65 results about "Generalized forces" patented technology

The invention discloses a parallel twelve-freedom loading device, used in spatial loading test and fatigue test on aviation material, comprising a Stewart active parallel six-freedom loading device, a SPS six-dimension force/torque sensor and a SPS inactive parallel six-freedom adjuster, wherein the Stewart active parallel six-freedom loading device simulates the spatial motion, the active and inactive platforms of inactive parallel six-freedom adjuster follows to operate and draw or compress the bidirectional isomorphism spring device, to test wide force dynamical load, to supply high accuracy and better reliability to the six-freedom wide force dynamic synchronous loading system, to be used in spatial-ground semi-physical simulation test or the like.

A forward/reverse mechanics calculation of an accurate model of a human body having bone geometrical data and muscle/cord/band data is carried out at high speed. When a new skeleton geometrical model is given, a mapping between the new skeleton geometrical model and a pre-defined normal body model representing a normal body is defined to automatically produce a new body model. A processing unit reads model data to be subjected to mechanics calculation, reads a produced force f of a wire/virtual link exerted on the body model, reads the angle, position and velocity of the current rigid body link, calculates the Jacobian J_L of the length of each wire concerning the joint angle, converts the read produced force f of the muscle/cord/band into a generalized force τ_G according to the defined Jacobian J_L, stores the generalized force, determines the acceleration of the whole body of a motion produced when the generalized force τ_G is exerted on the body and calculates the velocity and position of each rigid body link, and stores them.

The invention relates to a borehole wall sloughing analysis method which comprises the steps of parameter collection and input (1), initial stress processing (2), first time of stress release (3), first step of second time of stress release (4A), second step of second time of stress release (4B), characteristic value evaluation (5), generalized force and generalized displacement (6), path curve balancing (7), and collapse pressure processing (8). Evaluation is conducted according to a minimum obtained characteristic value (Mu1) m, and when the minimum obtained characteristic value (Mu1) m is more than 0, if m is less than M, m plus 1 arrows m, thus entering the second step of the second time of the stress release (4B); otherwise, a total field is obtained; when the minimum characteristic value (Mu1) m is less than 0, a disturbance field is calculated according to an interpolation method; and the collapse pressure qcr and a plastic area distribution area corresponding to the qcr are calculated, so as to determine the density of collapse prevention drilling fluid. The borehole wall sloughing analysis method has the effect of being capable of analyzing the borehole wall stability of a strain softening plastic stratum under the condition of non-uniform ground stress; and the density of the collapse prevention drilling fluid is designed, thus playing the role of protecting a reservoir stratum during on-site drilling.

The present invention relates to a Lagrange dynamic model of a space tether system and a controller. Aiming at the modeling problem of the space tether system, six parameters consisting of three attitude angles, a tether surface internal angle, a tether surface external angle, the tether length and the like are considered, the Lagrangian method is employed to detailedly deduce the generalized force model of the tether, and a generalized state stability controller is designed. The Lagrange dynamic model of space tether system and the controller can solve the tether system target attitude modeling problem when a platform is equivalent to the target quality; and the designed controller can realize the control of the tether system generalization state variables after target capture.

The invention discloses a certainty acoustic-structure coupling response prediction method based on dual-modality equations. The method comprises the following steps: (1) dividing structures and acoustic cavities in an acoustic-structure coupling system into different subsystems; (2) calculating modalities of structure subsystems and acoustic cavity subsystems; (3) calculating coupling parameters of modalities of adjacent subsystems; (4) establishing dual-modality equations of a coupling system; (5) performing preprocessing so as to obtain generalized force loads to subsystem modalities under the action of certainty loads; (6) calculating the dual-modality equations so as to obtain participation factors of all modalities; and (7) through modality overlapping, calculating certainty acoustic-structure coupling response. According to the certainty acoustic-structure coupling response prediction method disclosed by the invention, the system is divided into continuously coupled subsystems, certainty vibration of the system is described through subsystems inside limited frequency bands, and the analysis efficiency of the method is higher than that of conventional finite element methods.

The invention discloses a three-dimensional steel bridge tower vortex-induced vibration calculation method, which achieves the three-dimensional steel bridge tower fluid-solid coupling numerical simulation through the dynamic mesh technology. The method comprises the steps of extracting the bending vibration mode coordinate values in the bridge direction and the transverse bridge direction througha Modal module of ANSYS workbench; performing function fitting by utilizing Matlab software to obtain a corresponding vibration mode function; inputting the vibration mode function into a user-defined program code UDF of the Fluent; analyzing the fluid to obtain a velocity field and a pressure field, obtaining generalized force by the user-defined program code UDF embedded into the Fluent, and substituting the generalized force into a structural vibration equation to solve to obtain generalized displacement; and obtaining an actual response of the structure through modal coordinate conversion, finally utilizing a dynamic mesh macro command to specify mesh movement so as to update the mesh position, and performing calculation of the next time step until convergence. According to the method, a computational fluid dynamics method is applied, and the business software Fluent is subjected to secondary development by compiling the user-defined program code UDF, so that the three-dimensionalsteel bridge tower fluid-solid coupling numerical simulation is achieved, the UDF can achieve parallel computing of the Fluent, and efficiency is greatly improved.

The invention discloses an equivalent mass determination method of a 3-PRS series-parallel mechanism. Servo motors are set to work in a torque mode; the known torques of the servo motors are converted to axial forces of ball screws and acting forces of slide blocks on stand columns; system generalized force of the whole 3-PRS series-parallel mechanism is obtained by solving through a geometric method; then, a fixed coordinate system and a local coordinate system are respectively built on a static platform and a movable platform to calculate kinetic energy and potential energy of each system component to build a lagrange equation of the whole mechanism; and such multiple parameters as generalized velocity and acceleration in the equation are calculated through distance measurement grating rulers of the mechanism to obtain equivalent mass of the 3-PRS series-parallel mechanism. The method provides technical guidance for robot structure design and optimization, path planning and control system optimization.

The invention provides a dual-modal equation-based dynamic response analysis method for a random noise environment. The method comprises the following steps of (1) dividing a structure and a vocal cavity in an acoustic-structural coupling system into different subsystems; (2) calculating modes of the structure subsystem and the vocal cavity subsystem; (3) calculating coupling parameters between the modes in the adjacent subsystems; (4) establishing a dual-modal equation of the coupling system; (5) through preprocessing, obtaining a cross-power spectrum of generalized force loads on the modes of the subsystems under the action of random loads; (6) calculating the dual-modal equation to obtain a cross-power spectrum of participation factors of all the modes; and (7) through modal superposition, calculating a random acoustic-structural coupling response of the system. The random dynamic response analysis method provided by the invention is the dual-modal equation-based dynamic response analysis method for the random noise environment. According to the method, the system is divided into the continuous coupling subsystems, and random vibration of the system is described by using the modes of the subsystem in a limited frequency band; and the analysis efficiency of the method is higher than that of a conventional finite element method.

The invention provides a stress calculation method for a steel-concrete composite beam, and relates to the field of bridge construction. The method comprises the following steps: dividing a compositebeam into a plurality of beam section units, each beam section unit comprising at least two nodes; obtaining all generalized forces including an axial force and node forces of the two shear hysteresisunits on each node on the beam section unit, and forming a node force matrix; constructing a node displacement matrix corresponding to the node force matrix; obtaining a balance equation comprising the node force matrix and the node displacement matrix based on the node force matrix and the node displacement matrix; obtaining a node displacement matrix with known node displacement based on the balance equation; and calculating the stress of the beam section unit based on the node displacement matrix. The method solves the problem that a stress calculation method in the prior art cannot effectively analyze the stress change of the main beam of the composite beam cable-stayed bridge caused by the sudden change of the shear hysteresis displacement boundary condition, the continuous change ofthe load and the shear hysteresis displacement boundary condition and other factors in the construction process.

Aiming at the technical problem that power source driving force of existing trapezoidal acceleration and S-shaped acceleration methods cannot be fully used, the invention provides a speed optimization method of a 3-PRS parallel mechanism, which belongs to the field of robot kinematics. The method comprises the steps of calculating the height, which corresponds to a tail end required pose curve, of sliding blocks first, then calculating the speed and acceleration which correspond to the heights of the sliding blocks, then determining an optimized coefficient, and setting the movement law of the sliding blocks according to the optimized coefficient and controlling the movement of the parallel mechanism at last. The time-varying optimized coefficient is obtained by using a constraint condition that the sum of three branch equivalent loads and instantaneous generalized force is not larger than the driving force, so that the movement law of the three sliding blocks is controlled by using the optimized coefficient. According to the optimization method provided by the invention, the power source driving force is fully used by the 3-PRS parallel mechanism at different working states, and the tail end running speed and the working efficiency are increased.

The present invention discloses a generalized force and force moment measuring device of the multiple-degree-of-freedom parallel mechanism in a spring structure format. The measuring device includes a multiple-degree-of-freedom parallel mechanism, a transverse spring, a diagonal drawn spring, a fixed external frame and a connection mechanism; the fixed external frame does not move relatively to the base of the parallel mechanism, and the connection mechanism is connected to the moveable platform of the multiple-degree-of-freedom parallel mechanism in a rigid and moveable mode and is connected to the fixed external frame through a plurality of springs. The present invention provides a compact, ideal and succinct measuring device of force and force moment, and the device can be used for measuring the generalized force and force moment of all kinds of multiple-degree-of-freedom platforms and for loading.

The invention relates to a generalized force-loading multidimensional fore-measuring bench calibration device and calibration method. The calibration device comprises a main calibration bench frame, a multi-dimensional force-measuring bench, a force applying mechanism, a first steel cable, a second steel cable and a sensing device. The main calibration bench frame is in an L shape; the multi-dimensional force-measuring bench is fixed at one side of the main calibration bench frame and a loading point is arranged; and the loading point, the first steel cable, the sensing device, the second steel cable and the force applying mechanism are connected successively. The force applying mechanism fixedly connected with the other side of the main calibration bench frame consists of a brake valve hand wheel, a first bidirectional screw rod, a connecting sleeve, a second bidirectional screw rod and a traction box, wherein the brake valve hand wheel, the first bidirectional screw rod, the connecting sleeve, the second bidirectional screw rod and the traction box are connected successively from top to bottom. The first bidirectional screw rod is provided with a fixed plate; and one end, in an inverted L shape of the fixed plate is connected with the main calibration bench frame fixedly and the other end is arranged by corresponding to the traction box. And a groove is formed in the bottom of the traction box and a traction sliding rod is arranged. According to the invention, forces and moments at multiple directions can be applied; and continuous vector force loading also can be realized, so that the error can be effectively reduced.

The invention discloses a cooperative control method of upper limb exoskeleton with dynamic load compensation, which utilizes the generalized force of the load on the upper limb exoskeleton and the corresponding jacoby matrix to obtain a joint torque Tload required for compensating the load influence; the joint torque Tg caused by the dead weight of the upper limb exoskeleton is obtained through inverse dynamics, the torque Th of the human-machine interaction force mapped to the joint space is obtained by using the interaction force between the human and the upper limb exoskeleton and the corresponding jacoby matrix, and each joint of the upper limb exoskeleton is controlled by using the final joint torque T, wherein T = T g+T load+T h, and then the interaction force fhr between the humanand the exoskeleton is measured; when fhr is not 0, the human-machine interaction force caused by the load can be compensated in real time through feedback compensation of the direct force controllerand PID controller.

The invention discloses a flexible flight dynamics modeling method considering structural nonlinearity. The method comprises the following steps: establishing an aircraft flight dynamics equation containing nonlinear aeroelastic wings by using an unsteady aerodynamic force; fitting the relationship between the hysteresis nonlinear generalized force and the displacement by adopting a rational formula, so as to establish an aircraft flight kinetic equation containing nonlinear rigidity and nonlinear damping at the same time; and finally, solving response characteristics and stability of the nonlinear flight dynamics model by using a numerical method or a harmonic balance method. The unified expression form for describing the nonlinearity of the structure established by the invention can solve the problems of aircraft gap nonlinear dynamic modeling and subsequent dynamic analysis under the conditions of installation gaps between control surface hinges and connecting pieces, aging and loosening of parts and the like, so that a guiding idea is provided for related controller design; and the method has a certain engineering application value.

The invention relates to an engine misfire fault judgment method based on mass center generalized force recognition. The method comprises the following steps of (1), obtaining the coordinates of a suspension system of an engine, the inertia parameters of the engine, the dynamic stiffness of the main shafts of the suspension system, and the included angles between the main shafts and the axes of afixed coordinate system; (2), testing a vibration acceleration response signal under a steady-state working condition of the engine; (3), extracting the amplitudes, phases and frequencies of the harmonic components of the vibration acceleration response signal of the suspension system by means of a ratio correction method of a discrete spectrum correction technology added with a Hanning window; and (4), recognizing the mass center generalized force of the engine according to the following formula as shown in the description by utilizing the results in the steps (1) and (3), analyzing the characteristics of a vibration signal of the mass center generalized force of the engine, and distinguishing engine misfire faults. According to the method, the sensitivity of misfire fault judgment is high.

The invention relates to the technical field of dynamics system optimization, and provides a flexible multi-body system dynamics semi-analytical sensitivity analysis method based on absolute node coordinate description. The method comprises the following steps: firstly, establishing a mass matrix, a rigidity matrix and a generalized force array of the flexible multi-body system based on an absolute node coordinate method; secondly, establishing a kinetic equation and an optimization objective function of the flexible multi-body system; thirdly, based on a direct differential method or an adjoint variable method, establishing a semi-analytical sensitivity calculation formula of the flexible multi-body system dynamics; and finally, solving the dynamic differential algebraic equation of the flexible multi-body system to obtain a sensitivity calculation result. The method is based on an absolute node coordinate method and a multi-body system dynamics theory. A semi-analytical sensitivity calculation formula of the flexible multi-body system is established to solve the sensitivity analysis problem of dynamics of the flexible multi-body system, a set of new strategy for sensitivity analysis of the flexible multi-body system is provided, and convenience is provided for sensitivity calculation of the large-scale complex flexible multi-body system.

The invention relates to an engine camshaft bearing loose failure diagnosis method and an engine camshaft bearing loose failure diagnosis system. The engine camshaft bearing loose failure diagnosis method comprises the steps of: acquiring an engine inertia parameter and an engine suspension system parameter; acquiring a vibration signal of an engine in a steady-state condition; analyzing frequency domain characteristics of the vibration signal; and calculating a center-of-mass generalized force of the engine according to the engine inertia parameter, the engine suspension system parameter and the frequency domain characteristics of the vibration signal, and diagnosing a engine camshaft bearing loose failure according to characteristics of the center-of-mass generalized force.

The invention discloses a trajectory tracking control method for a space five-degree-of-freedom free flight mechanical arm. The trajectory tracking control method can solve the accurate problem that aspace object is captured and manipulated by the five-degree-of-freedom space free-flight mechanical arm installed on a spacecraft. The trajectory tracking control method mainly comprises the following four points that 1), a D-H method is applied to establish a forward kinematic model of the mechanical arm; 2) a Lagrange equation is applied to establish a dynamical model of the mechanical arm; 3),a Jacobi transpose matrix and a PD controller are combined to introduce a generalized force vector; and 4), Simulink software is used for constructing a simulation model according to a dynamical differential equation. According to the method, the kinematic and dynamical models of the mechanical arm are constructed at the same time, and the method of the Jacobi transpose matrix in combination withthe PD controller is applied, so that the problem that a kinematic control method applied widely at present cannot well track and control the space high-speed high-precision mechanical arm is effectively solved.

The invention relates to mechanics parameter sensing device and particularly relates to a sensor used for a robot actuating mechanism or engineering detection device which needs to simultaneously detect and sense six orthogonal components of a spatial generalized force. The six-component force sensor comprises a main platform and an auxiliary platform, wherein a shell is arranged between the main platform and the auxiliary platform; three ball pivots are uniformly arranged at intervals along the circumference of the main platform, a support bar in a horizontal direction and a support bar in a vertical direction are connected to each ball pivot, and the ball pivots and the support bars are arranged in the shell; and the tail end of the support bar in the horizontal direction is connected with the shell, and the support bar in the vertical direction are connected with the auxiliary platform. The six-component force sensor has the advantages of symmetrical and compact structure, simple process and the like, and can be used for realizing single-type or combined-type six-component force sensors; and compared with a six-component force sensor based on a classic Stewart six-bar platform, the six-component force sensor provided by the invention has the advantages of small coupling degree and easiness for realization of isotropic property.

The invention discloses a control method for a robot. The robot comprises at least one arm. Each arm comprises a bottom, joints, connection rods and an end executor. The control method comprises the steps that the arms are decomposed with the joints and the connection rods as basic units so that joint coordinate systems and connection rod coordinate systems can be obtained; corresponding generalized velocities of each joint coordinate system and each connection rod coordinate system are calculated; the generalized force subjected by each connection rod is calculated; according to the calculated generalized force borne by each connection rod, the generalized force needing to be applied to each joint is calculated from the corresponding end executer to the corresponding bottom; the moment offorce to be applied to each joint is worked out; and the robot is controlled through the calculated moment of force. By adopting the control method, the calculated amount in real-time control can beeffectively reduced, and the real-time control purpose is achieved.