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| Future trends in vehicle dynamics | |
June 2008 |
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| Lotus Martyn Anderson, vehicle dynamics chief engineer "Lotus ride and handling revolves around one word: linearity. Lotus always strives to implement a form of linearity into all aspects of our product’s vehicle dynamics, so this applies to the ride, handling and steering and means that each of these characteristics perform in a linear or predictable manner.
"The primary ride will be fluid and free from any high accelerations or decelerations during rebound and compression travel. The steering effort and response are relative to the level of cornering force to give a high level of “feedback” to the driver and that there is no sudden change in response levels. For handling it’s important for the vehicle to perform in a manner that the driver can predict, particularly on the limit. A good predictable linear handling car is a safe one. "To ensure our future vehicles possess these characteristics vehicle dynamics engineers have input at the concept stages. The final development of the vehicle becomes much easier and less expensive. Analysis tools such as the Lotus-developed Shark and Raven will reduce the iterations that development engineers have to make. More control systems are being implemented into vehicles – some will be unavoidable due to legislation, but they are expensive. It must be ensured that the best result can be achieved before control or safety systems intervene, resulting in less time spent on control system development and therefore less cost, and ultimately a better solution. "Lotus has always believed in "performance through light weight”, which benefits acceleration, braking, transient behaviour and steering feel, especially as our vehicles have traditionally had few driver aids. It is always better to carry the weight low, keeping the centre of gravity low and to try to maintain a fore-aft balance of weight distribution not too biased to one end or the other. "The main improvements in suspension in the future will be based on control systems such as adaptive damping and electric steering assistance. In theory they allow almost infinite variability and tuning options for development engineers and these options will be very easy and quick to assess via software. This leads to faster development times and less compromise between ride, handling and steering as sensors will be able to switch components to a configuration providing optimised characteristics. These control aspects are available today but have not been developed to a high enough standard to provide the equivalent performance of some of the passive systems. "Key handling technologies by 2012 will revolve around control systems. Our prime objective is class-leading handling and steering characteristics without too much compromise to ride. Systems such as adaptive damping and active roll control will help us to achieve this. Rhealogical damping is another promising technology. We’re also looking at the integrating these control systems with systems such as ABS and ESC. Active rear steer is always on the radar. "We’re looking at integration of control systems. These are usually from different suppliers and only have a basic level of interaction. The goal is to have one controller interacting with ABS, ESC, adaptive damping, active roll control, electric steering and the engine management. This will enable safe control of the vehicle at the limit without reducing the “fun to drive” aspect. "Full electric power steering systems don’t yet provide the same performance as hydraulic or electrohydraulic systems. The potential benefits are very high and the option of integrating steering with other suspension-related systems makes it a powerful alternative. Lotus has been involved with the development of several electric systems and it is extremely likely that a future Lotus product will have an electric power-assisted steering. Torque vectoring has a lot of potential. The examples that have been assessed have shown limitations, mainly in the area of limit handling but this may be due to tuning and not a reflection of the system. This is another technology that will benefit from intensive development in the future."
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