Big, Tough and Connected



How advancements in Ethernet EMC are transforming industrial vehicles.

The autonomous car has gained a lot of attention and holds promise for the future, but that is not the only vehicle that looks to be automated. Industrial vehicles and trucks also seek to gain the advantages of growing autonomy.

figure-1

Figure 1: Examples of industrial vehicles

Industrial vehicles, such as those used in construction, agriculture and transport, pose a unique challenge to communication technologies currently under development for the car—chief among them is size. Whether it is length or enormous girth, the communications cable length is much longer than the car. And to make matters worse, that increased cable length means more potential to be exposed to environmental noise, which adversely affects its electromagnetic compatibility (EMC) performance.

Autonomy in Industrial Vehicles

Safety and efficiency are two benefits that arise from autonomy in construction vehicles. Safety can be improved by integrating camera vision systems that provide 360-degree real-time vision around a dig site, for example, so that machine-to-man interaction is reduced. Remote control of industrial vehicles is another safety benefit of automation. One example would be implementing remote-control dozing at a construction site. By removing the operator from the vehicle, risk of harm to the operator is eliminated. Another efficiency boost comes from integrating Global Navigation Satellite Systems (GNSS) with blade position sensors and inertial sensors that can automate the task of soil grading, speeding the completion of work.

Efficiency is the goal of autonomy in farm equipment too. By combining camera systems with steering control, the amount of damaged crops by tire tracks is reduced. It also allows for increased vehicle speed due to the precision with which it can position the vehicle, increasing crop yield and reducing the time to perform work.

Finally, semi-trucks are integrating automation. Last year, a fully autonomous truck was put to the test by making a beer delivery. With the integration of cameras, Light Detection and Ranging (LIDAR), and other sensors, the truck was able to drive autonomously throughout several western U.S. states that permit autonomous vehicles. This technology promises massive savings in energy costs, increased safety, and higher vehicle utility.

To implement these advancements of safety and efficiency, communications are required throughout the vehicle over very long cable distances. Let’s examine the technologies that are most commonly used in automation and their compatibility with these huge industrial vehicles.

Communication Technologies

To connect the various video, audio, sensor and telematic sub-systems of autonomous vehicles, there are several options currently in consideration; CAN, CAN-FD, LVDS, MOST® and Ethernet are the most prominent. As we have seen, the cable reach of each technology and its associated bandwidth must be considered because of the enormous size of these vehicles.
Table 1 describes the data rate of communication technologies vs. transmission length at their highest bandwidth.

Table 1: Bandwidth and cable length of communication technologies

Table 1: Bandwidth and cable length of communication technologies

While suitable for localized sensor data, CAN and CAN-FD data rates are too low for video transmissions. 4k compressed video can consume more than 12 Mbps, considerably higher than CAN-FD. As more cameras are added, more bandwidth will be required. A semi-truck trailer in the U.S. can be up to 18 meters long. This would rule out LVDS and 802.3bw (100Base-T1) as technologies that can transmit video without repeaters or switches. That leaves just two communication options for delivering high data rates over long distances: MOST and Ethernet with Quiet-WIRE® technology.

Figure 2: Electromagnetic Energy

Figure 2: Electromagnetic Energy


EMC—Electromagnetic Compatibility

To be big and tough, you have to be robust in harsh environments. That means when there is electromagnetic energy in the neighborhood, you ignore it. And more importantly, you don’t cause EMC issues and the loss of communications throughput that comes with it.

All the technologies discussed above are robust, after all, that’s why they were selected for automotive use. Table 2 shows the signaling methods by which the robustness is designed into the cabling of each technology.

Table 2: Signaling methods of communication technologies

Table 2: Signaling methods of communication technologies

Ethernet technology is gaining traction in industrial vehicles over competitive technologies due to its respectable and well understood EMC performance, high bandwidth, and, most important, standards-based technology. Let’s examine how Ethernet performance is affected by EMC.

The components of EMC, emissions and susceptibility, can cause packet loss. That is the failure of the data to be properly transmitted or understood by the nodes or link partners. The source of the emissions might be from nearby electronics or electric motors inducing noise onto the Ethernet conductors. To reduce sensitivity to these emissions, technologies like Quiet-WIRE improve the sensitivity and filtering at the receiver circuit built into the device, while also reducing the emission of noise on the transmitter side.

Bulk Current Injection (BCI) is a commonly used method for gauging noise immunity performance. Figure 3 shows the performance of Quiet-WIRE-based receivers using the BCI method. The data confirms that Quiet-WIRE receivers have error-free transmissions in the presence of 200 mA noise current injection, across the complete frequency range 1 MHz to 400 MHz, exceeding automotive OEM limits. In contrast, receivers not using Quiet-WIRE technology experience significant degradation of signal reception of 9dBm—nearly 10X poorer performance.

Figure 3: Performance of Quiet-WIRE-connected PHY vs. standard PHY

Figure 3: Performance of Quiet-WIRE-connected PHY vs. standard PHY

Another benefit of Quiet-WIRE technology is the Signal Quality Indicator. This numerical value approximates a signal-to-noise ratio and is a measure of cable length, cable quality and coupled environmental noise. It can be monitored in real time and used to predict link failure or ensure that performance standards are being met for highly reliable, safe operation.

Quiet-WIRE® Switches and PHYs

A full Quiet-WIRE network can be implemented using the KSZ8061 PHY and the KSZ8567 switch from Microchip Technology. Figure 4 shows a block diagram for an industrial vehicle with these components. The KSZ8061 PHY and KSZ8567 switch have a strapping pin option enabling Quiet-WIRE at the time of manufacture without any software intervention required. However, if desired, the filtering can be disabled via software. An additional benefit of Quiet-WIRE technology is that it is compatible with standard Ethernet devices. For example, a standard Ethernet device, such as a diagnostic tool, may be used with the Quiet-WIRE switch and still demonstrate improved performance versus standard Ethernet alone.

Figure 4: Industrial vehicle networking

Figure 4: Industrial vehicle networking

There are twenty-four Ethernet products with Quiet-WIRE technology from Microchip to select from, including AEC-Q100 qualified products supporting extended temperatures up to 105 ⁰C.

Let’s Get Tough

It’s now possible to achieve robust, reliable operation in the biggest, toughest applications like those found in construction, agriculture, and semi trucks. With the availability of a complete portfolio of Quiet-WIRE products addressing cable length, data rate, EMC and other key design issues, integration of autonomous features into vehicles is underway. Quiet-WIRE and its enhanced EMC performance up to 10X over cable lengths of up to 80 meters is sure to be instrumental in ushering in an era of safer, more productive industrial vehicles.

For additional information on Quiet-WIRE technology, visit: www.microchip.com/quiet-wire


Jason-Tollefson-2011Jason Tollefson is a Senior Product Marketing Manager for Microchip, specializing in Ethernet products. His responsibilities include new-product definition and marketing for Microchip’s industrial and automotive Ethernet lines. Tollefson holds a Bachelors degree in Electrical Engineering from the University of Minnesota’s Institute of Technology, and a M.B.A. from the University of Phoenix. He worked in new-product development for eight years before moving to marketing.

Sources

http://www.forconstructionpros.com/equipment/earthmoving/excavators/product/12075529/volvo-construction-equipment-volvo-ew160e-ew180e-wheeled-excavators
https://www.youtube.com/watch?v=yAsi7m3X8pI
http://www.cat.com/en_US/by-industry/mining/surface-mining/surface-technology/command/command-for-dozing.html
http://www.komatsuamerica.com/innovation/intelligent-machine-control
https://www.deere.com/en_US/products/equipment/ag_management_solutions/guidance/guidance.page
https://www.forbes.com/sites/alanohnsman/2016/10/25/this-buds-for-the-robot-otto-anheuser-busch-claim-first-automated-truck-shipment/#5c122c845615
http://blog.streamingmedia.com/2015/01/4k-streaming-bandwidth-problem.html

Table 1 Sources:

https://en.wikipedia.org/wiki/CAN_bus
http://www.copleycontrols.com/Motion/pdf/CAN-Bus.pdf
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1856
http://www.ieee802.org/3/1TPCESG/public/BroadR_Reach_Automotive_Spec_V3.2.pdf

Bulk Current Injection:

http://www.cvel.clemson.edu/workshop/pdf/AutoEMC-Workshop-Steffka.pdf
http://www.rapidtables.com/convert/power/Watt_to_dBm.htm

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