Modelling and control of anaerobic digestion processes for biogas production

The research, set up as part of the activities of the project Fabbrica della Bioenergia, has been initially focused on the Object-Oriented modeling of biochemical processes involved in anaerobic digestion for biogas production, then it was directed towards the analysis and synthesis of advanced identification and control techniques.

Object-Oriented modeling of mechatronic systems

The research activity in the field of Object-Oriented modeling was concentrated on the development of models of vehicles, especially motorcycles, used in the study of ABS braking systems and attitude verification, and on the development of modular models  of mechanical systems with distributed compliance. More recently, the research has been focused to the development of tools for symbolic manipulation of models, aimed at a reduction of the model order and at the use of the same models in advanced control techniques.

Control of drives with elasticity, friction and torque disturbances

The experimental findings obtained from the analysis of the performance of force/position control strategies have suggested other lines of research, related to modeling, identification and compensation of torque disturbances and to the suppression of vibrations in servomechanisms with elasticity. The research on torque disturbances has led to the synthesis of a simple and compact model, easy to use even for adaptive compensation. The heavy influence of friction on the performance of the servomechanisms has finally led on one hand to a survey on modeling of friction, which has led to the development of an innovative model, and on the other hand to the analysis of some particular limit cycles.

Modelling and simulation of mechanical systems

The activity initially focused on the analysis of discontinuous mechanical phenomena. Subsequently, it was directed to the creation of an innovative environment for dynamic simulation, initially in the context of traditional techniques and then in the design of a modular and acausal environment, based on Object-Oriented concepts, techniques and tools. Research has been referred to by three case studies: the modeling of a gripper designed for space applications, of an agricultural tracked vehicle, and of a three-axis machining center. A research more closely related to applications, dealt with traditional tools, was instead directed towards the modeling of hard disk drives.

Hybrid force/position control for industrial robots

The research had as its main goal the design of a hybrid force/position control strategy minimizing the changes to the architecture of standard industrial robots, so as to facilitate the software implementation and integration. This approach has led to the choice of an implicit force control strategy, where the force control action is exerted by an offset added to the motor coordinate setpoint. The first version of the strategy, designed with reference to a rigid robot , has been modified according to the experimental results, which have emphasized the important role of elasticity in the joints . The research has been finally applied to an industrial application of robotic deburring . On one hand the feasibility of the application has been proven, on the other hand some limits have been pointed out, resulting largely from the use of standard industrial components . The research is then continued with the analysis and testing of impedance control techniques.

Identification of dynamical systems characterized by delays

The research theme was initially suggested by a problem of identification of the model of a mill for grinding coal, described by a simple first order system and by a delay. The identification algorithm designed for the delay in this particular case was later generalized and extended to the entire class of linear systems with uncertain parameters. The theoretical analysis of the properties of the algorithm, which highlighted the need for data filtering, has also led to the identification of criteria for the selection of the bandwidth of the filter, even in the case of a generic least squares algorithm applied to the identification of the delay.

Modelling, control and simulation of thermohydraulic processes

The activity began with the thesis “Simulation and control of a natural-circulation steam generator”, then continued with the study of innovative techniques for cascade control and digital control of hydroelectric plants. In the first case the better properties of robustness of the proposed scheme, compared to the classical scheme, have been verified, analytically and numerically, with reference to the case of the temperature control of superheated steam in a natural-circulation steam generator, while in the second case the reformulation of the model of conducts in terms of a discrete-time system has allowed the synthesis of a control system characterized by two properties: the impedance matching of the pipeline and an active damping of the oscillations of flow and pressure at low loads. As part of a research on techniques aimed at optimizing the use of fuel in power stations, compliant to the constraints on emissions of pollutants, a technique for estimating the emissions of nitrogen oxides based on the use of neural networks has been developed.