60 results about "Multibody system" patented technology

The MULTIBODY AIRCRANE performs relative positioning, predictive control, and ballast control to achieve very heavy-lifting tasks on land or sea. Such tasks allow station keeping and precise transfer of very heavy payloads between ships underway. This scalable multibody system features three subcomponents: AIRSHIP, SKYCRANE and LOADFRAME. This semi-autonomous system combines aerodynamic (kinetic) and aerostatic (buoyancy force) lift with efficient power and propulsion. During low-speed flight, the Airship and Skycrane are decoupled but linked via a reelable Tether Control Line. Beneath the Skycrane, centered on its hull, a patented NIST (National Institute of Standards and Technology) RoboCrane (featuring a computer controlled six degrees of freedom (DoF) cabling system,) is attached, to precisely suspend and control a Loadframe, with or without payload. During subsonic forward flight, these Airship and Skycrane are coupled as a single airframe (fuselage and delta wing.)

The invention discloses a recognition method of a critical geometrical error source of a machine tool and belongs to the technical field of machine precision designing. The recognition method of the critical geometrical error source of the machine tool is characterized by comprising the steps that the machine tool is abstracted into a multi-body system according to the structure and motion characteristics of the machine tool, relevance of parts of the machine tool is described by a topological structure and a low-order body array, a generalized coordinate system is built in the multi-body system, coupling relationship of error amounts of parts of the machine tool is described by a homogeneous transformation matrix, a characteristic matrix and a motion equation of the relative movement between two adjacent bodies of the machine tool are elicited, a precision model of a machining center is built, an ordinary mathematical model used for error sensitivity analysis of a four-shaft machine tool is built with a matrix differential method according to the precision model of the precision horizontal machining center, influence degrees on the whole space error of all error elements are compared by calculating the geometrical error sensitivities of all parts, and finally the critical error source influencing the machining precision of the machine tool is recognized.

The invention discloses a detection method for geometrical errors of a rotation shaft of a five-axis numerical control machine tool, belongs to the technical field of machine tool precision detection, and relates to a detection and identification method for the geometrical errors of the rotation shaft of the five-axis numerical control machine tool. The detection method comprises the steps that image information of a concentric target are collected by a binocular camera and used for representing the actual movement information of the rotation shaft, the three-dimensional coordinate information of a feature point is acquired finally through camera calibration and image processing, and the movement track represents the space movement track of one point on the rotation shaft; and through combination of a multi-body system theory of the machine tool and a subcoordinate transformation theory of the machine tool, the errors PIGE having no relation to the position of the rotation shaft and the errors PDGE having a relation to the movement position of the rotation shaft are identified and measured. The method effectively achieves detection and identification of the geometrical errors of the rotation shaft of the machine tool, the measurement process is simple and fast, and the measurement efficiency is high. The requirements for the operation track of the machine tool are simple in the measurement process, cooperation with other shafts is not needed, and other shaft linkage errors are avoided.

The invention discloses an analysis method on the basis of distribution characteristics of a space machining error of a numerical control machine tool, belongs to the field of accuracy design of a machine tool and particularly relates to an analysis method on the basis of the distribution characteristics of the space error. On the basis of space geometric error deterministic modeling and geometric error measurement which are established by a multibody system and the matrix total differential and random process principle, a space error deterministic analysis model of a precision horizontal machining center is established and the distribution characteristics of a geometric error and the space machining error of the machine tool are analyzed. The invention discloses a novel machine tool design concept and fundamentally solves the problem of accuracy of the machine tool. Guiding suggestions also can be given to actual assembling and machining, so that output of the error is reduced, machining accuracy of the numerical control machine tool is improved and the problem of accuracy of the machine tool is fundamentally solved.

The invention provides a spacecraft dynamics modeling method. The method comprises the following steps of: replacing a liquid sloshing equivalent mechanical model with an equivalent pendulum, enabling a closed loop topology structure to be equivalent to an open loop tree topology structure, defining a coordinate system at a hinge joint, defining a basic contact operator, characterizing elastic displacement of a flexible body, and performing recurrent calculation on the force and speed of the flexible body; and judging whether systematic calculation on a dynamics model is a forward dynamics modeling process or a backward dynamics modeling process, correspondingly substituting the forward dynamics modeling process or the backward dynamics modeling process, and deducing a system dynamics equation. The method provided by the invention is capable of not only meeting the precise modeling requirement, but also simplifying the design process, saving a lot of workload, accelerating the spacecraft development period, realizing high-precision high-efficiency dynamics modeling of a large flexible cable antenna spacecraft, achieving modeling of a flexible multi-body system capable of calculating closed loop spacecraft configuration in a simplest mode, and saving a lot of tedious and hard works.

Provided is a method for calculating dynamic characteristics of a contactor based on a piecewise linear kinetic equation, and belongs to the technical field of basic research design of general characteristics of contactors. The method comprises the steps that according to structural features of the contactor, segmentation is conducted on a contactor action process, plane collision and a continuouscollision force model with energy loss considered are used for being equivalent to a collision process, by means of the multi-body system kinematics based on a restrain method and a dynamic method, studying of the collision bounce situation of a contactor mechanical system under the action of external force is completed, and finally, dynamic characteristic calculation of the contactor with collision bounce considered is completed in combination of a coupling calculation method. The method has the advantages that the time-dependent situation of electromagnetic parameters such as the coil current and electromagnetic force in a working process of the contactor can be obtained, the electromagnetic dynamic characteristics of the contactor can be reflected more accurately, and errors are controlled within 5%; the bounce situation of an armature and a moving contact of the contactor can be reflected more really, and errors are controlled within 5%.

Along with increasing demand on machining precision, how to reasonably configure geometric error of a machine tool under the premise of ensuring the machining performance of the machine tool to balance the cost and machining precision is the problem demanding a prompt solution in manufacturing of the machine tool. The invention provides a novel multi-target optimal distributing method for geometric accuracy based on the manufacturing cost and quality loss of parts. The method comprises the following steps of: establishing a comprehensive spatial error model of geometric error of the machine tool by a multibody system theory; establishing a manufacturing cost model of a machine tool part according to the machining characteristic of the machine tool part which affects the geometric error to the maximum extent; meanwhile, combining the quality loss cost to establish a cost-based target function; establishing an optimal model associated to precise level of the part by identifying the geometric error, namely, maximizing European norms of all precision parameter variables as another target function; and realizing optimal distribution through Isight and Matlab integrated and combined with NSGA-II (Nondominated Sorting Genetic Algorithm-II).

The invention discloses a minor planet detection optimal multi-impulse transfer method of an interplanetary multibody system, and belongs to the technical field of aerospace engineering. The method includes steps of firstly, building a detector kinetic equation under a geological core rotating system, namely, a high-precision kinetic model; selecting a target minor planet according to task restriction and providing an initial state of the detector under the geological core rotating coordinate system; applying a disturbance method to obtain a detector single-impulse minor planet flyover track;applying an optimization algorithm to obtain a single-impulse minor planet flyover transfer track with the minimum flyover distance; based on a main vector theory, performing a multi-impulse transfertrack design, and acquiring an optimal multi-impulse transfer track which meets the main vector condition; bringing the acquired optimal multi-impulse transfer track to the high-precision kinetic model to progressively induce; amending the transfer track by a multi-grade parallel differential amending method, and realizing the accurate track transfer of minor planet detection under a multi-celestial-body strong disturbance nonlinear environment. The minor planet detection optimal multi-impulse transfer method has the advantages of small speed increment, good applicability, and good astringency.

The invention discloses a radiation open loop tethered satellite formation constant speed spinning deployment control method, relates to a dynamics construction and control strategy design in which the tethered satellite formation is spun and deployed at a constant speed into a radiation open loop form and belongs to the field of spacecraft formation control. In view of the radiation open loop tethered satellite formation running on a circular Kepler track in an earth center gravitational field, in consideration of multi-body system movement characteristics and gravity gradient moment effects, system spinning deployment dynamics is built via a Lagrange equation; on the basis, a closed loop control strategy is designed, the main satellite is spun and deployed at a constant speed, compensation in view of the gravity gradient moment is carried out, damping is added to the tail section of the deployment to restrain system oscillation; the dynamics and the control method are simple, effective and easy to realize; and the whole process of controlling the tethered satellite system to deploy at a constant speed is smooth, safe and high in reliability.

The invention relates to five-shaft structure error measuring method of a mirror image milling system, a system and a device thereof. The method comprises the steps of constructing a geometric model,based on a multi-body system kinetic theory, constructing a geometric model of spatial positioning errors of a cutter central point P0 of a mill image milling processing area and a supporting centralpoint P1 of a supporting head in a motion process; acquiring pose data, through a displacement measuring device on a processing head of the mirror image milling system, acquiring pose (position and attitude) data of P0 and P1 in a preset measuring path; calculating a dynamic error, performing calculation processing on the acquired pose data of the P0 and P1, and obtaining a characteristic value ofthe motion error of the five-shaft structure; and performing data feedback adjustment, and based on the characteristic value of the five-shaft structure, performing feedback of the error compensationdata of the five-shaft structure to the control system of the image mirror milling system, making adjustment of the five-shaft structure according to error compensation data by the control system, sothat the supporting head performs synchronous movement with the processing head.

The invention discloses a robust design method for positional parameters of front vehicle wheels. In the method, a robust design model for the positional parameters (a king pin inclination angle, a king pin caster angle, a front wheel camber angle, and a front wheel toe-in) of the front vehicle wheels is established by taking a multibody system dynamics theory as a basis, comprehensively considering the synergic relationship among a steering system, a drive system and a suspension system, analyzing the dynamics characteristics of the positional parameters of the front wheels under motor steering, straight running, wheel hopping and other various running states, integrating uncertain factors, such as the manufacturing errors of a steering trapezoidal arm, the assembling errors of a steering knuckle, a fit clearance between a steering mechanism and the suspension system, a designed variable numerical range, the preferences of all subgoal performances and the like, and taking the minimum angle turning error, the minimum sideslip during straight running and the minimum front wheel pivot angle during wheel hopping in a steering process as optimization goals. The robust design method disclosed by the invention has the advantage of improving the design level for the positional parameters of the front vehicle wheels in China, and can be widely applied to design of various types of vehicles.

The present invention relates to a method and system for describing the motion of a closed-loop multibody mechanism. In this case, equations of motion need to be obtained for constrained multibody systems. The invention is based on a forward dynamics formulation resulting in a recursive Hamiltonian formulation for closed-loop systems using generalised co-ordinates and conjugated canonical momenta. The method allows to limit the number of arithmetical operations necessary to obtain the equations of motion with a good evolution of the constraints violation errors. Calculations can be performed based on constrained articulated momentum vectors.

The invention relates to a steady design method for a vehicle steering trapezoid mechanism. The method comprises the following steps of: based on multi-body system dynamics theory, applying methods, such as a virtual model machine technology, multi-body dynamics, elasticity mechanics, steady design and the like, comprehensively considering a synergic relationship between a steering system and a suspension system, analyzing dynamics characteristics of the steering trapezoid mechanism under operating conditions, such as vehicle steering, vehicle wheel jumping and the like, and integrating uncertain factors impacting on a steering angle and a steering mechanism stress, such as a manufacturing error of a steering tie rod, a manufacturing error of a steering knuckle arm, an assembling error of a steering node, fit clearance between the steering mechanism and the suspension system, elastic deformation of the tie rod, and the like. An optimizing aim that corner error during the steering process is minimum, and a swing angle for a front wheel during vehicle jumping is minimum can be achieved, and a steady design model for the vehicle steering trapezoid mechanism is built. The steady design method has the advantages that: a design level of vehicle front wheel parameters can be improved, and the method can be widely applied to vehicle design with various types.

The invention discloses an interval theory-based geometric precision optimization allocation method for a precision horizontal machining center. The method comprises the following steps of (1) based on a multi-body system kinematics theory, building a mapping model between geometric errors and space errors of a machine tool; (2) based on an interval theory, performing sensitivity analysis on error sources; (3) based on the interval theory, building an interval optimization allocation model; and (4) based on a genetic algorithm, performing solving by applying MATLAB software to realize geometric precision optimization allocation. According to the method, the error sources difficult to realize are relaxed to a maximum feasible interval, so that the production cost is greatly reduced and the production and assembly efficiency of the machine tool is improved.

The invention relates to non-optical spherical elements, in particular to a splicing measurement method for two sections of profiles of a large-caliber optical aspheric element. The splicing measurement method includes providing a method of aligning data points of an overlapped area on the basis of a principle that radius of curvature is unchanged; building a preliminary optimized mathematic model for twp-section surface figure profile splicing according to a multibody system kinetic theory, a slope difference value and an inversion method; according to a simulation result of the preliminary splicing mathematic model, performing linear least square fitting on preliminary splicing errors, removing accumulated errors, and providing a final two-section splicing optimized algorithm. Experiments in which a Taylor Hobson contourgraph and an auxiliary measuring clamp are utilized to measure planar optical elements of 150mm and data processing by using the splicing optimized algorithm are performed, and results of the experiments show that maximum standard deviation of the splicing errors is 0.868 micrometer, and high-accuracy surface figure detection needs of optical elements at a grinding stage can be met.

The invention relates to a multi-axis numerical control machine tool C-axis geometrical error measuring system and a parameter identification method. A motion equation with geometrical error and a motion equation under an ideal state are established under radial, tangential and axial three linkage modes by aiming at the structure and the characteristics of the multi-axis numerical control machine tool C-axis and by using a multibody system theory according to the working principle of a ball bar instrument, the two-end coordinates of the ball bar instrument are expressed into the same coordinate system separately through the variable quantity of the two-end positions of the ball bar instrument, and the actual distance between the two points is evaluated, so that the relation between a theoretical model and an actual measurement value is established and identification of eight geometrical error parameters of the C axis is realized. All the error items of the rotary C axis are identified, the coupling phenomenon existing in the geometrical error parameters is solved, accuracy and rapidness are realized, the identification precision is high, and important theoretical significance and practical significance in realizing the rest rotating shafts of the multi-axis numerical control machine tool are achieved.

By receiving input of a crystal structure and atom numbers, and specifying an atom group that can generate fluctuations from an electronic state calculation of a normal Kohn-Sham theory, an electronic state calculation device calculates a reference system. Next, based on an extended Kohn-Sham theory, the electronic state calculation device performs self-consistent calculation for an effective many-body system, then determines whether or not density fluctuations obtained for the reference system and density fluctuations obtained by the self-consistent calculation coincide with each other, and in a case of coincidence, acquires parameters of an exchange correlation energy and a local interaction. By the acquired parameters, an effective Hamiltonian is decided, and optimization of an electronic state is performed for a known crystal structure.

The invention proposes a method for analyzing sensitivity of geometric errors of dual-rotation axes of a five-axis CNC machine tool, and the method comprises the following steps of firstly constructing a mathematical model of geometric errors of the dual-rotation axes based on a multi-body system theory and a homogeneous transformation matrix; performing error parameter sampling by using a Monte Carlo method, and analyzing the sensitivity of the geometric errors of the dual-rotation axes of the CNC machine tool; finally performing sensitivity analysis on the error parameters based on the positions of the specific rotation angles of the dual-rotation axes, and calculating the first-order sensitivity and global sensitivity of each geometric error of the dual-rotation axes at this position bysetting the positions of five groups of specific rotation angles, wherein the Sobol sensitivity analysis method can be used to identify the key geometric error among the 20 geometric errors of the dual-rotation axes, and complete the identification of the geometric errors of the dual-rotation axes of the five-axis CNC machine tool. The method has the advantages of simple detection steps, convenient measurement and high identification accuracy.

The invention belongs to the field of diesel engine air distribution system researches and relates to a diesel engine air distribution system dynamic calculation method based on a multi-body system transfer matrix. The diesel engine air distribution system dynamic calculation method based on the multi-body system transfer matrix comprises the following steps of: building a cam profile Nth harmonic fitting function, selecting a state vector, a boundary condition, an initial input quantity and the like required by a multi-body system transfer matrix method, analyzing the mechanical properties of all components of an air distribution system, deducing a transfer matrix which reflects the mechanical properties, integrating all parameters to obtain a total transfer equation, solving the total transfer equation to obtain the dynamic response situation of each part, drawing the dynamic characteristic curve of each part and the like. The diesel engine air distribution system dynamic calculation method based on the multi-body system transfer matrix has the advantages that the mechanical response situations of all parts during the movement of the air distribution system can be intuitively reflected through the dynamic characteristic curves, the dynamic response results and the like of all parts, the method is suitable for air distribution systems of diesel engines with different speed types, the measuring and modeling time needed for building a three-dimensional model is greatly saved, and the obtained results are more effective than the results obtained through solution by using the traditional multi-rigid-body differential equation set.

The invention discloses an underwater robot control method taking regard of multi-body coupling. The method comprises steps that 1), the multi-body system kinetics is utilized to realize control planning of reference tracks of an underwater robot base and an arm, and the reference tracks are respectively transmitted to the arm and the base in a speed signal mode; 2), the speed signal is received by a speed ring of the arm, and a position ring of the arm is formed by a kinetics control module; 3), the speed signal of the arm and base parameters are received by a combined body iteration dynamics module, and the coupling force of the arm for the base is outputted; and 4), the reference track of the base, a control error and the coupling force of the arm for the base are received by a base controller, and applied control force of the base is calculated.

The invention discloses a control surface system nonlinear flutter model modeling method based on a multi-body system transfer matrix method. The control surface system nonlinear flutter model modeling method comprises the following steps: deriving a bending-torsion coupling beam transfer matrix based on the multi-body system transfer matrix method; establishing a total transfer equation of the system, and solving a circular frequency and a vibration mode; establishing a motion control equation of a control surface system by using a Theodorsen unsteady flow theory; considering gap nonlinearityand friction nonlinearity, establishing a body dynamics equation based on MSTMM, and obtaining a system nonlinear flutter model; and solving the nonlinear flutter model of the system to obtain the vibration time domain response of the control surface system. According to the method, the problem that a linear flutter calculation method cannot accurately predict the flutter response of the nonlinear system is solved, and the nonlinear flutter response of the control surface system is rapidly solved.

The invention relates to a method for increasing the movement stability of a driving mechanism of a spaceborne antenna with a gap. The method is based on multibody system dynamics theories, flexible multibody system dynamics and a kinematic pair gap contact collision model. A spaceborne antenna driving mechanism dynamics model which taking a kinematic pair gap into consideration is established, and the influence of the gap on the dynamic characteristics of a reflecting plane of the spaceborne antenna is analyzed through value simulation. Minimizing the maximal peak value of movement acceleration jitter of the reflecting plane of the spaceborne antenna is taken as an optimization target. The element contact collision parameters of the kinematic pair with a gap are optimized without changing the basic structural parameters of the driving mechanism of the spaceborne antenna, and the auxiliary material of the elements of kinematic pair with a gap is selected to improve the movement stability of the driving mechanism of the spaceborne antenna. The element contact collision parameters of a kinematic pair with a gap are optimized, and proper auxiliary material of the kinematic pair is selected to substantially reduce the impact effect caused by gap contact collision of the kinematic pair, and reduce the influence of the gap on the movement stability of the driving mechanism of a spaceborne antenna. The method is simple, feasible and practical, and can be widely applicable to driving mechanisms of various spacecrafts.

The invention discloses a mechanical arm track planning method considering spacecraft body attitude motion, and belongs to the field of track planning of multi-body systems. The robot arm track planning method considering the spacecraft body attitude motion comprises the specific steps that firstly, under the initial state of a spacecraft, the position of the tail end of a mechanical arm and the change track of the attitude orientation are determined through a quintic polynomial path planning method; according to the planning of the attitude motion of a spacecraft center body, a original expected position and the change amount of the orientation under a spacecraft body coordinate system due to the attitude motion of the center body are obtained so as to compensate the motion planning of the mechanical arm; original track planning of the tail end of the mechanical arm and the compensation planning are correspondingly summed and recorded as the tail end point track of the mechanical arm,and the motion track of each joint angle of the mechanical arm is planned through a kinematic pseudo-inverse algorithm, so that the mechanical arm track planning considering the spacecraft body attitude motion is achieved. The robot arm track planning method considering the spacecraft body attitude motion has the advantages of reducing the real-time calculation pressure of an on-board computer, improving the track planning efficiency and the like.

The invention discloses a low-energy orbit capture method for a multi-body system taking into account initial and terminal constraints and particularly relates to the low-energy orbit capture method for the multi-body system taking into account the constraints of initial and terminal states. The invention belongs to the technical field of aeronautics and astronautics. The low-energy orbit capturemethod for the multi-body system taking into account the initial and terminal constraints achieves the orbit capture design which satisfies the terminal constraints based on the multi-body system andthe theory of weak stability boundary, by virtue of the gravitational action of the sun for assisting planet capture and by screening the inclination of a hyperbolic orbit of an arrived celestial bodyand applying orbital correction. An interplanetary transfer orbit starting from the earth can be accurately matched with a weak stability boundary orbit by virtue of B-plane parameters. A detector can eventually enter a mission orbit through two-time braking and one-time orbital correction. The low-energy orbit capture method for the multi-body system taking into account the initial and terminalconstraints has the advantages of small required speed increment, wide application range and easy implementation of the method.