164 research outputs found
Motion Planning And Control Of Cooperative Robotic Systems
No full textMOTION PLANNING AND CONTROL OF COOPERATIVE ROBOTIC SYSTEMS Jaydev P. Desai Vijay Kumar James P. Ostrowski This thesis addresses the problem of motion planning for cooperative robotic systems. The problem of motion planning for a robotic system is stated as: Given initial positions and orientations and goal positions and orientations for a collection, C, of robots, in workspace, W, generate a continuous trajectory for C avoiding contact with the obstacles, O i , subject to various dynamical constraints of the system. Because robots are physical systems subject to continuous laws of motion and driven by continuous actuators, we formulate the motion planning problem as an unconstrained variational problem using tools from optimal control and calculus of variations in the first part of the thesis. We develop a general framework for solving motion planning problems involving equality and inequality constraints. In the second part of the thesis, we study planar human manipulation and de..
Acoustic Masking of a Stealthy Outdoor Robot Tracking a Dynamic Target
No full textThis work is motivated by the desire to covertly track mobile targets, either animal or human, in previously unmapped outdoor natural environments using off-road robotic platforms with a non-negligible acoustic signature. The use of robots for stealthy surveillance is not new. Many studies exist but only consider the navigation problem to maintain visual covertness. However, robotic systems also have a significant acoustic footprint from the onboard sensors, motors, computers and cooling systems, and also from the wheels interacting with the terrain during motion. All these can jepordise any visual covertness. In this work, we experimentally explore the concepts of opportunistically utilizing naturally occurring sounds within outdoor environments to mask the motion of a robot, and being visually covert whilst maintaining constant observation of the target. Our experiments in a constrained outdoor built environment demonstrate the effectiveness of the concept by showing a reduced acoustic signature as perceived by a mobile target allowing the robot to covertly navigate to opportunistic vantage points for observation
13th International Symposium on Experimental Robotics
No full textThe International Symposium on Experimental Robotics (ISER) is a series of bi-annual meetings which are organized in a rotating fashion around North America, Europe and Asia/Oceania. The goal of ISER is to provide a forum for research in robotics that focuses on novelty of theoretical contributions validated by experimental results. The meetings are conceived to bring together, in a small group setting, researchers from around the world who are in the forefront of experimental robotics research. This unique reference presents the latest advances across the various fields of robotics, with ideas that are not only conceived conceptually but also explored experimentally. It collects robotics contributions on the current developments and new directions in the field of experimental robotics, which are based on the papers presented at the 13th ISER held held in Québec City, Canada, at the Fairmont Le Château Frontenac, on June 18-21, 2012. This present thirteenth edition of Experimental Robotics edited by Jaydev P. Desai, Gregory Dudek, Oussama Khatib, and Vijay Kumar offers a collection of a broad range of topics in field and human-centered robotics.
Characterization of soft tissue cutting for haptic display: experiments and computational models
No full textReal-time medical simulation for robotic surgery planning and surgery training requires realistic yet computationally fast models of the mechanical behavior of soft tissue. This work presents a study to develop such a model to enable fast haptics display in simulation of softtissue cutting. An apparatus was developed and experiments were conducted to generate force-displacement data for cutting of soft tissue such as pig liver. The force-displacement curve of cutting pig liver revealed a characteristic pattern: the overall curve is formed by repeating units consisting of a local deformation segment followed by a local crack-growth segment. The modeling effort reported here focused on characterizing the tissue in the local deformation segment for fast haptic display. The deformation resistance of the tissue was quantified in terms of the local effective modulus (LEM) consistent with experimental forcedisplacement data. An algorithm was developed to determine LEM by solving an inverse problem with iterative finite element models. To enable faster simulation of cutting of a threedimensional (3D) liver specimen of naturally varying thickness, three levels of model order reduction were studied. Additionally, the variation of the LEM with cutting speed was determined. The values of LEM decreased as the cutting speed increased. This thesis also includes the characteristic response of soft tissue to the growth of a cut (cracking) with a scalpel blade. The experimentally measured cut-force versus cut-length data was used to determine the soft tissue’s resistance to fracture (resistance to crack extension) in scalpel cutting. The resistance to fracture of the soft tissue is defined as the amount of mechanical work needed to cause a cut (crack) to extend for a unit length in a soft-tissue sample of unit thickness. The equipment, method, and model are applicable for all soft tissue.Finally, the method of determining the property of the pig liver tissue during cutting was verified. Dual C-arm fluoroscopes were used to obtain the motion of the beads embedded inside the specimen during cutting. The experimentally measured displacement field was compared to the displacement field obtained through finite element model based on the LEM values at each localized area.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 200
The DLR MiroSurge surgical robotic demonstrator
No full textThis chapter gives a brief overview of the DLR MiroSurge versatile surgical robotic demonstrator, its major components, mechatronic design and control paradigms. Central component is the robot arm Miro based on intelligent mechatronic technology developed at DLR. The system is adapted to various medical applications by attaching various instruments, e.g., the dedicated instrument MICA, and a surgeon workstation providing HD 3D vision and haptic feedback. Furthermore, a selection of current research topics concerning novel MIRS applications and system components are introduced
Motion Planning and Control of Cooperative Robotic Systems
No full textThis thesis addresses the problem of motion planning for cooperative robotic systems. The problem of motion planning for a robotic system is stated as:
Given initial positions and orientations and goal positions and orientations for a collection, C, of robots, in workspace, W, generate a continuous trajectory for C avoiding contact with the obstacles, Oi, subject to various dynamical constraints of the system.
Because robots are physical systems subject to continuous laws of motion and driven by continuous actuators, we formulate the motion planning problem as an unconstrained variational problem using tools from optimal control and calculus of variations in the first part of the thesis. We develop a general framework for solving motion planning problems involving equality and inequality constraints.
In the second part of the thesis, we study planar human manipulation and develop a computational model for friction-assisted dual arm manipulation tasks incorporating the dynamics of the musculo-skeletal system. We show that our computational model predicts the force distribution and object trajectory in voluntary, relaxed movements. We further study similar tasks in the vertical plane and our experimental findings suggest that there is a great degree of repeatability in trajectories and velocity profiles across trials and subjects.
In the third part, we focus on extending this computational model to plan and control cooperative robotic systems. We solve the dynamic motion planning problem for a system of cooperating robots in the presence of geometric and kinematic constraints, and test the resulting open-loop trajectories on the experimental testbed.
In the last part of the thesis, we explore the application of the motion planning algorithms when the number of robots in C is very large. Because of increased computational time, we use optimal sensor-based closed loop motion plans. These are combined with the framework of graph theory and optimal control to guarantee provable measure on the performance of the entire system.
The main contributions of the thesis are: (a) studying trajectory generation and force distribution in human dual arm manipulation; and (b) a set of motion planning algorithms for cooperating robot systems subject to dynamic constraints
Characterization and Control of Biological Microrobots
No full textThis work addresses the characterization and control of Magnetotactic Bacterium (MTB) which can be considered as a biological microrobot. Magnetic dipole moment of the MTB and response to a field-with-alternating-direction are characterized. First, the magnetic dipole moment is characterized using four tech-niques, i.e., Transmission Electron Microscope images, flip-time, rotating-field and u-turn techniques. This characterization results in an average magnetic dipole mo-ment of 3.32×10−16 A.m2 and 3.72×10−16 A.m2 for non-motile and motile MTB, respectively. Second, the frequency response analysis of MTB shows that its ve-locity decreases by 38% for a field-with-alternating-direction of 30 rad/s. Based on the characterized magnetic dipole moment, the magnetic force produced by our magnetic system is five orders-of-magnitude less than the propulsion force gener-ated by the flagellum of the MTB. Therefore, point-to-point positioning of MTB cannot be achieved by exerting a magnetic force. A closed-loop control strategy is devised based on calculating the position tracking error, and capitalizes on the fre-quency response analysis of the MTB. Point-to-point closed-loop control of MTB is achieved for a reference set-point of 60 mm with average velocity of 20 mm/s. The closed-loop control system positions the MTB within a region-of-convergence of 10 mm diameter
Accurate Localization with Ultra-Wideband: Tessellated Spatial Models and Collaboration
No full textDISA
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