Unionx Wireless Communication Project Case Study Sharing

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Unionx Wireless Communication Project Case Study Sharing

Intelligent Workshop for Automotive Wiring Harnesses: EMS Suspended Conveyor System with PLC-Based Wireless Data Transmission Project

Project Background

The automotive wiring harness is the backbone of a car's electrical system—essentially acting as the vehicle's "neural network," responsible for connecting various electronic and electrical components to transmit both power and signals. This industry is deeply intertwined with the evolution of the automotive sector, particularly in recent years as the auto industry embraces the "New Four Modernizations" (electrification, intelligence, connectivity, and sharing), which have profoundly reshaped the wiring harness market. As a result, the demand for wiring harnesses continues to grow—not only in volume but also in complexity—spurring manufacturing plants to undergo intelligent transformation and upgrades. Notably, the client company featured in this project case is a globally significant player in the automotive technology field; far from being a startup, it traces its roots back to Delphi, the century-old automotive industry giant. Following strategic restructuring, the company has emerged as a leading innovator focused exclusively on developing cutting-edge solutions for the automotive "nervous system."

Project Overview

To achieve cost reduction, efficiency enhancement, and capacity upgrades in the intelligent workshop, comprehensively improving its highly efficient and flexible production capabilities, a certain Electrical Systems Co., Ltd. has deployed a technologically advanced Loop Rail Car Suspension Conveying System (EMS). The system features an aerial track spanning approximately 2 kilometers in length, equipped with more than 60 strategically placed switches that collectively form a flexible, multi-path circular network (see Figure 1). Forty EMS carts travel automatically at a speed of 2 meters per second at a height of 10 meters above the ground, seamlessly transporting materials while precisely docking at multiple loading and unloading stations. To ensure stable system control, Unionx provided a customized wireless solution, utilizing a secure, high-performance local area network that supports rapid roaming, thereby guaranteeing seamless, real-time data transmission between the carts and the central PLC controller.

(Figure 1: EMS Loop Track Layout)

Project Challenges

When the EMS transport system is running, several to dozens of carts often move synchronously along the tracks—pausing, picking up components, and dropping them off. The real-time status of all carts must be accurately fed back to the master PLC. However, network fluctuations could lead to communication interruptions between the PLC and the carts. Therefore, the system places stringent demands on wireless communication, requiring high real-time performance, large channel capacity, and minimal network latency. Moreover, the transport system features a complex structure. Intricate metal components—such as aluminum alloy tracks and load-bearing beams—can significantly block and weaken wireless signals. On the other hand, mechanisms like electric hoists and telescopic scissor lifts generate substantial electromagnetic interference during operation, further degrading the communication environment. Additionally, the workshop already hosts a dense array of existing wireless devices, resulting in high channel occupancy rates. This, in turn, exacerbates severe co-channel interference, making it even more challenging to ensure stable wireless communication. The workshop operates continuously around the clock under a three-shift production model, meaning operations run non-stop day and night. As a result, the system must maintain unwavering stability and robust equipment durability to support this relentless, 24/7 production schedule.

The difficulties can be summarized as follows:

Solution

Based on a comprehensive assessment of factors such as multi-switch and multi-track line configurations, the number and operating speed of trolleys, on-site metal obstructions and blind spots at curves, as well as severe co-frequency interference, this project has developed a track-based wireless coverage solution (the communication principle is illustrated in Figure 2).

(Figure 2: Leaky Cable Solution for Wireless Roaming Networking)

The solution deploys leaky feeder cables along the entire length of the track, dividing it into segments and equipping each with 24 AP access modules for signal injection. Each cable segment is carefully controlled to span between 30 and 50 meters, ultimately achieving continuous and uniform wireless signal coverage across the 2-kilometer-long track (the solution configuration list is shown in Figure 3).

(Figure 3: Configuration List for Wireless Roaming Networking Using the Leaky Cable Solution)

All 40 EMS vehicles are equipped with client modules that support fast roaming, and each vehicle has been fitted with directional flat-panel antennas to precisely receive the wireless signals emitted by the leaky feeder cables. These leaky feeder cables feature uniform signal distribution and minimal signal fluctuations, ensuring—at a fundamental physical level—that all vehicles maintain the stringent requirements for seamless roaming handovers, robust communication stability, and highly responsive real-time performance, even at high speeds.

Scheme Advantages

Seamless, full-area coverage with a stable and reliable signal.

Leakage cables were deployed along the entire length of the track, creating a continuous and uniform signal channel that fundamentally eliminates signal dead zones caused by multiple switches, curved sections, and metal obstructions, ensuring uninterrupted wireless signals with minimal intensity fluctuations across the 2-kilometer-long, complex track.

Physical layer anti-interference, excellent communication quality

Leaky cable constrains and directs signal radiation, effectively suppressing spatial co-frequency interference and multipath reflection issues. This provides a high signal-to-noise ratio communication environment for 40 high-speed vehicles, ensuring low-latency, minimal packet loss, and superior real-time performance in data transmission.

Supports high-speed roaming, delivering exceptional mobile performance.

The collaborative design of segmented AP injection and leaky feeder cables, combined with fast-roaming client devices on the trolley and directional antennas, enables seamless millisecond-level handovers between APs, thereby meeting the continuous communication requirements of EMS systems operating at high speeds and with tight cycle times.

The system boasts strong robustness, ensuring operational safety.

This solution lays the physical foundation for stable wireless communication, thereby reducing the risk of data interruptions or roaming disconnections caused by network fluctuations, and providing core communication assurance for the long-term, reliable, and safe operation of aerial vehicles.

Service Support

Addressing the numerous challenges of this project, our company immediately assigned a dedicated team member to serve as the primary point of contact throughout the implementation phase. This team closely monitored project progress, efficiently delivering installation guidance for wireless equipment and configuring module parameters. Additionally, at the customer’s invitation, we provided on-site technical support five times in total.

In the initial phase of system production, our company arranged engineers to be on-site for three consecutive days, continuously monitoring the wireless communication status. During this period, all wireless modules maintained stable communication, and the equipment’s PROFINET communication remained flawless, with no instances of disconnections or fault diagnosis records reported.

As of December 2023, one year after the equipment was put into production, our company has conducted multiple unscheduled follow-up visits to confirm that the device is currently operating continuously around the clock. Even under high-intensity conditions—where each vehicle roams approximately 600 times per day—the system continues to remain stable, with outstanding communication performance.

Customer Feedback

Since the implementation of this plan, the system's communication performance has remained stable, earning high recognition and positive feedback from customers:

Communication stability significantly exceeded expectations.

Customer feedback indicates that the EMS vehicle achieved "zero communication interruptions" across a complex 2-kilometer-long track network. Even when navigating through fire-rated partitions, swiftly negotiating sharp curves, and passing through areas with high metal density, the system maintained seamless operation—no vehicle stalls or collisions occurred due to significant signal fluctuations or failed roaming transitions. Overall, the system’s reliability far exceeded expectations.

Production efficiency and system availability have been significantly improved.

Thanks to the real-time performance and stability of wireless communication, it has achieved nearly theoretical-level continuous operation capability, providing a solid guarantee for customers' three-shift production schedules.

Maintenance costs are significantly reduced, making operations more convenient.

After deploying the leaky cable solution, there’s no need to frequently add or adjust AP locations for specific coverage blind spots, significantly reducing the workload for later network optimization and maintenance. Customers have noted that the system "has required almost no communication-level maintenance since delivery," achieving a stable operational state that’s "set it and forget it."

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