Automatic tool-moving machine

An automatic machine for effecting required movements of an element over a two-dimensional work area, said machine comprising:

• fixed structure,
• first support means in the form of a cantilevered arm having inner and outer arm parts respectively articulated to said fixed structure and to said inner arm part,
• second support means mounting said element and carried at the free end of said outer arm part in a manner permitting relative movement between said second support means and the outer arm part within predetermined displacement limits whereby to enable the said element to be moved over a zone of the work area, the location of said zone within the work area being dependent on the instantaneous position of the first support means,
• a first servo control loop including first movement means in the form of respective motors for articulating the inner and outer arm parts whereby to enable the second support means and the said element to be displaced over substantially the whole of the work area;
• first sensing means arranged to generate output signals indicative of the approach of the second support means to a said limit of its displacement relative to the said outer arm part;
• and first control means for controlling operation of said first movement means in dependence on the output signals of said first sensing means;
• and
• a second servo control loop including second movement means in the form of two linear actuators operative to move the second support means relative to the outer arm part in respective mutually orthogonal directions, the said two linear actuators being arranged such that their respective lines of action are substantially parallel to each other, and the second movement means further including a linkage system effective to transpose the action of the said actuators from their lines of action to said mutually orthogonal directions;
• second sensing means arranged to generate feedback signals indicative of movement of the said element over the work area relative to the machine fixed structure;
• storage means for storing demand signals indicative of the required movement of the element relative to said fixed structure;
• and second control means arranged to receive said feedback and demand signals and being operative in dependence thereon to control the second movement means with a view to causing the latter to effect the said required movement by itself notwithstanding the said limits on the permitted relative movement between the outer arm part and the second support means;
• said first servo control loop being responsive to the second support means approaching a said limit of its displacement relative to the outer arm part, to so move the first support means relative to the fixed structure as to contribute to the said required movement of said element sufficiently to prevent the second servo control loop seeking to move the second support means beyond the relevant said displacement limit.