Underwater robots are being developed for various applications ranging from inspection to maintenance and cleaning of submerged surfaces and constructions. These platforms should be able to travel on these surfaces. Furthermore, these platforms should adapt and reconfigure for underwater environment conditions and should be autonomous. Regarding the adhesion to the surface, they should produce a proper attaching force using a lightweight technics. Taking these facts into consideration, this paper presents a survey of different technologies used for underwater cleaning and the available underwater robotics solutions for the locomotion and the adhesion to surfaces.

To apply industrial robots in friction stir welding (FSW) for difficult-to-weld materials and alloys has until recently been a proposed task. However, yet the laboratory experiments did not provide a feasible industrial application. We describe our approach to modify and provide an industrial robot with FS-welding capacity by modifying a standard industrial robot through replacing its sixth axis with FSW related equipment. The emphasis is on achieving reasonable welding speed and path complexity in 3-D space. As significant force is needed for FSW and at the same time position precision has to be kept, the control problems become complicated. We demonstrate our first experiments, highlighting this problem and point some possible solutions.

No abstract

In this article, new local matching measures, based on fuzzy similarity, for stereo matching of color images are proposed and evaluated. By formulating the individual similarity between a pair of pixels as a conjunction of the similarities of the respective color components, the field programmable gate array implementation problem becomes more computationally tractable, since the word-length of the numbers carrying the similarity information can be reduced compared to standard techniques (Sum of absolute differences and Sum of squared differences). It is also shown that combining information about color and local image structure (horizontal gradient component) in the matching measure and using a multi-scale measure is advantageous compared to using standard measures, in terms of percentage of correct matches and MSE for the erroneous matches. However, these improvements come at the prize of more complex implementations. Since the techniques are window-based, they share the typical drawbacks associated with other techniques of this type. This is expected, since the focus is on developing new local matching measure without addressing issues like post-processing of the resulting disparity maps. The techniques have been tested on two stereo color image pairs.

Impedance control and compliant behavior for safe human-robot physical interaction of industrial robots normally can be achieved by using active compliance control of actuators based on various sensor data. Alternatively, passive devices allow controllable compliance motion but usually are mechanically complex. We present another approach using a novel actuation mechanism based on magneto-rheological fluid (MRF) that incorporates variable stiffness directly into the joints. In this paper, we have investigated and analyzed principle characteristics of MRF actuation mechanism and presented the analytical model. Then we have developed the static and dynamic model based on experimental test results and have discussed three essential modes of motion needed for humanrobot manipulation interactive tasks.