'''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 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 laws of nature as a framework, including the gravitational 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 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 fluctuations 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, modeling and simulation using realistic 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 inerters is a very new possibility in this regard, although this technology is more destined to race cars 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 sensors, actuators and microcontrollers – 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 forces 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