Metro, as an important mode of public transportation for people in urban areas, carries tens of millions of passengers each day. Therefore, a major function of relevant underground departments is to ensure the public security of passengers.
At the mention of metro security, what occur to people are usually security check at the station entrance, and surveillance cameras, which, however, are actually far from adequate for construction of modern metro security facilities. On-site metro inspection by inspectors is still indispensable and crucial – every inch of rail and every screw should have a bearing on the safety of metro running. The inspection can only be accomplished by actual steps, and there are no shortcuts. It appears simple as metro is seemingly comprised of two tracks only, yet many inspection items are involved and it is a rather labor-intensive type of work. A metro operation company located in north China now has to face this problem.
02 Pain points
At present, manual inspection is still employed in most metro lines. Each line needs 10 to 20 workers to conduct pedestrian inspection and maintenance in the tunnel before dawn every day, at a pace of 5 kilometers per hour. Drawbacks include low efficiency, personal safety hazards, no objective criteria, lack of detailed raw data, increased labor costs, and omission due to night work.
“One has to bend over 6,000 times a day, and hike 15 km on the rail track each day, or even 25 km a night at most. How could one easily stand working a shift like this?” In the face of labor shortage for the special type of work, metro operating units have to avert their attention to the field of automation. Since “machine replacement” is being promoted in all walks of life,why can’t we introduce more robot solutions in metro operations against the current problems in view of heavy workload of personnel?
The company thereupon contacted experts from the Rail Transit Technology Research Institute and partners with integrated cross-industry automation experience, and eventually put forward the idea of replacing manual rail inspections with composite robots. It is planned to apply an AGV equipped with collaborative robot arm, which is capable of moving and detecting on the rail track, to perform all kinds of routine inspection tasks, thereby reducing the labor intensity of personnel.
A complete set of the program can run continuously for 8 hours on a single charge, and generally suffice to complete the inspection of a whole metro line. It integrates ELITE’s collaborative robot EC66 (6kg load), and weighs only 17.5kg. Compared with traditional industrial robots with the same load, it features a power of 250w only, 1/4 of the former, hence a better battery performance as the AGV runs. In addition, ELITE provides a 48V DC version for the collaborative robot arm, which can be integrated with the AGV to dispense with robot control cabinet and be directly powered by the AGV, making it more compact.
Now the customer has started using the equipment for accurate detection in accordance with more than a dozen norms on track bed, rail fastening and rail patrolling, which functions well to detect and report faults in a timely manner, including missing, broken and floating fasteners, cracks with rail, and ponding, foreign objects with track bed.
The use of the collaborative robot + AGV solution to replace manual inspection vehicles contributed to achieve “safe, efficient and accurate” track inspection process, and free the personnel from laborious and harsh tasks, thereby raising the overall operational efficiency.