Tools to Support Research in Agile Mechanical Systems

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Agile mechanical systems represent a class of mechanical systems designed for high-speed manoeuvres. Two examples of these are Schönflies-motion generators, a.k.a. parallel SCARA (Selective Compliance Assembly Robot Arm) systems, and grippers intended to grasp drifting objects. The former require a stiff, yet light structure, capable of withstanding high operation frequencies. For example, one commercial robot of this class, capable of performing a cycle test that requires traversing a 700-mm path, in the form of an open rectangle, in one-third of a second, reportedly produces accelerations of its moving plate of up to 15g. As this cycle includes sharp changes of direction, the excitation frequencies involved can be of the order of 1 kHz, well beyond a typical value for the excitation of a mechanical structure. Moreover, the structure in question is hyperstatic, which means that small manufacturing errors render the closed kinematic chain impossible to assemble. We intend to cope with the design and control challenges posed by such systems using robustness. Grippers of the above kind involve one not less challenging feature: while grabbing the drifting object with a fast closing of its fingers, the gripping action should be gentle enough to avoid breaking fragile objects. Applications of the latter, beyond the obvious grabbing of objects drifting in space, include the grasping of living tissue in robot-assisted surgical operations. The tools requested in this application are intended to support experimental work intended to validate the models formulated using sound knowledge of continuum mechanics and multibody mechanics, including the theory of kinematic chains, besides control and system theory.