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Running gear
Published in Andrew Livesey, Practical Motorsport Engineering, 2019
Hydraulic power steering – relies on hydraulic fluid pressure to move the steering rack, or in some cases a steering box. Some systems are speed sensitive – the amount of power steering assistance decreases with the road speed. In its simplest form this actually just measures engine speed, the argument being that engine speed correlates to road speed. The more complex systems pick up road speed information from the ECU (see Table 5.1).
Yaw and lateral stability control based on predicted trend of stable state of the vehicle
Published in Vehicle System Dynamics, 2023
Shaosong Li, Xuyang Wang, Gaojian Cui, Xiaohui Lu, Bangcheng Zhang
Fundamentally，vehicle stability control based on lateral tire force is mainly based on the control methods of steering system, such as electric power steering (EPS) [1], steer-by-wire (SBW) [2], and active front steering (AFS) [3]. Among these methods, AFS can give the driver softer steering feedback through the steering wheel than EPS and SBW, minimising the damage caused by steering wheel angle intervention to the driver’s hands in extreme working conditions [4].As a result, AFS was chosen as the control methods of this study. In terms of AFS-based lateral stability control, numerous local and foreign research results have been presented. In terms of control algorithms, the common ones are fuzzy control [5], proportional–integral–derivative control [6], robust control [7], linear quadratic optimal control [8], and model predictive control (MPC). Although these control methods can theoretically solve this type of control problem, MPC has numerous advantages in the face of strongly non-linear and constrained control systems, such as automobiles.
Coupling analysis of transient aerodynamic and dynamic response of cars in overtaking under crosswinds
Published in Engineering Applications of Computational Fluid Mechanics, 2020
Chuqi Su, Zhen Hu, Qianwen Zhang, Xiaohong Yuan, Chengcai Zhang, Yiping Wang
To obtain the dynamic response, a multi-body dynamics model was constructed according to the structure and performance parameters. As shown in Figure 7, the dynamic model was divided into ten subsystems, including rigid body, front and rear suspension, power, steering, and tire. The front suspensions are MacPherson suspensions, whereas the rear are multi-link suspensions. The magic formula tire model was introduced to obtain the accurate forces and moments of the tires (Pacejka & Bakker, 1992). Finally, the dynamic model which has 68 moving components, 62 constraints, and 160 degrees of freedom was constructed. In this study, a 2d_flat road with friction factor of 0.7 was used. The detailed parameters about the sedan are listed in Table 2.
Implementation and validation of a three degrees of freedom steering-system model in a full vehicle model
Published in Vehicle System Dynamics, 2019
Jan Loof, Igo Besselink, Henk Nijmeijer
During the J-turn manoeuvre there is a constant offset in the steering-wheel torque. This is odd since the measured yaw-rate and lateral acceleration are close to zero during this manoeuvre. An explanation for this can be that the road is slightly banked for drainage purposes, a-symmetry of the vehicle or improper zeroing of the sensors. The spike in steering-wheel torque when the step input is applied is mainly caused by dry friction as shown by an example of a model without dry friction. The steady-state value of the steering-wheel torque during cornering is caused by the tyre feed-back in combination with the power-steering system and the friction on the output side of the steering-house. The small variations on the steering-wheel torque are again caused by dry friction. The king-pin angles and pitman-arm angle show that it is necessary to to implement a stiffness between the steering-house and the left wheel and a stiffness between the left and the right wheel. The drag-link force shows that the tyres and geometry of the upright have been modelled correctly since the measured and predicted force shows a good similarity. The lateral acceleration and yaw-rate of both the chassis and the cabin are accurately predicted. The side-slip angle measurement is noisy and therefore it is hard to draw any conclusions based on this. The roll-rate of the cabin appears to be accurately represented which indicates an appropriate roll stiffness, height of the COG and inertia of the cabin.