133 results about "Viscous friction" patented technology

The invention provides an uncertain mechanical arm fixed time track following control method with input saturation, which can overcome influences of mechanical arm control input saturation effect anduncertainty, and improves robustness of a system. The method comprises the following steps: establishing a kinetic equation of an n-freedom rotary joint rigid mechanical arm system with a viscous friction item; according to the established kinetic equation and a mechanical arm track error following signal, establishing a following error kinetic equation which takes parameter uncertainty into consideration; establishing a state space model of mechanical arm track following errors; establishing a fixed time disturbance observer according to the established space model; establishing a fixed timenon-singular terminal sliding mode surface according to the mechanical arm track following error signal; preliminarily determining each joint drive motor control moment instruction of a mechanical arm, and integrating a moment output range of a performer, thereby obtaining each joint control moment of the mechanical arm. The invention relates to the field of mechanical arm control.

The invention relates to a zero-force control method and system for a robot. The zero-force control method comprises the following steps: S1, a robot kinetic model is built on the basis of inertia force, centrifugal force, coriolis force, viscous friction force, static friction force and gravity; S2, external force moments of all the joints of the robot are calculated on the basis of the robot kinetic model and feedback data; S3, a speed command is calculated according to the external force moments calculated in the step 2; and S4, a position command is calculated according to the speed command and position feedback. Through the building of the kinetic model, the external force moments of all the joints can be directly calculated, without the assistance of a power-assisted sensor or a torque sensor, so that the cost and the complexity of the system are reduced; by the adoption of a position command control manner instead of a direct torque control manner, the design difficulty in the safety and the stability of the system is reduced; and in addition, since inertia force is considered when the external force moments are calculated, the zero-force control method and system can be suitable for robots with greater dead weight.

The invention relates to a road gradient and car state parameter combined estimation method based on a parameter estimation error, and belongs to the field of vehicle engineering. The method comprises the steps of firstly establishing a car driving longitudinal kinetic model according to a car kinetics theory and the newton second law; measuring a car speed and a driving force of an engine by virtue of a car-borne sensor, and adopting the measured car speed and the driving force as input quantities of an estimation algorithm; filtering the car driving longitudinal kinetic model, and extracting a parameter estimation error; judging whether an excitation condition is satisfied: estimating an unknown parameter vector by utilizing a vector designing self-adaptive law containing the parameter estimation error if the excitation condition is satisfied; adding random interference to the driving force if the excitation condition is not satisfied, and returning for re-measurement; finally calculating estimated values of a road gradient, car weight, viscous friction coefficient, rolling friction coefficient and air resistance coefficient by virtue of basic mathematical manipulation. By adopting the method, the cost is reduced, the accumulation of measurement noise can be avoided, and the precision is improved; the calculation quantity is reduced.

The invention relates to an energy dissipation beam column joint for a building steel structure. The energy dissipation beam column joint comprises a frame beam column, T-shaped connection parts, a viscous friction damper, a small I-shaped steel connection part, a metal energy dissipation bar and the like. Connection of the beam end comprises the upper T-shaped connection part, a frame beam, the small I-shaped steel connection part, the viscous friction damper and the lower T-shaped connection part. Except that the viscous friction damper and the small I-shaped steel connection part as well as the lower T-shaped connection part are bonded through strong glue, the others are all connected through high-strength bolts. The upper T-shaped connection part and the lower T-shaped connection part are connected with the frame beam through high-strength bolts. The whole metal energy dissipation bar penetrates through the lower flange of the frame beam to the lower T-shaped connection part and is fixed through a nut. When horizontal seismic force is small, the viscous friction damper can provide certain lateral resisting stiffness. When horizontal seismic force is large, relative sliding occurs to all layers of the viscous friction damper, the metal energy dissipation bar is driven to be subjected to bending deformation, joint energy dissipation is achieved, and a mixed energy dissipation system is formed. The energy dissipation beam column joint is simple in structure, significant in energy dissipation and seismic mitigation effect and suitable for various connection positions and does not occupy additional space.

The invention provides gun, artillery and rocket jet engines, steam turbines, internal combustion engines and air vehicles with an additional magnetic device. A magnet is included, translational motion, through Lorentz force, rotation and vibration of fluid molecules near the magnet in the direction of being perpendicular to the micro-flow direction of fluid are strongly inhibited, and pressure and temperature of the fluid molecules in the direction of being perpendicular to the micro-flow direction of the fluid are significantly lowered, so that the speed that the fluid molecules diffuse in the needed micro-flow direction is significantly increased. Viscous friction, turbulent shear stress, friction force and heat conduction in a boundary layer and shock waves, resistance generated by the shock waves and negative influences of heating on relative movement between air flow and an object are eliminated fundamentally in the microcosmic level or at least weakened greatly. By equipping the magnet on various gun, artillery and rocket engines, jet engines, turbines, gasoline engines, diesel engines and the like, radial pressure and temperature must be significantly lowered, the initial speed of pills is significantly increased, the power and the speed of the rock engines and the jet engines are increased, the energy utilization rate of the gas turbines, the turbines and the internal combustion engines is increased, and various resistances borne by the air vehicles and heating of the air vehicles are significantly reduced.

The invention discloses a device for measuring viscous friction force of an oil film of a plunger pair in a plunger pump. The device comprises a cylinder body, an induction feeler lever, a connecting rod, a fastening screw, a sensor cable, a friction force sensor, a fixing nut, a plunger bushing, a spring closing ring, a flow guide rod and a check valve component. The flow guide rod and the plunger bushing are connected together by the spring closing ring to form a floating bushing assembly supported by static pressure, the viscous force in the 3D direction of the oil film is induced by the induction feller lever and is transmitted to the friction force sensor by the connecting rod with higher rigidity, and the cable of the friction force sensor is led to the central position of the cylinder body by a neck groove on the cylinder body, and the cable is led out by a main shaft of the plunger pump. The structure of the device reasonably uses a void part between plunger chambers on the cylinder body, which causes the friction force sensor with larger volume to have sufficient mounting space and ensures reliable and stable structure and reliable performance; and the ingenious design and the application of the integral mechanical structure realizes compact structure and reduced volume.

The invention discloses a location control method of a 2R underactuated planar mechanical arm based on subdivision control. The location control method of the 2R underactuated planar mechanical arm based on subdivision control comprises the following steps: establishing an underactuated planar mechanical arm mechanics module with a driving first joint and a driven second joint, and considering Coulomb friction force and viscous friction force of joints in the module. To an underactuated robot, the friction of the driving joint can be directly compensated by a motor, but the driven joint can not be compensated, and the friction force of the driven joint is utilized. By adopting a time scale method and a proportion integration differentiation (PID) control method, the location control method of the 2R underactuated planar mechanical arm based on subdivision periodically starts joint space and location control to the 2R underactuated planar mechanical arm, and further achieves positioning control to the tail end of the robot. A research objective of the location control method is an underactuation system which includes entirely free joints, and so that the location control method of the 2R underactuated planar mechanical arm based on subdivision control has the advantages of being simplified in a mechanical device and pervasive in the control objective. The location control method of the 2R underactuated planar mechanical arm based on subdivision control utilizes a simple and feasible control method to realize the location control of the 2R underactuated planar mechanical arm, avoids to adopt complex and profound nonlinear control methods, and achieves the purposes of being distinct in train of thought, simple to programming and easy to achieve.

The invention relates to an electromechanical servo system parameter identification method based on large-inertia friction load. The method is characterized in that, to begin with, under a motor no-load operation state, determining an initial mechanical movement equation offline through a velocity reduction method, and serving the equation as controller parameters; and then, under a motor with-inertia operation state, determining a mechanical movement equation with inertia online through the same velocity reduction method, and calculating motor rotor rotational inertia J and viscous friction coefficient Bm online by utilizing the initial mechanical movement equation and the mechanical movement equation with inertia. The method can realize online identification, that is, the rotational inertia and the viscous friction coefficient of a motor rotor are calculated in real time during the system operation process, and the control strategy is adjusted according to characteristics in different time periods to allow the servo system to have excellent performance.

The invention discloses an off-line identification method for moment of inertia of a permanent magnet synchronous motor. The method comprises the steps of planning a speed instruction given by a speedring to enable the motor to operate for twice identification; sampling a feedback current value and a rotor position from a servo system at the same time when the motor runs in a controllable stroke;and inputting the current feedback signal and the rotor position signal into a designed model to calculate the moment of inertia so as to obtain a relatively accurate inertia identification result. According to the method, the problems that the influence caused by viscous friction cannot be ignored by a traditional off-line identification method, errors are introduced by differential operation inthe calculation process, and the application occasions are limited are solved. According to the method, the accuracy of an identification result can be effectively improved, and the total inertia ofthe system can be rapidly and accurately identified in an occasion with a load.

This invention prevents seizure of a dynamic pressure gas bearing caused upon swinging contact between a motor shaft and a sleeve and an increase in contact friction torque. It also detects rotation of auxiliary bearings. A motor includes auxiliary bearings in series with a dynamic pressure gas bearing, and a non-contact detent torque generation mechanism parallel to the auxiliary bearings suppresses rotation of the auxiliary bearings. Where Ta denotes rotation-time viscous friction torque of the dynamic pressure gas bearing, Tka denotes contact friction torque possibly causing damage to the dynamic pressure gas bearing, Tb denotes rotation friction torque of the auxiliary bearings, and Td_max denotes maximum torque generated when rotation of the auxiliary bearings is suppressed by the non-contact detent torque generation mechanism, (Ta+Tka)>(Tb+Td_max)>(Ta), and the rotation detecting means detects the rotation of the auxiliary bearings.

A viscous friction clutch for driving a cooling fan in a motor vehicle is disclosed, wherein the viscous friction clutch comprises a driving pulley and a housing, a supply chamber and a working chamber, a device for supplying shear fluid from the supply chamber to the working chamber and a device for returning the shear fluid from the working chamber to the supply chamber.

The invention discloses an air purification method, which comprises the steps that (1) the air flowing randomness is increased, and turbulent flow is formed or enhanced; (2) the turbulent flow air is in contact with a purification surface. The invention also discloses an air purification device, which comprises a turbulent flow forming and enhancing device and the purification surface, wherein the purification surface is a viscous surface, and the viscous friction stress of the viscous surface on particles in the air is obviously greater than the viscous friction stress of gas phase substances in the air on the particles. The method and the device provided by the invention have the following advantages and beneficial effects that through the turbulent flow formation of the air and the turbulent flow enhancement, the inertia collision between the particles in the air and the viscous surface is effectively enhanced, the sedimentation effect at the maximum efficiency is generated, in addition, the contact occasion between the particles in the air and the viscous surface is increased, particles which are not sedimented are effectively pasted by the viscous surface and are removed, so the air purification effect can be effectively improved.

The invention discloses a friction recognition and compensation control method for a Lorentz inertially stabilized platform. Aiming at the non-linear friction force between a bearing and a stator whenthe Lorentz inertial stabilization platform works, LuGre friction models of static and dynamic friction characteristics under platform deflection are established. Measuring a Stribeck curve through aconstant-speed deflection experiment, carrying out data fitting by adopting a linear regression equation based on a least square method, and identifying static parameters of the model; based on the viscous friction coefficient in the static parameters, the micro bristle deformation idea is adopted, the pre-sliding phenomenon is equivalent to second-order damping oscillation motion, and the dynamic parameters are solved by measuring the step response of the system. According to identified static and dynamic parameters, a Lyapunov function is constructed by adopting a back-stepping recursion thought, the design of a nonlinear feedback compensation controller is completed, and the problem of interference of nonlinear friction torque on rotor deflection is solved. The invention belongs to thefield of inertially stabilized platform control, and is suitable for recognition and compensation control of nonlinear friction torque of a platform.

The invention relates to the technical field of oil production, in particular to a method for measuring and calculating downhole power loss of rod-pumped wells, which mainly solves problems that existing measurement and calculation methods are incapable of reflecting components of downhole power loss objectively, incapable of properly handling irregularity of well deflection tracks and the defect that viscosity of crude oil varies along with temperature. The method includes the following steps: measuring and calculating downhole sliding friction power loss of the rod-pumped wells; measuring and calculating downhole viscous friction power loss of the rod-pumped wells; and measuring and calculating the downhole power loss of the rod-pumped wells according to the measured and calculated downhole sliding friction power loss and downhole viscous friction power loss. The method reflects components of the downhole power loss objectively, effectively prevents affection of irregularity of well deflection tracks and the defect that viscosity of crude oil varies along with temperature onto measurement and calculation of the downhole power loss, is capable of accurately measuring and calculating the downhole power loss of specific mechanical production systems, and thereby laying a fine foundation for calculation and improvement of input power and efficiency of the mechanical production systems.

A method for identifying friction parameters for a linear module is disclosed. Since an acting interval of a friction is determined by a relative velocity between two contacting surfaces, and when the relative velocity is much greater than a Stribeck velocity, there is only a Coulomb friction and a viscous friction exist between the contacting surfaces, it is possible to use a measured torque signal of this interval to identify a Coulomb friction torque, a the linear module's friction torque, and the linear module's equivalent inertia. When the relative velocity between the two contacting surfaces is smaller than the Stribeck velocity, it is possible to identify a maximum static friction torque and the Stribeck velocity by referring to the three known parameters. Thereby, all the friction parameters can be identified within one reciprocating movement of the linear module, making the method highly feasible in practice.

The invention belongs to the technical field of electromechanical servo systems, and particularly relates to a ball socket nozzle load characteristic identification method for servo system load matching. The method comprises a coulomb friction torque identification method, a viscous friction torque identification method, an elastic torque identification method and an inertia torque calculation method. By means of the method, accurate load characteristic parameters of a large ball socket nozzle can be identified, matching of the servo system and the load characteristics of the ball socket nozzle is achieved, and the performance requirement for thrust vector control of a solid rocket is met.

The invention belongs to the technical field of hydraulic testing, and particularly relates to a system and method for testing sealing friction force and viscous friction coefficients of a hydraulic linear moving element. The testing problems of viscous friction force and viscous friction coefficients of a high-water-based hydraulic element are solved. The system for testing the testing sealing friction force and the viscous friction coefficients of the hydraulic linear moving element is characterized in that a driving part comprises a filter I, a driving pump, an overflow valve I, an electro-hydraulic proportional directional valve, a hydraulic control one-way valve I, a hydraulic control one-way valve II, a displacement sensor and a driving oil cylinder, and a tested part comprises a pressure gauge I, an energy accumulator I, a stop valve I, a stop valve II, an energy accumulator II, a pressure gauge II, a tested cylinder, a shifting piece, a travel switch I, a travel switch II, a one-way valve I, a one-way valve II, an electro-hydraulic reversing valve, an overflow valve II, a liquid filling pump and a filter II. According to the system and method for testing the testing sealingfriction force and the viscous friction coefficients of the hydraulic linear moving element, the sealing friction resistance and the friction coefficients under different differential pressure and movement speeds can be measured.