Browsing by Subject "Robots--Dynamics"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Geometric-based spatial path planning(2008-08) March, Peter Setterlund, 1978-; Tesar, DelbertCartesian space path planning involves generating the position and orientation trajectories for a manipulator end-effector. Currently, much of the literature in motion planning for robotics concentrates on topics such as obstacle avoidance, dynamic optimizations, or high-level task planning. The focus of this research is on operator-generated motions. This will involve analytically studying the effects of higher-order properties (such as curvature and torsion) on the shape of spatial Cartesian curves. A particular emphasis will be placed on developing physical meanings and graphical visualization for these properties to aid the operator in generating geometrically complex motions. This research begins with a brief introduction to the domain of robotics and manipulator motion planning. An overview of work in the area of manipulator motion planning will demonstrate a lack of research on generating geometrically complex spatial paths. To pursue this goal, this report will then provide a review of the theory of algrebraic curves and their higher-order properties. This involves an evaluation of several different representations for both planar and spatial curves. Then, a survey of interactive curve generation techniques will be performed, which will draw from fields outside of robotics such as Computer Graphics and Computer-Aided Design (CAD). In addition to the reviewed methods, a new method for describing and generating spatial curves is proposed and demonstrated. This method begins with the study of a finite set of local geometric motion shapes (circular arcs, cusps, helices, etc). The local geometric shapes are studied in terms of their geometric parameters (curvature and torsion), analyzed to give physical meaning to these parameters, and displayed graphically as a family of curves based on these controlling parameters. This leads to the development of path constraints with well-defined physical meaning. Then, a curve generation method is developed that can convert these geometric constraints into parametric constraints and blend between them to form a complete motion program (cycle) of smooth paths connecting several carefully developed local curve properties. Up to ten distinct local curve shapes were developed in detail and one curve cycle demonstrated how all this could be combined into a full path planning scenario. Finally, the developed methods are packaged together into existing software and applied to an example demonstration.Item Physical modeling of tools necessary for robot manipulation(2006) Chang, Kyogun; Tesar, DelbertPrevious research on modeling general processes has focused on physical and empirical modeling of dedicated process machines which have sufficient stiffness and accuracy. For example, machining centers have relatively high stiffness and exhibit negligible deflections. Robot manipulators have low stiffness which easily allows undesirable deflections under large reaction forces. Also, models for intuitive decision surfaces for users, decision making systems, or system controllers have not been embedded or otherwise deployed effectively. The objective of this research is to suggest graphical and parametric models of robotic processes suited for intuitive user friendly graphs and modeling nonlinear systems and to initiate a program which proves usefulness of performance maps. Performance maps are primitive surface representations which can be used to create decision surfaces. General robotic processes considered are robotic drilling, grinding, deburring, chiseling, sawing, peg insertion, force-fit insertion, forming for assembly, screw fastening, and riveting. To achieve the objective, a framework for in-depth parametric and analytic modeling of robotic processes is presented. First, relevant process parameters such as process operating variables, system condition parameters, and process performance criteria are defined. Process operating variables are the robot controller inputs. System condition parameters are process parameters which define system constraints and characteristics. Process performance criteria are critical parameters to define, anticipate, and evaluate product quality, system stability, economic performance, and system performance. Second, performance maps which describe the graphical relationship of the relevant process parameters are developed. A performance map is the surface representation of a process performance criterion as a function of process operating variable(s), system condition parameter(s), or other process performance criteria. Third, the application of performance maps of robotic drilling is simulated, to illustrate their advantages. Whether robot deflections generated during the process satisfy tolerance requirements or not is evaluated and suitable robot postures are recommended. Pertinent literature is extensively reviewed to recognize current research trends in modeling and parameterizing relevant process parameters. Approximately, 100 performance maps were created as graphical and parametric models based on process performance. Two performance envelopes were developed. Proper robot postures were suggested to drill a hole with constant feed-rate or bounded ranges of that feed-rate.