A new approach to railway track switch actuation: Dynamic simulation and control of a self-adjusting switch

Abstract

The track switch is one of the key assets in any railway network. It is essential to allow trains to change route; however, when it fails, significant delays are almost inevitable. A relatively common fault is ‘loss of detection’, which can happen when there is a gradual track movement and the switch machines (actuators) no longer close the gap between the switch rail and stock rail to within safe tolerance levels. Currently, such misalignment is mitigated by a preventative programme of inspection and manual re-adjustment. In contrast to many other industries, the actuators are exclusively operated in open loop, with sensors (often limit switches) mainly being used for detection. Hence, an opportunity exists to investigate the closed loop control concepts for improving the operation of the switch. This paper proposes two advances: first, a novel approach is taken for modelling the dynamic performance of track switch actuators and the moving permanent-way components of the switch. The model is validated against real data from an operational switch. Secondly, the resulting dynamic model is then used to examine the implementation of closed loop feedback control as an integral part of track switch actuation. The proposed controller is found to perform well and offers the potential of ‘self-adjustment’, i.e. re-adjusting itself to close any gap (within a predefined range) between the stock and switch rails, thereby completing the switching operation.

Continuous Time Parameter Estimation Method for a Railway Track Switch Actuator

“…2). The governing equation of the actuator has been derived from using the method discussed in [13]. The two sensors connected to the actuator are the motor current sensor and LVDT connected at the front toe to measure the displacement of the switch rails.…”

Realisation of a Novel Functionally Redundant Actuation System for a Railway Track-Switch

“…The second contribution of the work is the development and validation of a simulation model using multi-body simulation software. A modelling approach, similar to that presented in [22] for a traditional switch, is used. The models are useful during the design phase to calculate the actuation forces required and to specify the different electromechanical elements in sub-systems, they are also essential for design and validation of the feedback control loops (allowing safe testing before implementation).…”

“…The full modelling approach undertaken to design and develop the track switch actuators is explained in [22] and the top-level diagram for the resulting model can be seen in Figure 4. The goal is to develop a simulation model of the complete switch system (the moving switchblades/rails and the actuators) which is then used in the design process to specify motor and gearbox components, to design the controller, and ultimately to integrate the different elements and predict the dynamic behaviour of the designed system for the various operating conditions.…”

Simulation analysis of high-speed turnout point rail switching force considering influence of external locking device

“…The lateral stiffness of the inter-point rail connecting spring is 200 MN/m, the cross-sectional area of the spacer block on the heel end is 10,000 mm 2 , and the inertia moment is 1,00,00,000 mm 4 . Refer to Dutta et al 12 and Ping et al, 13 both the closing stiffness and the non-linear spring stiffness at the end of the switch rail are set as 100 MN/m. The movable section of the point rail is 7.505 m long, equipped with two traction points, which are 3.6 m away from each other.…”

“…Bemment et al 11 developed a novel concept for rail track switching, and the novel design meets the set of functional requirements for track switching solutions. Dutta et al 12 presented a simulation model of a railway track switch and proposed a closed loop controller to obtain a self-adjusting switch system.…”