Robert P. Judd

A technique to calibrate industrial robots with experimental verification

This paper presents a method to calibrate industriaI robots. Models developed in the paper correct problems with robot accuracy resulting from errors in the Iink and joint parameter, imperfections in the main spur and encoder pinion gears, and structuraI deformations. Additionaliy, a method that places a singIe transformation which is a simple cyclic function of the joint angles, at the robots end plate to compensate for the remaining inaccuracies is explored, The models used for each of the links contain only four parameters to identify. The experimental procedures used to identify the parameters of the various models proposed are discussed, An iterative technique to solve the inverse kinematic solution is presented. The procedures developed have been applied to an industrial robot. Finally, the relative affects of each of the models used to calibrate the robot are discussed.

A hierarchical cost estimation tool

The estimation of the manufacturing cost of a part in all phases of the design stage is crucial to concurrent engineering. To better estimate the cost for a product, data must be available from both engineering systems and business systems. This paper presents a cost estimation system being developed to support design time cost estimation using the Federated Intelligent Product EnviRonment (FIPER), which is being developed as part of the National Institute of Standards and Technology (NIST) Advanced Technology Program (ATP). The FIPER research team is developing an architecture that interconnects design and analysis software tools in a peer level architecture to support multidisciplinary design optimization (MDO), design for six sigma (DFSS) and robust design.

Mathematical analysis of single-cut osteotomy for complex long bone deformity

This paper presents a model for complex long bone deformity, which is compatible with current medical assessment techniques, and develops a mathematical method for characterization and correction of the deformity.

Frequency domain analysis of learning systems

Frequency domain arguments on a general learning law are presented to verify claims of convergence which relax earlier requirements on the learning law transfer function. Known convergence properties are used to develop a pole-placement interpretation for an example for which simulations using a proportional-derivative learning law form are carried out. Physically relevant disturbances are introduced, and the ability of the learning law to damp out their effects is studied. A significant state-dependent disturbance is shown to be attenuated for reliable trajectory tracking.<<ETX>>

Manufacturing system design methodology: execute the specification

An improved method for designing manufacturing systems is presented. Primary features of the improved method include frequent design iterations by executing the specification early in the life cycle, flexibility to accommodate changing requirements, coordination of engineering disciplines in evolving integrated solutions, and reuseability of commonly used software and hardware portions of a system. Benefits of the improved method include more optimal systems designs, solving integration issues during design phase rather than installation, and verification of design specifications. The improved method is called XSpec, which stands for eXecutable Specification. The XSpec notation and design process are described. Specifications are executed on a tool called XFaST, which stands for eXecutable Factory Simulation Tool.<<ETX>>

Deadlock detection and avoidance for a class of manufacturing systems

A method to avoid deadlock for a large class of manufacturing systems is presented. It is shown that deadlock can be avoided if the system satisfies a set of simple linear constraints. Several examples of the approach are presented and results compared to other deadlock avoidance schemes. The examples demonstrate that significantly higher utilization can be obtained using the proposed scheme.

Hierarchial modeling of manufacturing systems using max-plus algebra

The paper describes a novel approach to model any deterministic manufacturing system. A function block diagram type of model is proposed. A block can be a single machine or a factory. The model is expressed as a system of linear event timing equations using max-plus algebra. One of the advantages of block diagram representation is the simplicity of algebraic relations between the sub-system transfer functions [1]. It is expected that the proposed model will make it possible to develop and use techniques similar to those found in classical transfer function block diagrams.

Necessary and sufficient conditions for deadlock in manufacturing systems

Scheduling resources to avoid deadlock in a manufacturing system has been studied extensively over the past decade. Previous work developed sufficient conditions to avoid deadlocked states. What distinguishes the different approaches is the number of nondeadlocked states that are allowed by the application of the method. This is an important consideration since in all the methods these non-deadlocked states are those with high resource allocation. This paper presents both sufficient and necessary conditions to determine deadlocked states in a manufacturing system. Several examples showing the applications of the theory are presented and are compared with other methods.

EQL an express query language

EQL, an acronym for EXPRESS Query Language, is an SQL-like query language that is used to perform ad hoc queries on data in PART 21 files. PART 21 is the clear text encoding of data in the object-oriented EXPRESS modeling format and is the format for the STEP standards like AP203. Traditional uses for STEP files have been for transferring data between similar tools and populating a data model in one tool with the data from another tool. For example, moving a part design from one CAD system to another CAD system. If however, a software system has a different view of the information, a STEP file from one system contains significant amounts of data not applicable to other system. The receiving system needs the ability to query the STEP file for the objects important to its processing. Additionally, to integrate software systems using EXPRESS and PART 21 as a data transfer mechanism; an ad hoc query language is needed to account for the data in multiple schemas that a tool might expect to encounter. EQL is designed to accept data files in schemas that are not predefined to the tool and has the ability to perform all traditional data manipulation (DML) operations: select, update, insert and delete. EQL does not support data definition (DDL) like creating new object classes.

Max-plus-based mathematical formulation for cyclic permutation flow-shops

Scheduling is a decision-making process that concerns the allocation of limited resources to a set of tasks with the view of optimising one or more objectives. In this work, we are concerned with the cyclic permutation flow-shop problem where a set of parts is repeatedly produced (cyclic) and the sequence of parts on all the machines remains the same (permutation). We develop a mathematical formulation for the above problem using max-plus algebra. We show that this formulation makes it easier to compute the period of a cyclic system and can be used to evaluate solutions in a cyclic flow-shop scheduling problem.