In the process of elevator inspection, there are risks of injuries caused by many uncertain factors, such as falling injury, mechanical injury, electrical injury and so on. At the same time, with the rapid development of computer technology and network technology, the future elevator inspection will also be developed in the direction of information, intelligence and integration. In this paper, the author tried to break through the traditional thinking and think about whether we can use the single comprehensive index to determine the inspection results, and carry out the "one-stop" inspection for the elevator.

1 domestic and foreign gap of safety inspection technology for special equipment

In recent years, the technical field of special equipment safety inspection on foreign to improve the detection efficiency and reliability of the emergence of a series of new technology: (1) acoustic emission technique; (2) magnetic leakage detection technology; (3) the wall climbing robot automatic thickness measurement technology; (4) pulsed eddy current testing technology, without insulating layer measurement of metal body corrosion; 5) ultrasonic guided wave technology; (6) portable spectrometer; (7) ultrasonic phased array detection technology and ultrasonic Time-of-flight diffraction (TOFD) detection technology.

The overall level of safety technology of special equipment in China needs to be further improved: (1) part of the law, the standard system is not perfect; (2) design, the overall level of manufacturing and industrial developed countries compared to the larger gap; (3) detection technology is difficult to satisfy the need of special equipment safety; (4) life prediction, safety assessment, risk assessment the foundation is weak, the lack of basic data; (5) security monitoring, monitoring equipment, emergency rescue, rescue and repair technology needs to be improved; (6) special equipment safety science and technology platform to integrate and complement.

2 current inspection status of elevator

Although domestic elevator inspection technology and inspection equipment has been developing rapidly in recent years, compared with the developed countries, the overall technology level and testing means are relatively backward. According to the relevant provisions since 2009 has implemented six "elevator supervision and inspection and regular inspection rules", the main content of the elevator inspection can be summarized into 3 parts: (1) technical data review, (2) the effectiveness of elevator related facilities and parts set and the conformity, (3) functional test project. The test method is mainly by visual inspection of the elevator inspection, through the manual switch operation test of various functions and the use of steel tape, steel ruler measurement by calculation and inspection or testing of elevator related facilities and parts set the validity, the reliability of the switch function and compliance with various security dimensions. Through a number of indicators of the test, the final determination of the elevator is qualified or not.

3 "one stop" elevator test in the future

3.1 development trend

The development trend of elevator detection technology should be as follows: (1) to improve the detection of numerical accuracy, reduce the measurement uncertainty of the system, improve the measurement value and the actual value of effective compliance; (2) extended detection diagnosis and detection and prediction function, and improve the function of the technical level; (3) to strengthen the research of detection technology. The development of simulation, nondestructive testing technology; (4) improve the detection technology to develop new technology for elevator service consciousness and service effect.

3.2 "one stop" test

The "elevator station inspection" conceived by the author is based on the idea of "the development direction of elevator detection technology", and it can also satisfy two points: (1) detect the validity and conformity of the elevator related facilities and parts, (2) verify the effectiveness of the functional test. According to the design of a powerful, wide range of comprehensive elevator detection instrument. It uses a single comprehensive index test results to replace the results of multiple indicators to determine whether the elevator is qualified or not.

The instrument consists of two parts: (1) x - ray scanning and measuring device; (2) computer system. The former is mainly composed of generators that generate X harness, as well as receivers and detectors. The latter includes data acquisition system, central processing system and operation platform. In addition, there should be auxiliary equipment, such as displays, multiple cameras, or laser cameras. The working principle of the instrument is used to lift the X-ray beam or other parts of a component level of scanning and measurement, X-ray detector through the level, converted to visible light, and photoelectric conversion into electrical signals, the analog to digital converter into a digital signal input, computer processing and matching.

The technical features of the instrument are as follows: (1) the scanning layer is continuous without missing the defect, and can be recorded and preserved after three dimensional reconstruction. (2) super high speed scanning time can get multi frame images per second. At the same time, the scanning time is very short, which can make the movie images, and avoid the artifacts caused by motion. For example, measuring the lowest point of the bottom of a car car buffer distance, the required inspection personnel to enter the pit, then the level position of the car at a normal speed down to the lower end of the station, inspection personnel with steel tape to measure the distance between the two. So there is a risk of extrusion and shear. By using the instrument, the elevator can be operated and the inspectors can know the results without the bottom pit. At the same time, to test the effectiveness of test circuit, safety components and functional test through a plurality of data lines and the computer system and the elevator control cabinet is connected, and then according to the output data of the computer connected with - read the code, analysis of their effectiveness.

Of course, before this, first of all, the domestic code must be unified to achieve the same nature and generality. In view of the fragmentary nature of the elevator inspection and the complexity of the scene, the equipment can be carried around, and the personnel can directly scan and measure the elevator and auxiliary facilities near the engine room, outside the well path or near the machine equipment. Through data analysis, the results can be printed out. From this, we can truly speak with the detection instrument and exclude the human factors in the current detection process, so that we can have traceability basis and determine the fairness and effectiveness of the conclusion, so as to avoid misjudgement.

Analysis of measurement error in 3.3 "one station" test

In the design of the instrument, the following factors should be considered when the instrument and equipment are used to influence the measurement error of the data. (1) the factor of the body itself. The material and optical properties of the measured objects are very different to the degree of reflection and absorption of light. For example, when measuring the object profile, if the normal line at the incident point on the object surface does not coincide with the incident optical axis, the spatial distribution of the scattered light field will change, resulting in the offset of the center of gravity of the spot, which will directly affect the measurement error. (2) the factor of demarcation. The calibration technique for the nonlinear relation of point to point is the key to obtain the three-dimensional coordinate of the object. Due to the deformation of the probe and the many ideal assumptions of optical system when calibrating, it will bring some very complicated nonlinear system errors, which will affect the accuracy of the measurement data. But they have a characteristic, that is, once the system is determined, these factors are also determined. Through the actual calibration of the system parameters, these factors can be eliminated or reduced to the allowable range. (3) the resolution of the camera. For the resolution of the whole measurement system, it mainly depends on the range of measurement. In addition, the moving error of the motion device of the scanning system will also reduce the measurement accuracy. Therefore, in the laser scanning measurement system, take effective measures to reduce the incidence, through the refinement of beam spot size, improve the laser beam focusing depth, increase the aperture, reduce speckle contrast, control light spot center before extraction of image filtering to reduce the measurement error caused by the surface characteristics. In order to reduce the algorithm of error extraction algorithm which has high precision improved spot center. (4) the problem of testability. Although in most cases, the extension rod or a plurality of point scanning way, but not in the through hole and surface treatment as such, by using the method of optical scanning can not obtain complete data sampling. The blocking problem is caused by the shadow or obstacle blocking the scanning medium. (5) the error of the reference point. The error caused by a reference point in the case of multiple measurements of an object and then the combination of the objects. Because even though we set up feature points, feature lines and feature surfaces, we will inevitably produce some errors due to the calculation of the software itself and the change of shooting conditions during many shooting. (6) measuring the compensation error of the radius of the probe. (7) the visual and operational errors of the surveyors.  (8) data processing error.

4 Conclusion

If this kind of testing equipment can be developed and promoted, it will not only greatly improve the efficiency of elevator detection and the accuracy of inspection results, but also reduce the risk of labor cost and personal injury detection. More importantly, through the use of new technology (computer technology, high technology, high precision display integrated sensor technology and electronics, optics, acoustics, chemical, mechanical and other principle of combining etc.), detection means the elevator jumped to a new level.