bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Control of a Plate Using Segmented Distributed Sensors and Actuators: Finite Element Development and Analysis
Authors: Tzou H. S. , Bahrami H.
Published: April 2021

Distributed sensing and control of flexible structures have drawn much attention in recent years. Piezoelectric elements can be used with an elastic structure as sensors and actuators for structural monitoring and control applications. This paper presents a development of a thin piezoelectric finite element applied to active control of flexible structures. A piezoelectric finite element is derived using the variational equation and Hamilton’s principle. System equations of a piezoelectric structure are formulated accordingly. Guyan’s reduction technique is incorporated to improve the computation efficiency. Feedback control algorithms are also derived and implemented in the finite element code. Applications of the technique to a plate with segmented distributed sensora/actuators are studied and effectiveness evaluated.
Finite Element Analysis of Turbine Blades
Authors: Carnero A. , Kubiak J. , López A.
Published: April 2021

Frequent failures of long turbine blades forced an electrical utility to sponsor research work to find out the causes of the failures. One of the techniques applied in this work was finite element analysis.

The paper presents an application of the finite element method for computation of the natural frequencies, steady-state and alternating stresses, deformations due to forces acting on the blades and modal shapes of the turbine long blade groups. Two stages, L-1 and L-0 of the low pressure part of a steam turbine, were analyzed.

It has been postulated that the results of the FEM analysis of the blades groups would be complementary to those obtained from the radio telemetry test (which was carried out during operation of the turbine) for the purpose of blade group failure diagnosis. However, the results of the analysis show that the FEM results were decisive in blade failure identification (L-1 stage moving blades).

The graphical post processor of the FEM code revealed that the first blade in the group was the one most protruding from the stage rotating plane, thus indicating that this blade was the most prone to erosion. This was confirmed in the inspection of the turbine. This finding showed why only the first blade in the group was cracked (erosion induced cracks). The mode shapes were also very helpful in identifying other types of cracks which affected other parts of the blades.

It can be concluded that the finite element method is very useful for identification of very difficult cases of blade faults and indispensable for carrying out modifications to prevent future failures.
Finite Element Mesh Generator Applying Constraints’ Propagation and Isoparametric Mapping
Authors: Rodriguez J. , Him M.
Published: April 2021

This paper presents a finite element mesh generation algorithm (PREPAT) designed to automatically discretize two-dimensional domains. The mesh generation algorithm is a mapping scheme which creates a uniform isoparametric FE model based on a pre-partitioned domain of the component. The proposed algorithm provides a faster and more accurate tool in the pre-processing phase of a Finite Element Analysis (FEA).

A primary goal of the developed mesh generator is to create a finite element model requiring only essential input from the analyst. As a result, the generator code utilizes only a sketch, based on geometric primitives, and information relating to loading/boundary conditions. These conditions represents the constraints that are propagated throughout the model and the available finite elements are uniformly mapped in the resulting sub-domains.

Relative advantages and limitations of the mesh generator are discussed. Examples are presented to illustrate the accuracy, efficiency and applicability of PREPAT.
Computer-Aided Geometry Design of Trapezoidal Threaded Variable Pitch Conical Lead Screws
Authors: Liu Jen-Yu , Yan Hong-Sen
Published: April 2021

Based on conical screw matrix transformation, equations of variable pitch conical helix and helicoid are derived. The surface geometry of a trapezoidal threaded variable pitch conical lead screw is generated by a trapezoid with a variable pitch conical screw motion. A computer-aided design code is developed with Patran Plus solid modeling. The result of this work is necessary for the computer-aided machining of trapezoidal threaded variable pitch conical lead screws.
Line Integral Computation of Geometrical Properties of Plane Faces and Polyhedra
Authors: Wilson H. B. , Chang G. S.
Published: April 2021

Surface integrals arising during computation of geometrical properties of volumes are studied. Line integrals are formulated which give the contributions of a general plane surface area. These integrals are evaluated to provide more concise exact formulas for the geometrical properties of polyhedra than have been obtained previously. A short computer program for polyhedron properties is presented, along with numerical examples.
Using Expert Systems and the Personal Computer in the Design of Machine Elements
Authors: Shoup Terry E.
Published: April 2021

This paper presents guidelines for the preparation of software that exploits the advantages of expert systems and the personal computer to augment the design of machine elements. An example software package CSPRING is presented to illustrate the use of these guidelines for the design of helical wire compression springs.
Using Demostration Programs in a Numerical Methods Course
Authors: Toogood R. W.
Published: April 2021

This paper discusses some pedagogical issues related to the use of computers in undergraduate engineering programs. Some computer programs are described which illustrate several methods used for effective demonstration and computer aided instruction of material presented in a first course in numerical methods.
Incorporating Solid Modeling Into Engineering Curriculum
Authors: Pao Y. C.
Published: April 2021

Solid modeling is proposed as an integral part of freshman teaching on engineering drafting, computer programming, and computer-aided design. A low-cost, commercially available software, SilverScreen, is recommended for the students to experiment on wireframe and solid modelings. In addition to providing the basic drafting needs of dimensioning, labelling text of various size and orientation, chamfering, and filleting, other topics of solid modeling are proposed for the higher-level engineering courses. It enables the students to apply multiple-view, split-screen display (such as showing the top, front, right-side, auxiliary, and section views all on one screen), and Boolean manipulation of solids (union, subtraction, and others). Moreover, students can also use SilverScreen in conjunction with other programs written in BASIC and C languages.
Computer-Aided Design of Bicycles
Authors: Khosrowjerdi M. , Azar Robert C. , Salehi Ali , Nazari G. H.
Published: April 2021

Traditional manual designing of bicycles often relies on prototype building and testing and since structural deficiencies often are not obvious until a prototype fails, several build-and-test iterations are usually required before a satisfactory design is obtained. Also, the final design may be less than optimal because of quick fixes inserted at the last minute. However, by utilizing computer-aided design, better bicycles can be designed at smaller investments of time and money.

The development and utilization of a DI-3000 based (graphics subroutines developed by Precision Visual), user-friendly, self contained computer aided design package for the analysis and design of bicycle frames and forks are presented. The software, written in Fortran 77 and executable on most passive and active graphics devices, creates the necessary analysis input files for the ANSYS finite element program (developed and marketed by Swanson Analysis System Inc.). These pre and post processing files in conjunction with the ANSYS program are used to determine deflections and stress components. The graphics user interface module of the software allows users to enter bicycle geometry, loading and other pertinent data quickly and efficiently. Tubing configuration and specifications are selected from a data base through the use of cursor-controlled menus. The loading menu presents users with seven different types of realistic and self-consistent loading conditions from which to choose. Computer graphics is also used extensively wherever appropriate to enhance user-computer interaction. Contrasting color and text size are used to explain pictorially as well as visually unfamiliar terminology and to clarify vague sign or orientation conventions, thus, leading to more accurate input.

While this package has been designed for instructional purposes, it can also be used by design engineers involved in the design of bicycles to facilitate the creation of ANSYS pre and post processing files.
Teaching Computer-Based Data Acquisition Through an Airfoil Experiment
Authors: Yip T. Gary
Published: April 2021

This paper describes a three-week long project for teaching microcomputer-based data acquisition. The project is part of a senior level laboratory course for mechanical engineering students at Santa Clara University. The subject of investigation is the lift coefficient of an airfoil.

Students in groups of two carried out the project in three phases. The laboratory activities in each phase are designed to provide the students hands-on experience with the basic functions, hardware and software of a microcomputer-based data acquisition system. Typical results obtained by the students are presented. The project has been proved to be successful for the students to learn and practice the three basic concepts in data acquisition which are measurements, controls and programming.
Developing a CAD Tutorial Using Hypermedia Concepts
Authors: Cwiakala Martin , Stamp Scott
Published: April 2021

This paper presents implementation of techniques formerly developed by one of the authors (Cwiakala) to create an interactive CAD tutorial for students. By using the hypermedia concept of command buttons, students can maneuver through the tutorial by following a “default path”, or jump to a specific point of interest. The knowledge required to work the tutorial is minimal. By developing the tutorial directly within the CAD package, commands may be tested at any time during the tutorial session. CAD software requirements are specified. Students were surveyed on their opinion regarding the tutorial and its supporting documentation. Strong points as well as weak are presented, and alternative methods of creating a tutorial are also discussed.
Computer Modeling of Flow Through Engineering Devices: Exercises for the Undergraduate Student
Authors: Bazaar J. J. , Shanebrook J. R.
Published: April 2021

The purpose of this paper is to describe four computer exercises that have been developed for undergraduate engineering students at Union College. Each exercise involves a computer model for predicting steady, viscous flow through an engineering device. All of the analyses were performed using FLUENT, a finite-difference fluid modeling program marketed by Creare, Inc. The following cases are described in this paper:

1. The flow through a square-edged orifice was modeled and results for discharge coefficient are compared with experimental data published by the American Society of Mechanical Engineers (ASME).

2. The flow through a quadrant-edged orifice was modeled and results for discharge coefficient are compared with published data.

3. The flow through a Herschel-type Venturi meter was calculated and results for discharge coefficient are compared with ASME data.

4. The flow through a sudden pipe expansion was modeled and results for head loss are compared with a theoretical model.
Development of an Integrated Simulation and Experimentation Approach to Engineering Education
Authors: Buffinton Keith W. , Baish James W. , Moffitt James H.
Published: April 2021

Many universities currently make extensive use of computer simulations in the teaching of undergraduate courses in engineering. This paper considers the proper role of computer simulations in an engineering curriculum and suggests that simulations alone do not provide the fundamental understanding of physical systems required of practicing engineers. An alternate approach in the use of simulations in engineering education is under development at Bucknell University that integrates both the computational and the laboratory experiences of students. This integration is achieved through the creation of a laboratory environment that provides both the computational hardware and software for preforming sophisticated simulations of various engineering systems and the physical hardware needed to verify the simulations. The unique aspect of this environment is the emphasis on the interactive integration of the computational and experimentation experiences of the student, thereby allowing them both to quickly see the limits of their simulations and to gain a firsthand understanding of the actual performance of complex physical systems.
Optimum Design of a Bipedal Walking Robot
Authors: Martin Karen , Reuber Mark
Published: April 2021

This paper describes the design, fabrication, and testing of “Bigfoot,” a bipedal walking machine designed to optimize speed, cost, and ease of assembly. Bigfoot walks at near-human walking speed (0.24 m/s), can be assembled/disassembled in two hours, and has a programmable, computer-controlled start-up procedure. Design for manufacturing and assembly techniques (DFMA) were used to reduce the final weight of the robot to 12 kg, the number of structural parts to 39 individual pieces held together with 50 fasteners, and the final robot cost to $300.
Combustion Modelling to Evaluate Turbulent Burning Velocities During Spark Ignition Engine Combustion
Authors: James E. H.
Published: April 2021

“Phenomenological” computer models of the spark ignition engine combustion process are predominantly used in a “predictive” mode i.e. the modeller develops the computer program by utilising the best current understanding of phenomena associated with the process. Thus, suitable expressions are incorporated to depict turbulent burning velocity, heat exchange with the surroundings, flame pattern development, exhaust emissions etc.. The accuracy of the model is then tested by subsequent comparison with pertinent “global” engine performance parameters such as pressure-time diagrams, average flame speeds and exhaust emissions. The “predictiveness” of the model arises from the inclusion of the turbulent burning velocity expression and assumed flame pattern development. These are notoriously difficult to specify precisely and resort is often made to generalised approximations. Thus, turbulent burning velocity is frequently accounted for by the use of expressions developed from experiments on dissimilar engine designs or even “out-of-engine” flames. Accurate flame pattern development is an equally unknown quantity since it is influenced by turbulence and swirl levels, combustion chamber surface temperatures and design, mixture homogeneity etc.. These difficulties are invariably overcome by subsuming them in a general inaccurate assumption that the flame development is spherical in nature and centred at the spark plug. Even though the “global” computer model predictions may be acceptably accurate with such assumptions, it is highly unlikely that the detailed flame progression across the chamber is modelled correctly. To overcome such criticisms, the computer model can be used in a different operational mode (1) with the ultimate aim of more precise specifications of turbulent burning velocity and how it varies across the combustion chamber.
Computer Modeling, Simulation, and Validation at FMC
Authors: Fatemi B. , Wiederrick J.
Published: April 2021

Increasing performance requirements of present and future mechanical systems, along with the development of cost effective high performance computers, is creating an environment where new designs require the support of numerical simulations to be successful both technically and commercially. This new design environment requires an integrated systems approach to design with more exhaustive and accurate engineering analyses being made earlier, faster, and at reduced cost and physical risk. The use of analysis in design provides better prototypes, and the same computer models provide a basis for properly interpreting/understanding empirical results. The combined effect is a shorter development cycle and a superior product based on well understood principles.

FMC, because of its diversified product lines has recognized this need and has been developing verified numerical simulation tools in support of design activities. The overall objective has been to develop verified modeling and numerical simulation capabilities to predict the performance of a total mechanical system. Our approach is to incrementally develop, validate, and integrate subsystem models into a total system level model that includes all significant subsystem interactions. Hardware and software tools for computer graphic rendering, test data acquisition, reduction, and comparison are also being developed that facilitate our goals. This presentation will provide a summary of our computer simulation and validation activities in areas of finite element techniques, kinematic and dynamic analyses, vehicle systems analysis, computer-aided testing, interactive simulation, dynamic modeling using symbolic code generation, high-performance computing, and scientific visualization.
A Least-Squared Optimization Approach to the Design of Belleville Springs
Authors: Shoup Terry E. , Sanchez Lilia
Published: April 2021

Belleville spring washers, also known as coned-disk springs were patented in France by Julien Belleville in 1867 and were the topic of a fundamental engineering study by Almen and Laszlo in 1936. The main advantage to these devices is their compactness and their ability to handle large loads. The deflection of these springs has been found to be nonlinear and stiffening springs have been shown to be quite useful for the design of vibration isolation mounts where combined vibration and shock loading are present. It is the purpose of this investigation to demonstrate the use of the method of least-squares optimization to design Belleville springs having prescribed load-vs-deflection performance behavior.
Monte Carlo Simulations of Two and Three Dimensional Fluids Revisited: A Successful Demonstration of the Use of Polar Coordinates
Authors: Conlan Francis J.
Published: April 2021

Standard Monte Carlo (MC) simulation techniques in current use (Valleau and Whittington, Valleau and Torrie, 1977) in the study of Statistical properties of fluids are limited to being performed in rectangular coordinates and rely on a non-physical construct called virtual images. Virtual imaging was a technique used in the early days of computer simulations (1950–1960) to reduce extraneous boundary effects in Monte Carlo simulations of fluids (Wood, 1968). Simulations were restricted to rectangular sampling regions providing the central sampling area with virtual images of itself. All particles, including those near the boundary, by other particles.
Assemblability Evaluation Method Based on an Assembly Model and an Assembly Process Model
Authors: Okano Akira
Published: April 2021

An evaluation of assemblability at an early design phase leads to a better product and a better assembly process plan. This paper proposes a method for computerized evaluation of assemblability, based on an assembly model and an assembly process model, which are also proposed in the paper. An assembly model consists of form features, assembly features, and constraints among those features. An AND/OR graph is used to represent all the assembly processes. A node has the direction of access to a subassembly as an attribute. This make it possible to create an actual assembly process plan. To generate a graph efficiently, the system interacts with the user and acquires knowledge about order of precedence of operations. In the evaluation of assemblability, consideration is given to factors such as assembly operations and direction of access. These are calculated from the assembly model. The assembly process model is then used to calculate the best assembly process.
Multi-Criteria Optimal Placement of Manipulators in Cluttered Environments
Authors: Pamanes G. J. A. , Zeghloul S.
Published: April 2021

A general method is presented to automatically determine the placement of manipulators which allows to optimize multiple kinematic performances indices during the execution of their tasks. It considers the presence of obstacles in the workstation and constraints on the motion of the manipulator’s joints. The algorithm used for obstacle avoidance allows to limit the proximity between the manipulator and the obstacles to an admissible minimum value. The complete formulation is included, and an example with a six-degree-of-freedom manipulator in a cluttered environment is solved which shows the improvements achieved for the manipulator performances by applying the proposed method.
On Fast Computation of Minimum Distance Between Convex Polyhedrons: Application to Collision Detection in a Robotic Simulation System
Authors: Zeghloul S. , Rambeaud P. , Lallemand J. P.
Published: April 2021

In this paper, we suggest an algorithm which detects collisions based on the computation of the minimum distance between two convex polyhedrons. This algorithm can be used for simulations of robotic structure movement. It offers two advantages: first, it detects the collisions between two convex polyhedral shapes and secondly, if there is no collision, it calculates the distance between the solids. This information is of greatest importance for more advanced path planning systems which must not only detect collisions but also avoid them.
Multi-Axis Motion Controllers for Robots and AGVs
Authors: Rajagopalan Ramesh , Cheng R. M. H. , Huard Gilles
Published: April 2021

A micro computer based multi-axis motion controller for servo control of d.c. motors for robotic applications is presented in this paper. The motion controller interface uses LM628 precision motion controller chips. The design presented in this paper facilitates control of four motors from a single PC board consisting of four LM628 chips. The motion controller board has provisions to issue commands to all or some chips simultaneously. The presence of LM628 chips relieves the host computer of the responsibility of feedback control and it is free to perform other tasks once the necessary commands are downloaded to the motion controller board. The motion controller chips perform the closed loop control to drive the motors to the desired positions and/or to run at the desired velocity. The motion controller board also has safety features to stop the motors in case of problems and provide self diagnostics. This motion controller is used to control a prototype Automatic Guided Vehicle (AGV) and a five axis robot. The performance of the motion controller board is observed to be satisfactory.
Feasibility Study of Designing a Three Legged Walking Robot: Tribot
Authors: Lin Yueh-Jaw , Tegland Aaron
Published: April 2021

In recent years, walking robot research has become an important robotic research topic because walking robots possess mobility, as oppose to stationary robots. However, current walking robot research has only concentrated on even numbered legged robots. Walking robots with odd numbered legs are still lack of attention. This paper presents the study on an odd numbered legged (three-legged) walking robot — Tribot. The feasibility of three-legged walking is first investigated using computer simulation based on a scaled down tribot model. The computer display of motion simulation shows that a walking robot with three legs is feasible with a periodic gait. During the course of the feasibility study, the general design of the three-legged robot is also analyzed for various weights, weight distributions, and link lengths. In addition, the optimized design parameters and limitations are found for certain knee arrangements. These design considerations and feasibility study using computer display can serve as a general guideline for designing odd numbered legged robots.
Microcomputer-Based Control System for a Surface-Climbing Robot
Authors: Bahr Behnam , Lankarani Hamid M. , Motavalli Saeid
Published: April 2021

A new portable surface-climbing robot is presented for the inspection and maintenance of structures such as nuclear power plants, aircraft, bridges, and so on. The robot uses vacuum suction cups for sticking to the surface of the structure. It is capable of climbing on straight or curved surfaces in four directions, up/down or left/right in strokes of 55 millimeters. The positioning of the robot is achieved by the use of a joy-stick or a personal computer. The emphasis of this paper is on the hardware and software designs of this new surface-climbing robot. The robot is maneuvered by a microcomputer which is linked to a logical network for receiving the feedback and the status of the robot at any time. The address and data lines of the computer are used to issue control commands.
Combining Heuristics With Inverse Kinematics for Automatic Path Planning
Authors: Agba Emmanuel I. , Huang Ming Z. , Wong Tin-Lup
Published: April 2021

In manipulator path planning, degeneracies from inverse kinematics solutions has been observed to exist for certain arm configurations, although the manipulator can physically attain such configurations. In addition, closed-form inverse kinematics offers multiple sets of solutions from which one set must be selected. In this paper, using an increasingly popular manipulator, we discuss the implementation issues of the closed-form inverse kinematics solution in planning trajectory to ensure that joint solutions exist for all possible manipulator configurations. We use an approach based on known facts about the manipulator geometry and physical constraints coupled with heuristics to generate physically attainable joint solutions from the inverse kinematics. The conditions that cause solution degeneracy will be demonstrated to be related to singularity conditions, and allowable solutions will be selected based on physical constraints of the joints.
Robot Path Planning by Means of Binary Algebra
Authors: Yannoulakis Nicholas J. , Wysk Richard A.
Published: April 2021

The issues of robot path planning and collision avoidance have been addressed extensively in literature. This paper examines these problems for a specific domain: that of a rectangular gripper moving in a two-dimensional space of iso-oriented rectangular obstacles. The free space is represented by a set of binary strings. These strings are manipulated through Boolean algebra to yield the largest convex areas in which the gripper can move without colliding with any obstacles. The largest convex areas then become the nodes of two networks (one for each of the orthogonal orientations of the gripper), the arcs of which indicate the possible gripper paths and roll locations. Based on these networks, a search procedure can produce the shortest path from a start to a target position. This algorithm is easy to implement on a PC and will go from a workspace representation to robot control commands.
Two Robot Arm Cooperative Path Planning Using String Stretching
Authors: Schima Francis , Derby Stephen
Published: April 2021

Two arm robot path planning has many applications. Potential uses of 2 arm robot path planning include terrestrial and space based construction, and general movement of objects. The U.S. space station will most likely be built using robots so that humans do not have to be put into space regularly at great expense and risk. Control of robots from Earth via telerobotics is not practical because the robots will be so far away that there is a delay in the signals due to the great distance between the robots and the controllers and the fact that the signals are limited by the speed of light. The robot arms could also be controlled remotely from space, but only one at a time could be controlled and thus many people would need to be sent up to control all of the robots. One pair of robot arms can replace one human to manually build a structure. However, there would not be any savings in the number of humans sent into space because each pair of robot arms would require a human operator in space. Thus the robot arms should be autonomous or at least semi-autonomous to reduce the number of humans required in space for construction of the space station.
Optimization in Trajectory Planning of Multi-Jointed Fingers in Dextrous Hand Designs
Authors: Meghdari A. , Sayyaadi H.
Published: April 2021

An optimization technique based on the well known Dynamic Programming Algorithm is applied to the motion control trajectories and path planning of multi-jointed fingers in dextrous hand designs. A three fingered hand with each finger containing four degrees of freedom is considered for analysis. After generating the kinematics and dynamics equations of such a hand, optimum values of the joints torques and velocities are computed such that the finger-tips of the hand are moved through their prescribed trajectories with the least time or/and energy to reach the object being grasped. Finally, optimal as well as feasible solutions for the multi-jointed fingers are identified and the results are presented.
Optimization of Polynomial Trajectories for Robotic Manipulators
Authors: Yildirim Yüksel , Onwubiko Chinyere , Fichter Eugene F.
Published: April 2021

This paper utilizes the modified pattern search method to solve the nonlinear optimization problem of design of minimum-time robot trajectories between given end states in a workspace containing obstacles. This method is applied to a collision-free path of a two-degree-of-freedom elbow manipulator. Bezier curves, B-spline curves, and parabolic blend curves are used to simplify end-effector path planning.

Motion of the manipulator, represented by a sequence of Cartesian knots along the end-effector path, is first transformed into sets of joints displacements. Piecewise cubic spline functions are then fit to the sequence of joint displacements. The minimum-time trajectory planning problem is formulated as the problem of minimizing the total traveling time, taken as objective function, subject to constraints on joint positions, velocities, accelerations, jerks, motor torques, and end-effector acceleration.

The computer program, ROBOPATH, has been developed to implement this algorithm for generating end-effector paths and joint trajectories for a manipulator with two links. The results show the modified pattern search method to be a very effective nonlinear optimization technique in design of minimum-time robot trajectories. Also, ROBOPATH can be a useful tool in the design of manipulators, robot tasks and workcells.
A Multi-Assessment Diagnosis for Robot Manipulators
Authors: Tzou H. S. , Fang M. , Rong Y. , Bahrami H.
Published: April 2021

Robot manipulators are highly integrated into manufacturing systems today. Similar to other manufacturing machines, robot failure can also significantly disrupt a production process. Thus, dynamic monitoring and diagnosis of robot manipulators is of importance, similar to other machines. This paper describes a diagnostic monitoring procedure for robot operations using a time series based multi-assessment technique. Experimental results shows the applicability of the technique.
An Adaptive Control Subsystem for Quasi-Static Cutting Force Control in Turning
Authors: Harder Lars , Lundholm Thomas , Lindström Bo
Published: April 2021

The future capital intensive manufacturing industry will demand efficient utilization of machine tools. Thus, a modular real-time adaptive control (AC) system for turning is being developed. Different real-time monitoring and control tasks are assigned to integral subsystems respectively, organized in a distributed computer system and supervised by a master computer in accordance with a main AC strategy. The subsystem for quasi-static cutting force control adapts the feedrate to the present machining situation in order to keep the tangential cutting force constant at a maximum level, given by the machine tool and the tool constraints. Since the cutting process is nonlinear and time-varying, it is difficult to control Therefore, a linearized process model has been introduced and a constant-gain, incremental Pi-controller has been designed and tested with good results. In this paper we will present the AC turning system, focusing on the subsystem for quasi-static cutting force control.
A Micro-Computer Based Part/Tool Monitoring System for a Robotic Cell
Authors: Motavalli Saeid , Bahr Behnam , Lankarani Hamid M.
Published: April 2021

This paper describes the elements of a unique robotic cell integrated with a vision system. The cell consists of a PUMA 560 robot, a vision system, and a conveyor belt. The robot end effector is a drill used in a drilling operation. The vision system has a two fold function: monitoring tool wear, and recognizing parts passing over the conveyor belt. Both tool monitoring and part recognition are performed using the vision system. The vision system is PC-based and uses two CCD video cameras. One camera is mounted vertically overlooking the conveyor belt, and the other camera is mounted horizontally for tool wear monitoring.

Algorithms have been developed that interface the vision system with the robot. Whenever a part reaches the view point of the camera, an image of the part is captured. A recognition algorithm has been developed that recognizes the part and signals the robot to perform a specific sequence of operation on that part. The part is then moved to the drilling station where the PUMA robot perform the operation sequence according to the stored process plan. After each part is manufactured, the robot moves the drill to the view point of the tool monitoring camera, where an image of the drill head is captured. This image is then processed with the developed tool monitoring algorithm and tool wear is identified.
Inverse Dynamics Based Trajectory Tracking for a One-Link Flexible Arm
Authors: López-Linares Santiago , Jacobus Roberto F. , Carrera Eliodoro , Serna Miguel A.
Published: April 2021

This paper presents a new method for controlling a one-link flexible manipulator, based on the solution to the Inverse Dynamic Problem and on a Linear Quadratic Gaussian regulator (LQG). The inverse dynamic solution provides the torque that must be applied by the actuator at the hub to obtain a given trajectory at the tip. This torque can then be used in an open-loop control but, in practice, errors in tip position will appear along the way due to friction, unknown parameters in the model, disturbances, etc. To cope with these problems a trajectory following control is suggested. The technique consists in designing an LQG capable of driving the arm to intermediate states computed in the Inverse Dynamic Problem. Computer simulations with a Finite Element Model of the flexible arm are presented showing a very accurate trajectory tracking.
Architecture of Operating System Software of an Autonomous Vehicle
Authors: Rajagopalan Ramesh , Cheng R. M. H.
Published: April 2021

Operating system software of a prototype autonomous vehicle is presented in this paper. The prototype Autonomous Vehicle employs binary camera vision for navigation and is differentially steered. The software is a top-down design, modular in architecture to facilitate software maintenance and continual enhancement. At this present stage of development, it contains several parameter definition files and close to 50 major sub functions/sub function groups besides the main supervisory module. The subroutines range from system validation (data acquisition in real-time) and equipment calibration, image data filtering and processing to the driving and steering of the vehicle. The control codes are developed using the Borland Turbo-C compiler.
An Analytic Solution for Minimum-Norm Rate Coordination in Redundant Manipulators
Authors: Varma Hareendra , Huang Ming Z.
Published: April 2021

In this paper, we present a novel method which results in efficient minimum norm solution for the rate coordination problem in redundant manipulators. The theory is developed based on a geometric interpretation that, for minimum norm criterion, vectors orthogonal to constraint space should pass through the origin of the solution space. It is shown that for any spacial manipulator with 1, 2 or 3 degrees of redundancy, the minimum norm rate solution can be derived in analytic closed form. The method offers an equivalent but much more efficient alternative to using the pseudoinverse in redundancy resolution and, in fact, is applicable to any underdetermined linear system. An alternative formulation of pseudo-inverse arrived at in the course of the development is also presented.
Dynamics Equations of Robots Mounted on Moving Bases
Authors: Toogood R. W.
Published: April 2021

A number of programs have been developed for the automatic symbolic generation of efficient computer code for the dynamic analysis of serial rigid and flexible link manipulators. Code for both the inverse and the direct dynamics computations can be generated. The symbolic generators allow the robot base to be given an arbitrary linear acceleration anchor angular velocity and acceleration. The efficiency of the generated code is an important consideration for simulation studies and/or implementation in control systems. This paper briefly describes the symbolic generation and simplification techniques. The added computational load due to including the base motion is discussed. Some dynamics simulation results are presented for a 3R rigid link manipulator mounted on an oscillating base, which graphically illustrates the effect of the base movement on the dynamics.
Robotic Manipulator Optimal Control Algorithm Based on Central Difference Approximation of Equation of Motion
Authors: Bahrami Mohsen , Jazar G. R. Nakhaie
Published: April 2021

The complex nature of robotic manipulator dynamic equations is well studied. Many different control algorithms have been developed; among them optimal control ones. However, most of them are either based on simplified equations of motion or are tedious to implement or set up.

In this work equations of motion are approximated using central difference technics and Taylor series expansion, while path of motion is divided in finite segments. The motion is assumed to have zero velocity at the beginning and at the end of the motion without loss of generality. Showing that Pontryagin principle is applicable and the optimal controller is bang bang. Actuator torques, iscolines, and switching points, can be calculated. The preparation time, problem set up and execution time are relatively small, and programming efforts are reasonably low.

The algorithm is implemented for a 2R planar robotic manipulator, and results are presented.
A Kalman Filter for Nonlinear Differential Algebraic Systems
Authors: Perz E. , Sargent R. W. H.
Published: April 2021

This paper describes a filtering algorithm for measurements from dynamical systems which are corrupted by noise. The standard Kalman filter is applicable only to systems which can be modelled by linear ordinary differential equations. In this work, the basic idea of the Kalman filter is extended to the more general case of systems which require a differential algebraic (DAE) system as the numerical model. The paper describes the mathematical formulation of this extension to the Kalman filter and its implementation. Finally some results obtained with a test system are given.
Database Considerations for an ICU Patient Data Management System
Authors: Fumai N. , Collet C. , Petroni M. , Roger K. , Saab E. , Malowany A. S. , Carnevale F. A. , Gottesman R. D.
Published: April 2021

A Patient Data Management System (PDMS) is being developed for use in the Intensive Care Unit (ICU) of the Montreal Children’s Hospital. The PDMS acquires real-time patient data from a network of physiological bedside monitors and facilitates the review and interpretation of this data by presenting it as graphical trends, charts and plots on a color video display.

Due to the large amounts of data involved, the data storage and data management processes are an important task of the PDMS. The data management structure must integrate varied data types and provide database support for different applications, while preserving the real-time acquisition of network data. This paper outlines a new data management structure which is based primarily on OS/2’s Extended Edition relational database. The relational database design is expected to solve the query shortcomings of the previous data management structure, as well as offer support for security and concurrency. The discussion will also highlight future advantages available from a network implementation.
Contribution to Computer Control and Optimization of Hydro-Abrasive Jet Machining Process
Authors: Groppetti Roberto , Comi Giuseppe
Published: April 2021

Hydro-Abrasive Jet Machining (HAJM) has demonstrated its suitability for several applications in the machining of a wide spectrum of materials (metals, polymers, ceramics, fibre reinforced composites, etc.). The paper is a contribution to the computer control, integration and optimization of HAJM process in order to establish a hierarchical control architecture and a platform for the implementation of a real-time Adaptive Control Optimization (ACO) module. The paper presents the approach followed and the main results obtained during the development and implementation of a HAJM cell and its computerized controller. A critical analysis of the process variables available in the literature is presented, in order to identify the process variables and to define a process model suitable for HAJM real-time control and optimization. Besides for HAJM computer control, in order to correlate process variables and parameters with machining results, a process model and an optimization procedure are necessary in order to avoid expensive and time-consuming experiments for the determination of optimal machining conditions. The paper presents the configuration of the cell and the specific components adopted in order to make possible a fully computerized control of the process, and the architecture of the controller, capable to manage the several logical and analogical signals from the different modules of the cell, for multiprogramming, process monitoring, controlling, process parameters predetermination, process condition multiobjective optimization. A prediction and an optimization model is presented allowing the identification of optimal machining conditions using multiobjective programming. This model is based on the definition of an economy function and a productivity function, with suitable constraints relevant to the required machining quality, the required kerfing depth and the available resources. A test case based on experimental results is discussed in order to validate the model.
Representing and Manipulating Interacting and Interfeature Relationships in Engineering Design for Manufacture
Authors: da Silva R. E. , Wood K. L. , Beaman J. J.
Published: April 2021

The objective of design for manufacture is to sever the dichotomy of design and manufacturing practices so that these two areas will be pursued as a homogeneous activity. Many issues are important for this “marriage” of design and manufacturing: the representation of manufacturing information for reasoning in the early stages of a design; the development of computer-aided tools for process planning, tolerance design and analysis, and automatic assembly; the formulation of design systems to facilitate reasoning about the topology and geometric structure of mechanical parts; etc. In this paper, a strategy for the representation and manipulation of spatial relationships between features is described. A language, made up of a set of primitives (lexical icons and geometric concepts), is developed for the domain of standard cavity-type features encountered in discrete parts manufacturing. A formal methodology is subsequently discussed for modeling these features in the context of interacting and interfeature relationships. Two applications, in the areas of fixture design and process planning, illustrate the utility of the formalism.
A Prototype of Feature-Based Design for Assembly
Authors: DeFazio T. L. , Edsall A. C. , Gustavson R. E. , Hernandez J. A. , Hutchins P. M. , Leung H.-W. , Luby S. C. , Metzinger R. W. , Nevins J. L. , Tung K. K. , Whitney D. E.
Published: April 2021

This paper describes a prototype software system that implements a form of feature-based design for assembly. It is not an automated design system but instead a decision and design aid for designers interested in Concurrent Design. Feature-based design captures design intent (assembly topology, product function, manufacturing, or field use) while creating part and product geometry. Design for assembly as used here extends existing ideas about critiquing part shapes and part count to include assembly process planning, assembly sequence generation, assembly fixturing assessments, and assembly process costs. This work was primarily Interested in identifying the information important to DFA tasks, and how that information could be captured using feature-based design. It was not intended to extend the state of the art in feature-based geometry creation, but rather to explore the uses of the information that can be captured. The prototype system has been programmed in LISP on Sun workstations. Its research contributions comprise integration of feature-based design with several existing and new assembly analysis and synthesis algorithms; construction of feature properties to meet the needs of those algorithms; a carefully chosen division of labor between designer and computer; and illustration of feature-based models of products as the information source for assembly analysis and process design. Some of its functions have been implemented approximately or partially but they give the flavor of the benefits to be expected from a fully functional system.
A Design System for Parametric Design of Complex Products
Authors: Malmqvist Johan
Published: April 2021

In this report a design system for parametric design of complex products is presented. The system is based on product models for complex products and components. These models were implemented as general framework models using the data base management system TORNADO. The user creates models for specific products by filling out forms. Consequently, all products can be represented in a uniform way. This gives the advantage that all service software (for storage in the product data base, retrieval of component data etc.) associated to a certain product model can be shared. The only lines of code the designer writes when creating a new component family are the design rules of the component. In association with the models a design system for complex products is presented. Benefitting from the uniform representations of the products, the system lets the user control the design process, while a system kernel handles the constraint management.

The product models and the design system have been applied to hydraulic cylinder design.
The Use of Algebraic Functions As a Solid Modeling Alternative: An Investigation
Authors: Blechschmidt James L. , Nagasuru D.
Published: April 2021

An investigation of surface and solid modeling using a single unbounded algebraic function for objects requiring free form surfaces is discussed. The purpose of this investigation is to determine if a single closed algebraic function can be effectively used to represent objects. Curve fitting techniques are developed. Surfaces using implicit algebraic functions are developed using the techniques of revolution about an axis and extrusion along a curve segment. Infinite extrusions of a planar cross section along an axis of the form y = f(x) are developed. The boolean operators of union, intersection, and difference are developed using the defining function form of algebraic functions. All of the operations have been accomplished in algebra using polynomial multiplication, addition, and subtraction. Examples of all the operations are presented.