"Micro-manufacturing" is a key sector for the EU industry. Flexible and cost efficient manufacturing tools are essential to gain competitive edge in the manufacturing of high value-added miniaturised products. The manual assembly or manipulation of micro-parts required for miniaturised assemblies is required by several markets; most notably in high-end horology. To fix ideas, up-market watches in the world represents 6.4 billion Euros per year for one million watches produced.
In today’s state-of-the-art micro-manipulation workstations, feedback to the operators is exclusively provided by viewing the parts through optical microscopy. These technicians must work under intense attentional pressure, which is detrimental to their health, and must undergo extensive training to be productive. Imagine a world where objects to not behave from the result of the action of gravity and friction, as is the case in our familiar macroscopic world. Instead the behaviour of parts is dominated by short-range forces including electrostatic, capillary, and van der Waals forces. It is as if objects you manipulate had no mass and their surfaces were covered with magnets and sticky paste. What is more, you must work with hands made of metal, like those of Tim Burton's Edward Scissorhands. To make things even more difficult, you are forced to watch your work through a microscope or from a graphic display giving no depth cues. This situation results in work arduousness, repeated stress injury disorders, attentional stress leading to blurred vision and anxiety.
Taking advantage of highly promising results recently obtained with a single degree-of-freedom high-fidelity force-feedback user interface we developed a prototype of the core component of a workstation with a two degree-of-freedom interface optimised for application to the micro-assembly. The objective is two-fold. The first object is to eliminate the sensory interference from the interaction while performing micro-part assembly tasks. The second objective is to scale up forces and to scale down movements to give technicians the illusion of work with parts at a much larger scale.
The result of this research is a system where the forces applied to the fingers of users are produced by three linear, in-house-developed induction motors arranged in a three point star configuration. They act on a flat, extremely light armature made of 0.5 mm aluminium plates reinforced by honeycomb composite material. Since this armature levitates on a thin air-cushion without solid contact, these forces are transmitted, untainted, to the user's fingers, resulting in a single-part mechanical arrangement of ultimate simplicity, yet capable of very high fidelity and high forces. Significant research and development effort was required in the development of multi-phase, micro-processor driven electronic circuits needed to drive the induction motors with a sufficient level of accuracy. To track the movements of the plate in contact with the fingers of the user, three laser motions sensors are employed, giving signals that can be processed at a much faster rate than one kHz. All the controls can be effected by a low-cost single board computer. The system was successfully demonstrated at the conclusion of the project and is now ready for an industrialisation phase.
In the meantime Intellectual Protection was pursed and market analysis was performed. The latter revealed that high-fidelity interfaces of this nature would find application not only in the micro-manufacturing sector by also in those industries involved in the manipulation of biomedical objects such as eggs.
