Irene Fassi

Calibration of Serial Manipulators: Theory and Applications

The kinematic calibration is a procedure to improve the manipulator accuracy without mechanical means by acting on the manipulator controller. Although manipulators are composed by accurate mechanical components, the precision of their motion is affected by many sources of error (Mooring et al, 1991). The final position accuracy is mainly influenced by: kinematic inaccuracy (due to manufacturing and assembly errors in both actuated and passive joints), load deformation (due to external forces including gravity) and thermal deformation (Reinhar et al, 2004). This is true for serial (Mooring et al, 1991) as for parallel (Wildenberg, 2000) manipulators as well. Each of these factors should be addressed with an appropriate compensation or calibration methodology. This work deals with kinematic inaccuracy, related to robot geometry, assembly and joint motion. One possibility to compensate for geometrical errors is to perform a

Calibration of Parallel Kinematic Machines: Theory and Applications

As already stated in the chapter addressing the calibration of serial manipulators, kinematic calibration is a procedure for the identification and the consequent compensation of the geometrical pose errors of a robot. This chapter extends the discussion to Parallel Manipulators (also called PKM Parallel Kinematic Machines). As described in the following (Section 2) this extension is not obvious but requires special care. Although for serial manipulators some procedures for the calibration based on automatic generation of a MCPC (Minimum Complete Parametrically Continuos) model exist, for PKMs only methodologies for individual manipulators have been proposed but a general strategy has not been presented since now. A few examples of the numerous approaches for the calibration of individual PKMs are proposed in (Parenti-Castelli & Di Gregorio, 1995), (Jokiel et al., 2000) for direct calibration and (Neugebauer et al., 1999), (Smollett, 1996) for indirect or self calibration techniques.

Micro-FDM process capability and comparison with micro-injection moulding

In recent years, fused deposition modelling technology (FDM) has become one of the most important additive manufacturing technology due to its capability to produce functional prototypes with complex shape in a cost effective way. Recently, the trend towards miniaturization invested also this technology, since the request of micro-component is rapidly growing due to the increasing number industrial sectors involved. Mechanical properties are fundamental in some sectors of high-quality micro-parts, so the knowledge of the influence of FDM process parameters on mechanical properties can be useful to extend its application and help the optimization of the parameter selection. In this context, the aim of this study is the analysis of the FDM capability and the room for improvement, through a comparison with a well-consolidated industrial process, such as the micro-injection moulding. Although FDM quality cannot compete with the technologies industrially used for final products, its low cost and short time are very attractive for some applications. Moreover, the comparison can be interesting since FDM is often used to manufacture prototypes eventually made with more performing industrial technologies, so that a measure of the quality and functionality of these prototypes can be extremely useful for product developers.In recent years, fused deposition modelling technology (FDM) has become one of the most important additive manufacturing technology due to its capability to produce functional prototypes with complex shape in a cost effective way. Recently, the trend towards miniaturization invested also this technology, since the request of micro-component is rapidly growing due to the increasing number industrial sectors involved. Mechanical properties are fundamental in some sectors of high-quality micro-parts, so the knowledge of the influence of FDM process parameters on mechanical properties can be useful to extend its application and help the optimization of the parameter selection. In this context, the aim of this study is the analysis of the FDM capability and the room for improvement, through a comparison with a well-consolidated industrial process, such as the micro-injection moulding. Although FDM quality cannot compete with the technologies industrially used for final products, its low cost and short time are...

Introduction to Miniaturisation

Miniaturisation of systems and devices is a trend that started a few decades ago, and which is becoming more and more relevant to our everyday lives. The concept of micro-manufacturing evolved as a direct result of manufacturing technologies used for integrated circuit fabrication. These allowed batch processing, but limited the range of materials and geometries. A range of micro-manufacturing technologies has been developed to overcome these limitations. The aim of this chapter is to review the main physical phenomena related to miniaturisation, in terms of scaling laws, forces, materials, processes and production systems. Indeed, when approaching the micro-scale, some physical phenomena considered negligible at the macro-scale, become significant and have to be taken into account in the design, manufacturing, and assembly of micro-devices.

Influence of micro injection moulding process parameters on mechanical characteristics of POM and POM/CNT composites

Micro injection moulding is one of the most used thermoplastic technology for the manufacturing of miniaturized products, due to the high productivity of the process. Thermoplastic micro manufacturing has reached nowadays an incredible spread: polymeric components are used in several fields, such as biomedical, IT, telecommunication, automotive and aerospace. In recent years, an innovation in polymer area was the addition of fillers on the pure polymer, in order to improve the physical properties and/or to reduce the cost of the composite. nThe aim of the present work is to carry out a comparison between the mechanical properties of POM base material and POM filled with carbon nanotubes micro injected using different process parameters - melting temperature, injection speed and holding pressure. Uniaxial mechanical tests were performed to obtain the main mechanical properties: yield stress, deformation at break and stress at break. nThe results, analyzed with Analysis of Variance statistical approach show that the mechanical response of the micro¬ specimens is mainly affected by the CNT presence, whereas the other factors seems to play only a secondary role. The presence of CNT induces a remarkable increase in the mechanical resistance, but drastically reduces the material ductility.