Hierarchical, Dense and Dynamic 3D Reconstruction Based on VDB Data Structure for Robotic Manipulation Tasks.

This paper presents a novel approach to implement hierarchical, dense and dynamic reconstruction of 3D objects based on the VDB (Variational Dynamic B + Trees) data structure for robotic applications. The scene reconstruction is done by the integration of depth-images using the Truncated Signed Distance Field (TSDF). The proposed reconstruction method is based on dynamic trees in order to provide similar reconstruction results to the current state-of-the-art methods (i.e., complete volumes, hashing voxels and hierarchical volumes) in terms of execution time but with a direct multi-level representation that remains real-time. This representation provides two major advantages: it is a hierarchical and unbounded space representation. The proposed method is optimally implemented to be used on a GPU architecture, exploiting the parallelism skills of this hardware. A series of experiments will be presented to prove the performance of this approach in a robot arm platform.

Effect of levobupivacaine on articular chondrocytes: an in-vitro investigation.

BACKGROUND: Intra-articular injection of local anaesthetics is a technique commonly used to enhance postoperative analgesia following arthroscopic surgery. However, the potential for cartilage damage due to toxicity of intra-articular local anaesthetics is a concern. Most studies indicate that the toxic effect is drug and time dependent. OBJECTIVES: The objective of this study is to compare the in-vitro chondrotoxic effect of levobupivacaine on human cartilage with saline and bupivacaine. DESIGN: An experimental study. SETTING: University hospital. PARTICIPANTS: Adult patients undergoing knee surgery. INTERVENTIONS: Human articular cartilage was harvested and removed from five patients during knee replacement surgery. Chondrocytes were cultured and divided into three groups exposed to bupivacaine 0.5%, levobupivacaine 0.5% or physiological saline for 15, 30 or 60 min. MAIN OUTCOME MEASURES: Viability of human cartilage cells after contact with the different study drugs at different durations of exposure using two techniques: live/dead cell viability flow cytometry analysis and trypan blue exclusion assay. RESULTS: At 1 h of exposure, chondrocyte mortality in cartilage explants was significantly greater after treatment with levobupivacaine or bupivacaine than with saline (25.9% ±â€Š14.1, 20.7% ±â€Š10.4 and 9.6% ±â€Š5.4, respectively). No differences between groups were found when exposure to the experimental drug was limited to 15 or 30 min. CONCLUSION: In-vitro 0.5% levobupivacaine is more chondrotoxic than saline in human articular cartilage after 1 h of exposure. Bupivacaine seems to be less chondrotoxic than levobupivacaine. With shorter exposures, no clear chondrotoxic effect was shown.

A multi-sensorial hybrid control for robotic manipulation in human-robot workspaces.

Autonomous manipulation in semi-structured environments where human operators can interact is an increasingly common task in robotic applications. This paper describes an intelligent multi-sensorial approach that solves this issue by providing a multi-robotic platform with a high degree of autonomy and the capability to perform complex tasks. The proposed sensorial system is composed of a hybrid visual servo control to efficiently guide the robot towards the object to be manipulated, an inertial motion capture system and an indoor localization system to avoid possible collisions between human operators and robots working in the same workspace, and a tactile sensor algorithm to correctly manipulate the object. The proposed controller employs the whole multi-sensorial system and combines the measurements of each one of the used sensors during two different phases considered in the robot task: a first phase where the robot approaches the object to be grasped, and a second phase of manipulation of the object. In both phases, the unexpected presence of humans is taken into account. This paper also presents the successful results obtained in several experimental setups which verify the validity of the proposed approach.

Survey of visual and force/tactile control of robots for physical interaction in Spain.

Sensors provide robotic systems with the information required to perceive the changes that happen in unstructured environments and modify their actions accordingly. The robotic controllers which process and analyze this sensory information are usually based on three types of sensors (visual, force/torque and tactile) which identify the most widespread robotic control strategies: visual servoing control, force control and tactile control. This paper presents a detailed review on the sensor architectures, algorithmic techniques and applications which have been developed by Spanish researchers in order to implement these mono-sensor and multi-sensor controllers which combine several sensors.