Which Role Do Fiber Optic Cables Play in Vehicles?

Which Role Do Fiber Optic Cables Play in Vehicles?

Both EVs and ICE vehicles have undergone rapid transformations over the past few years, and the evolution is still ongoing. It has reached the tipping point where current wiring technologies (copper wires) are insufficient for the job, making fiber optic cables relevant and necessary in this application. Let’s look at why fiber is better than copper and the role it plays in modern vehicles as well as cars for the future.

Why Fiber is Better than Copper

Although optical fiber cables cannot transmit electricity, the technology’s glass interior has a higher bandwidth (transmission capacity), lower weight, and better EMI immunity than copper. These three benefits have made optical fiber the go-to option for supporting ADAS and MOST, as well as the best candidate for enabling CASE in future cars.

The Role of Optical Fiber in Current and Modern Vehicles

Supporting MOST

MOST (Media Oriented Systems Transport) is a high-speed network technology that is used in vehicles to transmit video, audio, voice, data, and control signals. As in-vehicle media and entertainment became more sophisticated with features like HD video, multichannel stereo audio, birds-eye view camera, and 360° camera, cars needed high-bandwidth connectivity to support this heavy data traffic flow in real-time.

The initial MOST specification (MOST25) used a 1mm core POF (Plastic/Polymer Optical Fiber) with red LEDs as transmitters and had a bandwidth of 705.6 kbit/s. This cable could transmit 2670 control messages per second and supported 15 uncompressed stereo audio channels or 15 MPEG-1 channels.

MOST25 was replaced by MOST50 and later MOST150, which used both fiber and copper wire electrical connections (twisted pair). MOST150 is no longer new because it was introduced in 2007, but it has a data rate of 150Mbps, making it relevant even in today’s vehicles.

Supporting ADAS

ADAS (Advanced Driver Assistance Systems) like collision avoidance, lane keeping assist, blind spot detection, and autonomous emergency braking have become lifesavers on the road. These systems use various sensors and cameras placed on the vehicle to gather information about the surrounding situation in real-time. This data is then processed using sophisticated algorithms running in the relevant control units to determine the next course of action, which can be to alert the driver or perform the corrective action autonomously.

Such functions don’t need high bandwidths or data rates. However, if the signals are corrupted, erroneous data can put the life of the driver and occupants in danger. Fiber optic cables are immune to EMI, making them safer for transmitting ADAS signals. EMI is particularly higher in EVs because of the electric motors, battery systems, and power converters, so optical fiber cable assemblies are necessary.

Enabling CASE

CASE is more about the future, where fiber optic is being considered for Connected, Autonomous, Shared, and Electric vehicles. To support this feature, custom optical fiber harnesses for cars are being developed to handle speeds reaching 10Gbps. These high data rates are required to support high-resolution cameras and sensors like LiDAR and radar for complete autonomous (level 5) driving.

This feature will use a polymer-based fiber optic cable with a splitting function to transmit the sensor/camera signal simultaneously to the ADAS ECU and dashboard display.

Simplifying Wiring Design

Since fiber optic cables are immune to EMI, they don’t need complex shielding mechanisms on the cable or the connectors. Additionally, these cables can be bent to fit into tight corners and are durable enough to withstand multiple bend cycles.

These benefits simplify the wiring design in two ways. First is that the wires can be routed even along areas exposed to high EMR levels, such as near the motors or power converters, with no worry about signal losses. Secondly, you can place the sensors or cameras almost anywhere in the vehicle because the glass cables can be bent to fit.

Reducing Vehicle Weight

Optical fiber cables can weigh up to 4 pounds per 1000 feet, while their copper counterparts can reach up to 39 pounds for the same length. And this doesn’t include the shielding that is needed on copper cables to prevent EMI.

So using these glass cables instead of copper for CASE, ADAS, and MOST reduces the vehicle’s weight significantly, especially considering some can have up to a mile of wiring. A lower car weight has its benefits in both ICE and EV applications. In ICE, this improves the fuel economy and reduces the wear on tires and suspension components. For EVs, you can expect a longer range with reduced wear on the same parts.

Improving Sustainability

Fiber optic cable production is generally more environmentally friendly than that of copper because the material (silicon dioxide) used is more abundant naturally. Copper has to be mined, which leaves a higher carbon footprint.

While in use, optical fiber cables require light for signal transmission, which is less energy-intensive than using electric currents in copper wires. This reduces power consumption, which is more noticeable in EVs, resulting in a slightly longer range.

Glass-core cables also require minimal maintenance over the car’s lifespan compared to their copper counterparts, and they take up less space in the vehicle.

Conclusion

Fiber optic cable use in vehicles is still evolving and probably the only limitation is it cannot transmit electrical current. If it could, all car wiring would switch to this technology. But going forward, all automotive wiring harnesses will utilize a blend of fiber and copper wires to achieve the benefits of both, specifically those provided by optical fiber. Wiringo and CloomTech specialize in manufacturing such automotive cables and can advise you during the design process to help you create efficient, low-cost wire harnesses for your vehicle wiring projects. They can even make them to OEM specifications. Contact them to learn about their capabilities, lead times, and more.