Research On The Key Technology Of Large-scale Equipment Mass Properties Measurement And System Development

Mass-property parameters are important in many engineering areas,and experimental measurement methods are indispensable methods to obtain them.It is quite significant to access the mass-property parameters with the measurement equipment in the practical engineering projects,such as the mass,center of mass,moment of inertia and other parameters.However,in practical applications,there exist some problems.For example,a unified measurement basis is hard to be maintained with multiple loading and unloading;a large disturbance may be caused by the friction torque of the motion;an elastically deformation may be emerged on the platform and the supporting base systems;some coupling may exist among sensors,and so on.All these mentioned problems may enlarge the measurement errors.Therefore,it is with great theoretical and practical significance to enhance the measurement accuracy by overcoming or decreasing these factors.According to the structural characteristics and the measurement requirements,an improved four-point method is proposed in this paper,and a measurement system of quality characteristic parameters is developed.The main work of this paper is following:(1)An improved four-point method is proposed.In this paper,based on the derivation of the three-point method and the four-point method,from the perspective of the layout and the optimal force for the load cell,an improved four-point method is proposed.The new method has two advantages: first,it is a direct contact measurement method,which can avoid the influence of the V-type block in the indirect contact measurement;Second,the four sets of weighing sensor can achieve independent measurements,which avoided mutual coupling between sensors.(2)3D model of the measurement system based on the improved four-point method is completed using the modern design method.The measurement system is divided into three subsystems: mechanical structure subsystem,control subsystem and measurement subsystem.The model of the system is designed by virtual design technology,and the support distance of the measured object is optimized.The error model of the measurement system is established.Based on the modeling method of multi-body system dynamics,the kinematic chain of the measurement system is modeled.The model shows that the system error consists of two parts.The first part is about the error of the kinematic joint,which is related to the motion variables.The second part is the error caused by the manufacturing process.(3)The tolerance modeling of the main components is completed,and the tolerance optimization is carried out based on the improved genetic algorithm.According to the method of error prevention,it is necessary to control the error in the design stage.The component design error is part tolerance.In this paper,the dimension tolerance,form tolerance and assembly error of the kinematic chain of the system are modeled and analyzed.(4)According to the finite element theory,the finite element analysis of the symmetrical heavy sensor module is carried out to obtain the deformation of different action points under different force.By means of the finite element analysis,the load and the corresponding deformation value are obtained,which provides the analysis object and the basic data for the research of the soft compensation method.An improved artificial neural network for adaptive decision of hidden layer nodes is proposed.In this paper,the artificial neural network is improved based on the number of hidden nodes.The modified neural network is used to predict the deformation of the symmetrical heavy sensor module,which is applied to determine the compensation amount of the deformation error of the weighing sensor component and improve the measurement accuracy of the system.(5)The mechanical structure subsystem are manufactured.According to the theory of error control and optimization of the design results,the quality characteristics of the test system is manufactured by designing the detailed structure and arranging the appropriate processing methods and manufacturing processes.Through the PLC control system,the servo control of the two motion chain of the mechanical structure subsystem is realized.The measurement subsystem of the quality characteristic test system is designed.The function design,signal acquisition,serial communication and so on,which are composed of weighing sensor,grating displacement sensor and host computer,are completed.In the environment of Visual studio,the software system is designed based on three layer architecture.The standard calibration method for the measurement system was designed and the standard column was processed and the mass characteristics were measured.