An overview,
Pavement flatness instrument adopts the most advanced ARM microcomputer processing and large-scale integrated circuit technology, improve the integration of the whole machine, reduce many unnecessary connectors in the original instrument, thus increasing the reliability of the system work, make the performance of the whole system more stable. the instrument contains a real-time clock, which can display the time and date and record automatically. the display adopts the method of liquid crystal display, which reduces the power consumption and makes the display clearer. the displacement sensor adopts high precision displacement sensor, which has higher accuracy, better stability and faster test speed. the power supply uses 12V7.2AH colloidal maintenance free battery, replacing the traditional storage battery. In the mechanical aspect, under the premise of ensuring the test accuracy, test accuracy and frame stiffness, the weight of the instrument is reduced as much as possible, so that the transportation and loading and unloading of the instrument is more convenient and flexible. Therefore, the instrument and the current three meter ruler measurement and other similar measuring instruments, not only has the advantages of high measurement accuracy, fast speed, reliable data, scientific evaluation, and simple operation, reliable work, at the same time greatly reduce the labor intensity, improve the work efficiency and economic benefits. Suitable FOR highway, city road, square, airport runway and other pavement construction inspection, completion acceptance and road maintenance, but also for teaching, design and research units to provide reliable pavement folding data. In the national standard "Asphalt pavement Construction and Acceptance Code" (GBJ02-86) and the Ministry of Communications "Maintenance Technical Code" (JTJ073-85), the instrument is re-listed as the standard measuring instrument.
Two, the main technical performance
(a) detection function and accuracy
1, can automatically determine, calculate, print the mean square error value σ. the sampling spacing was 0.05m and 0.1m, and the sampling error was less than 0.04mm. the statistical deviation was less than 0.2mm when the test was repeated under the same condition.
2. by manual delivery, the test date (year, month, day) and the number of the section under test (road number, mileage number, pile number, road amplitude number, out-of-range setting, sampling distance) can be automatically printed every time, and the serial number of the summary can be automatically added or decreased by one.
3. Automatically calculate and print the one-way cumulative value H (unit: mm) of the measured road section.
4. Automatically calculate and print the graphic area value S (unit: cm2) between the section curve of the measured road section and the reference line.
5. Automatic detection, calculation and printing of the measured road length value L (unit: m), the error is less than 1%.
6, automatic determination, calculation and printing of positive and negative excess number (K+, K-), the use of excess standard can be selected according to the requirements of the road grade, limited to 1-15 range (mm).
7, can automatically determine, calculate and print the test speed value v (unit: km/h).
(1) Traction mode and detection speed
It can be pulled by human or motor vehicle, the minimum turning radius is 5 m, the detection speed should be 6-8 km/h, and the maximum speed should not exceed 12km/h. Traction speed (25 km/h) under non-detection conditions (frame shortening, measuring wheel suspension).
(2) working environment temperature: - 10 ℃ - + 60 ℃.
(3) Power supply and power consumption: colloidal maintenance free battery, 12V7.2AH.
Three, structure introduction
TD932-3 flatness meter is composed of mechanical and electrical parts. the ELECTRICAL part is separately installed in the instrument box, and a cable is connected with the interface of displacement sensor and distance sensor, which can be disassembled and installed at any time.
(1) Mechanical structure (see the picture below)
the mechanical part consists of the following parts;

1. Traction part: composed of a connecting plug and a tie rod, connected with the front bridge through a nut.
2. Front bridge.
3. Wheels: Motorcycle wheels in the form of eight pneumatic tires are composed of front and rear frames.
4, displacement sensor: frequency modulation inductance displacement measurement system.
5. Locking mechanism.
6, the main frame: including telescopic square tube, guide structure, rear frame, etc.
7, measuring wheel: by pressure spring and lifting mechanism, rubber wheel, distance sensor.
8. Rear axle.
9. Wheel rack.
(2) Electrical structure

this instrument is the use of advanced 32-bit ARM chip and the use of high precision AD chip and displacement sensor, so that the system acquisition accuracy is higher and faster, so that the data is more stable.
1. the display module is 128*64 liquid crystal display, which has lower power consumption and long standby time.
2. Key function:
"Menu" key: Set instrument parameters and view data information.
Back/Clear key: Exit system parameters and the displacement sensor to clear.
Confirm/Print: Confirm the set data and print data information.
up key: Data increment by one.
Down: subtract one from the data.
"Left" key: Shift left to set parameters.
"Right" key: Shift to the right to set parameters.
"Start" key: start experiment and end experiment.
Query key: Queries the data in the memory card.
Power on: Power on the system.
Shutdown button: turns off the system power.
2. Printer: this printer is a thermal printer.
3. RS232: the port is a communication port and a charging port.
4. Memory card: TF card and SD card can be inserted into this port. Switch the switch to LOCK for system operation, and switch the switch to the other end for system upgrade.
5. Sensor: the port is connected to the 6-core wire of the sensor of the eight-wheel meter.
6. Power supply: this is the main switch of the system. When the instrument is not in use, it is recommended to dial in the off position.
Four, the operation method
(I) Preparation for use of test vehicle
1. the instrument test vehicle has two states, one is the storage and transportation state, the other is the measurement and detection state. during transportation, remove the fixing bolts, indent the front telescopic square tube and rear frame to the middle, and then fix with bolts, suspend the measuring wheel, and remove all plugs. When testing the detection status, remove the fixing bolts, lengthen the frame into position, and then fix and lower the measuring wheel with bolts so that it is close to the ground.
2. Install the printing paper, pay attention to the front and back of the printing paper.
3. Connect all cables and pay attention to the direction when connecting cables.
(2) Use steps
1) Parameter description
If the parameters are incorrect, the test result will be affected. Therefore, you must set the parameters correctly. Select 1.
Display format: R106 -- K0200 -- M500 -- F1 -- 05mm -- N02 indicates the road number, mileage number, starting pile number, road number, limit overdifference value, sampling interval (5cm2=10 cm), increasing or decreasing pile number setting.
the road number is manually set, ranging from 0 to 9.
the limit overdifference value is manually set, ranging from 00 to 99mm.
Sampling interval N01 indicates sampling every 5 cm, N02 indicates sampling every 10 cm, and so on
at the same sampling interval, in general, N02 should be set according to the standard, that is, sampling every 10 cm.
in the measurement process, if the pile number is increasing, it is set as X0; if the pile number is decreasing, it is set as X1.
2) Clear the displacement sensor
Zero clearing operation of displacement sensor during static detection: press the "zero clearing" key, and the displacement sensor will display zero clearing.
3) Start testing
after the above three steps are done, the test can be carried out. It is not necessary to zero the displacement sensor separately when detecting the state. Press the "Start" button to start work, and the displacement sensor will automatically clear the zero. There is a real-time display of the number of sampling points in the upper right corner of the screen. When the collection reaches 100m, the pile number and mileage number set will automatically accumulate or decrease, and the calculation results will also be displayed.
R107 - K1000, M100 approximately, F1-0001
1.02 0.98V = 12K + 005K -004 *0.88
H+029    H-012          S=041
12:30:1005mm
Represents: instantaneous value average driving speed
Positive out of tolerance negative out of tolerance
Standard deviation of flatness
Positive cumulative value negative cumulative value cumulative area
Hour: minute: second out of range
(3) the average value is the arithmetic average value of the flatness (high and low difference) of this section. Precautions for Use
1, transportation, steering, parking and other non-measuring state must be the measurement wheel suspension, avoid unnecessary wear and collision.
2. the test speed must be kept within 10 km/h. When the road surface is bad, the measuring speed should be slowed down accordingly, so as not to affect the measuring accuracy too much. for long-distance transportation, the test instrument should be installed in the box of the transport vehicle. for short-distance transportation, it can be directly pulled by the motor vehicle, but the speed should be less than 25 km/h, so as to avoid excessive speed and large damage to the parts due to vibration.
3, the delivery of the controller has been debugging, the user shall not open the panel of the controller, but also can not replace the components, welding line, so as not to damage the instrument, otherwise our factory will not repair, such as line fault please contact our factory.
Five, maintenance and maintenance
1. the instrument is powered by internal rechargeable battery, which can be used continuously for more than 20 hours after full charge (if the background light is turned off, the service time can be extended).
2. Before each use, it should be fully charged (generally charging for about 10 hours).
3. If the instrument is not used for a long time, it should be charged once every 2-3 months to ensure that the battery is not damaged.
4, flatness meter is a precision electronic instrument, such as sensors, meters, printers and other parts, do not get wet, wet, not to properly keep, regular electricity, so as not to damage.
5. the bearing and moving part of the frame should be lubricated frequently to prevent rust and wear. Check whether the connecting bolts are fastened before and after use. It is especially important to check carefully after long-distance transportation.
6, the wear of the measuring wheel will affect the accuracy of the measurement, so after driving enough mileage, it is necessary to check the diameter and replace it in time. In addition, the standard diameter of the measuring wheel is 127.40mm.
7, the instrument cable in use, due to improper use is prone to open phenomenon, at this time can be used to check the connection of the multimeter, cable connection position diagram see the attached page, troubleshooting, the broken line must be welded firmly, do not contact between the lines, so as not to affect the use of the instrument.
the displacement sensor rod must be wiped clean before and after use.