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Principle Total Station is a new type of angle measuring instrument integrating light, machine and electricity. Compared with optical theodolite, the electronic theodolite changes the optical dial to photoelectric scanning disk and replaces artificial optical micrometer reading with automatic recording and Display readings simplify sculpting and avoid reading errors. The electronic theodolite's automatic recording, storage, calculation functions, and data communication functions further improve the automation of the measurement operation.
The difference between the total station and the optical theodolite lies in the dial reading and display system. The electronic theodolite's horizontal dial and vertical dial and its reading device use two identical grating disks (or encoder disks) and reading sensor respectively to make angles measured. According to the accuracy of angle measurement, it can be divided into several levels of 0. 5′′, 1′′, 2′′, 3′′, 5′′, 10′′, etc.
The brief history total station instrument was born in the process of automation of angle measurement. Various electronic theodolites play an important role in various surveying and mapping operations.
The development of the total station experienced a combination of a combination of an optical distance meter and an optical theodolite, or a combination of an optical distance meter and an electronic theodolite, and an optical axis and a theodolite view of an optical wave transmitting and receiving system that is an integrated photoelectric distance meter. The quasi-axis combination is a coaxial one-piece total station and several other stages.
The distance measurement of the initial speedometer was achieved by optical methods. We call this speedometer an "optical speedometer." In fact, "optical speed measuring instrument" refers to a theodolite with a line of sight wire. The plane position of the measured point is determined by the direction measurement and the optical line of sight, and the elevation is determined by the triangulation method.
An optical speed measuring instrument with "line of sight", because of its quickness and simplicity, in short distance (within 100 meters) and low accuracy (1/200 (1/500) in the measurement, such as the measurement of broken points It has its advantages and has been widely used.
With the advent of electronic ranging technology, the development of speedometers has been greatly promoted. The use of electromagnetic range finder instead of optical line of sight theodolite makes the measuring range larger, the measurement time shorter and the accuracy higher. People call the speedometers measured by electromagnetic range finder a "Electronic Tachymeter."
However, with the advent of electronic angle measurement technology. The concept of this "electronic quick tester" has changed accordingly. According to the difference in the angle measurement method, it is divided into a semi-station electronic quick tester and a full-station electronic quick tester. Semi-station type electronic quick tester refers to an electronic fast measuring instrument for optical angle measurement, also known as “distance theodoliteâ€. The speedometer appeared earlier and continuously improved. The optical angle reading can be input to the distance meter through the keyboard to calculate the slant range. Finally, the horizontal distance, height difference, direction angle, and coordinate difference are obtained. These results can be automatically transferred to external memory. The full-station electronic quick tester is a three-dimensional coordinate measuring system consisting of electronic angle measurement, electronic distance measurement, electronic calculation, and data storage unit. The measurement result can be automatically displayed and the multi-function measuring instrument can exchange information with peripheral equipment. . Because the full-station type electronic quick tester has realized the electronicization and integration of measurement and processing in a relatively complete manner, people often call it a full-station electronic quick tester or simply a total station.
At the end of the 1980s, according to the unbalanced development of electronic angle measurement systems and electronic distance measurement systems, total stations were divided into two major categories, namely the building block type and the integral type.
Since the 1990s, basically all of them have been developed into monolithic total stations.
The classification total station uses a photoelectric scanning angle measurement system. The types include: coded disk angle measurement system, grating disk angle measurement system, and dynamic (raster disk) angle measurement system.
Structural total stations can be used in almost all areas of measurement. The electronic total station consists of power supply, angle measurement system, distance measurement system, data processing part, communication interface, display screen and keyboard. Compared with electronic theodolites and optical theodolites, the total station adds many special components, which makes the total station has more functions than other angle measuring and distance measuring instruments, and is more convenient to use. These special components make up the unique characteristics of the total station in terms of its structure.
1. The telescope of the total telescope of the coaxial telescope realizes the coaxial axis, the transmission of the distance lightwave, and the coaxiality of the receiving optical axis. The basic principle of coaxialization is to set a dichroic prism system between the telephoto objective lens and the focus lens. The system can realize the multi-function of the telescope by aiming the target at the crosshair reticle for angle measurement. At the same time, the external light path system of the distance measuring part can make the modulated infrared light emitted by the photodiode of the distance measuring part be reflected by the same path after being reflected by the objective lens and reflected by the same path, and then the light is received by the photodiode via the action of the dichroic prism. For the distance measurement, an internal light path system needs to be set inside the instrument. The modulated infrared light emitted by the photodiode is also transmitted to the photodiode through the optical fiber in the spectroscopic prism system, and the phase of the light modulated by the internal and external light paths is performed. The difference is calculated indirectly by the light propagation time and the measured distance is calculated.
The coaxiality enables the telescope to aim at one time to measure all the basic measurement elements such as the horizontal angle, vertical angle and slant range. Combined with the powerful and convenient data processing function of the total station, the total station is extremely convenient to use.
2. Biaxial automatic compensation has introduced the principle of dual axis automatic compensation in the inspection and calibration of the instrument. If the vertical axis of the total station is tilted during operation, it will cause the error of the angle observation. The left and right face 2 observations cannot be cancelled out. The special-purpose dual-axis (or single-axis) tilt automatic compensation system of the total station can monitor the tilt of the vertical axis and automatically correct the angle error caused by the tilt of the vertical axis in the dial reading (some The maximum tilt of the station's vertical axis can be up to ±6'). Can also be through the angle error caused by the tilt of the vertical axis, by the microprocessor automatically calculate the vertical axis tilt correction formula, and add the dial readings to correct, so that the dial display reads the correct value, the so-called vertical axis tilt Automatic compensation.
3. The keyboard and keyboard are the hardware for inputting operation instructions or data when the total station is measuring. The keyboard and display screen of the full-station type instrument are double-sided, which is convenient for operation when the front and back mirror operations are performed.
4. The function of the memory total station memory is to store the measured data collected in real time, and then transmit it to other equipment such as a computer or the like as needed for further processing or utilization. The total station memory has two kinds of internal memory and memory card.
The total station memory is equivalent to the computer's memory (RAM). The memory card is an external storage medium, also known as a PC card, which acts like a computer's disk.
5. Communication interface The total station can input the data stored in the memory into the computer through BS-232C communication interface and communication cable, or transmit the data and information in the computer to the total station through the communication cable to realize the two-way information transmission.
The use of a total station has a variety of uses such as angle measurement, distance (slope, horizontal distance, height difference) measurement, three-dimensional coordinate measurement, wire measurement, intersection point measurement, and stakeout measurement. Built-in special software, the function can be further expanded.
The basic operation and usage of the total station:
1) Horizontal angle measurement (1) Press the angle measurement key to make the total station in the angle measurement mode and sight the first target A.
(2) Set the horizontal dial reading in direction A to 0°00′00°.
(3) sighting the second target B, the horizontal dial reading shown at this time is the horizontal angle between the two directions.
2) Distance measurement (1) Set the prism constant. Before the distance measurement, the prism constant must be input into the instrument. The instrument will automatically correct the measured distance.
(2) Setting atmospheric correction value or air temperature, pressure value The propagation speed of light in the atmosphere will change with the atmospheric temperature and air pressure. 15°C and 760mmHg are the standard values ​​set by the instrument. At this time, atmospheric correction is 0ppm. In actual measurement, the temperature and pressure values ​​can be input. The total station will automatically calculate the atmospheric correction value (or directly input the atmospheric correction value), and correct the distance measurement result.
(3) The instrument is high, the prism is high and the total station is entered.
(4) Measure the target prism center, press the range key, the distance measurement starts, and the slant range, horizontal distance, and height difference are displayed when the distance measurement is completed.
There are three types of ranging modes for the total station: fine measurement mode, tracking mode, and coarse measurement mode. Precision measurement mode is the most commonly used ranging mode, measuring time is about 2.5S, the minimum display unit 1mm; tracking mode, often used to track the moving target or continuous range when setting out, the minimum display is generally 1cm, each time about ranging 0.3 S; coarse measurement mode, measuring time about 0.7S, minimum display unit 1cm or 1mm. In distance measurement or coordinate measurement, different ranging modes can be selected by the MODE key.
It should be noted that some models of total stations cannot set the instrument height and prism height during distance measurement, and the displayed height difference is the height difference between the center of the total station's horizontal axis and the center of the prism.
3) Coordinate measurement (1) Set the three-dimensional coordinates of the station point.
(2) Set the coordinates of the backsight point or set the horizontal dial reading of the backsight direction to its azimuth. When the coordinates of the backsight point are set, the total station will automatically calculate the azimuth of the backsight direction and set the horizontal dial reading of the backsight direction as its azimuth.
(3) Set the prism constant.
(4) Set the atmospheric correction value or air temperature and pressure value.
(5) The instrument height, prism height, and total station input.
(6) Sight the target prism, press the coordinate measurement key, the total station starts to measure distance and calculate the three-dimensional coordinates of the displayed measurement point.
Total station data communication Total station data communication refers to the two-way data exchange between the total station and the electronic computer. There are two main ways of data communication between the total station and the computer. One is to use PCMCIA (Personal Computer Memory International Association, Personal Computer Memory Card International Association, PC Card, also called memory card) card for digital communication. The features are versatility, all kinds of electronic products can be used interchangeably; the other is the use of the total station's communication interface, through the cable for data transmission.
Inspection (1) The horizontal axis of the sighting department shall be perpendicular to the vertical axis. When testing and correcting, the instrument shall be roughly flattened first. Turn the sighting part so that the leveling tube is parallel to the connection line of any two helix, and adjust the helix of the foot. The bubble is centered, and the sighting part is rotated 180 degrees. If the bubble is still centered, the condition is satisfied. Otherwise, the correction should be made.
The purpose of the calibration is to make the tube axis perpendicular to the vertical axis. That is, use the correction pin to toggle the calibration screw at the end of the leveling tube to retract the bubble half way to the middle position. To make the vertical axis vertical, use a helix to center the bubble. This test and correction must be repeated until the conditions are met.
(2) The crosshair vertical wire should be perpendicular to the horizontal axis for inspection and calibration. Use a crosshair vertical wire to aim at a clear small point, so that the telescope can rotate up and down around the horizontal axis. If the small point always moves on the vertical wire, the conditions are met. Otherwise it needs to be corrected.
During calibration, loosen the four compression ring screws (the eyepiece with reticle ring is connected with the pressure ring and four pressure ring screws to the telescope barrel. Turn the eyepiece tube so that the small points always move on the crosshair vertical threads, after correcting Tighten the ring screw.
(3) The collimation axis should be perpendicular to the horizontal axis of the test and calibration to select a horizontal position of the target, the left side of the disk to observe the right, take their readings (taking into account the constant 180 degrees) that is twice the c (c = 1 / 2 (left-right)
(4) The horizontal axis should be perpendicular to the vertical axis for inspection and calibration. Aim at the left side of the wall and aim at the height of the wall at a point p (the angle of elevation is better than 30 degrees), and set the telescope on the wall to a point of m1. Turn the telescope upside down and aim at the p-point again. Set the telescope on the wall to set another point m2. If m1 and m2 coincide, the condition is met, otherwise it needs to be corrected. When correcting, aim at the midpoint m of m1 and m2, fix the sighting part, and rotate the telescope upwards. At this time, the cross point of the cross wire will not be aligned with the p point. Raise or lower one end of the horizontal axis so that the intersection of the reticle is aligned with p. This test must be repeated until the conditions are met. The above four test corrections, one, three, and four, are the most important and are often performed during the observation period. After each test, the relevant calibration screw must be tightened.
With the continuous development and application of computer technology and the special requirements of users and the application of other industrial technologies, the total station has seen a new period of development, with the emergence of a full memory, waterproof, explosion-proof, computer-type, etc. Station.
At present, the world's most accurate total station: angle measurement accuracy (standard deviation of a measurement direction) of 0.52, ranging accuracy of 1mm + 1ppm. With the ATR function, day and night (without lighting) can work. The total station has reached incredible angle and distance measurement accuracy. It can be operated manually or automatically. It can be used both remotely and remotely as well as under the control of airborne applications. It can be used in precision engineering measurements. Deformation monitoring, application areas such as machine guidance control with virtually no tolerance limits.
Total Station, the most common measuring instrument, will more and more satisfy the needs of various surveying and mapping tasks and play a greater role.
The total station is the electronic total station (Electronic Total Station). It is a high-tech measuring instrument integrating light, machine and electricity. It is a surveying and mapping instrument system integrating horizontal angle, vertical angle, distance (slope distance, horizontal distance) and height difference measurement function. Because the instrument can be set up once to complete all the measurement work on the station, it is called a total station. Widely used in the field of large-scale construction and underground tunnel construction and other precision engineering measurement or deformation monitoring.