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Project SeeGrip
Duration: 01.09.2009 – 31.03.2013
The goal of the SeeGrip project is the development of an underwater manipulator which is able to perform form- and force closed object manipulation tasks by using tactile sensor arrays and multi-limb end-effectors.
With the increasing complexity of manipulation tasks in deep sea environments, there is an increasing need for feedback of sensor data from the manipulation system. Besides visual information through cameras, the sensory feedback of underwater manipulators nowadays is limited to proprioceptive information (like joint positions), thus no further exterioceptive information (like applied forces) are available.
Under these conditions, manipulation tasks become a time-consuming and challenging task for manipulator operators. In cases where the field of view is limited or where even no direct view on the operation scene is realisable, manipulation tasks have to be handled blindly which is why these tasks cannot be performed under such conditions.
Through the use of large-area sensor networks, the SeeGrip Manipulator System will massively increase the efficiency and the range of missions for underwater manipulation systems. Besides the realisable feedback of haptic information for the operator, the tactile sensors can be used to implement autonomous behavior which will detect and react to critical situations like slipping of objects. Unlike current available underwater manipulator systems, the use of multi-limb structures for the gripper together with the integrated sensors will allow gentle manipulation tasks.
In order to evaluate and verify different modules for the use in deep sea environments, the manipulator and its components will be exposed to ambient pressure of up to 600 bar in the pressure-chamber of the underwater testbed.
Johannes Lemburg, Peter Kampmann and Frank Kirchner
The valve was selected based on the required flow trough rate, and the needed max. working pressure of 55 bar. The cylindrical mounting was the best solution for this application, because it enables a space efficent integration in to the hydraulic system.
The main components, i.e. the main piston, four valves, two balancing pistons and two pressure sensors, have to be placed in a design space of 40 mm width, which leads to a elongated, serial placement with their frontal area facing each other. By this arrangement it is possible to design the main-piston similar to a plunger instead as a differential cylinder, resulting in a symmetrical setup that facilitates control and manufacturing.
The SeeGrip manipulation system is a three-fingered manipulator with seven degrees of freedom. The system is designed to be working in deep-sea, at depths of up to 6000m. A variety of tactile sensors of different modality equip thisgripper with a sense of touch, which is one of the specialitiesof this gripper.
