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ASI Gripper

A 3-dof gripper

This gripper has three degrees of freedom, and is particularly suited for no-gravity manipulation tasks.

The gripper has been designed by DIEM (Dept. of Mechanics), DEIS (Dept. of Electronics, Computer Science and Systems).

The activity is supported by ASI (Italian Space Agency), and by MURST, under the RAMSETE project.


The gripper is developed for space applications, for which the possibility of interacting with free-floating, irregular objects can be realistically considered a future need. In the inital stage of the design activity, different kinematic and mechanical configurations have been evaluated and compared, trying to find an optimal solution suitable for the main tasks of the device. In particular, the facts of having more contacts than those present in a simple two-jaw gripper, the possibility of moving independently the fingers, and the overall simplicity of the device have constituted the main guidelines of the design and realization process. Moreover, the design of the gripper has been inspired by specifications deriving from a possible application within PaT, the Payload Tutor, proposed by ASI (Italian Space Agency). This system aims to substitute the astronauts in periodical operations with a semi-autonomous robotic device. The solution proposed by ASI integrates a small robot arm within a fixed structure, where a set of drawers can host and protect as many different experiments: the mobility of the robot arm is increased by placing it on slide joints, in order to cover all the front surface of the facility even with reduced size of the robot limbs. The experiments to be performed inside each drawer may include manipulation of complex-shape "non-technical" objects, freely floating within their allowed space. The end-effector for the PaT manipulator needs therefore compactness, simplicity and reduced weight as well as capability of operation even on irregular floating objects. The final configuration is a three-finger, three degrees of freedom gripper, as shown. With this solution, a sufficient number of contacts may be established, increasing the grasp robustness, while maintaining at a sufficient level the dexterity and manipulation capabilities of the gripper.

The bibliografy can be found here.

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