This paper aims to provide an overview of the present status of research in pantograph–overhead line interaction and to outline future research challenges. A review of currently used modelling and simulation approaches is provided, also including hybrid simulation, and emerging trends are outlined. Then, line testing methods for the certification of pantographs and catenaries are described and the limitations of measuring methods now in use are highlighted. Issues related to the reliability and availability of the pantograph–overhead line system and to life-cycle costs are then covered in the paper, particularly concerning wear and other damage phenomena and condition monitoring solutions enabling the efficient maintenance of the system. Pantograph aerodynamics and active control of pantographs are finally identified as two emerging trends of research. For both subjects, a review of problems currently at stake and of future research directions is provided.

The dynamic interaction between a pantograph and a catenary influences the quality of the current collection; in particular, when two pantographs are used to collect current, the second pantograph is subjected to the disturbances originated on the overhead line by the transit of the first pantograph, generally causing a deterioration of current collection quality. Under these conditions, the occurrence of continuous sparking, contact loss, and arcing cause an increase of wear for both contact wire and collector strips, but also cause variations of contact voltage and feed current that in turn produce interferences on the on-board electrical systems like drive motors and signalling system. In order to investigate the latter, a procedure for the correlation of the quality of current collection with the level of electrical interference is proposed in this article. The procedure is based on experimental and numerical models combining relationships obtained by means of laboratory tests with simulation tools. An application to a real case of double pantograph collection is presented.

Intelligent interaction control is required in many fields of application, in which different operative situations have to be faced with different controllers. Being able to switch between optimized controllers is, indeed, of extreme importance to maximize the task performance in the different operative conditions ( i.e. , free-space motion and contact), especially when considering sensorless robots. To deal with the proposed context, a sensorless optimal switching impact/force (OSIF) controller is proposed. The low-level robot control is composed of an inner joint position controller, fed by an outer Cartesian impedance controller with a reference position. The estimation of the external wrench is implemented by means of an Extended Kalman Filter (EKF). The high-level controller (feeding the Cartesian impedance controller with the setpoint) is composed of an optimized impact controller (LQR-based controller), an optimized force controller (SDRE-based controller), and a continuous switching mechanism (Fuzzy Logic-based). In addition, the output of the switching mechanism is used to adapt the Cartesian impedance control parameters ( i.e. , stiffness and damping parameters). Experimental tests have been performed on a Franka EMIKA panda robot to validate the proposed controller. Obtained results show the capabilities of the OSIF controller, being able to detect task phase transitions while satisfying the target performance.