Clevon is a design and manufacturing company focused on autonomous vehicles. Their main focus is autonomous robot carriers. The company started as a spin-off of the parent company, Cleveron, and picked up the challenging task of designing an autonomous vehicle from scratch. Among other very challenging engineering feats, the newly designed vehicle needed a powerful gateway capable of pushing vast amounts of diagnostic and video data for both the development of autonomous driving algorithms and seamless remote control of the car.
Project Requirements
Because the gateway design turned out to be a large enough project with well-defined boundaries, Clevon approached Conclusive Engineering asking to outsource the hardware design, Linux-based BSP, and low-level firmware components. The CLEVON 1 vehicle was selected as the target platform for the device.
The gateway was tasked to gather, aggregate and route data sourced from various external wired and wireless data sources:
- 2x 5G – cellular data link
- V2X – Vehicle to Everything: automotive vehicle to vehicle, vehicle to infrastructure, and vehicle to pedestrian communication protocol
- Wi-Fi 6E
- Bluetooth 5.2
- GNSS – high precision localization data source
- Ethernet:
- 1000BASE-T and 10GBASE-T – 4x twisted pair
- 1000BASE-T1 – automotive single twisted pair
- 10GBASE-LR – 1310nm long-range optical fiber link
- 2x CAN FD
- 2x RS-232
- USB 2.0 OTG
Besides the most obvious requirement of providing a redundant high-performance 5G data link to the vehicle’s interfaces, the requirements list included one more important role of the gateway device: emergency vehicle detection. Because of this requirement, one last data source was added to the list of input interfaces of the gateway: an array of 8 microphones.
The other design requirements related to environmental factors, storage, and power supply boiled down to:
- AEC-Q100 Grade 2 compatibility (-40C – 105C ambient operating temperature range)
- IP55 water and dust resistance
- Enclosure compatible with the vehicle’s water cooling system
- Support for redundant 8-20V DC power supply
- Internal SSD storage easily replaceable through a sealed port on the enclosure
- Internal SIM card slots easily replaceable through a sealed port on the enclosure
Solution
CPU Selection
The NXP Layerscape family was selected as the main CPU of the system for its broad range of supported high-speed digital interfaces. The SoCs in this family are well known for their design focus on networking, line rate routing, and forwarding capabilities, high processing power, and support for various storage options. The real-time processing capabilities needed by the emergency vehicle detection algorithms were added to the design by including NXP i.MX RT1160 MCU. The USB link was selected as a data transport layer between the CPU and the MCU.
Component Selection and Block Diagram
After selecting specialized components for the wireless and wired communication, we created a block diagram of the device. At this stage, cooperation with 5G modem manufacturers, such as Rolling Wireless and Quectel, was crucial to ensure the availability of stock and proper performance of the selected solution. In the end, Rolling Wireless was selected as a supplier of automotive 5G modems for the solution.
Power Supply System Development
A very important stage of the design was the development of a power supply system that would enable the device to operate from two redundant sources, as well as seamless switching between them. The large number of local power domains exerted additional pressure on the proper design of the power tree as well as on control over the sequence of their activation. An additional aspect that we paid special attention to was energy efficiency, driven by the requirement to be able to operate the device for a long time in sleep mode, for example when the vehicle is parked.
Selection of External Connectors
Another challenging factor was related to the selection of appropriate external connectors. The connectors had to match the customer's specifications because it was crucial to match the existing wiring harnesses of the vehicle. All external connectors and the housings had to meet the water and dust tightness class. The front panel of the device housing the connectors was internally covered with a protective coating to further supplement the water and dust tightness of the solution.
Housing and Cooling System
The housing itself, in addition to tightness, had to ensure proper cooling of the internal components in extremely unfavorable environmental conditions, such as high ambient temperature. Hence, the enclosure had to integrate a heat exchange interface that fed coolant from the vehicle’s cooling system.
Prototype Development
The first stage of implementation was targeted around the design and manufacturing of a working prototype of the device, ensuring full feature parity with the requirements sheet. Achieving feature coverage and fitting the device into a prototype vehicle was the main goal while reaching full coverage of the environmental threats was considered a nice to have to speed up the development process. Because of that the initial prototype enclosure was 3D printed from plastic and used air cooling instead of water cooling, but on the other hand, met all the size requirements for fitting the gateway into CLEVON 1.
Scope of work
The summary of specific areas of the 5G gateway project handled by Conclusive Engineering is listed below:
1. Hardware
- Electronic design: schematic, PCB, BOM optimizations
- Mechanical design: enclosure, external connectors, sealing, water cooling.
- Electrical bring-up and pre-certification tests
2. Firmware and software
- Device bring-up
- Development of the BSP based on U-Boot, mainline Linux, and Buildroot
- Development of the i.MX RT1160 firmware for emergency vehicle detection and low-speed industrial interface handling based on Zephyr RTOS
3. Documentation
- Design documentation in the form of an Altium Designer project
- Manufacturing files: Gerbers, pick&place, BOM, PDF schematic, stack-up information
- Mechanical design of the enclosure in Solidworks format,
- assembly instructions
- Bring-up report
- Git repositories for all the software components: BSP, bring-up scripts, test scripts, i.MX RT1160 firmware
Technologies used by Conclusive Engineering
- NXP Layerscape LS1026A Armv8 CPU with DDR4 memory
- NXP i.MX RT1166 MCU for real-time control
- 1000Base-T1 – 1 Gbit/s Ethernet over a single twisted pair for automotive and industrial applications.
- 10GBase-T – 10 Gbit/s Ethernet over regular 4-pair cable
- 1000Base-T – 1 Gbit/s Ethernet over regular 4-pair cable
- 10GBase-LR – 10 Gbit/s Ethernet over a 1310nm optical fiber
- Wi-Fi 6E (IEEE 802.11a/b/g/n/ac/ax)
- Bluetooth BT5.2 (BR/EDR+BLE)
- Dual active 5G Cellular connectivity
- Primary eUICC with a backup physical nano SIM slot
- High Precision GNSS
- V2X (vehicle-to-everything)
- USB 2.0 (High Speed) with OTG
- CAN bus
- An array of 8 microphones for emergency vehicle detection (tone and direction)
- Fully sealed chassis (IP55 or more) with liquid cooling
- Dual power inputs for safety
- Altium Designer IDE was used for Schematics and PCB design
- ASIL B and AEC-Q100 Grade 2 system-level compliance
The functionality of CLEVON 1
Here we highlight the functionalities enabled on CLEVON 1 thanks to the involvement of Conclusive Engineering:
- Certifiable automotive-grade vehicle gateway with much better reliability suitable for teleoperated driving
- 5G redundant connectivity to enable operation in more locations and in worse environmental conditions
- Fast data offloading both over wired and wireless connections
- V2X for future integration with road infrastructure and additional safety functionality with other vehicles
- Emergency vehicle detection and direction determination
Results
A device prototype meeting the feature parity with the specification ready for the certification, fitting into the target vehicle, and finalizing the enclosure design.
We have been delighted with Conclusive's close cooperation and suggestions. Our cooperation resulted in a powerful synergy yielding a much better end product than we otherwise would have had.
–Raul Tambre, Software Architect at Clevon