Since September 2020,under the commission of China Railway Second Bureau Group, Professor Cai Chenglin's team from the Intelligent Navigation and Remote Sensing Research Center of Xiangtan University and Zhuzhou Changyuan Intelligent Manufacturing Co., Ltd. (hereinafter referred to as "Changyuan Intelligent Manufacturing") have carried out industry-university-research cooperation to intelligently transform the CYP500 Type Group-sleeper Long Rail Laying Unit (hereinafter referred to as the "track laying unit") produced by Changyuan Intelligent Manufacturing.

The renovated intelligent track laying unit integrates tires, wheel-rail, and crawler travel, and adopts the domestically pioneered group-sleeper stepping operation method. The model is an integrated machine for laying long rails and laying sleepers. The track laying unit consists of several parts, including a long rail towing tractor,a main machine, auxiliary machines, sleepers transport vehicle, sleepers carrying vehicle,a power hydraulic system,an electrical control system,an intelligent guidance system,a construction satellite positioning system, and a construction comprehensive management system. It makes full use of cutting-edge high-tech technologies such as Beidou high-precision positioning technology. The track laying unit simultaneously solves two key difficulties in the existing construction process: firstly, the accuracy of the track laying unit is affected by working conditions, human factors, and other interference factors; Secondly,the relative positioning accuracy of the group sleepers is not high. In July 2021, the track laying unit was successfully constructed on the Chengdu-Kunming Railway, achieving good results. This is a typical successful application of BeiDou positioning technology in the intelligent process of rail transit construction machinery and equipment, and it is also a new field for the transformation of scientific and technological achievements of BeiDou satellite navigation system positioning technology.

Figure 1 Construction Site of CYP500 Type Group-sleeper Long Rail Laying Unit

The track laying unit after intelligent transformation has broken the inherent mode of traditional long steel rail laying, replacing the method that requires manpower for plumb bob positioning,remote control of track laying machine movement and visual alignment. This not only saves economic, time, and labor costs, but also greatly improves the accuracy of track laying construction for the track laying unit. After the intelligent transformation, the track laying unit adopts the BeiDou satellite navigation system to ensure positioning accuracy, combined with independently developed RTK positioning technology to save costs. Although a single-frequency positioning receiving module is used, its static positioning accuracy can also reach millimeter level. The improved whole cycle ambiguity solving algorithm it used makes it only takes about 10 seconds to fix the whole cycle ambiguity, and the positioning accuracy converges to within a few millimeters in only about 30 seconds. The accuracy of on-site testing on the construction section of the Xichang Railway is less than 10mm, which fully meets the construction requirements. The horizontal and vertical installation spacing errors of the group-sleepers are all less than ± 3cm.

Figure 2 Diagrammatic Sketch of Beidou RTK System and Antenna Installation

Figure 3: Rail Laying Completed

In the later stage, both sides will continue to strengthen cooperation and explore the application of Beidou satellite navigation system related technologies in railway engineering construction machinery and equipment, as well as the transformation of related scientific and technological achievements.