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Drive Train
Published in Georg Rill, Abel Arrieta Castro, Road Vehicle Dynamics, 2020
Georg Rill, Abel Arrieta Castro
When the car is accelerated in a left corner for example, the clutch on the outer side (clutch 2) is engaged, which by friction will generate a torque (TF2) and speed up the corresponding half-shaft (Ω2 ↑) and finally the attached wheel too. As a result, the longitudinal slip at the outer tire is increased, which induces an additional driving force and reduces or completely eliminates the understeer tendency of the car. As the friction torque reacts on the gearbox too, the drive torque transferred to the opposite wheel is decreased accordingly. Thus, this active differential is able to torque the drive torque (torque vectoring) to the left and to the right wheel as needed in specific driving situations. Usually, almost the complete input torque can be diverted to one rear wheel in this way. The torque shift from the inner to the outer wheels also reduces the cornering resistance, in particular in sharp bends [54].
Torque vectoring with active steering for improved lateral performance in electric vehicles
Published in Maksym Spiryagin, Timothy Gordon, Colin Cole, Tim McSweeney, The Dynamics of Vehicles on Roads and Tracks, 2018
One way to implement torque vectoring an electric vehicle is to connect each wheel to its own electric motor (Burgess, 2009, Tahimi et al. 2004 & McTrustry et al., 2015). Power is distributed from a centralize power source, such as a battery pack, through a network of electric cables and motor controllers. Each controller can precisely control the torque generated by each motor using appropriate current control algorithms. The torque generated by a Permanent Magnet Synchronous Motor (PMSM) is directly proportional to the Q axis current in the motor, which is easily monitored and can be precisely controlled. The electric motor can generate very fast torque response, in the order of milliseconds using the controller and is capable of generating full torque in positive or negative directions throughout its speed range including zero. When the vehicle is in forward motion, a negative torque can be produced for regenerative braking for improved energy efficiency. These excellent torque delivery characteristics lend EVs well to torque vectoring.
Inversion based feedforward design to improve the lateral dynamics of high performance sports cars
Published in Johannes Edelmann, Manfred Plöchl, Peter E. Pfeffer, Advanced Vehicle Control AVEC’16, 2017
S. Rahimi Fetrati, C. Kandler, C. Kärcher, D. Schramm
The aim of a torque vectoring (TV)-system is to vary the distribution of wheel torque at the driven axle based on driving situation, to enhance the required driving performance and prevent loss of traction. Asymmetric distribution of torque between wheels generates a corrective yaw torque around the vertical axis, which can improve the handling response of the vehicle. The torque distribution should keep the tires in their optimal longitudinal slip. In this paper we propose a control concept, to use the benefits of TV particularly in the lateral domain. This controller considers the tire potential defined as lateral and longitudinal forces, which form kamms circle. During the design process of chassis control systems, great attention should be paid to performance and handling characteristics of the vehicle. According to Milliken (Milliken & Milliken 1995) acceleration limit in both longitudinal and lateral direction can be defined as a performance criteria. Moreover, he emphasizes that a vehicle should present a good degree of controllability and stability that allows a driver to exploit the performance potential of the vehicle. Isermann (Isermann 2006) describes performance as a measure of responsiveness of a vehicle to driver inputs and stability as a remain potential of longitudinal, lateral and vertical forces to their physical limits in a driving situation. The longitudinal performance is usually limited due to the engine power and tire maximal longitudinal forces. However, the lateral performance depends on the optimal and individual utilization of tire lateral forces.
Model Predictive Control for integrated lateral stability, traction/braking control, and rollover prevention of electric vehicles
Published in Vehicle System Dynamics, 2020
Mansour Ataei, Amir Khajepour, Soo Jeon
In order to obtain the above-mentioned stability and safety objectives, different approaches are suggested and developed for vehicles. Anti-lock brake system (ABS) [8,9], traction control system (TCS) [10,11], differential braking [12,13], Torque Vectoring (TV) [14–16], active steering (AS) [2,17,18] and active camber system [19] are some of the most important developed strategies. Early studies started by focusing on tire slip control in braking. ABS keeps the wheels from locking during braking to provide longitudinal and lateral stability. TCS provides slip control in traction and prevents the wheels from large slip ratio. ABS and TCS increase the longitudinal performance of the vehicle. They also consider the longitudinal and lateral force coupling of tires and keep the slip ratio in regions that the lateral stability and handling of the vehicle is not highly sacrificed. As an early approach, deferential braking was proposed to improve handling and lateral stability of vehicles. This strategy applies different brake forces on left and right sides of the vehicle. Thus, a yaw moment is generated on the vehicle body for yaw motion control and lateral stabilisation of the vehicle. Torque vectoring is later suggested for vehicles with independent drive wheels, especially for electric vehicles. Similar to the differential braking strategy, torque vectoring applies different traction forces on left and right sides of the vehicle to generate a yaw moment on the vehicle body. Active front steering, active rear steering and four-wheel steering systems have also been developed as other approaches for handling improvement and lateral stability of vehicles [20,21].
A prioritisation model predictive control for multi-actuated vehicle stability with experimental verification
Published in Vehicle System Dynamics, 2023
Reza Hajiloo, Amir Khajepour, Alireza Kasaiezadeh, Shih-Ken Chen, Bakhtiar Litkouhi
The increasing level of vehicle actuation technologies is empowering improved vehicle handling and stability in modern vehicles. For instance, in electric vehicles equipped with individual electric motors on each wheel, torque vectoring effectively improves the vehicles handling characteristics [1,2]. Some other actuations which are being broadly studied in the literature include active front/rear steering [3,4], differential braking [5], and active/semi-active suspension [6,7]. Despite the availability and additional capabilities offered by these actuation systems, the best way to optimally select or prioritise the operation of these actuators to meet different objectives, remains an open-ended question.
Optimal motion control for collision avoidance at Left Turn Across Path/Opposite Direction intersection scenarios using electric propulsion
Published in Vehicle System Dynamics, 2019
Adithya Arikere, Derong Yang, Matthijs Klomp
The controller outlined in the previous section was implemented in a CarMaker simulation environment with a validated Volvo XC90 vehicle model. A driver assist intervention is considered in this case. The steering performed by CarMaker's own driver model and the intervention is started at the beginning of the turn, i.e. at . Propulsion capability is assumed on both axles as is the ability to apply individual wheel brake torques. The availability of electric propulsion and individual wheel brakes means that they can then be combined to perform torque vectoring by braking. Hence effectively, independent wheel force control capability is assumed.