In the process of project construction, it is necessary to use the construction elevator to transport goods and personnel.

1. During the operation of the construction elevator, how to accurately position the construction elevator is particularly important.

2. Therefore, the accurate positioning technology of construction elevators has become a hot issue that needs to be studied in the engineering field, and has attracted the attention of many scholars.

3. At this stage, the main construction elevator positioning methods include infrared induction-based construction elevator positioning methods, image-based construction elevator positioning methods, and UHF RFID-based construction elevator positioning methods.

4. Among them, the most commonly used is the construction elevator positioning method based on UHF RFID.

5. With the expansion of the scope of application, this conflict is obvious. At present, the more popular anti-tag conflict algorithm is based on the time-rotating film. In the state of high-frequency transmission of tags by the construction elevator, the time slice needs to be extremely small to meet the requirements, resulting in unsatisfactory conflict adjustment effects and unable to meet the needs of actual production. .

6. In order to avoid the above shortcomings, a point-based positioning method for construction elevators based on UHF RFID is proposed. Using the tag time slot estimation method, the number of UHF RFID tags in the channel per unit time is estimated to lay a data foundation for the anti-collision calculation of tags in the channel. The tag search method is used to calculate the probability of tag conflict in the channel, so as to realize the anti-collision calculation of UHF RFID tags. When the tags in the channel do not conflict, the point positioning of the construction elevator is completed.

2. Construction elevator positioning principle bookmark4 During the operation of the construction elevator, assuming that the tag transmission frequency is too high, channel preemption is easy to occur when the channel capacity remains unchanged. Therefore, label anti-collision calculations are required. The principle of anti-collision can be described.

Third, the construction elevator point positioning method bookmark5 uses traditional algorithms to locate the construction elevator, which cannot avoid the defect of label conflicts in the channel caused by the excessively high frequency of sending tags, thereby reducing the accuracy of the construction elevator positioning. Therefore, a construction hoist point positioning method based on UHF RFID is proposed.

In the process of UHF RFID construction elevator point positioning, the time slot sent by the construction elevator tag is set to /=丨(0), /(1), /(Q-1)T, the number of all tags is r, The transmission time slots of these tags should all obey the distribution of the number of tags sent (ep/r).

Calculate the number of all tags according to formula (3): set the carrying capacity of the construction elevator is T, the time it takes for the construction elevator to run for 10 meters is t, the number of tags sent at a specified time is M, and the number of channels used for tag transmission is n The data set composed of all tags is 1, 2, the data set composed of all channels is Ui, and the signature sending frequency is.

In the process of tag anti-collision calculation, the following formula can be used to calculate the number of tags in the specified channel: The following formula can be used to calculate the time slice sent by UHF RFID construction elevator tags: function, is the transmission speed of all tags, and can be used (4) Calculation: maximum number of values. The label cost function can be expressed by formula (5): the above formula is incorporated into formula (3), and the following results can be obtained: the absolute label estimation function is obtained as follows: the above formula is incorporated into formula (3), The following results can be obtained: according to the method described above, it is possible to calculate the time slice of tag transmission when the channel does not conflict, and to send the tag through the channel, so as to realize the control information transmission and finally complete the construction elevator positioning.

The construction hoist uses UHF RFID tag identification technology in the working process. Once the tag transmission frequency is too high, it is easy to cause channel preemption under the condition of unchanged channel capacity. In the traditional anti-tag collision algorithm based on time-rotating slices, the time slice needs to be extremely small to meet the requirements when the construction hoist sends tags at high frequency, which leads to poor conflict adjustment effects, thereby reducing the accuracy of positioning. According to formula (1), it can be known that if the frequency of UHF RFID construction elevators sending tags increases, the number of tags in the designated channel will increase. According to formula (2), it can be known that an increase in the number of tags in a designated channel will shorten the time slice for UHF RFID construction elevator tags to send, thereby reducing the accuracy of positioning.

The maximum number of tags in the channel can be estimated according to the following formula: Calculate the number of tags in the channel: According to the above method, the number of tags in the UHF RFID construction hoist channel can be estimated to provide point-based positioning for the construction hoist Accurate data basis.

3.2 Realizing the point-based positioning of the construction elevator In the process of transmitting the tags of the construction elevator based on UHF RFID, the control end sends the tag reading request, so that the tag is sent. In the process of point positioning of the construction elevator, the energy required to set the tag transmission is Tt, and the energy required by the receiver is yv. The following formula can be used to express the energy relationship during tag transmission: Among them, Sp is the number of times the tag is sent. , Wp is the number of responses when the tag is sent.

The number of all tags in the point positioning process of the construction hoist based on UHF RFID is set to p. The sending time slot of the tag is H. The number of binary tree levels in the search process is N. The number of time slots can be calculated by the following formula: the label of the Nth binary tree The probability of sending in a specified time slot can be represented by Rn. According to the following formula, the probability of successful tag transmission in this time slot can be calculated: in unit time, according to the following formula, a single tag can be calculated to be transmitted in unit time. According to the following formula, it can be calculated that all tags have not been successfully transmitted. Probability: In unit time, the probability of tag collision can be calculated according to the following formula: Among them, Rqe=H/H(Hm). In the tag search process, the probability of tag collision per unit time can be calculated according to the following formula: 1-Rqe(H, p), according to the following formula, the tag in the Nth binary tree search layer can be calculated in the yth time slot Conflict probability: Estimate the number of UHF RFID tags in the channel per unit time, laying a data foundation for the anti-collision calculation of tags in the channel. The tag search method is used to calculate the probability of tag conflict in the channel, so as to realize the anti-collision calculation of UHF RFID tags. When the tags in the channel do not conflict, the point positioning of the construction elevator is completed.

4. Analysis of experimental results In order to verify the effectiveness of the UHF RFID-based construction hoist point positioning method, a simulation experiment is required. During the experiment, set the number of experiments to 100 times. The experimental environment can be described.

Set during the positioning process of the construction elevator, the average length of each frame of data in the tags to be transferred is N=128. During the experiment, the tags need to be sent. The relationship between the change in the number of tags to be sent and the sending time can be expressed. The following formula can be used to calculate the collision probability in the transmission process of the UHF RFID-based construction hoist point positioning tag: According to the above formula, the probability of the tag collision can be obtained, so as to realize the anti-collision calculation of the tag in the channel, and the tag is successfully sent To the control end, according to the control requirements, the construction elevator point positioning based on UHF RFID is realized.

Through the above-explained method, the tag time slot estimation method can be used to express the relationship between the tag arrival rate and the transmission frequency in the process of using different algorithms to locate the construction elevator.

If the tag is successfully sent, the construction elevator can be controlled according to the content of the tag, and the control error can be described.

Using the algorithm in this paper to locate the construction elevator based on UHF RFID can quickly transfer a large number of tags to the control end, so as to realize the accurate positioning of the construction elevator, which fully reflects the superiority of the algorithm in this paper. ―264― and Table 2. Table 1 Experimental results of traditional algorithm Serial number label sending frequency Label successful sending probability positioning error According to the above experiment, we can know that using the algorithm in this paper to locate the construction elevator can effectively avoid the traditional algorithm caused by the high frequency of sending tags The defect of channel preemption, thereby improving the accuracy of construction hoist positioning.

V. Concluding remarks This article proposes a construction hoist point positioning method based on UHF RFID. Using the tag time slot estimation method, the number of UHF RFID tags in the channel per unit time is estimated to lay a data foundation for the anti-collision calculation of tags in the channel. The tag search method is used to calculate the probability of tag conflict in the channel, so as to realize the anti-collision calculation of UHF RFID tags. When the tags in the channel do not conflict, the point positioning of the construction elevator is completed. The experimental results show that the use of this algorithm for point positioning of construction elevators can effectively improve the accuracy of positioning.