Page 31 - 2019 How-to-Specify E-Book
P. 31

In mechanical LiDAR applications, modules often need to interconnect both locally and remotely throughout the vehicle. With copper conductors, there is a limit to the speed and distance of each twisted pair. Fiber optics can provide data speeds and bandwidths beyond those of copper, offering both increased speed as well as the ability to carry low-power laser, but also add design considerations for insertion loss, return loss, and power budgets.
Connector selections for power circuits depend on application-specific electrical requirements. However, if an application allows for the use of a higher voltage connector with smaller conductors it can help minimize total system cost and overall installation weight. Consideration should also be given to a connector’s gender so live conductors are never exposed when the connectors are unmated. For this reason, recessed female contacts are often chosen for the live side.
Autonomous and unmanned aerial vehicle
applications often require the ability to
change out components — sometimes
frequently and almost always quickly.
Connector housings are generally made
from either plastic or metal materials.
Plastic is lightweight and usually less
costly, but isn’t optimal for applications that
require electrical shielding. Metal housings
or sleeves are required to provide 360° protection for internal components and, when connected to the outer shield of a cable, can also prevent EMI from exiting the connector to protect sensitive surrounding circuits. Shielding is especially critical for UAV applications, as these designs tend to have high-density components in close quarters with adjacent circuitry or payloads and are also subject to powerful terrestrial radio transmitter signals or jammers when the craft is at altitude. For applications that require both lightweight and EMI-shielded components, consider an aluminum housing rather than brass or stainless steel.
 Fiber and copper combined in a single LEMO connector.
 LEMO’s REDEL P and REDEL SP Connectors have lightweight plastic housings with a patented push-pull system and alignment key.
Environmental Resistance
In most cases, the connectors employed in autonomous vehicles and UAVs are well protected from the elements due to their position in these systems, so an IP50 rating is usually enough. When these connections are exposed to oil, fuel, washdowns, or other environmental hazards, they require seals rated IP67 or higher. Both metal and plastic connectors can be designed to withstand chemical exposure and extreme temperatures and prevent the ingress of water, dust, and more. A brass connector housing plated with chromium, for instance, can ruggedly withstand more than 1,000 hours of salt spray corrosion testing and wide temperature fluctuations. A plastic connector may be able to survive high salt spray corrosion environments as well, but will generally offer a narrower temperature range, as plastic can become brittle at lower temperatures.

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