工程师和产品规划师应对当今的自动驾驶汽车复杂度就已十分艰难，而今后复杂度只增不减，他们又该如何应对？现代车辆通过高带宽网络以管理高级传感器融合，通过车载计算机以运行人工智能算法，完成千兆级别的数据处理。各个模块各司其职，而将这些不同模块连接起来的就是线束。随着功能的不断增加，如今的汽车“线束”已经越堆越重，给厂商带来高昂的成本和封装挑战。
事实上，高档轿车和全尺寸卡车可能使用了 40 种不同的“线束”，搭载了超过 700 个连接器和 3000 条电线。给大家一个更直观的数据，如果把汽车上的电线全部连起来，其长度可以超过2.5 英里（4 公里），重量也将达 132 磅（60 公斤）。而且，汽车所需的电线多种多样，有时甚至会用到高达 70 多种专用电线，包括同轴电缆、高速数据线和 USB 电线等。
事实上，上述数据还是在不包含“自动驾驶”相关设计下的测算结果。自动驾驶技术一旦部署，势必会进一步增加汽车线束的规模、重量、成本和复杂程度。对于基于电动汽车平台构建的自动驾驶汽车而言，更多的电子内容也会带来严峻挑战。对此，工程师可以从汽车架构层面和线束层面采用不同策略进行应对。
汽车制造商正在研究新的电子电气架构，从而通过简化线路设计，最大程度地降低成本和重量。此类设计可以减少支持各类车辆功能所需的布线，并有机会降低重量、便利自动化生产，从而降低成本。此外，在OEM中已经兴起了整合电子组件的趋势，比如将 ECU 和传感器模块整合起来，从高度分布式结构向集中式结构转型。这种架构整合有助于精简物料清单（BoM），并直接简化线路的复杂性。
随着汽车制造商开始向车辆嵌入功能强劲的集成电路（IC）和微处理器，ECU 整合已经成为一种流行趋势。如今，芯片的运算能力大幅增强，一个单元已足以承担过去多个单元才能完成的任务。这样一来，车辆架构整合的趋势愈发明显，各类强大的域控制器将借助传感器融合和人工智能算法，首先对传感器数据进行预处理，而后再将其发送至车辆的中央处理单元。
然而，架构整合不能过度。如果所有汽车功能均仅有 1 或 2 个控制单元全权负责，则势必产生大量布线需求，将分布在车辆各处的所有组件连接起来。OEM将需要执行大量分析，从而在分布式和集中式功能管理之间达到最佳平衡。
OEM和一级制造商也在积极寻求新型线材，从而达到降低线束重量的目标。举个例子，业内已经推出了一款横截面积只有 0.13 平方毫米的新型超细电线。遗憾的是，虽然有了超细电线，但电线两端的连接器配套却仍跟不上，因此这种超细电线很难在市场上进行大规模推广。铝质电线的情况也一样，纯铝材质太脆，因此无法做到太细。如今，相关供应商均在开发适合极细电路的终端连接器材料，比如铝合金。一时间，市场上的合金材料也形形色色，而且绝大多数情况无法相互兼容。这意味着，如果使用任何一种电线，整辆车都需要使用同一家供应商的连接器，这并不现实。
新型特种电缆的出现也可以进一步缩小线束直径，并降低线束重量和成本。未来，车辆上的数据密集型传感器和显示器的数量只会继续增加。因此，通过标准化线路传输视频和其他数据丰富的信号愈发重要。另一个思路是，在多种设备同时接入的大背景之下，通过线路复用将多路信号部署在同一条共用专用电缆上，这也可以达到降低重量、成本、电线直径的效果。
除了架构和线束层面的优化外，在开发过程中采用电子电气软件解决方案也至关重要。我们需要使用软件工具来进行快速权衡分析，以优化模块安装位置，并识别可以进行集成的模块，从而节省重量、成本或降低复杂度。也就是说，软件工具可以快速分析改变任何布局可能带来的影响，帮助工程师选择出最优系统架构。
此外，最先进的电子电气工程解决方案还可以在整个线束开发过程中保证数据的连续性，与其他工程软件和自动化设计软件完美兼容。比如，Mentor 公司的 Capital 软件套件即可支持车辆等大型平台进行电气系统工程设计，帮助OEM成功完成哪怕最复杂的车辆线束设计。
数据连续性可确保工程师在电子电气架构和线束开发的各个阶段均可以访问最新的准确信息，即通过为车辆架构和线束创建一个数字化“副本”，以避免手动交换数据的需求。这样一来，工程师可以通过自动数据交换，避免手动数据交换和重复输入可能产生的错误，从而实现更有效的协作。此外，由于具备与其他领域软件（比如机械设计工具和产品周期管理解决方案）进行集成的能力，该解决方案还可以便利跨工程领域的协作和自动数据交换。
自动化功能可帮助工程师进一步优化车辆架构和线束。综合线路设计可以将系统连接性信息（例如设备和信号类型）与物理线束限制相结合，从而在车辆范围内生成最优的线路布局和连接方式。如今的综合线路设计工具支持复杂的电线类型、丰富的屏蔽材料选择、多种网络协议，甚至可以自动创建接地点。
最后，结构性优化和系统级改变也会对电子电气和汽车线束带来广泛影响。此外，这种方法还允许在工程和制造的任何环节启动变更流程，从而让持续优化成为一种常态。值得注意的是，最重要的是要在项目的早期阶段引入结构性的变更管理规范。
先进的电子电气工程软件是一套非常优雅的解决方案。借助于变更控制机制，这套软件的内置设备数据库功能得到了极大的增强，可以判断特定设计数据的负责人，并提示变更的开展方向。
通过这些增强特性，该数据库可以立即提供自动化、结构化的变更管理程序。
电气化进程的推进和自动驾驶的到来将给车辆的线束布局带来更多负担。OEM在紧跟趋势之余必须考虑新增任何功能可能带来的复杂度，因为这将给线束重量、直径和成本带来显著的直接影响。
现代线束设计和工程工具可以解决随汽车创新而来的问题。这些解决方案的自动化程度非常高，支持多种先进指标，还具有分析能力，可以帮助工程师克服这些挑战。此外，此类解决方案还可以帮助设计人员更好地进行取舍，从而在线束材料、元件放置和布线之间做出最佳平衡，并最终最小化线束重量、成本及直径。
然后，该解决方案可以根据设备型号、信号位置及车辆的物理限制，自动生成最佳布线设计。随着电子电气架构和线束的发展，全面的变更管理设施和强大的数字“副本”可确保各大工程领域之间实现的信息实时同步。车辆自动化、电气化和连接性将更加接近主流，这些技术将逐步推动汽车工程从机械系统向电子电气系统转型。
为了推出强大、可靠且经济高效的车辆平台，采用先进的电子电气工程软件解决方案至关重要。
Engineers and product planners are already grappling with the complexity of autonomous vehicles (AVs), with the prospect of complexity increasing. Every second, AVs manage advanced-sensor fusion via high-bandwidth networks, while onboard computers run AI algorithms to process gigabits of data. Connecting it all is the wiring harness, which has become increasingly heavy, more expensive and more difficult to package within the vehicle.
Premium-segment cars and full-size trucks can contain 40 different harnesses comprised of 700 connectors and more than 3,000 wires. Stretched in a continuous line, these wires would span 2. 5 mi (4 km) and weigh approximately 132 lb. (60 kg). In addition, there can be more than 70 specialty cables that include coax, high-speed data and USB runs.
This does not encompass the added AV sensors and processing content that will further expand harness size, mass, complexity and cost. The implications of escalating electronic content are a significant issue for AVs built on electric-vehicle (EV) platforms. Engineers can undertake several strategies at the architectural and harness-level to resolve this dilemma.
Architectural optimizations
Automakers are investigating new electronic/electrical (E/E) architectures that will simplify the harness design to minimize cost and weight. Such designs can reduce the wiring needed to support vehicle functionality and offer an opportunity to reduce mass while making automated production easier, driving down cost. And OEMs have begun consolidating electronic components, such as ECUs and sensor modules, moving from highly distributed to increasingly centralized architectures. The architectural consolidation is driving reduced bills-of-material (BoM), which directly impacts harness complexity.
ECU consolidation has become a popular strategy as automakers integrate more powerful integrated circuits (IC) and microprocessors into their vehicles. The increased computational capabilities of these chips enables a single box to manage tasks that used to require multiple units. As a result, vehicle architectures are converging with powerful domain controller units using sensor fusion and artificial intelligence algorithms to pre-process sensor data before sending it to a centralized processing unit.
However, there is a balance to be struck with consolidation. An architecture that features only one or two control units managing all vehicle functions will require an immense amount of wiring to connect with all the components that are necessarily distributed around the vehicle. OEMs will need to perform dozens of analyses to determine the optimal balance between distribution and centralization for harness functionality.
OEMs and Tier 1s also are developing technologies that directly reduce harness weight through smaller wires and new materials. Ultra-thin-diameter wiring (0.13 mm2) is a notable example. Unfortunately, the industry still is struggling to develop sufficient terminal substitutions for all currently existing terminals that can crimp to such a small diameter. The available products on the market currently do not support a large-scale migration to ultra-small diameter wiring. The same applies to aluminum wiring. For small diameter wiring, pure aluminum is too brittle and thus not a feasible option. Terminal suppliers are developing optimal aluminum alloys for the specifications of their terminals. This has led to a multitude of different alloys on the market that, in most cases, are incompatible with other suppliers’ terminals. To use these wires, a vehicle would have to use one supplier’s connectors across the full vehicle, which is not realistic.
Finding alternatives to specialty cables will further reduce weight/cost and bundle diameters of harnesses. The number of data-intense sensors and displays will only increase in the future, making it crucial to develop solutions to transmit video and other data-rich signals via standardized wiring. Alternatively, finding ways to multiplex signals onto a single shared specialty cable while multiple devices tap in will have the same effect: reducing weight/cost/bundle diameters.
Leveraging digitalization
In concert with architectural and harness optimizations, adopting E/E software solutions to support development flow will be crucial. Software solutions need to enable rapid tradeoff studies to optimize module locations and identify any module that can be combined to save weight/cost/complexity. With the ability to compare and analyze layouts for their impact, engineers will be able to choose the optimal system architecture.
Additionally, the most advanced E/E engineering solutions support data continuity throughout harness development, integrate with other engineering software and automate design tasks. An example is Mentor’s Capital software suite that enables the engineering of electrical systems for large platforms such as vehicles. Such capabilities will help OEMs to design harnesses for even the most sophisticated vehicles.
Data continuity ensures that engineers at all stages of E/E architecture and harness development have access to accurate and up-to-date information. This replaces manual data exchange with a robust digital twin of the vehicle architecture and wiring harnesses. As a result, engineers can collaborate more effectively through automated data exchanges that remove errors from manual data exchange and reentry. Likewise, integrations with software from other domains, such as mechanical design tools and product lifecycle management solutions, facilitate collaboration and automated data exchanges across engineering domains.
Automation capabilities help engineers further optimize vehicle architectures and wiring harnesses. Wiring synthesis combines system connectivity information, such as device and signal types, with the physical harness constraints to generate optimized wiring and splices within the context of the vehicle. Today’s wiring synthesis tools support complex wiring types, multiple shielding materials, various network protocols and can even automatically create ground points.
Finally, ongoing architectural optimizations and system-level changes can have wide-ranging effects on the E/E system and wiring harness. In addition, changes can be initiated throughout the engineering and manufacturing processes, driving constant redesign efforts. It is extremely important to develop a structured and disciplined approach to change management early on in the project.
Advanced E/E engineering software can provide an elegant solution. Integrated device databases can be enhanced with change-control mechanisms to determine ownership over design data and the direction in which certain changes should flow.
With these enhancements, this database will immediately provide automated and structured change-management procedures.
New challenges, new solutions
The move to electrification and AV driving places additional burdens on the wiring harness. As OEMs pursue these trends, they must consider the number and sophistication of technology features they integrate into vehicles, as they have a direct effect on wiring harness weight/diameter/cost.
Modern harness design and engineering tools provide a solution to problems wrought by automotive innovation. By leveraging engineering solutions with high levels of automation, advanced metrics and analytical capabilities, engineers can overcome these challenges. Such solutions enable tradeoff studies to optimize harness materials, component placement and routing for minimal harness weight/cost/diameter.
Design automation then can generate optimal wiring based on device and signal location, and the physical constraints of the vehicle. As the development of the E/E architecture and wiring harness progresses, comprehensive change-management facilities and a robust digital twin ensure that the various engineering domains remain in step with all needed information. Vehicle automation, electrification and connectivity are coming closer to mainstream reality. These technologies will progressively shift the emphasis in automotive engineering from mechanical systems to E/E architecture.
The resulting capabilities provided by an advanced E/E engineering software solution will be critical to delivering a robust, reliable and cost-effective vehicle platform.
Engineer Dan Scott is Integrated Electrical Systems market director at Mentor, A Siemens Business. Ulrike Hoff is an independent automotive wiring consultant.
Author: Dan Scott & Ulrike Hoff
Source: SAE Automotive Engineering Magazine
随着OEM开始将自动驾驶等越来越多的新功能集成至车辆产品中，车辆线束设计将面临更大的尺寸、复杂性、成本和重量挑战。
自动驾驶依靠强大而密集的传感器和计算机网络来检测不断变化的驾驶场景，并对其做出反应。
自动化的数据传输可以简化域与域之间的交互，从而减少线束设计中的错误。
Capital软件套件可以帮助工程师在成本、重量和尺寸指标之间进行权衡，从而达到最优线束设计。