China
Africa
Explore chapters and articles related to this topic
Running gear
Published in Andrew Livesey, Practical Motorsport Engineering, 2019
On many independent suspension systems the bump and rebound movement of the suspension causes changes in the TW. This is because of the geometry of the suspension pivots. The problem is that variation in track width causes lateral forces which give rise to variations in slip angle (α). This leads to an increased rolling resistance and adverse affects on the vehicle’s directional stability, which may include steering effects. That is bump steer. The loss in performance and the detrimental effects on the steering at high speed are to be avoided. Changes in track width also cause tyre noise and increases tyre wear. The tyres used on motorsport vehicles are expensive, so excessive wear generating geometry should be avoided, and for environmental reasons vehicle noise should be kept to the minimum.
Practical aspects of the design of an integrated flight and propulsion control system
Published in Mark B. Tischler, Advances in Aircraft Flight Control, 2018
David J. Moorhouse, Kevin D. Citurs
The lateral control laws use a conventional roll-rate feedback path and a limited roll-rate feedback path for gust rejection. The directional control laws incorporate lateral acceleration and estimated sideslip-rate feedbacks. Interconnects from the lateral control commands to the directional controls are used for roll coordination. Differential stabilator is used to provide additional directional stability augmentation at high angle of attack. Equivalent-system analysis verified that the resulting control system design provided the desired response characteristics. Sideslip excursions due to lateral stick were small, with no oscillatory roll component. All of the analytical parameters were within the Level 1 MIL-F-8785C boundaries; however, manned simulation testing resulted in Level 2 pilot ratings for fine tracking. After extensive analysis and simulation testing, a solution was identified which required modification of the roll/yaw phase angle relationship as a result of turn coordination. The investigation of this problem was thorough enough to result in a tentative criterion for use in future efforts (see Moorhouse 1990, Moorhouse et al. 1990).
Chassis
Published in Andrew Livesey, Advanced Motorsport Engineering, 2012
On many independent suspension systems the bump and rebound movement of the suspension causes changes in the TW. This is because of the geometry of the suspension pivots. The problem is that variation in track width causes lateral forces which give rise to variations in slip angle (a). This leads to an increased rolling resistance and adverse affects on the vehicle’s directional stability which may include steering effects. That is bump steer. The loss in performance and the detrimental effects on the steering at high speed are to be avoided. Changes in track width also cause tyre noise and increases tyre wear. The tyres used on motorsport vehicles are expensive, so excessive wear generating geometry should be avoided, and for environmental reasons vehicle noise should be kept to the minimum.
Road vehicles travelling with time-dependent speed: theoretical study on the directional stability
Published in Vehicle System Dynamics, 2021
Elena Pierro, Antonio D'Angola, Giuseppe Carbone
The directional stability of a vehicle refers to its ability to stabilise its direction of motion against disturbances. The disturbance may arise from crosswind, transient forces acting on the tyres from the road, a slight movement of the steering wheel, and a variety of other causes. Starting from the case of constant forward speed V and constant steering angle δ and solving Equation (1), the steady-state equilibrium ratio between the Ackermann angle [5] L/R and the imposed steering angle δ becomes where is called the stability factor. A vehicle is oversteer if K is negative, understeer when positive and neutral when vanishes. Stability properties of the system can be inferred from the eigenvalues of the matrix and in particular from the sign of , being the trace of always negative [1–3]. When the vehicle is always directionally stable, otherwise unstable. The transition curve between stable and unstable regions is given by the critical value for the forward speed , which becomes, by using the linear relation between cornering stiffness and normal loads (see Equation (5)), and the definitions of oversteer and understeer vehicles is related to the relative value of the cornering coefficients between the axles.