在智能移动机器人的定位和导航系统中,路径规划是其中的核心问题.传统的A*算法是一种基于栅格的最小路径方法,通过这种方法得到的路径与实际中的最小路径相比,存在路径长、多拐点、不平滑等缺点,不利于双轮差速机器人的运动.在这里,利用Floyd算法将A*算法进行优化,缩短A*算法得到路径的长度,降低A*算法的拐点,利用圆弧平滑方法将拐点处进行光滑处理,最终得到一条适合双轮差速机器人的行驶路线,降低路径长度约4％～10％,减少累计转折次数约66％～80％.
气密性是工业中密封器件一项关键指标,而泄露检测是是保证气密性的方法之一,随着科学技术的不断进步,差压泄漏检测法因其检测精度高,能够实现定时定量检测等优点正在逐步替代传统的依靠工人主观判断的水检冒泡法,成为了未来漏检行业的主要方法。通过差压原理并结合现有气密性检测技术及设备,研究设计了高精确的汽车驱动桥壳总成气密性自动检测试验台。通过对机械结构的整体设计及优化,使该试验台具有更好的通用性和稳定性;通过设计全新的检测系统和气动控制系统来提高了试验台的测量精度;并通过PLC控制系统与触摸屏的通信实现了人机交互式操作,简化试验过程,降低了该试验台的生产成本。
Parallel robots have some advantages of strong load capacity,fast speed moving and large stiffness. It makes up for the deficiency of series robot and will become a potential platform with high speed and high precision. These problems of more singularities in working space,poor bearing capacity and low stiffness about classic five pole parallel robot have been improved in plane six pole parallel robot system. Kinematic positive and reverse solution model is established based on the structure of high speed six pole parallel robot system. The influence of location error of foundation bed,driving angle error and rod processing error to control accuracy is systematically and deeply researched. Theoretical basis has been established to realize optimal design of robotic structure and controlling in high speed,high precision.
In order to improve the precision and the efficiency of pipeline internal detection,it studies the motion control method of differential in pipe robot. According to the driving force and the controllability index design of the structure of the robot,based on the dynamic model of differential pressure pipeline inspection robot,motion control of differential in pipe robot is analyzed. According to the results of the analysis of the control scheme for robot design,the control flowchart is given,and the experiment results demonstrate that the proposed method effect.
Using software FLUENT,steady analysis of flow field were carried out for large-diameter center butterfly valve.On the basis of steady results,cons idering the case of sudden increase in speed,it underwent the unsteady analyses of the corresponding flow field.The results showed that the sudden increase in speed cause instant promotion of the field pressure and velocity.And the peaks of pressure and velocity were bigger than that in the case of high speed steady state.And then the pressure and velocity gradually decreased to reach basic stability. On the contrary,when the inlet velocity suddenly returned to low speed,the flow field pressure and velocity instantaneously reduced.The valleys of pressure and velocity were lower than that case of low velocity steady state.Then the flow field pressure and velocity gradually increased to reach the basic stability.Otherwise,the opening size had an effect on mutation flow field parameters as well as the speed to restore balance of butterfly valve.
A new method for the determination of optimized process parameters of cold punching drawing formation was discussed,which could be used in prediction and control of the quality of cold punching products efficiently. The experiment scheme was designed by means of quadratic orthogonal regression tests,and the simulations of cold punching drawing formation were carried out with Dynaform. The simulation results was analyzed by quadratic regression to find out the relationships between the variation of wall thickness and wrinkle degree of cold punching products and the two process parameters of blank holder force and the clearance between convex and concave die,and the regression model between them was built. The response surface methodology of the model was carried out by Origin and the most reasonable solutions was determined,which was the optimized process conditions. This method could be used in the analysis of other drawing products as well,which offered certain reference valve for the engineers and technicians of related fields.
It presents a mobile robot which adopts all-wheel-leg-drive mechanism under unstructured terrain. Firstly,the overall structure of robot is designed,and the quantities of obstacle-climbing poles are optimized. It builds dynamic model by means of analyzing the process of surpassing vertical obstacles,and this model describes the influence of movement states and gravity allocation on motors' torque;the effects of various factors on maximal output torques are investigated,such as attachment coefficient,the center of gravity location,speed of the robot,height of the obstacles and so on. Finally,the results are worked out that robot can traverse the maximal height,and are verified with ADAMS,and the theoretical foundation is brought forward to improve the robot's adaptability under unstructured terrain.
In railway operation today,there is a general trend towards increased vehicle speeds. The lightweight design of carbody reduces the structure stiffness and increases the accelerations and forces on the vehicle,which has a negative impact on the ride quality. It is necessary to pay special attention to the structure vibration and find effectively methods to control it.To save those problems,an active vibration reduction system using piezoelectric actuators is proposed. The calculation results show that the active control can effectively suppress vibration modes of the carbody,especially the first bending mode vibration and improves the riding quality. The rationality and superiority of this active control method is reflected.
Taking a certain type of metro vehicle bogie frame as the research object,according to the basic principle of modal synthesis method,the frame modal neutral file hasbeen get through the modal analysis of the frame by free degree reduction.The rigid flexible coupling multibody dynamics model is set up by using the neutral file,which can get access to the stress time history of key part of theframe under different conditions through simulation. Finally,quasi static stress analysis of the key part of the frame hasbeen conductedby inertia relief method of finite element analysis.The boundary loads ofthe key parts of bogie frame can be calculated based on the coupled multi-body dynamics model of vehicle.Combined with the material SN curve,fatigue life of the key parts of the frame have been predicted by the method of virtual fatigue simulation.
Regarding to the strong demand of texture mapping technology for the manufacturers of laser machining devices,the machining principle based on 5-axes NC laser machining system is introduced, and the numerical methods of texture mapping parameterization solver, including the restriction and control of texture mapping position, size and direction based on the method of LSCM free boundary, 3D mapping from 2D vector texture, GUI display of grids of 3D texture are developed and presented. The reliability and accuracy of the numerical methods are validated by laser experiment based on a mold cavity of a mouse part.
Tooling system for high-speed machining is one of the key components of high-end CNC machine , its stability and reliability directly affects the quality and performance of the machine. Based on the finite element method, developing a 3D finite model of high-speed machining tool system, studying on the stability of the high Speed machining tool from the natural frequency by the method of modal analysis. Analysis the amount of the overhang and clamping of the tooling , different shank taper interference fit and under different speed conditions, which affects the natural frequency of high-speed machining tool system. Proposed to the approach of improving system stability, which also provides a theoretical basis for the development of new high-speed machining tool system.
Gooses have good hearing sensitivity,and vigilance is very strong,being easily frightened and having stress reaction and changingits the normal egg production. Traditional way of breeding goose is,according to the size of the goose,registering the serial number appearance of a goose respectively in different growth stage; selecting the better goose continuously for many times and recording every goose egg production one by one. In order to solve the problem of low efficiency and the complexity of the traditional breeding methods,an automatic breeding boxes based on electronic identification system is designed,its function is to distinguish individual egg production situation in the group. Compared with traditional selection box,new type selection box's biggest advantage has the ability to identify types of individual identity,goose egg,sit situation rapidly. Accordingly weeds out the low yield of goose,selects the high yield of goose and improves the breeding geese quality.
The primary goal is the simulation optimization of a spatial 3 degree-of-freedom parallel manipulator(a 3PRRR parallel manipulator). The architecture of the mechanism is comprised of a moving platform attached to a fixed platform through three similar parallel-revolute-revolute- revolute jointed serial linkages. It analyzed the movement relationship and then established the kinematics model. By taking maximum workspace as the objective,an optimization program was written in C language in the MATLAB environment. A set of lengths of bars was obtained through the optimization design. Then,design and manufacture the prototype.
In order to understand the wall-sleeving crane's dynamic characteristics,its dynamics equation was established.And a FEA simulation model of the 2t/8.7m wall-sleeving crane was established by use of the finite element analysis software ANSYS Workbench,and its corresponding constraints were applied. Then the natural vibration characteristics were analyzed.The first ten natural frequencies and mode shapes of vibration were obtained. According to harmonic response analysis,when the crane was loaded,the steady-state response was obtained. The resonance frequency within the frequency range were calculated,which provided a basis for further dynamic optimal design of the wall-sleeving crane. During the actual running process,avoiding long-term operation under these frequencies helps the wall-sleeving crane run smoothly and reduce dynamic load and noise.
The key components of spindle for machining center,the necessity of reliability test were described,and a reliability testing method of fast loading had been put forward. And according to the structure characteristics of the spindle and specific requirements for reliability test,the scheme design and detailed design of spindle reliability test device were completed.Through building the test device for spindle of reliability,related loading test for spindle reliability was carried out,and the test results and the other machining center reliability test were combined,using the corresponding data analysis software,the reliability index of machine tools are assessed. In order to take countermeasures and measures from the design,manufacture,use and maintenance of all aspects which guide reliability design of spindle unit,it ensures the reliability growth of spindle design and use of the process.
Uses the method of union topology optimization and orthogonal experimental design is proposed to satisfy the need of precise design. Topology optimization is aimd to tackle the initial-shape design for the purpose to search the best shape of structure. Then,there is a problem that the initial shape designed by topology optimization should be adjusted for its complexity surface or complexity structure as it is unable to manufactureor it is uneconomic in manufacturing. There for it uses or thogonal experimental designto optimize the structure that has been changed,to search the best design for the given restriction. After then,itcan complete the overall design process. The method canbe used to tackle the problem of structure design in a broad way with or without the similar restriction.
Leading by the thinking of module design and the parametric design theory of cylindrical helical spring,using visible and object-oriented programming software VB as development tool,the parametric design system of alter-rigidity spring assembly in railway vehicles has been established by Solid Works secondary development with its API interface.According to the spring design demand,the system achieves the spring computer program design when the spring assembly load is distributed and the spring parameter is determined. It also realizes various functions consist of structure size design,strength checking,fatigue life estimation,design of fatigue test program,generation of flexibility-force drawing,parametric three-dimensional modeling and automatic generation of drawing. Spring assembly design system provides important parameters for later spring parametric design and improves the design quality and the level of automation.
Based on computational fluid dynamics,an automotive purifier simulation model of flow field,temperature field and pressure field is set up with ANSYS FLOTRAN software according to the road condition of city vehicle,taking one local1.6L vehicle as the object to do the numerical simulation research of gas flow characteristics inside automotive purifier. In consideration of the features of city road conditions,analyzes the airflow distribution pattern of exhaust flow velocity and pressure loss inside the purifier at common engine speed of 2200r/min. The result suggests that as the load increases 10%,50%,100%,the gas flow rate increases gradually at purifier entrance,the air flow distribution uneven degree and the pressure loss both increase inside the purifier.
Bolt connection is a common form of connection between missile compartment. To analyze the locking problem of preloading bolt connection between the key missile cabins(KMC),the scope of preloading of bolt connection between KFC has been under study. Firstly,according to the bolt strength theory and structure design requirements,an initial scope of preloading force value can be calculated. Secondly,finite element analysis software is used for the finite element analysis(FEA)of the bolt group connection of the KMC. The locally finite element model is established by means of the finite element analysis software and the initial scope of pre-tightening force can be check. Finally,moment load and the different preloading force is applied to the entire missile model to get a property range of torque values and calculate the relationship between the?preloading force and Install torque.
It studied the effect of Installation error on meshing performance for spiral bevel gears based on finite element analysis. Manufacture parameters were designed according to local synthesis,the tooth surfaces and finite element model of spiral bevel gears were formed. The pinion and gear were assembled together through tooth contact analysis with Installation error,which could avoid cumulate artificial errors. The results of models with different installation error were obtained by ABAQUS. The contact stress curves and contact path was obtained by post-treatment through Python,and the results showed that the meshing performance of spiral bevel gears are affected more seriously by axial installation error than shaft angle error and offset error.
