Generation of Surface Models of 3D Objects From Their Wire-Frame Models

This paper presents an algorithm to generate surface models of 3D objects from their wire-frame models. The algorithm firstly, obtains information about edges of the object from the wire-frame model of the object and uses this edge information to generate the pairs. A pair of an object is a combination of two non-collinear edges which have a common vertex. The algorithm then determines the unique plane passing through each pair and groups the coplanar pairs together. Then it sorts each of the groups of coplanar pairs to form one or more loops of edges. Finally for each group of coplanar pairs, all the loops are combined, using a few rules, to form faces of the object. Hence a surface model of the object is generated.

Nonparametric Object Recognition With a New Tactile Sensor

Adding sensing capability to a robot provides the robot with intelligent perception capability and flexibility of decision making. To perform intelligent tasks, robots are highly required to perceive their operating environment, and react accordingly. With this regard, tactile sensors offer to extend the scope of intelligence of a robot for performing tasks which require object touching, recognition, and manipulation. This paper presents the design of an inexpensive pneumatic binary-array tactile sensor for such robotic applications. The paper describes some of the techniques implemented for object recognition from binary sensory information. Furthermore, it details the development of software and hardware which facilitate the sensor to provide useful information to a robot so that the robot perceives its operating environment during manipulation of objects.

Modular Robot Connection Design

The ability to reconfigure automation equipment will reduce the manufacturing costs of obsolesence, training and maintenance while allowing for a faster response to changes in the product line. A modular philosophy will give the user these advantages, but only if based on a common connection standard. A mechanical connection was selected for the UT Modular Robotics Testbed and used in the designs of four robot joint modules and nine robot link modules. The standard was also used for assecories, such as the testand, loading fixtures and endeffectors. Three years of experiments with this connection standard are reviewed, and used as the basis for new connection designs. Experiments using multiple modules assembled as dextrous robots, as well as experiments focusing on the connection itself, will be described. Goals for future connection standards include designs with upward compatibility, combinations of both mechanical and electrical fittings, and robot triendly constraints that allow for automated or remote assembly of modular robots.

Robotic Assembly Cell Simulation

A flexible robotic assembly cell is described, and some of the research activities involving the cell and robot applications in manufacturing environments are presented. This research relies heavily on computer simulation. Assembly cell computer modeling, cell calibration, robot collision detection, and off-line programming are described in this paper.

Selective Robotic Assembly

A new approach to robotic high precision selective assembly is presented. The basis for this selective assembly is a gripper which both grips the part to be assembled along its mating planes and inspects its dimensions while gripping. One hundred percent interchangeability of spare parts is achieved by selecting the appropriate parts for inventory, during assembly. Cost reduction and the increase in product quality are shown by example.

A Robotic Tool Transformation Teacher

The objective of this project was to design and build a system for teaching robot tool transformations. A PUMA and an Adept One robot were used for testing the feasibility of the system. The Tool Transformation Teacher provides for both the manual and programmed control of a robotic manipulator with respect to a tool coordinate system, thus increasing robot flexibility.

Collision-Free Path Generation for Autonomous Manipulators Using Non-Uniform Rational B-Spline (NURBS) via Artificial Transformation

This paper presents an algorithm for collision free path planning of autonomous manipulators among obstacles. The algorithm uses powerful features of Non-Uniform Rational B-splines (NURBS) to determine the path of the manipulator in the complimentary space of the obstacles. Initially the algorithm artificially transforms the obstacles to point size. It then uses these point obstacles and start & target position of the manipulator as control points to determine a NURBS path which is the initial collision-free path. Obstacles are then iteratively increased in size by small increments. After each increment the new collision control points with obstacles are determined and a new collision-free NURBS path is generated to guide the manipulator through crowded obstacles. This procedure is continued till all the obstacles attain their full size and resulting path is maintained free of collision. The developed algorithm is most suited for manipulators facilitated with range sensors for remote detection of obstacles. The paper details the technique for obtaining a smooth collision-free path of a manipulator moving around a crowded environment with static obstacles.

The Design of Manipulator System With Pole Placement Approach

The manipulator system is a sequence of mechanisms jointed with each other. It is difficult to establish the dynamic state equation of such a mechanism system. By means of the bond graph method, it is easy to derive the state equation of a mechanism, then one have the transfer function matrix. According to the combined situation of mechanisms for manipulator, whose transfer function matrix may be obtained. Based on the modern control theory, one will find that in a controllable system, it is possible to place the poles anywhere we wish in the complex plane. In this paper one will develop a new procedure concerning system pole assignment within desired places by using two controllers. An example is illustrated.

Virtual Wedging in Three Dimensional Peg Insertion Tasks

Quasi-static wedging of three-point contacts is investigated, wherein the concepts of virtual and redundant wedging due to a resultant force falling into a friction cone are proposed. We consider the fully-started case of a square peg and hole consisting of two point-surface contacts and one line-line contact. An analysis of the wedging diagram for this highly constrained configuration is carried out and compared to the two dimensional case. An approximate wedging diagram is constructed which shows that wedging of square pegs into square holes is more likely than cylindrical pegs and holes of similar sizes.

Automated Welding Process Fixture Planning Using Features

Flexible robotic welding cells have been established as an integral part of manufacturing. In order to plan the entire welding process in the design stage, mathematical modeling of the planning procedure has become very important. Both the geometric and non-geometric representations, such as the geometric description of workpieces, fixtures, and end-effectors and the planning of the welding process, are the key elements to success. Emphasis in this paper is fixture planning, in which an automated fixturing approach is examined to greatly increase workcell flexibility. A feature-based modeling approach is proposed to simulate the fixturing process in an automated welding cell.