172results about How to "Avoid the impact of measurement accuracy" patented technology

The present invention relates to a two-dimension large-range laser displacement / deflection measuring equipment and its measuring method. Said equipment includes laser transmitting portion and two-dimension laser speckle receiving and measuring portion. The laser transmitting portion is formed-form laser and mounting frame, and said laser mounting frame is a variable damping hinge structure, and the two-dimension laser speckle receiving and measuring portion consists of receiving screen, camera and luminous or non-luminous mark. Said invention also provides the concrete steps of its measurement method.

The invention relates to an on-line non-contact laser stereo scanning detection device for the internal screw threads of a tubing coupling, which is used for carrying out one-by-one all-around dynamic on-line three-dimensional stereo scanning detection on the tooth profile parameters of all the internal screw threads to be processed in the processing process of special purpose machine tools, suchas a threading machine tool of the tubing coupling and the like, to the internal screw threads. The on-line non-contact laser three-dimensional scanning detection device comprises an axial movement mechanism assembly, a radial rotation mechanism assembly and a laser detection probe assembly. The radial rotation mechanism assembly is fixedly connected with the end of the axial movement mechanism assembly, and the laser detection probe assembly is fixedly connected at the end of the radial rotation mechanism assembly. The invention has a three-dimensional stereo scanning detection function, cancarry out high-speed high-accuracy on-line laser stereo scanning on the tooth profiles of the sections of different radial axles of the internal screw threads of the tubing coupling and obtains the three-dimensional stereo geometric information of the tooth profiles of the internal screw threads of the tubing coupling. The invention can enhance the detection accuracy and speed of the parameters of the internal screw threads, lightens the labor strength of a detection worker greatly and avoids the influence of human factors to the measurement accuracy. Moreover, the invention can be used for on-line quality monitoring and prediction and enhances the product quality.

The invention relates to a method for measuring thickness of sea surface spilled oil film based on differential laser triangulation. The method uses dual laser triangulation ranging system, and laser beams emitted by two lasers are respectively irradiated to the upper and the lower surfaces of an oil film to be measured in any vertical direction; the off-plane displacements of the upper and the lower surfaces can be obtained simultaneously according to the size of image drift and configuration parameters of imaging system; the thickness of the measured oil film can be determined by subtracting; and the thickness distribution of oil film in spilled oil area can be obtained by multi-point sampling. The non-contact measuring method has the characteristics of simple theory, convenient measurement, low cost, high precision, small volume and the like, and can be applied to dynamic on-line measurement of oil film thickness at the surface of aqueous solution.

The invention discloses a temperature sensor for pulse-width modulation. The technical problem to be solved is to improve measuring accuracy of the temperature sensor. The temperature sensor for the pulse-width modulation comprises a band gap reference circuit, a temperature detection circuit and a pulse-width modulation oscillator circuit. Compared with the prior art, the temperature sensor adopts the band gap reference circuit based on standard CMOS technology and a temperature sensor circuit output by a pulse-width modulation PWM mode to effectively overcome the influence of power supply voltage and technological deviation under a frequency output mode on measuring accuracy, and generates PWM signal output of which the duty factor is directly proportional to the temperature through a current multiplexing oscillator circuit; and the duty factor is only relevant to band gap reference voltage and measurement temperature, but is irrelevant to the power supply voltage and magnitude of charging current and capacitance, the temperature sensor eliminates the influence of the technological deviation and offset voltage of a comparator on the duty factor, so the accuracy of temperature measurement is higher.

The invention provides a device for measuring deflection / displacement line shape by pressure difference and a method thereof. The device comprises a trolley and an L-shaped pipeline filled with liquid, wherein the horizontal section of the L-shaped pipeline is arranged on the trolley along the length direction of the trolley; the two ends of the horizontal section of the L-shaped pipeline are respectively provided with pressure sensors A and B, and the bottom is provided with a temperature sensor; a wheel of the trolley is provided with a displacement transducer; the temperature sensor, the pressure sensors A and B and the displacement transducer are connected with a control system provided with an interface and a memorizer by a data bus; and the displacement transducer is used for controlling the measurement to start for once after the trolley rotates for N rounds. The two pressure sensors are used for measuring the pressure difference at the two ends of the pipeline, and calculating by the liquid density at the different temperatures, thus measuring the vertical altitude difference between two points. The invention has the advantages of wide measuring plane, high accuracy, no influence by light interference, high degree of automation, low measuring cost, etc.

A scattered solid material intelligent metering device belongs to the automation detection metering technology field, which can be applied widely to industries using a belt transporter for example coal, metallurgy, power generation, characterized in that the device is composed of a funnel 1, downspoutings 2, 3, punchings 4, 5, weighing sensors 6, 7 and an intelligent measuring and control instrument 14. The funnel 1 and the punching 4, 5 form weighing frame structure; the weighing sensor 6, 7 and the intelligent measuring and control instrument 14 form the measuring system; the invention not only has high precision, wide measuring range, reasonable structure, strong overload capacity but also does not change original on site devices. The invention is applied to continuously dynamic scattered solid material metering for example the coal, the dock, the electricity power plant, which replaces traditional electronic belt weigh meter and nuclear scale. The metering device can be used even under condition that the belt weigh meter can not be used, for example, various material transporter and storage material feeding opening of chain board, scrapping board, screw and so on.

The invention provides a stay cable force measuring device and a measuring method therefor. The device is simple in structure, and no expensive high precision equipment such as sensors is needed; a corresponding relation between cable force of a stay cable and radial elastic stress is adopted by the device, a contact type displacement sensor with guaranteed measurement accuracy is adopted for measuring variation of radial deformation and displacement before and after specified radial pressure is applied on the stay cable, and the cable force of the stay cable is measured via a pre-established function relation model between the cable force and deformation under stress; whether the stay cable is in installation processes or is put into use after installation, the cable force of the stay cable can be measured; based on a measurement principle adopted by the device, measurement precision can be prevented from being affected by interference factors such as span, sag, vibration, environment electromagnetic waves and the like of the stay cable; high measurement precision can be guaranteed, universality can be well ensured, convenience of use and operation is realized, and a new solution is provided for measurement of the cable force of the stay cable which is put into use after installation.

The invention relates to the rib-expansible density logging while drilling apparatus for use in the petroleum drilling industry. A density detector pup joint and a gamma radioactive source are sealed and arranged on a drill collar. An expandable rib is arranged on the surface of the drill collar at position of a groove, and the groove and the density detector pup joint are arranged at an interval of about 120 degrees in a circumferential direction. The expandable rib relies on a piston assembly to extend outward under the action of pressure drop (difference between inner pressure and outer pressure) generated due to instruments such as a drill bit (and a motor) arranged at the lower part of the apparatus and presses the detector pup joint against a well wall on a corresponding side by using counterforce of the well wall to realize density measurement by the well wall. And when a pump stops, the expandable rib retracts under the action of a return spring. The rib-expansible density logging while drilling apparatus is applicable to various wells, ensures measurement by the well wall, overcomes influence of slurry, mud cake or complex well structure on measurement precision, improves underground safety and is applicable to logging while drilling and geosteering drilling.

The invention discloses a deep-sea sediment soil mechanics in-situ tester capable of carrying a submersible vehicle. The tester comprises a shear strength testing mechanism and a penetration resistance testing mechanism, wherein the shear strength testing mechanism comprises a shear driving device, a shear rod, a cross plate, a high-pressure chamber, torque testers and a torque motor; the torque testers are arranged in the high-pressure chamber and are used for detecting the torque of the torque motor; one end of the shear rod is fixedly connected with the cross plate, and the other end of the shear rod stretches into the high-pressure chamber and is connected with the torque motor; the shear driving device is used for driving the shear rod to move up and down; the torque motor is used for driving the shear rod and the cross plate to rotate; the penetration resistance testing mechanism comprises a penetration driving device, a penetration rod and a displacement sensor; the penetration rod and the displacement sensor are arranged on the penetration driving device; the penetration rod is connected with the displacement sensor; and the penetration driving device is used for driving the penetration rod to move up and down. The in-situ tester disclosed by the invention has the advantages that the submersible vehicle is convenient to carry, the measuring operation time is reduced, the working efficiency is high and the like.

The invention relates to a core wire extruding production line for a flame-retardant power cable. The core wire extruding production line comprises an electric power pay-off machine, a vertical tension bracket, a wire preheater, a plastic extrusion mechanism, a cooling and drying mechanism, a traction mechanism, a spark tester, a laser marking machine, a wire storage tension bracket, a take-up mechanism and a PLC electronic control platform, which are sequentially arranged, wherein the plastic extrusion mechanism comprises an automatic feeding device and a twin-screw extruder; the cooling and drying mechanism comprises a first segment of cooling water channel, a second segment of cooling rotary box and a blowing dryer; a hot end outside diameter measuring instrument is arranged between the twin-screw extruder and the first segment of cooling water channel; a cold end outside diameter measuring instrument is arranged between the spark tester and the laser marking machine; the take-up mechanism comprises a take-up meter counter and a double-shaft winding take-up machine; the PLC electronic control platform is arranged at the tail end of the double-shaft winding take-up machine, and is in communication connection with equipment on the production line through a field bus; and intelligent full-automatic control is carried out on the overall production line, so that high-speed and high-quality production of the flame-retardant power cable is achieved.

The invention discloses a height measurement method and apparatus. The height measurement method is realized based on a depth camera, and in particular, the depth camera is adopted to acquire the multi-frames of background depth pictures that are converted into multi-frames of background point cloud images, by means of the multi-frames of background point cloud images, and through the background model extraction, the foreground image extraction, the foreground image edge information extraction, the default template matching and the calculation of the world coordinates and the height to be measured, the height of the object to be measured in each frame of image can be obtained, so that the aim of non-contact height measurement is realized; and moreover, the height measurement method has good generalization and good robustness, can realize the all-weather height measurement, and does not need the calibration process before and after the application of the depth camera, and has no risk of personal information leakage.

The invention discloses a portable ultrasonic detector and a detection method for liquid food quality. The detector comprises an ultrasonic sensor device, a the control unit mainly comprising digital signal processing, timing and memory modules, a temperature compensation unit and a man-machine interface comprising a USB standard interface, a keyboard and a liquid crystal display (LCD). Through use of the portable ultrasonic detector and the detection method for the liquid food quality, consumers can perform, without opening sealing caps, nondestructive detection of bottled and canned liquid food to be purchased such as wine, edible oil, soy sauce, vinegar, milk, beverage and the like whenever and wherever, influences of bottle wall thickness and signal processing module time delay on detection results can be avoided, and relevant characteristic parameters of the detected liquid food can be accurately obtained. The relevant characteristic parameter values are compared with a cloud database established through a lot of experiments for detecting good food, so that if the detected liquid food is true or false and good or bad can be identified.

The invention discloses a weightlessness-principle-based powdery material continuous metering control method and a device thereof. The device relates to a weightlessness balance and comprises a storage bin and a weighing bin which are arranged from top to bottom and communicated by virtue of a material conveying channel, wherein the material conveying channel between the storage bin and the weighing bin is provided with an upper pneumatic gate valve and a lower pneumatic gate valve which are used for controlling make-break of the material conveying channel, the material conveying channel between the storage bin and the weighing bin is also provided with a surge bin in a serial connection manner, the upper pneumatic gate valve is arranged on the material conveying channel between the storage bin and the surge bin, and the lower pneumatic gate valve is arranged on the material conveying channel between the surge bin and the weighing bin. By controlling opening and closing of the upper pneumatic gate valve and the lower pneumatic gate valve, material flows into the weighing bin by virtue of the surge bin, the storage bin is prevented from directly impacting the weighing bin, and the influence on the measuring accuracy of a weighing sensor is avoided.

The invention relates to a DC system insulation monitoring method based on a fixed-frequency switching resistor principle. The method is characterized by comprising steps of low frequency switching resistor branch establishment, DC leakage current measurement carried out through utilizing an AC sensor, calculation based on a circuit equation, and error analysis on current voltage waveform formed through switching, specifically, a switching resistor is utilized to convert a current passing through a transformer into DC rectangular waves; the AC sensor is utilized to realize accurate detection on a branch ten-microamp-grade ground leakage current; a ground resistor and a distribution capacitor are measured through detection and calculation in real time; accurate DC system ground fault monitoring and fault branch positioning are realized, and influence of the distribution capacitor on measurement precision of the ground resistor can be directly avoided. The method has advantages of scientific and reasonable performance, easy realization, strong applicability, high monitoring accuracy and good effects.

The invention relates to a method for detecting residual stress for high-molecular injection molding processing. The method comprises the following steps of: performing injection-molding and processing conductive fiber subjected to modification treatment and a high-molecular material; arranging electrode lead-out wires at two ends of the conductive fiber; performing thermal treatment on an injection-molding product; measuring resistance of the conductive fiber before and after the thermal treatment on the injection-molding product; and converting the corresponding residual stress of the injection-molding product by the change of the resistance of the conductive fiber. By utilizing the method, the residual stress formed in the processing process of the different parts of the injection-molding product can be accurately measured, and a basis is provided for researching high-molecular new materials, new techniques and optimization design of moulds.

The invention relates to a three-dimensional measuring device for suspension characteristics of a high-temperature superconducting magnetic suspension bearing. A permanent-magnet rotor fixing device (13) is installed at a sliding block (30) of a vertical mechanical arm (6) of a triaxial movement manipulator; the back surface of the permanent-magnet rotor fixing device (13) is in contact with the upper end surface of the sliding block (30); and the lower end surface of the permanent-magnet rotor fixing device (13) is perpendicular to the upper end surface of the sliding block (30). A double-layer low-temperature Dewar includes a Dewar unit (14) and a Dewar support device; a plurality of force cell sensors are arranged at a peripheral outer wall or bottom surface of the Dewar unit (14); one end of each force cell sensor is connected with the Dewar unit (14) and the other end is fixed at a sensor fixation unit. The sensor fixation unit is arranged at the bottom of the Dewar unit (14) or the peripheral outer wall of the Dewar. A manipulator motion control system is connected with the triaxial movement manipulator. An automatic control system is connected with the force cell sensors and the manipulator motion control system and is also connected with a serial port of an upper computer.

The invention belongs to the testing technological field and discloses a bearing dynamic friction torque tester. The bearing dynamic friction torque tester comprises a host, a controller, and a display; and the bearing dynamic friction torque tester is a bearing detection device. The bearing dynamic friction torque tester is driven by a precision spindle at a rate of 1r / min (or 0.5r / min or 10r / min) to drive a bearing under test to rotate at a low speed; under an actual preload condition, the dynamic torque of the bearing is detected by a dynamometer, and a test curve is displayed in real time;bearing quality information such as bearing tracks, steel ball surface smoothness, groove surface smoothness, cleanliness, lubrication states and friction torque mean values can be judged by means ofcontinuous torque curve analysis; and therefore, with the bearing dynamic friction torque tester adopted, the quality control of the bearing can be carried out, the improvement of the accuracy of a product and the prolonging of the service life of the product can be benefitted. The bearing dynamic friction torque tester can be a device used by a bearing user to carry out bearing screening and bearing quality inspection.

The invention discloses a constant water temperature control method and system. The constant water temperature control method includes the following steps that A, the current water flow is detected through a pulse flowmeter, and temperature data are measured through temperature sensors arranged on a water inlet and a water outlet respectively; B, the current water temperature adjusting capacity value is calculated; C, the target water flow used for achieving constant temperature control is calculated according to the current water flow, the temperature data, the current water temperature adjusting capacity value and a constant temperature target value; D, a water valve is controlled according to the target water flow. As the water flow is detected through the pulse flowmeter, and the temperature is detected through the temperature sensors, it is avoided that in the prior art, the measuring accuracy of the temperature sensors is affected by the environment temperature because single sensors are used; the water valve is accurately adjusted through the pulse flowmeter, and the effect of control over the constant water temperature is improved. The constant water temperature control method and system can be widely applied to the technical field of heat pumps.

The invention discloses a fine dried noodle elasticity modulus measuring method based on pressure lever post-buckling. A load measuring device is installed firstly, a static pressure head of the load measuring device is fixed on a base, a force sensor is arranged on a movable arm of the load measuring device, and then a dynamic pressure head is fixedly connected with the force sensor; a certain number of fine dried noodles cut to have corresponding length are respectively arranged between the static pressure head and the dynamic pressure head; and the amount of movement of the dynamic pressure head is determined according to the length of the fine dried noodle and an set intersection angle of the end part of a twisted curve, then the load measuring device is started again, the dynamic pressure head is driven by the load measuring device to load the fine dried noodles in a speed of 0.01mm / s, load corresponding to the amount of movement of the dynamic pressure head is measured by the load measuring device, and at last the fine dried noodle elasticity modulus is counted by a formula relationship. The invention uses pressure lever stability principle and large deflection theory of mechanics of materials to establish the relationship of axial compression, the end part intersection angle and pressure, establishes a counting method of the fine dried noodle elasticity modulus, has simple and convenient measuring method and high precision, and can control the length of the fine dried noodle elasticity modulus to be between 60 mm and 220mm.

The invention discloses a controller area network (CAN) bus-based settlement deformation monitoring system which comprises a power module, a remote transmission module, at least one monitoring subsystem, and a remote monitoring server and a monitoring mobile phone that are used for carrying out data processing, wherein the monitoring subsystem comprises a data acquisition unit and a plurality of inductive transducers used for acquiring the foundation settlement deformation; the plurality of inductive transducers are arranged on the foundation and are respectively connected with the corresponding data acquisition unit so as to realize data exchange; every two adjacent data acquisition units are connected with each other in series by a CAN bus; the remote transmission module is connected with the CAN bus, so that data transmission can be realized; and the remote transmission module is also respectively connected with the monitoring mobile phone and the remote monitoring server by a wireless network, so that data exchange can be realized. The CAN bus-based settlement deformation monitoring system can be used for monitoring the foundation settlement deformation in real time effectively and rapidly, and is high in reliability, thus not only reducing the work load of operators, but also being long in communication distance and realizing real-time data transmission and data resource sharing; and the monitoring system integrates multiple monitoring ways.

The invention relates to a differential pressure type flow sensor capable of realizing direct pressure tapping and two-way measurement, which solves the problems that a differential pressure type flowmeter must be provided with a pressure guiding pipe, has large occupation space, lower measuring precision and narrower range and can only measure flow along one direction in prior art. The differential pressure type flow sensor is characterized in that a shell is internally welded with a throttle disc with symmetrical double surfaces, a pipe wall of the shell is provided with pressure guiding hole, the shell is provided with a pressure tapping sylphon corresponding to the pressure guiding hole, the pressure tapping sylphon is internally provided with a coplanar pressure tapping type differential pressure transmitter with the precision of 0.04 percent, and the pressure tapping sylphon is also externally connected with a differential pressure flow converter which can realize the two-direction measurement of flow, has flow output ranged from 4 to 20 mA and a zero point of 12 mA. The invention has the advantage that the pressure tapping sylphon is attached to the wall of the shell so as to omit the traditional pressure guiding pipe, thereby having compact structure, eliminating the standstill space of bubbles on mechanism and overcoming the flow measurement fluctuation caused in such a way that the bubbles stop in the pressure guiding pipe, and the differential pressure transmitter can realize positive and negative two-direction flow measurement.

The invention belongs to the technical field of vehicle detection and discloses a road detection vehicle distance triggering device and method based on information fusion. Longitudinal running speed of a vehicle is estimated in real time through fusing output signals of a GPS (global positioning system) module, a longitudinal acceleration sensor, a vertical acceleration sensor, a gyroscope and a vehicle speed sensor, the longitudinal running speed is then integrated to obtain a vehicle running distance, and whether a road pattern sensor on a detection vehicle is triggered or not is judged according to the running distance; therefore, errors due to changes in rolling radius of tires are avoided; in addition, since the GPS module, the vertical acceleration sensor, the gyroscope and the vehicle speed sensor are standard parts to a traditional road detection vehicle, the device related in the technical scheme of the invention is added with only one longitudinal acceleration sensor to measure longitudinal acceleration of a vehicle, and manufacture cost of the detection vehicle can be reduced.

The invention discloses an MEMS (micro-electro-mechanical system) motion sensor based wave measurement method. Specifically, an MEMS motion sensor is mounted in a buoy to acquire various motion parameters of the buoy, an ocean wave directional spectrum is obtained according to the motion parameters, and then wave parameters can be calculated. The wave measurement method consists of: acquiring the buoy motion parameters, i.e. acquiring the roll angle phi, pitch angle theta, yaw angle psi and three-dimensional motion speed of the buoy in an ECEF coordinate system with the MEMS motion sensor in the buoy; combining the buoy motion parameters and calculating an original wave directional spectrum, i.e. constructing 7 combinations according to the acquired 12 buoy motion parameters to calculate the original wave directional spectrum; calculating the wave directional spectrum by coefficient weighting, i.e. performing coefficient weighting on the original wave directional spectrum of the 7 combinations so as to obtain the sea wave directional spectrum; and calculating the wave height, wave period, wave direction and other ocean wave parameter information. The wave measurement method provided by the invention is simple, and has stable and reliable wave measurement accuracy, thus having very broad application prospect.

The invention discloses a method for testing dynamic shearing of a composite material, and belongs to the technical field of materials. The method comprises the following steps of (1) processing the composite material into a convex-shaped specimen according to the main direction of each material; (2) arranging the specimen on a Hopkinson press rod, dynamically loading, and calculating the anti-shear strength and strain rate of the specimen according to the recorded incidence strain signal, reflection strain signal and transmittance strain signal in the experiment process. The method has the advantages that the additional processing clamp is not needed, and the shearing mechanical property of the composite material in each direction can be measured by the existing Hopkinson press rod, so that the testing cost is reduced, and the influence of the mechanical connection to the measuring accuracy of the Hopkinson press rod can be effectively avoided; in addition, the convex-shaped specimenof the composite material is of a symmetric type, and the bottom part is provided with a connecting area, so as to ensure the occurrence of the shearing damage to the specimen in the loading process.

The invention relates to a mass air flow sensor with silica-based thin-film structure on the basis of the MEMS technique. The silica-based material 1 is covered with a layer of insulation film 2, the middle part of the whole structure is etched with a heat insulation cavity 5, and a heating resistance 3 and a resistance temperature detector 4 are arranged on the base material by one time by adopting the MEMS technique. For the arrangement, the heating resistance 3 is arranged on the insulation film 2 of the heat insulation cavity 5, and the resistance temperature detector is arranged on the insulation film on the silica-based material. By adopting the mass air flow sensor of the invention, a hot type mass air flow sensor which has high measuring precision, low power consumption, large measuring range, good consistency of measurement, low cost and constant temperature difference.

An experimental device of a compact magnetic levitation worktable comprises a stator portion and a rotor portion. The stator portion comprises a base and a cylindrical stator housing arranged on the base, and a circular top cap is arranged at the top end of the stator housing. The rotor portion comprises a rotor arranged in the stator housing, a support column is fixed on the rotor and penetrates the top cap, and an objective table is arranged at the top of the support column. A plurality of first electromagnets used for vertical driving and a plurality of first eddy current sensors used for detecting vertical displacement are arranged on the top cap, and a plurality of second electromagnets used for horizontal driving and a plurality of second eddy current sensors used for detecting horizontal displacement are arranged on the side wall of the stator housing. The experimental device suitable for precise positioning magnetic levitation worktables is designed in order to meet the requirement on ultraprecise positioning, can be used for positioning of lithography machine wafer stages, can also be used for laser processing or other occasions needing micro-motion worktables, and is particularly suitable for occasions needing vacuum and free of friction.

The invention provides a fracture-width adjustable type inner visible three-dimensional fracture permeating device. The device comprises a permeating instrument, an air-liquid supplying control systemand a data acquiring analyzing system, wherein the permeating instrument mainly comprises an upper cover steel plate, a silica gel plate, toughened glass plates, cellophane which is attached to a 3Dprinted coarse fracture surface, and a lower coiled steel plate; a water guide channel is formed between the two toughened glass plates to which the cellophanes are attached, and the opening degree ofthe water guide channel is adjusted through a feeler gauge; the fiver parts of the permeating instrument are connected and sealed through high-strength bolts; an electric pressure testing pump and ahigh-pressure air pipe are used for supplying pressure to an air-liquid supplying part; the fluid pressure is adjusted by a control part through a valve; permeating pipelines are connected through oxygen rubber tubes, and each connecting part is sealed through a combination gasket; the data acquiring analyzing part comprises a pressure sensor, a flow meter and a paper-free recorder; and data are transmitted to the paper-free recorder through the pressure sensor and the flow meter, and the data are acquired and analyzed through a computer.

The present invention relates to a non-contact optical digital tensiometer. It is composed of two groups of optical lens, two imagers, two linear image sensors, comparison logic and counting circuit, clock pulse generator, microcontroller and two reflecting marks fixed on the sample to be measured. Said invention also provides its working principle and application method.

The invention discloses a resistance measuring instrument and a resistance measuring method, wherein the resistance measuring instrument comprises a bidirectional constant current source, a voltage acquisition and amplifying device, an AD converter, a bidirectional constant current source, a series loop composed of a standard resistor and a measured resistor. The voltage acquisition and amplifying device is electrically connected with a controller through the AD converter, and the controller and the display terminal are electrically connected. The resistance measuring instrument also comprises a switching switch module used for controlling the voltage acquisition and amplifying device to be connected at two ends of the standard resistor or two ends of the measured resistor, and the controller is electrically connected with the control end of a switching switch. The circuit structure is simple, and the positive and negative constant current values generated by the bidirectional constant current source need not be strictly equal, which reduces the requirement for the hardware precision. The leakage current of the electronic switch is prevented from influencing the measurement precision. The temperature drift of the measurement result only relates to the temperature drift of the standard resistor, and the standard resistor of the low temperature drift is selected to improve the measurement precision under the wide temperature range condition of the instrument. The influences of oriented interference on the measurement result can be eliminated.

The invention discloses a time-grating linear displacement sensor, and the sensor comprises a fixed ruler which consists of a fixed ruler base body and two sensing units, and also comprises a moving ruler which consists of a moving ruler base body and two magnetic conduction units. Each sensing unit comprises an excitation coil and an induction coil, wherein the induction coil starts at a zero point, and two ends of the induction coil are wound along two staggered piecewise functions to form N 90-degree inverted 8-shaped continuous winding tracks, wherein the period of the piecewise functions is W. The winding mode of the induction coils is the same as the winding mode of the excitation coils, and the winding tracks of the induction coils are curves of the winding tracks of the excitation coils after the winding tracks of the excitation coils move by W / 4 towards the right in the measurement direction. The induction coils of the two sensing units are in series connection. Each magnetic conduction unit is formed by the arrangement of a plurality of magnetizers in the measurement direction at equal intervals, and the center distance of two adjacent magnetizers is equal to W / 2. The width b and length L of each magnetizer meet a specific condition, and the starting positions of magnetizers in two magnetic conduction units meet a specific condition. The sensor can prevent the turns of the excitation coils and the distribution condition of all coils from affecting the measurement precision.