ALEXANDER HÄGELE is Director Chassis Technology, Head of Development, Business Unit Chassis Systems, Pkw-Fahrwerktechnik/Car Chassis Technology at ZF in Dielingen (Germany).
Globally there is a movement towards embracing technologies that will help to achieve the zero emissions and zero accidents goal. To help achieve zero emissions, electric mobility technologies are crucial and are also collectively touted as the next big technological leap for the industry.
A decade ago, car design was driven by the design language to accommodate more cabin space, cross over architecture, more variation in ride & handling feel of the vehicle, etc. With e-mobility today, the requirement of being able to package battery packs and e-drive motors plays a critical role. And the next decade will be dictated by the need to be able to support ADAS, connected vehicles, etc.
To support future mobility trends, there will be structural reengineering. This also presents us and our customers with entirely new possibilities for adjusting the chassis systems and adding intelligence to mechanical systems.
The question arises how different of an approach the mechanically designed rolling chassis will be, when it comes to support the future of e-mobility and ADAS. Rolling chassis here comprises of suspension, steering, brakes and tyres. The current challenge is to lighten the vehicle and at the same time adapt to electric drives. OEMs have to think along these lines to stay competitive and be in a mode of constant update.
To support this, ZF has envisioned fully modular solutions, which combine axle, drive and chassis systems. The Mstars (modular Semi-Trailing Arm Rear Suspension) gives flexibility to adapt a conventional rear drive differential or the fully electric motor drive unit. The whole electric unit is integrated in the centre of the axle carrier, along with AKC (Active Kinematics Control) tracking alignment for active rear-wheel steering control.
In terms of vehicle architecture, the added weight of the electric motor at the rear adds an additional parameter for weight control not just in the vertical direction but also due to lateral dynamics. The elastokinematic linkages, which were conventionally designed to target a specific self-steer gradient of the car (under steer typically for passenger cars) have to consider the additional component of yaw acceleration generated due to the added rear weight. This then cascades to the response behaviour being actuated by a camera-controlled input, as in an ADAS environment.
More so, a higher precision of control would require feedback from each contact patch to be able to be processed separately. A favoured suspension architecture here would be to have less deteriorating influence of the opposite wheel, which inclines the trend to be more towards independent suspension. Today, however, this need is being addressed by inducing control by the braking system of the vehicle.
ZF has been able to provide a systems solution here by introducing the Active Kinematics Control technology solution. Tremendous benefits are seen by being able to control the yaw generation of the vehicle, when required. Low speed and high speed control in rear wheel steering not only enhances safety but is a step towards supporting ADAS, which will require controlling fleets from a central control tower reminiscent to air traffic control, managing drive through congested streets, and on surfaces having different coefficients of friction, etc.
India is fast moving towards growing the e-mobility landscape. The coming years will be a crucial period of evolution for the automotive industry. For ZF, we have the technological expertise to jump in, when the market is ready.