Alberto Claudio Oldani

Experimental activities on step motor drives

Thanks to their robustness, reliability and ease of use, step motor drives are widely used in several fields, mainly for small size automation. Step motor drives have also some well known bad running conditions related to their oscillatory behaviour and synchronism loss. In order to properly design the application, those conditions must be accurately taken into account setting-up proper mathematical models. In particular in this paper we refer to a simplified electro-mechanical model where the most of the parameters can be drawn from datasheets, while the others, as the equivalent damping factor, need experimental investigation. This paper deals with preliminary experimental activities performed on small size step motor drives for both testing the suitability of a test bench designed and developed in previous works, and outlining some remarks on the behaviour of the tested motors.

MLA Piezoelectric-Mechanical Systems: Modelling and Simulation

Multilayer actuators (MLA) are among the piezoelectric devices best suited to be introduced into fast and high-precision mechanical systems, because of their relatively large strokes and short actuation time. Several analytical models of their dynamic behaviour were developed during the last decades but none considered the real structure of the multilayer actuator. In this paper a more detailed model of a generic mechanical system driven by a piezoelectric multilayer actuator is presented. A complete description of such model is given and a comparison to existing modelling techniques is made. The behaviour of some commercially available actuators is analysed and results are discussed.

Real-Time Multi-Body Software for HIL Simulations

The Hardware in the Loop simulation is an useful instrument to simulate complex mechanical systems in which the subject of the test is an hardware component. The results of the simulation, closer to the real behavior of the system, are the main advantage of this approach. This application is often used during the design process to test components of a complex mechanical system before the development of the prototype (e.g. embedded systems). The literature examples show, in general, mathematical model finalized to the application. The objective of this work is focused on the development of a generic Multi-Body software for HIL applications. Some simulations examples, the dynamic of a slider-crank and of a McPherson suspension, are presented at the end of the paper.Copyright

Modeling of a Hydraulic Elevator Driven by an Open-Loop Control

Electro-hydraulic elevators are widely used systems, especially in low level buildings, due to their very good ratio between power generation and dynamic response. Generally, the goal of an elevator system is just to reach the floor with a precision enough to be comfortable for the passengers, without the need to follow a specific law of motion; hence an open-loop control system could be enough. Otherwise such a kind of solution reduces the number of components, bringing down the costs of production. On the other hand a complete knowledge of the mechanical system’s behaviour is required. In this work we deal with the analysis of the behaviour of a commercial hydraulic elevator driven by an open loop control that monitors the downstream pressure of the proportional valve supplying the cylinder. At the end of the paper, a closed loop solution based on the pressure measurement and on the motion time is proposed.Copyright