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The adaptation of high capacity vehicles (HCVs) into existing commercial vehicle fleets have been considered a potential solution for reducing emissions, operational costs and infrastructure damages. However, due to increased length and number of articulations, there are challenges associated with HCVs with regard to their manoeuvrability at low-speeds and stability at high-speeds. This paper presents a Virtual Rigid Axle Command Steering control strategy for dolly steering, due to which both low- and high-speed performance of HCVs may be improved significantly compared to their conventional version with non-steered dolly. To demonstrate this, two HCVs, namely, A-double (tractor-semitrailer-dolly-semitrailer) and LHV-D (truck-dolly-semitrailer) are considered in this work.

This paper establishes new analytical results in the mathematical theory of brush tyre models. In the first part, the exact problem which considers large camber angles is analysed from the perspective of linear dynamical systems. Under the assumption of vanishing sliding, the most salient properties of the model are discussed with some insights on concepts as existence and uniqueness of the solution. A comparison against the classic steady-state theory suggests that the latter represents a very good approximation even in case of large camber angles. Furthermore, in respect to the classic theory, the more general situation of limited friction is explored. It is demonstrated that, in transient conditions, exact sliding solutions can be determined for all the one-dimensional problems. For the case of pure lateral slip, the investigation is conducted under the assumption of a strictly concave pressure distribution in the rolling direction.

Knowledge about the tyre to road friction is central to many vehicle functions as well as the overall performance of the vehicle. In this paper, a new real-time algorithm is presented for estimating the coefficient of friction using available on-board sensor information. A computationally efficient algorithm is presented, that reduces resources usage compared to previously published approaches. Issues connected to heavy vehicles and friction estimation is addressed, such as wind up of hub assembly and vehicle speed sensing. The performance of the algorithm is illustrated on data sets acquired from the test track recordings in winter conditions.

This paper investigates the rolling dynamics of spherical wheels using the theoretical framework provided by the brush models. The analysis is mainly conducted under the assumption of vanishing sliding inside the contact patch. Different types of kinematics are considered: simply rolling wheels, rolling and tilting, and purely spinning. For the first two cases, a complete solution is derived concerning both the steady-state and transient behaviours. Some qualitative trends for the forces and moments generated inside the contact patch are then provided when accounting for limited friction. For the case of a purely spinning spherical wheel, it is shown that steady-state conditions are never possible owing to the assumption of vanishing sliding. Moreover, it is demonstrated that the shear stresses acting inside the contact patch grow unbounded if the additional contribution relating to the deflection of the bristle is not taken into account when calculating the total sliding velocity. In this case, a stationary solution may be eventually recovered as an asymptotic distribution only by assuming limited friction inside the contact patch.

This paper presents the development of a state observer for the estimation of output torque of an electromechanical actuator in the application of active wheelset control for railway vehicles. The output from the state estimator is essential to ensure that actuator responds appropriately and deliver accurate and fast control effort as demanded to maintain the stability of wheelsets. The formulation and design of the observer is based on the use of the actuator model only, so that it reduces substantially the complexity and difficult uncertainties related to the model of a full rail vehicle. The performance and robustness assessments of the state estimator integrated active control system are carried out with the use of a full bogie vehicle model.

This paper presents a detailed study of semi-active approach for railway wheelsets. A number of control strategies for active primary suspensions for both solid axle wheelset and independently rotating wheelsets are examined in detail and the key requirements of energy flows on both curved and straight tracks are investigated. A semi-active control scheme is then proposed for the independently rotating wheels and a comprehensive performance evaluation is provided to demonstrate that the proposed semi active control system can be used to continuously and reliably provide the necessary steering control without the need for the energy injection of full active control.

State observer design turned out to be crucial in several recent railway vehicles projects on active control and condition monitoring at DLR, but may also be useful for emerging technologies like the cyber physical system and the digital twin approach or the realization of predictive maintenance concepts. With this background and motivation the paper presents a process in three steps: (i) an initial analysis results in a physical model, (ii) the subsequent transfer to state space representation facilitates the prove of observability and (iii) the observer synthesis supports the design of the observer feedback law. Results from two projects, one related to longitudinal or traction dynamics, the other associated to the guidance task of independently rotating wheels, demonstrate the application of the observer design process and offers a comparison of observer estimates with measurements.