最新刊期
期 8 ， 2021
- 摘要：In order to realize the fast erection of electromechanical actuator， and the influence rule of the hinge position and output speed on output power and force in erection device is revealed， the hinge position and the output speed of the system are optimized and researched. The kinetics models of load and electromechanical actuator are found respectively. The relation between output speed and output power， the relation between output speed and output force， the relation between hinge position and output power， the relation between hinge position and output force are explored. The Genetic Algorithm is taken to optimize the output speed and the hinge position. The optimum match relation between the output speed and the hinge position is got. It can improve work efficiency， make space layout of the whole device optimal and make the installation space the best compact.关键词：Erection device;Electromechanical actuator;Kinetics;Optimization design
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发布时间：2022-11-10 - 摘要：Based on the lumped mass method， bending and torsion coupled dynamics model of the concentric face gear transmission system is established. The calculation method of floating quantity of input pinion is studied， the system dynamic equation is modified， and the calculation method of dynamic load sharing coefficient is defined. A practical calculation example is given to analyze the influence of input gear floating quantity on system load sharing performance. The results show that the dynamic load sharing performance of the system is affected by the fluctuation of the input pinion， the dynamic load sharing performance of the system is the best when the two input pinions are floating， and the dynamic load sharing performance of the system is the worst when a certain input pinion is floating alone. The load sharing performance test is carried out on the concentric face gear test bench， which verified the reliability of the load sharing performance analysis when the two input gears are floating under a certain supporting structure.关键词：Concentric face gear;Gear dynamics;Floating quantity;Load sharing performance
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发布时间：2022-11-10 - 摘要：The torsional dynamics model of herringbone gear pair considering time-varying meshing stiffness， constant backlash， dynamic backlash， static transmission error and external dynamic excitation is established. The frequency response characteristics of the system under constant and dynamic backlashes are solved by incremental harmonic balance method， and the results are further verified by Runge-Kutta numerical integration method. The influence of time-varying meshing stiffness， damping， static transmission error and external load excitation on the amplitude frequency characteristics of the system is analyzed. The results show that， there is not only main harmonic response， but also super-harmonic response in the system. The time-varying meshing stiffness and static transmission error can stimulate the amplitude frequency response of the system， while the damping can restrain the amplitude frequency response of the system. Changing the external load excitation has little effect on the amplitude frequency response state change of the system. Compared with the constant backlash， increasing the dynamic backlash amplitude can further control the nonlinear vibration of the gear system.关键词：Herringbone gear;Backlash;Incremental harmonic balance method;Nonlinear;Frequency response characteristic
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发布时间：2022-11-10 - 摘要：Based on the modification of single roller enveloping hourglass worm drive， a new type of worm drive， parallel inclined double roller enveloping hourglass worm drive is proposed. According to the principle of single roller enveloping worm drive and spatial meshing theory， the basic mathematical model of parallel inclined double roller enveloping hourglass worm drive is constructed. Based on the established mathematical model， the basic characteristic parameters of the new type worm drive， such as induced normal curvature， lubrication angle， self-rotation angle， meshing equation and tooth surface equation are analyzed and deduced. According to the obtained basic characteristic parameters， the meshing performance of the new worm drive is analyzed. The analysis results show that this new type of worm drive has good meshing performance.关键词：Hourglass worm;Meshing theory;Double roller;Parallel inclined
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发布时间：2022-11-10 - 摘要：Fatigue spalling is one of the main failure forms of bearing， and the change of contact stress between rolling body and raceway is an important factor causing fatigue spalling of bearing. Taking the angular contact ball bearing as study object， based on the classical pseudo-statics model， considering the effect of inertia force on the rolling body under the condition of high rotation speed， the internal geometry relationship and force balance relationship expression of angular contact ball bearings are built， the characteristic parameters of the bearing at high speed are obtained through solving the model by numerical method. The accuracy of the model is verified by comparing the characteristic parameters to the literature. On this basis， the axial force， the radial force and the speed of rotation are respectively controlled， and the distribution characteristics and changes of the contact stress of the bearing under special working conditions are studied， and the relationship between the variation of the external load and the speed of rotation and the fatigue spalling of the bearing is obtained， which provides certain technical guidance for reducing fatigue spalling of bearing.关键词：Angular contact ball bearing;Pseudo-static model;Contact stress;Inertia force;Fatigue spalling
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发布时间：2022-11-10 - 摘要：Taking the main bearing of a diesel engine as the study object， the lubrication state analysis model of the main bearing is established by taking the roughness and elastic deformation of the main bearing surface into account， and the influence of the radial profile of the main bearing on the lubrication state is analyzed. The results show that， compared with the calculated results without considering the radial journal profile， when the influence of the radial journal profile is taken into account， the minimum oil film thickness of the main bearing increases by 25.95%， the maximum oil film pressure decreases by 17.69%， the mean friction power loss decreases by 6.14% and the inclination of the spindle neck is improved. With the increase of journal roughness， the minimum oil film thickness increases， the maximum oil film pressure almost invariably， and the mean friction power loss increases.关键词：Diesel;Main bearing;Radial;Journal profile;Lubrication state
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发布时间：2022-11-10 - 摘要：A nonlinear stiffness modeling method for collaborative robots（Cobots） is proposed， which is combine the finite element analysis method （FEA） with the virtual joint method （VJM）. This modeling method not only includes the linear and coupled stiffness of the link and joint modules， but also takes into account the nonlinear stiffness of transmission systems of robot， the change rate of Jacobian matrix under loads and the influence of the changes of poses are caused by the load and deadweight on nonlinear stiffness of robot. The structure stiffness matrices of link modules and joint modules are obtained by finite element substructure method. Combined with the nonlinear stiffness model of the transmission system， the nonlinear comprehensive stiffness model of each robot module is established. The static equilibrium pose and the force of each module under external force and self-weight condition are calculated by numerical calculation method. Based on the VJM， a nonlinear stiffness model of robot is built， and the validity of this method is proved by nonlinear finite element simulation.关键词：Collaborative robot;Nonlinear;Stiffness modeling;Substructure method
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发布时间：2022-11-10 - 摘要：The cardioid crank is a planet mechanism which is able to generate cardioid curve， with cardioid crank as the driven crank of the guide-bar mechanism is equal to the mechanism which has a crank of the varying length and varying speed and moving along the cardioid， which changed the kinematic characteristics of the guide-bar. A cardioid crank guide bar dwell motion mechanism is presented. The motion analysis and the calculation method of the limit position and oscillate angle of guide-bar are presented. The design method of approximate dwell motion mechanism is studied according to the guide-bar oscillate angle， the minimum length of guide bar is calculated， and the influence of center distance on the motion performance of the mechanism is discussed. The least square method is used to approximate the mechanism parameters.关键词：Dwell mechanism;Guide-bar mechanism;Kinematic analysis;Mechanism synthesis;Cardioid crank mechanism
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发布时间：2022-11-10
Theory·Reserach
- 摘要：Aiming to solve the strong coupling problem of parallel mechanism， a novel uncoupled two-translational parallel mechanism is proposed， which includes three branch chains. The first and the second branch chains have the same structure， they are all RURR-type structures. The third branch chain， called a pure constraint branch， is composed of three rotational joints whose axes are with parallel to each other. Based on the screw theory， the degree of freedom and output motion characteristics of the mechanism are analyzed. The kinematics models of the mechanism are established by using the actuation screw wrench theory and the closed loop vector method. Position， velocity and acceleration equations are derived. Singularity is also analyzed in detail and the singular configurations of the mechanism are obtained. The kinematics simulation is performed by using Matlab and Adams software. The correctness of the theoretical analysis is verified by the simulation results.关键词：Parallel mechanism;Kinematics analysis;Uncoupled;Singularity;Simulation
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发布时间：2022-11-10 - 摘要：Non-circular gear planetary gear train is the core component of non-circular gear hydraulic motor， and its pitch curve design is the key to the overall structure design. Aiming at the problems of non-circular gear planetary gear train pitch curve of order 4-6， which is not unique and difficult to design， based on the design method of pitch curve of 4-6 order non-circular gear planetary gear train， the eccentricity is selected as the control parameter to design different pitch curves of non-circular gear planetary gear train. The influence of eccentricity on the motion characteristics of non-circular gear planetary gear train is compared and analyzed. The results show that， in the process of non-circular gear planetary gear train transmission， the center acceleration and angular acceleration of planetary gear will have a sudden change， and the mutation positions are at the maximum position of inner gear ring radial diameter， and with the increase of eccentricity of pitch curve， the abrupt values of center acceleration and angular acceleration of planetary gear increase.关键词：Non-circular gear planetary gear train;Pitch curve;Eccentricity;Kinematics
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发布时间：2022-11-10 - 摘要：Aiming at the problems of the deformation wheel posture adjustment and lower step buffering of the current deformable wheel mobile robot， a novel deformable wheel mobile robot is designed based on the mechanical self-locking principle. With the self-locking effect between the "push rod" and the "plane screw pair"， the lifting universal wheel mechanism is set up， which effectively solves the "wheel plate retraction" phenomenon of the deformation wheel， and optimizes the mechanism of the system control. The robot has a lifting universal wheel mechanism， which can effectively guarantee the obstacle crossing ability of the system and reduce the impact effect in the process of descending the steps. Through the design of key structural dimensions such as wheel radius and center distance， the obstacle crossing stability of robot is improved. Finally， the effectiveness of the design scheme is verified by simulation analysis.关键词：Deformable wheel;Mobile robot;Wheel plate retraction;Obstacle crossing ability
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发布时间：2022-11-10 - 关键词：9-speed automatic transmission;Planetary gear;Motion equation;Transmission ratio
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发布时间：2022-11-10 - 摘要：A multi-mode grab underactuated hand is proposed for the multifunctional requirements of robot end-effector manipulator. Based on the underactuated theory， the manipulator solves the disadvantages of the traditional compound underactuated hand， such as complex structure， many control elements and weak adaptability. The structure and motion process of multi-mode grab underactuated hand are introduced， and the mathematical model of underactuated manipulator is established. According to the geometric relationship of the manipulator motion analysis and adaptability analysis， and the manipulator grab parameters range is solved. Under different grab modes， the manipulator is analyzed respectively， and the virtual work principle is used to calculate the theoretical output force. The simulation results of virtual prototype show that the manipulator does not need to install force sensor and complex control system， and it can realize two grab modes， namely， flat clip and envelope， which verifies the feasibility of the design.关键词：Underactuated manipulator;Multimode grab;Contact force analysis;Virtual work principle
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发布时间：2022-11-10 - 摘要：Combining robot technology and CNC machining technology， a three -degree-of-freedom high-stiffness robot is designed. The three-degree-of-freedom structure is determined by the analysis of processing requirements， and the theoretical analysis of the multi-degree-of-freedom space is performed， and the structural design plan is determined. The brake is added to each axis of the robot to clamp the brake disc of the robotic arm， the end rigidity of the robot is improved by the structure scheme.关键词：Faucet;Three-degree-of-freedom;High-stiffness
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发布时间：2022-11-10 - 摘要：A method is proposed to calculate the tooth meshing stiffness based on Transmission3D （T3D）. FE/CM model is built to ensure the solving accuracy and efficiency. By using this method， the time-varying meshing stiffness and average value of a spur gear pair are both calculated， and the difference is 2.6% compared with the value solved by ISO 6336—1996， the rationality of the solution method is proved. Aiming at the deficiency of existing standards， the influence of shaft hole radius on the meshing stiffness is analyzed based on T3D and the mechanism is discussed combing the general FE method. On this basis， the meshing stiffness treatment method for the dynamics modeling and modal analysis of the aero-gear system is given.关键词：Aircraft gear system;Tooth meshing stiffness;T3D;Accuracy and efficiency;Shaft hole radius
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发布时间：2022-11-10
Design· Calculation
- 摘要：Based on the human structure as the prototype， a humanoid robot with a lower limb and 7 degrees of freedom is designed based on bionics. The motion coordinates of human body during normal walking are collected through the three-dimensional optical motion capture system， and the joint angle and the variation rule of the moment of each lower extremity joint during walking are obtained by analyzing the data. A 7-degree-of-freedom kinematics model of the lower extremity is established and inverse kinematics analysis is carried out to solve the variation of the lower extremity joint angles. According to the gait programming， the rotation angles of the lower extremity joints during the humanoid robot walking are solved. In the lower extremity in UG environment， the 3D model of 7 DOF humanoid robot is established， and the dynamics simulation is carried out by using multi-body dynamics software Adams， combining with the gait motion planning from the angle of the changing situation to set the simulation parameters， through virtual prototype humanoid robot gait， and the simulation data and the data results from the motion capture experimental are compared. Research results show， the humanoid robot can achieve stable walking gait， the overall accuracy of the modeling ideas， analysis of kinematics and dynamics simulation is confirmed. Based on the results of the experiment simulation for hip and knee torque value compared with the experimental value of relative error of 6.7% and 9.6% respectively in a reasonable scope， the basis for the humanoid robot structure design and motor selection is provided.关键词：Motion capture;Humanoid robot;Inverse kinematics;Gait planning;Motion simulation
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发布时间：2022-11-10 - 摘要：The loss of a hybrid magnetized magnetic gear composite motor is studied， and the magnetic field and air gap magnetic density and harmonics of the hybrid magnetized magnetic gear composite motor and the radial magnetized magnetic gear composite motor are compared and analyzed. The iron loss and eddy current loss of the two magnetic gear compound motors at different speeds are obtained， and the shape of the magnetic adjustment block is optimized. The results show that， compared with the radial magnetized magnetic gear composite motor， the hybrid magnetized magnetic gear composite motor has lower iron loss， stronger magnetic field strength， and greater inner and middle air gap magnetic density. The harmonic amplitude of the outer radial magnetic flux and tangential magnetic flux is relatively small， which helps to reduce the eddy current loss， and the optimized circular magnetic modulation block structure can reduce the eddy current loss and iron loss of the composite motor.关键词：Hybrid magnetization;Composite motor;Iron loss;Eddy current loss
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发布时间：2022-11-10 - 摘要：Aiming at the problem of excessive noise in the gearbox of a certain sweeper， a gearbox dynamics model is established in the multi-body dynamics software RecurDyn， the dynamic meshing force of the gear pair under steady-state conditions is obtained， and the effect of the meshing force on the box body is analyzed. By using the Ansys， the analysis of the modal and dynamic response of the box is carried out， it shows that the peak vibration response is mainly concentrated at the fundamental frequency， double frequency， and double frequency of the gear meshing frequency， which arouses the resonance noise with the gear pair. In order to avoid the resonance zone， a scheme for optimizing the geometric parameters of the gear and improving the structure of the motor assembly is proposed without increasing the box space， and the optimization scheme is tested for noise. The results show that the combination scheme of optimizing gear geometric parameters and reinforcing the motor assembly is the best scheme， and the noise of the whole machine is reduced by about 8.9 dB. It has certain research significance and reference value for the optimization design and vibration and noise reduction of this type of product.关键词：Sweeper gearbox;Dynamics modeling;Dynamic response;Optimization design;Noise experimental
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发布时间：2022-11-10 - 摘要：In order to improve the meshing performance of the involute tooth profile harmonic gear， the conjugate tooth profile discrete points in design section are obtained with an exact conjugate algorithm using assembly deformation of the flexspline，and the involute tooth profile of circular spline is obtained by fitting the conjugate tooth profile discrete points based on the involute features. Considering the influence of flexspline taper deformation， clearance optimal control model is established to optimize the modification coefficient of the flexspline section with different radial displacement， choose reasonable modification coefficient for part of the flexspline section on the basis of reducing tooth profile high. The harmonic gear with involute tooth profile that meets the requirements of spatial meshing is designed， and the design result is verified by the movement simulation analysis. The results show that， compared with the design section，the section with the maximum radial displacement increasing can avoid interference by reducing the modification coefficient，and the section with the maximum radial displacement decreasing can obtain good meshing performance by increasing the modification coefficient. In order to obtain good meshing performance， it is necessary to reduce the tooth height and reasonably change the modification coefficient of the flexspline when the maximum radial displacement decreases greatly and the interference occurs at the back section of the flexspline. Compared with the plane tooth profile， the designed spatial tooth profile can increase the engagement range and tooth profile contact area，and greatly improve the transmission performance.关键词：Involute tooth profile;Harmonic gear;Spatial meshing;Parameter optimization
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发布时间：2022-11-10 -
Design and Experiment of a New Type of Multi-position Rehabilitation Training Lower Limb Exoskeleton
摘要：The medical rehabilitation training equipment exists the problem that training method of is too single. A new type of multi-position rehabilitation training lower limb exoskeleton is designed， a mathematical model of the lower limb exoskeleton is established， and kinematics simulation and analysis are carried out. A multi-position lower limb rehabilitation exoskeleton experimental platform is built， and a gait walking experiment based on a physical prototype model is carried out. The simulation data and the experimental data are compared， it shows the correctness and rationality of the multi-position lower limb exoskeleton design.关键词：Rehabilitation training;Mult-position exoskeleton;Simulation analysis;Prototype test- 5
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发布时间：2022-11-10 - 摘要：In order to improve the processing efficiency of aviation conduit， a new type of three coordinate conduit handling robot is designed to cooperate with the CNC pipe bender for straight pipe bending. The static stiffness and dynamic characteristics of the robot are important factors that affect the quality and accuracy of the work. According to the characteristics of the three coordinate type handling robot， the Jacobian matrix of the robot is solved by using the screw theory， the static stiffness of the robot is analyzed by using the finite element simulation software to find out the limit pose of the robot， and the modal simulation analysis of the robot is carried out. Combining with the static stiffness mapping theory， the static stiffness identification test is carried out，and the stiffness matrix is solved， and then the modal test is carried out. Comparing the theoretical analysis results with the simulation results，the error is less than 10%，which proves the effectiveness of the model， and makes the robot maintain high quality and continuity.
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发布时间：2022-11-10
Test·Analysis
- 摘要：Cycloidal gear adopts one-dimensional probe sampling mechanism when detecting on the gear measuring center. Due to the sensitive direction of one-dimensional probe is inconsistent with the definition direction of tooth profile normal error， the error calculation process is tedious， and even the error result is inaccurate， which can not truly reflect the machining shape of the actual tooth profile. For this， a closed reconstruction method is proposed and it is applied to the error detection process of RV cycloidal gear， which can not only accurately obtain the machining error of any point of cycloid gear tooth profile， but also the error result can reflect the actual shape of tooth profile. Based on the closed curve reconstruction theory， using the characteristics of the periodic extension of the closed curve， the nodal vector and control vertex of the head and end points are determined， and the reconstructed tooth profile is completely closed and continuous at the closed point. On this basis， an error calculation model is established， and the real tooth profile error is calculated. The practicality and effectiveness of this method are verified by comparison of examples， which provides data basis for subsequent finishing processing.关键词：Cycloidal gear;One dimensional probe;Machining error detection;Closed reconstruction;Tooth profile error
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发布时间：2022-11-10 - 摘要：To extend the application of the swashplate engine from special engines to the field of general power machinery， it is necessary to considerate speed stability， dynamic balance performance and manufacturing， etc. A new swashplate engine is designed， it used the nutation movement of a pair of spiral bevel gears to drive the body of the swashplate engine to rotate， so that there is a relative angular displacement between the cylinder cover and the cylinder， and then the differential speed distribution is realized. This scheme not only eliminates the planetary gear system and reduces the kinetic energy loss， but also uses arc bevel gear instead of traditional straight bevel gear to reduce vibration and noise， and the distribution system layout is optimized. A three-dimensional model built with SolidWorks is simulated and comparative analyzed by the Adams platform. The results show that the presented structure scheme has a better stable performance of rotating speed and can effectively control vibration than the conventional straight bevel gear mechanism.关键词：Swashplate engine;Differential speed distribution mechanism;Nutation deceleration mechanism;Design;Simulation
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发布时间：2022-11-10 - 摘要：In order to solve the problems of high labor intensity， difficulty in picking， and low efficiency of manual pineapple picking， a pineapple picking device based on crank slider， offset linear sliding rod and multi-link transmission mechanism is designed. The Adams is used to simulate and analyze the movement of the mechanism， and the parameters of each component of the device are optimized. The actual prototype has been tested， and the results show that the device is suitable for picking pineapples with a stem diameter of 3-6 cm. The test statistics show that the single picking time of the device is 1.2 s less than manual picking， and the efficiency is increased by 26%. The stationary motion of the device and the cutting stability of the tool are also verified.关键词：Hand held pineapple picking;Cutting and picking machine;Compound connecting rod mechanism
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发布时间：2022-11-10 - 摘要：A line laser non-contact measurement method which can detect the worm profile quickly and reliably is proposed. The worm comprehensive deviation detection platform is constructed mainly based on the line laser displacement sensor， which can quickly and accurately collect and analyze the data of the worm profile. At the same time， the real three-dimensional model and equation expression of the measured worm are constructed based on the least square method， by comparing with the theoretical model of worm， the geometric dimension deviation data of worm can be obtained. This method is fast and efficient， and the deviation data is accurate and reliable.关键词：Worm profile measuring;Line laser displacement;Non-contact measurement;Worm deviation analysis
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发布时间：2022-11-10
Development·Application
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