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Lateral Dynamics
Published in Georg Rill, Abel Arrieta Castro, Road Vehicle Dynamics, 2020
Georg Rill, Abel Arrieta Castro
Modern steer-by-wire systems can improve the handling properties of vehicles [66]. Usually an electronically controlled actuator is used to convert the rotation of the steering wheel into steer movements of the wheels. Steer-by-wire systems are based on mechanics, micro-controllers, electro-motors, power electronics, and digital sensors. At present, fail-safe systems with a mechanical backup system are under investigation. The potential of a modern active steering system can be demonstrated by the maneuver of braking on a μ-split [48]. The layout of a modern steering system and the different reactions of the vehicle are shown in Figure 9.26. The coefficient of friction on the left side of the vehicle is supposed to be 10% of the normal friction value on the right side. The vehicle speeds to v=130km/h and then the driver applies full brake pressure and fixes the steering wheel like he would do first in a panic reaction. During the whole maneuver, the anti-lock brake system was disabled. The different brake forces on the left and right tires make the car spin around the vertical axis.
Hardware
Published in Hanky Sjafrie, Introduction to Self-Driving Vehicle Technology, 2019
Because SDVs are controlled by software running on the computing platform, the vehicle’s actuators must be fully programmable, or ‘drive-by-wire-ready‘. In a fully drive-by-wire vehicle, the driving functions are controlled by one or more electronic control units (ECUs) based on commands retrieved from the bus system as shown in Figure 2.20. To allow fully programmable lateral and longitudinal control, an SDV needs to have at least the following drive-by-wire components: steer-by-wire, brake-by-wire, and throttle-by-wire. Steer-by-wire allows lateral vehicle control using electronic steering commands (or messages) sent over the communication bus. Brake-by-wire and throttle-by-wire enable longitudinal vehicle control programmatically without any mechanical pedals. On receipt of braking or throttle commands, the responsible ECU translates these into an actual (physical) braking and acceleration action, respectively.
Innovative Environmental Design in Means and Systems of Transport with Particular Emphasis on the Human Factor
Published in Gavriel Salvendy, Advances in Human Aspects of Road and Rail Transportation, 2012
Grabarek Iwona, Choromanski Wlodzimierz
Functionalities shown in figure 2 can be achieved by a system of movable and foldable seats. This design, along with the microprocessor-control system, is considered a significant innovation by the authors. The steer-by-wire technology applied in the design of the Eco-car controls wheels’ turning angles, enhances driving comfort and allows the vehicle control system to intervene independently from the driver. The brake-by-wire technology controls the braking system and enables interventions independent from the driver, in order to adjust the braking force of each wheel to road conditions. The pneumatic suspension allows the lowering of the vehicle platform, shock-absorption and maintaining a constant ground-clearance.
Rider control identification in cycling taking into account steering torque feedback and sensory delays
Published in Vehicle System Dynamics, 2023
Georgios Dialynas, Christos Christoforidis, Riender Happee, A.L. Schwab
The steer-by-wire system enables flexible adjustment of steering actions and haptic feedback (steering torque). In this paper we mimic normal steering motion, where the fork rotation is approximately equal to the handlebar rotation. We manipulate steering torque, where the controller was programmed to approximate: 1) normal steering torque (haptics on) and 2) reduced steering torque (haptics off) isolating the rider from torques resulting from tyre to road interaction. The applied controller is described by Dialynas et al. [19] and here we adopted the parameters (, , , Nms/rad in normal steering with and ) in the haptics off condition.
Variable wheelbase reference for vehicle with active front and rear-wheel steering
Published in Vehicle System Dynamics, 2022
Implementing rear-wheel steering typically means a compromise in planar dynamics. The lateral acceleration and yaw rate are coupled together because the driver has direct control over the front wheels. Using just the rear wheels to change the vehicle dynamics is restrictive. The future of automobiles are trending to steer-by-wire technology, and eventually, autonomous vehicles where a driver is no longer needed. Nissan has released the first steer-by-wire vehicle with the Infiniti Q50 in 2013, and research has proposed alternative methods of implementing the technology [10]. Autonomous systems will shift the focus on passenger comfort over the handling characteristics and driver feel. Decoupling the yaw and lateral motion of the vehicle can open up design possibilities for engineers. Actuation of the front wheels as well as the rear wheels allows for this decoupling. These actuation abilities can be realised in either a steer-by-wire system or autonomous vehicle system with RWS.
Modeling and friction estimation for automotive steering torque at very low speeds
Published in Vehicle System Dynamics, 2021
Hydraulic power steering systems have historically addressed the steering torques needed for low-speed vehicle operation [1], but steering technologies have recently gained vast capability improvements in sensing and actuation developments. Energy efficiency, packaging advantages, installation and maintenance improvements, and tunable dynamics [2] have led to the dominance of electric power steering systems in current state-of-the-art vehicles. A few manufacturers have also begun to introduce fully steer-by-wire vehicles such as those incorporating the Infinity Direct Adaptive Steering system [3]. However, these new systems require significant development to ensure good tracking of the driver steering intent, a reasonable level of driver effort, and communicative feedback to the driver through handwheel torque. Such development is greatly aided by physics-based models of the steering torque dynamics, and further the use of such models, combined with the measurements available in electric power steering and steer-by-wire systems, offer the potential for estimating the surface friction coefficient at low speeds and thus relatively benign operating conditions.