'''Road-holding''' – also written as '''roadholding''' and '''road holding''' – (in French being called "tenue de route", in German "Beibehaltung der Spur"), is essentially determined by the ability of a [[vehicle]] to stay on the [[road]] and on a desired [[trajectory]] of [[motion]], whatever the circumstances (in curves, on greasy, wet or low-grip ground, loaded or not, etc.) may be, but also by the degree of ease that a [[Driving|driver]] may sense in controlling it in an [[emergency]] situation.<ref>Campbell, C.: ''Automobile suspensions.'' Chapman&Hall, London 1981, pp. 105 f.</ref> (Hereby, the [[Scientific law|laws of nature]] as a framework, including the [[gravitation]]al [[Gravitational field|field]] of the planet [[Earth]] as well as the phenomenon of [[inertia]], are tacitly assumed as given.)
In the above context, the straight-line stability of a vehicle – which is concomitant with its ability to stay on a desired trajectory of motion – necessitates a certain degree of [[understeering]].<ref>Campbell, C.: ''Automobile suspensions.'' Chapman&Hall, London 1981, p. 106.</ref>
The capability to smooth down the [[Road surface#Surface deterioration|road imperfections]], affects both the [[comfort]] and the road-holding of a vehicle. To improve comfort in this regard means, basically, to limit the vertical [[acceleration]] [[wikt:fluctuation|fluctuation]]s of the vehicle body and hence of passengers. To improve road-holding means, among other things, to limit the fluctuations of the [[vertical force]] that each [[tire]] exchanges with the road. Therefore, [[Conceptual model|modeling]] and [[simulation]] using realistic [[Suspension (mechanics)|suspension]]-[[damping]] models, taking the vehicle tires into account, offer a straightforward opportunity for road-holding improvement of vehicles.<ref>Guiggiani, M.: ''The science of vehicle dynamics: handling, braking, and ride of road and race cars.'' 2nd edition. Springer, Cham [2018], {{ISBN|978-3-319-73219-0}}, pp. 417-460.</ref> Optimization techniques for this purpose are also known.<ref>Shirahatti, A., Prasad, P. S. S.: ''Optimal design of passenger car suspension for ride and road holding.'' In: ''Journal of the Brazilian Society of Mechanical Sciences and Engineering.'' Vol. 30, Fasc. 1, pp. 66-76, 2008.</ref> The application of [[Inerter (mechanical networks)|inerters]] is a very new possibility in this regard, although this [[technology]] is more destined to [[race car]]s than to ordinary vehicle applications.<ref>Guiggiani, M.: ''The science of vehicle dynamics: handling, braking, and ride of road and race cars.'' 2nd edition. Springer, Cham [2018], {{ISBN|978-3-319-73219-0}}, p. 426.</ref>
As a more sophisticated means for improving road-holding, [[active suspension]] – involving [[sensor]]s, [[actuator]]s and [[microcontroller]]s – may also serve.<ref>Bharali, J., Garg, N.: ''Efficient ride quality and road holding improvement for active suspension system.'' In: ''14th IEEE India Council International Conference (INDICON)'', December 15–17, 2017, Roorkee, India. IEEE 2018, pp. 1179-1184.</ref>
For vehicle speeds above approximately 40 meters per second, the effects of [[aerodynamic force]]s at an [[automobile]] (that is not designed in a too odd manner) tend to become sensible for its road-holding.<ref>Doniselli, C. et al.: ''Aerodynamic effects on ride comfort and road holding of automobiles.'' In: ''International Journal of Vehicle Mechanics and Mobility.'' Vol. 25, Issue Suppl. 1, pp. 99-125, 1996.</ref>
Beyond what has been previously mentioned, [[electronic stability control]], if being present on a vehicle and properly tuned, will have a stabilizing influence on the trajectory of motion and accordingly an improving effect on road-holding of that vehicle.
== See also == * [[Automobile handling]] * [[Cornering force]] * [[Directional stability]] * [[Grip (auto racing)]] * [[Traction (engineering)]]
== References == <references />
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[[Category:Vehicle dynamics]]