With the development of science and technology and-
The increase of scale engineering measurement practice, through the combination of angle and distance measurement to establish a non-orthogonal coordinate system to achieve large
Measurement of dimensional accuracy, such as geometric parameter measurement, structural inspection, adjustment and assembly of large parts.
The scale space non-orthogonal coordinate system usually includes: photoelectric measurement system, laser tracking system, joint coordinate measuring instrument, digital photographic measurement system and iGPS (
Indoor global positioning system
As stated in .
The first iGPS inspired by GPS was developed by US Arcsecond in its 90 s and for large-
Coordinate measurement of proportional accuracy]2, 3].
In recent years, some domestic universities and research institutions have done a lot of work in the theoretical research and prototype experiment of iGPS. wMPS (
Measurement and positioning system in workspace)
It is such a system developed by Tianjin University .
In the above common system, target the target point by optical alidade and get the coordinate value by reading the angle scale.
It has the advantages of wide range and high precision, but the degree of automation is not high due to manual aiming.
The laser tracking system requires a cat's eye reflector fixed on the target to work together.
By tracking the laser reflected by the cat's eye, the target coordinates can be obtained.
However, under the condition of accurate measurement, the laser tracking system does not allow restrictions on visibility and reduces efficiency.
WMPS is an angular crossover system similar to theodolitessystem, but somewhat different from it.
The basic unit of WMPS consists of a transmitter and a receiver.
The receiver is photoelectric.
Sensors are fixed at points that need to be measured, such as key points during assembly of aircraft parts.
Each transmitter scans two infrared laser beams continuously, detected by the receiver and converted to a time pulse through a high-speed timing circuit to obtain the value.
Then the point coordinates can be determined by the intersection of several angles.
Unlike the photoelectric system and the laser tracking system, WMPS has a high degree of automation and allows lighting.
In addition, the most significant feature of wMPS is that the accuracy will not decrease as the measurement range expands.
This paper mainly introduces the key technologies of wMPS.
The system configuration is described in the next section.
Section 3 establishes a multi-plane constraint model suitable for installation and measurement.
Section 4 relates to the adjustment calibration used in the settings.
The fifth part introduces the experimental results, and the sixth and seventh parts discuss some issues related to errors and summarize some relevant comments. 2.
The system is configured to efficiently manage system resources and perform tasks in parallel,
The Decker Building was designed and mapped. 1shown.
It includes four parts: transmitter, receiver, central control device and task computer. [
Figure 1 slightly]
Before measuring, the position Relationship parameters and laser beam parameters between the transmitters should be known.
System resources and the process of getting these parameter settings.
The central control unit is the central computer responsible for storing and managing system resources.
The task computer is used to obtain resources from the central computer, process time signals, calculate and store the location of the receiver to perform different tasks such as tracking, adjustment, etc.
The structure of the transmitter is shown in the figure. 2.
The rotating head of the transmitter scans two beams of fan-shot beams, and the fixed body of the transmitter transmits the flash with a single pulse to determine the zero-time of the system.
Both beams are tilted at a vertical angle and offset at an angle between each other.
Tilt and tilt determine the measurement range and angle error lever of single station measurement. [
Receiver, distinguish the transmitter from 1000 to 3000 according to the different speed of the transmitter (r/min)
, Is a photoelectric sensor that can detect pulse signals and two laser beam signals according to time series, as shown in the figure
3 and send the time information to the control computer through wireless communication. [
Figure 3 slightly]Fig.
4 is the description of the system application scenario.
Simplify the object to a dot marked on the surface of the object.
They receive the light signal from the transmitter and send the time signal to the task computer to calculate their location. [
Figure 4 slightly]3.
We abstract the measurement model as a graph. 5.
The local coordinate system of the transmitter is defined as follows: Z-
The axis is the axis of rotation.
The origin is the intersection of the axis of rotation and the laserplane1. X-
The axis through the origin is located on Plane 1, perpendicular to z-axis. Y-
Determine the axis according to the right-hand rule.
Point tp represents the center of sensitivity of the receiver fixed on the surface of the object.
Let's say the transmitter is anti-lock.
Rotate around the axis of rotation at the speed of w (rad/s)
The tilt angle of Plane1 is [[phi]. sub. 1]
The inclination of Plane 2 is [[phi]. sub. 2].
The horizontal offset angle between the two planes is [[theta]. sub. off]. [
Figure 5 Slightly]
According to any line perpendicular to the plane of the normal vector of the plane, set the measurement point coordinate to beP, I-
Th transmitter and global coordination system [[R. sub. i][T. sub. i]]
Therefore, in the global coordinate system, each transmitter has the following equation [R. sub. i][[? ? ]. sub. mt][P -[T. sub. i]]= 0 (
A mathematical model of error analysis should be established and all relevant sources of error, such as settings and system arrangement, need to be systematically analyzed.
In addition, system software is also an important part of making this system more powerful .
WMPS make up for the shortcomings in industrial applications, in photoelectric measurement systems and laser tracking systems.
It's a competent forreal-
Time monitoring of key points, online navigation of work fixtures, real-time
Time guidance for assembly, etc.
The experimental results show that the overall accuracy of the system can be achieved within 0.
Reach 1mm of the iGPS level within 10 metres.
It is foreseeable that wMPS will be widely used in modern digital manufacturing with its advanced principles and unique advantages. 10. 5755/j01. mech. 18. 1.
1289 thanks papers have been supported by key projects of the National Natural Science Foundation of China (Grant No. 50735003)
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Xiong, State Key Laboratory of Precision measurement technology and instruments, Tianjin University, Tianjin, 300072, China
Mail: roth0611 @ yahoocom. cn J. G.
Zhu, State Key Laboratory of Precision measurement technology and instruments, Tianjin University, Tianjin, 300072, China
Mail: gathering Guizhu @ tju. edu. cn Z. Y.
Zhao, State Key Laboratory of Precision measurement technology and instruments, Tianjin University, Tianjin, 300072, China
Email: hexie1111 @ sohu. com X. Y.
Yang, State Key Laboratory of Precision measurement technology and instruments, Tianjin University, Tianjin, 300072, China
Email: Student @ tju. edu. cn S. H.
Ye, State Key Laboratory of Precision measurement technology and instruments, Tianjin University, Tianjin, 300072, China
Email: shhuaye @ tjuedu.