New pneumatically actuated gripper and miniaturized STIFF-FLOP arm

Miniturized Stiff-Flop arm

Scuola Superiore Sant’Anna (SSSA) has been working on the optimization and integration of the multi-module STIFF-FLOP manipulator and on the development of the end effector tool. The work on the multi-module manipulator included the optimization of the module structure integrating fibre-reinforced chambers for the bending/elongation of each section and additional chambers for the stiffening modulation based on the principle of granular jamming.

The developed end effector tool is a pneumatically actuated gripper which involves the same soft actuator approach used for the actuation chambers of the modules.

Since the tool is intended to be used in Minimally Invasive Surgery (MIS) tasks, it is composed of jaws similar to those used for commercial, surgical graspers. Commercial graspers are already optimized for managing surgical tasks, thus, shaping our gripper jaws using traditional devices as a template is likely to increase acceptance levels of the tool by surgeons.


In collaboration with KCL, PIAP and UNITO, the SSSA team has developed, a miniaturized prototype of a two-module STIFF FLOP manipulator for use in human cadaver tests. The prototype has an overall diameter of 14.3 mm in diameter, thus, it can be deployed in laparoscopic procedures through a standard trocar port with an inner diameter of 15 mm.

The miniaturized manipulator integrates a camera for vision at the tip. The control of the device is achieved by means of a joystick interface which allows the user to control separately the motion of each module.


The operations at IMSaT in Dundee focused on a surgical procedure, called Total Mesorectal Excision (TME). The plan was to conduct this procedure on human cadavers in a minimally invasive fashion. The pro-cedure was performed on two ca-davers by a team of surgeons from UNITO with the assistance of the STIFF-FLOP robot arm. For these operations, the robot arm was attached to a rigid shaft and externally supported by an anthropomorphic manipulator robot arm (a Martin Arm) with six Degrees of Freedom (DoFs).

The procedure was performed using three standard laparoscopic instruments for traction and dissection, with the aid of an additional standard laparoscope to observe the motion of the STIFF-FLOP robot arm for documentation. The STIFF-FLOP robot arm with its attached camera proved effective in assisting during a laparoscopically conducted TME in human cadavers, providing a superior field of vision compared to standard laparoscopic vision. This small-scale prototype has also been presented to the European reviewers during the final review meeting at King’s College London (London, December 11th, 2015)


The Gripper


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