator based on the DS-FPCB micromirror is developed and tested, whose laser power density along the line is uniform and independent on the projection distance, while the conventional laser line generator's laser power density varies along the laser line and is highly dependent on the projection distance.

Biaxial scanning mirror with large rotation angle and low resonance frequency for LIDAR application

We propose a biaxial scanning mirror with a large rotation angle and low resonance frequency for a compact and low-power-consuming LIDAR. The scanning mirror in LIDAR, which is driven by a rotating motor, requires a wide field of view and a low working frequency. To achieve these requirements, we develop an electromagnetic actuator for a biaxial scanning mirror that consists of two pairs of coils, one yoke with a cross shape, one rare-earth permanent magnet, and one gimbal structure frame. The gap distance between the permanent magnet and yoke is adjusted to find the optimum condition. The overall size of the developed system is 20 mm × 20 mm × 12 mm (width × depth × height) with a gap distance of 3 mm. Experiments and simulations are performed with various gap distances. The experimental results indicate that the maximum rotation angle is ± 51° at 37 Hz when the gap distance is 3 mm and the applied voltage is ± 5 V.

Research on an innovative multifunction steering wheel for individuals with reduced mobility

This article presents the results of an experimental comparative study assessing the functionality of a prototype for a new interface for driving electric vehicles equipped with a steer-by-wire system. The interface was developed under the umbrella of the Eco-Mobility project, co-financed by European funds. Unlike classical steering solutions, the prototype interface described in this report is characterized by an absence of foot controls. Main control is achieved via a multifunctional steering wheel using only the upper limbs, which makes it accessible to drivers with varying degrees of mobility. The steer-by-wire system provides the opportunity to alter the sensitivity of the steering ratio, defined as the ratio of the maximum angle of rotation of the steering wheel to the maximum steering angle of the front wheels. Studies were performed in a dynamic 3D simulator. The goal of these studies was to assess the quality of driving with both a classic and the multifunctional steering wheel (with two steering ratio variants). Simulator studies used a proprietary methodology that enabled assessment of the interface’s functionality. The assessment was made using quality indicators developed for the purpose of quantifying the correctness of test performance. Statistical analysis of these parameters exhibited significant differences between the results of the steering wheel indicators.

Hip Range of Motion Estimation using CT-derived 3D Models

The success of the total hip arthroplasty is revealed as initial stability, range of motion, and long term pain, etc. Depending upon choice of implantation options such as femoral neck offset, diameter of the femoral head, the lateral opening tilt. Especially the impingement between femoral head component and acetabular cup limits the range of motion of the hip. In this sense, estimation or evaluation of the range of motion before and after the total hip arthroplasty is important. This study provides the details of a computer simulation technique for the hip range of motion of intact hip as well as arthroplasty. The suggested method defines the hip rotation center and rotation axes for flexion and abduction, respectively. The simulation uses CT-based reconstructed 3D models and an STL treating software. The abduction angle of the hip is defined as the superolateral rotation angle from sagittal plane. The flexion angle of the hip is defined as the superoanterior angle from the coronal plane. The maximum abduction angle is found as the maximum rotation angle by which the femoral head can rotate superolaterally about the anterior-posterior axis without impingement. The maximum flexion angle is found as the maximum rotation angle by which the femoral head can rotate superoanteriorly about the medial-lateral axis without impingement. Compared to the normal hip, the total hip replacement hip showed decreased abduction by 60 degrees and decreased flexion by 4 degrees. This measured value implies that the proposed measurement technique can make surgeons find a modification of increase in the femoral neck offset or femoral head, to secure larger range of motion.

Configuration Optimization and a Tension Distribution Algorithm for Cable-Driven Parallel Robots

In order to improve the performance of cable-driven parallel robots (CDPRs), the configuration of the redundantly actuated CDPRs is optimized, and a feasible continuous tension distribution method for tracking the trajectory of the robot is proposed. A convex analysis method is used to determine the wrench-feasible workspace of CDPRs and the grouped coordinate descent method is used to determine the size of the redundantly actuated six-degree-of-freedom CDPRs. By changing the cable layout and using the geometric analysis method for the redundantly actuated CDPRs, the maximum rotation angle of the mobile platform in 3-D space is determined. The optimal size and layout of the CDPR are determined by comparison and analysis. The high dynamic CDPRs require real-time control to adjust the cable tension. In order to solve this issue, a real-time cable tension distribution algorithm for a non-iteration two-degree-of-freedom actuation redundancy CDPR is proposed. The proposed tension distribution algorithm is applied to the optimized six-degree-of-freedom eight-cable CDPR, and compared with other existing cable tension distribution algorithms. The simulation results demonstrated that the feasibility and the advantages of the proposed cable tension distribution algorithm.

A novel robotic arm driven by sandwich piezoelectric transducers

In this work, a novel robotic arm driven by sandwich piezoelectric transducers is proposed. The proposed robotic arm is composed of three arms and four joints. Each arm consists of a sandwich piezoelectric transducer and an H-shaped hollow frame. The sandwich piezoelectric transducer utilizes frictional force to drive the joints on its both sides to rotate simultaneously. The joint between two arms can be driven to rotate in two perpendicular directions by two sandwich piezoelectric transducers. The rotation of joints results in the arm motion. Utilizing the finite element method, the optimized geometrical parameters of the sandwiched piezoelectric transducer are obtained, and the operating principle is demonstrated. A prototype of the robotic arm is also fabricated and assembled, it is 573 g in weight and 412 mm in length, and the maximum rotation angle of each joint is 160°. The mechanical characteristics of the robotic arm prototype are investigated by experiments. The results indicate that, when the excitation frequency of one sandwich piezoelectric transducer is 37.4 kHz, the arms on its two sides rotate in opposite directions with an average rotational velocity of 320 deg/s at 330 Vpp, a resolution of 100 μrad at 230 Vpp, and a startup and shutdown response time of 40 ms and 30 ms at 230 Vpp, respectively.