The research project “Railcab” designs a shuttle-based transportation system, which combines innovative mechatronic technologies with existing railway tracks. The traction and braking forces are generated by a linear electromagnetic drive while the tracking and guidance is performed using classical wheel/rail technology. By adopting different mechatronic modules, a modular structuring of the overall system, the driving safety, vehicle dynamics and the travelling comfort can be increased.

In the present paper, we concentrate on the development of the active tracking module which reduces the sensitivity of the system behaviour with respect to the friction in the wheel/rail contact. Basic ideas of the tracking module are self-optimizing active tracking, camber adjustment, and mechanical locking device. Based on a-priori identified risks, like e.g. strong cross-wind, frosted rails and crossing of switches, the safety concepts are described in detail together with the methodology that was used in the design process.

Controlling mechanical systems with position and velocity cascade loops is one of the most effective methods to operate this type of systems. However, when using low-rate sampling electronics, the implementation is not trivial and the resulting performance can be poor. This paper proposes effective tuning rules that only require establishing the bandwidth of the inner velocity loop and an estimation of the inertia of the mechanism. Since discrete-time mechatronic systems can also exhibit unstable behavior, several stability conditions are also derived. By using the proposed methodology, a P-PI control algorithm is developed for a desktop haptic device, obtaining good experimental performance with low sampling-rate electronics.