BatEm: Our idea for an electronic device to manage Greenpower car speeds, protect batteries so they last longer and eliminate battery differences between teams.Car Performance with different battery capacities.Greenpower car virtual wind tunnel: GreenVwt.Car speed calculator and Motor Heat Calculator.Some information on the science and maths of a Greenpower racing Car.Rightfully or wrongfully, Ackermann’s name survives with these newer systems, not Darwin’s or Lankensperger’s – two centuries after publication of his eponymous British patent.Greenpower Technical Information Science And Maths Steering systems such as rack-and-pinion mechanisms conforming to variations in early four-bar trapezoidal linkages began in earnest with the development of motorized road transport, and improvements continue today. Both steering modes tend toward oversteer at moderate to higher speeds, but operate well at low speeds when maneuverability is required. Conversely, vehicles featuring either rear-wheel steering systems (such as forklifts) or four-wheel steer are apt to remain relegated The supposition follows: if steered wheels remain parallel during cornering, or operate with reverse Ackermann, the outside tire-wheel assembly, already more heavily loaded due to centrifugal force, would suffer additional lateral scrubbing, which would further improve handling. Race cars, on the other hand, might utilize parallel steer, or even reverse or anti-Ackermann, with toe-out for maximizing tire scrub and steering. Both vehicle platforms would normally have tire toe-in for stability. Sports cars tend to be configured toward parallel steer while sedans tend toward pure Ackermann. Although not immediately self-evident, rear tires also steer via these angles – but passively.Īutomobile steering mechanisms are generally designed to operate in the sector between low-speed Ackermann and parallel steer. Importantly, the cornering-force-induced slip angles reduce turn radii and assist vehicle handling. These angles, averaged at the front and rear, can be accommodated, with simplifying but reasonable assumptions, within an expanded ‘dynamic Ackermann’ equation. These equilibrating forces cause the laterally flexible tires to generate increased slip angles. Traversing a curve during moderate- or high-speed driving produces a centrifugal force that is balanced by a cornering force acting on each tire. The main drawback of pure Ackermann steering for today’s automobiles is that its premise is based on low-speed turning – quasistatic motion. Although Lankensperger was named as the inventor in the text, his contribution has been mostly forgotten. Rudolph Ackermann (1764-1834), his German-born agent living in London, filed for a British patent (GB 4212) in 1818. Lankensperger was a wagon maker, wheelwright and inventor who built coaches and sleighs for the Bavarian court. The idea was independently reinvented by Georg Lankensperger (1779-1847) in Munich almost a half-century later in 1816. This concept, the kinematics of steering, was captured in Darwin’s sketch 253 years ago for a horse-drawn carriage featuring axletrees paired with wooden wheels – though Darwin did not secure a patent. ![]() Curves described by the rear wheels of a conventional automobile. A positive caster angle aids in directional stability, as the wheel tends to trail, but a large angle makes steering more difficult. On vehicles equipped with pneumatic tires, a common turn center minimizes tire scrub and steering effort. Ackermann steering geometry Caster angle indicates kingpinpivot line and gray area indicates vehicle's tire with the wheel moving from right to left. Recall that the Ackermann principle is based only on geometry: if the inside wheel on a front axle turns through a greater angle than the outside wheel, both wheels can be made to track around a common center determined solely by wheelbase and radius. ![]() Darwin was an English physician with an interest in mechanical inventions (and best known today as the grandfather of Charles Darwin) and Watt was a well-known Scottish inventor. The story of Ackermann steering begins with a rough sketch in an obscure note written by Erasmus Darwin (1731-1802) to James Watt (1736-1819) in 1767, depicting carriage wheels and axles. Most road car steering is based on this layout this also provides a symmetric response for both left- and right-hand turns. To help minimize unnecessary tire sliding during vehicle cornering, a four-bar linkage with an isosceles trapezoid planform, or Ackermann geometry, is generally used as the foundation for front-wheel steering control. Such relative motion between tires and roads promotes tread wear. Even tires rolling and turning at low speed on a dry surface will undergo overall longitudinal slip and lateral scrubbing coupled with individual tread element squirm. Slippage in the contact patch is further exacerbated by vehicle braking, driving and/or cornering. Pneumatic tires always roll with slip unless traveling straight ahead with their loaded rolling radius coinciding with their effective radius – an infrequent circumstance.
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