基于“無依賴(system-agnostic)”概念打造的這一系統(tǒng)可以整合來自其他供應(yīng)商的組件和系統(tǒng)。
未來底盤會是什么樣的?這是采埃孚在最近于其英國研發(fā)中心舉辦的活動上提出的問題。該中心專注于控制技術(shù)、材料、機電一體化、軟件、系統(tǒng)集成、嵌入式電子和電力電子系統(tǒng)的研發(fā)。
和其他汽車領(lǐng)域一樣,底盤也將不可避免地適應(yīng)新興趨勢,如電氣化、軟件定義汽車、自動駕駛和新型電氣架構(gòu)。不過,未來的底盤動力學(xué)仍然需要處理車輛的側(cè)傾、偏轉(zhuǎn)和俯仰等問題。為了整合需求,如L5級自動駕駛以及包括駕駛員參與的所有階段,采埃孚設(shè)想了一個同時適用于內(nèi)燃機和電驅(qū)系統(tǒng)的系統(tǒng),該系統(tǒng)基于一個底盤控制器打造,比如在2022年末在Lotus Eletre上首次亮相的cubiX系統(tǒng)。cubiX的設(shè)計采用了“system agnostic”概念,因此可以整合來自其他供應(yīng)商的組件和系統(tǒng)。
cubiX系統(tǒng)并沒有對轉(zhuǎn)向、制動、側(cè)傾控制或扭矩矢量等方面進行單獨優(yōu)化,而是將所有功能集成至一個中央系統(tǒng),以實現(xiàn)各車載系統(tǒng)的交互,并使其能夠利用來自云端的外部輸入信號,從而實現(xiàn)提高乘客舒適度和底盤性能、以及優(yōu)化運行狀況、減少維修成本等多種效益。不僅如此,它還可以用來控制主動阻尼系統(tǒng)、主動穩(wěn)定桿和后輪轉(zhuǎn)向等多個系統(tǒng)。
采埃孚在一條較短的操控測試路線上,利用改裝版大眾ID.3演示了線控轉(zhuǎn)向系統(tǒng)的功能。在這次演示中,ID.3的前軸上不再配備方向盤、轉(zhuǎn)向柱和轉(zhuǎn)向機,而是只在前橋上配備了一個方向盤(或手輪)。采埃孚線控轉(zhuǎn)向產(chǎn)品組合總監(jiān) Jake Morris表示,“線控轉(zhuǎn)向系統(tǒng)可通過小幅度轉(zhuǎn)動方向盤,實現(xiàn)車輪的較大幅度轉(zhuǎn)動。憑借該系統(tǒng),在更高級別的自動駕駛汽車中,你可以改裝方向盤或移動其位置;在L4級及以上的自動駕駛汽車中,甚至可能移除方向盤。不過,在大型車輛中,可能需要將該系統(tǒng)與兩個不同的動力裝置與后輪轉(zhuǎn)向配合使用。”
ID.3演示車保留了方向盤,而且采埃孚為其設(shè)置了三種轉(zhuǎn)向模式:模擬標(biāo)準(zhǔn)機械轉(zhuǎn)向模式、自動適應(yīng)車速的轉(zhuǎn)向比模式,以及提供180度左右轉(zhuǎn)向角的“軛式轉(zhuǎn)向(steering yoke)”模式。
在自動適應(yīng)車速的轉(zhuǎn)向比模式下,方向盤的轉(zhuǎn)動幅度變小,因此小幅轉(zhuǎn)動方向盤就能實現(xiàn)前輪的較大幅度轉(zhuǎn)向,從而使泊車和倒車變得更加簡單;在汽車高速行駛時,轉(zhuǎn)向比則更接近于傳統(tǒng)機械系統(tǒng)。而Yoke轉(zhuǎn)向模式是對這種模式的自然延伸,低速時便于操控,高速時更接近傳統(tǒng)轉(zhuǎn)向模式。采埃孚表示,根據(jù)迄今為止的測試結(jié)果,所有模式都很容易上手。
Harvey Smith是采埃孚電磁設(shè)計團隊負責(zé)人,負責(zé)磁性材料和組件(如電機、傳感器和電磁閥執(zhí)行器等)的設(shè)計管理工作。他表示,我們多年來一直使用仿真模擬進行設(shè)計,而人工智能可以帶來更多的可能性。“作為電磁設(shè)計工程師,我們密切關(guān)注仿真結(jié)果,因為它為我們提供了寶貴的信息。隨著仿真工具的不斷進步,我們可以將其與更多新技術(shù)(如AI)結(jié)合使用。Smith提到,“傳統(tǒng)方案需要預(yù)先選擇一個傳統(tǒng)的拓撲結(jié)構(gòu),然后再將所有尺寸參數(shù)化,利用AI算法確定最佳參數(shù)組合,以找到最符合預(yù)期的拓撲結(jié)構(gòu)。而我們的新設(shè)想是,能否利用AI技術(shù)自動分配磁鋼和銅的區(qū)域分布,然后通過嘗試無數(shù)的組合方案來進行調(diào)整,最終得出我們想要的拓撲結(jié)構(gòu)?”
他指出,“我個人認為, AI機器人或許可以很好地完成90%的工作,從而找到滿足性能要求的拓撲結(jié)構(gòu)。AI機器人能通過經(jīng)驗和模式匹配,分析其數(shù)據(jù)庫中大量不同的電機拓撲結(jié)構(gòu)和尺寸數(shù)據(jù),然后據(jù)此推薦有關(guān)電機極數(shù)、槽數(shù)和繞組線圈類型的信息,這些信息可幫助你以80%的準(zhǔn)確度選擇符合要求的電機。當(dāng)超出AI力所能及的范圍時,最后的微調(diào)工作或許會采用更傳統(tǒng)的技術(shù)。”
What can we expect from the chassis of the future? That was the question posed by ZF at a recent event staged at its UK Hub, a center for R&D into control, materials, mechatronics, software, system integration, embedded electronics and power electronics.
Inevitably, chassis will adapt to emerging trends such as electrification, software defined vehicles, autonomous driving, and new electrical architectures. Chassis dynamics will still need to deal with vehicle roll, yaw and pitch. To integrate future requirements such as autonomy at Level 5, and all stages including with a driver, using either an internal combustion engine or electric drive, ZF envisages a system based around a chassis controller such as its cubiX system, first seen on the Lotus Eletre in late 2022. CubiX is designed to be system agnostic, so can integrate components and systems from other suppliers.
Instead of further optimizing the individual dimensions of steering, braking, roll control or torque vectoring, CubiX integrates all features in a central system, enabling interaction between various on-board systems, while also factoring in external inputs from the cloud. The results from this could be wide ranging, from improved passenger comfort and chassis performance to optimization of operational and warranty costs. Systems such as active damping, active stabilizer bars and rear-wheel steering could all be handled by such a system.
ZF provided a demonstration of steer-by-wire systems on a short maneuvering course, using a modified Volkswagen ID.3. In place of a steering wheel, column, and rack, the ID.3 was equipped with just a steering, or hand, wheel on the front axle. “Potentially, you’re now having fewer rotations of the steering wheel, compared to the movement of the steered wheels”, said Jake Morris, ZF’s portfolio director for steer-by-wire products. “Then in higher levels of autonomous driving, that also allows you to change or move the steering wheel, or retract it away from the driver potentially in autonomous levels 4 and above. For larger vehicles, you may need two different power units driving it in combination with rear steer.”
The demonstration ID.3 retained its steering wheel and ZF had set it up with three steering modes, including a simulation of standard mechanical steering and one with an adaptive ratio that changed with vehicle speed. The third used a “steering yoke” mode offering just 180 degrees of rotation to left or right.
The adaptive ratio provided greater front wheel movements from relatively small steering wheel inputs, making parking, and reversing simpler as they required less wheel movement. At higher speeds, steering wheel movement and steered wheel movement was closer to what one might expect from a conventional, mechanical system. The yoke mode was a natural progression from this, offering easy maneuvering at low speeds and more conventional movements at higher speeds. Both modes were easy to adapt to, which ZF says has been the case in tests carried out so far.
AI in Design
Harvey Smith is ZF’s team leader in electro-magnetic design and has wide-ranging responsibilities for magnetic materials and components from motors to sensors to solenoid actuators. While simulation has been part of the design process used for many years, there’s more AI can offer, he said. “As electromagnetic design engineers, we live and breathe the simulations because it really tells us something. As we’re able to advance our simulation tools, we can couple this into more and more things,” Smith said. “Can we literally ask an AI bot to assign regions of magnet steel and copper and then manipulate those regions in infinite combinations until they come up with a topology that gives us what we want? How would that work versus the more traditional approach where you take traditional topologies, parameterize all the dimensions and ask your AI bot to learn which combination of parameters give you the result that is most likely what you want?
“I’m thinking, in my own mind that AI could perhaps do a really good job of getting 90% of the way there to do this job, for these performance requirements. The AI bot can have learned through experience and pattern matching, it can look at its large bank of different machine topologies and dimensions and say, ‘What you probably want is this many poles, this many slots, these kinds of windings. These sorts of things to get 80% towards selecting good options for machines that match these requirements.’ The jury is out, but it might be that you then do the last bits of refinement using the more traditional techniques.”