1993 Volume 29 Issue 4 Pages 429-436
Described in this paper, is a pneumatic grasping device which performs a similar catching operation to insectivorous plants.
Two sets of double bellows, which have the same construction, are aligned. A nozzle is attached to each centre of movable ends of both sets of bellows, and one of the movable ends faces to the other at a distance. Inside chambers of the double bellows are pneumatically interconnected, and air is fed from a constant low pressure source into the chambers and it flows out to the atmosphere from the nozzles. Outside chambers of the double bellows are enclosed and interconnected. A sensing head of a nozzle-flapper system faces to a moving part of a bellows chamber which is connected to the inside chambers of the double bellows, and the output port of the nozzle-flapper system is connected to the outside chambers of the double bellows.
When an object is inserted in the space between the movable ends, the pressure in the inside chambers increases corresponding to the total length of gaps between the nozzles and their counter-faces. The pressure increase causes high pressure change in the outside chamber by the nozzle-flapper system, and the pressure change makes the gaps more and more small, due to the elongation of the double bellows. Owing to such regenerative action of the pneumatic circuit, the movable ends contact the faces of the object quickly and maintain to grasp the object with a force proportional to the supply pressure of the nozzle-flapper system.
