Stephen Derby

A Safety and Collision Avoidance System for Industrial Robots

As more and more robots are installed in the industrial sector, the statistical likelihood for accidents involving robots increases unless careful design and implementation of safety features occurs. Some worker deaths related to robot accidents have been reported in Japan. Most workers and users of robots have embarked on a safety program depending on personnel training, preventative maintenance, and perimeter barriers and/or interlocks. Most of these necessary methods still do not address the issue of personnel required to be close to a robot during teaching, maintenance, and troubleshooting. The results of a research project underway at Rensselaer Polytechnic Institute to develop a computer controlled sensor system that will monitor the working envelope of a robot are discussed. If an dangerous situation occurs, this system will cause the robot to take corrective action to avoid personnel injury or damage to the robot or equipment.

Simulating Motion Elements of General-Purpose Robot Arms

Robot arm displacement curves are constructed, assuming that all links in the arm are rigid. This can be accomplished by using familiar, cam-motion profile techniques whenever possible. The benefits of these considerations can help achieve smoother motion while minimizing wear on and effort by the robot actuators. A set of motion primitives within the General Robot Arm Simulation Program (GRASP) are presented as examples.

Designed experiments to investigate the solder joint quality output of a prototype automated surface mount replacement system

A robotic remanufacturing system at Rensselaer has been developed to replace fine pitch surface mounted components on a populated printed circuit board (PCB). The performance goal is to maximize the quality of the solder joint output to optimize the systems throughput. The purpose of this paper is to present the process parameters determined for obtaining a good solder joint with the rework cell. Developed here and to show an analysis of the solder joint quality obtained from the developed system. Maximizing the rate of correctly reworked components by the system is not chosen as a goal for measuring the systems performance. This is because rework is a low volume process and the cell being used, is an experimental prototype system.

The maximum reach of revolute jointed manipulators

Abstract The maximum reach of a manipulator consisting of 3 or more revolute joints is achieved when the line connecting the hand to the base is made to intersect all the intermediate joint axes. By a one to one mapping, the working volume can be generated.

Integration steps of a fully-automated remanufacturing cell system for fine-pitch surface mounted devices

Surface mounted components have become the choice of the electronics manufacturing industry to allow the production of complex circuit boards. New components using increased lead counts on finer pitches make successful assembly difficult. The increased complexity, cost, and lead count of the surface mount technology (SMT) components, and also the increasing compactness of the SMT assemblies have demanded the creation of newer rework tools as an essential part of electronics manufacturing. Therefore, it becomes essential to have a well-controlled process to assure that rework is not only possible but that it is consistent and flawless. Automation is the common answer to achieve both efficiency and quality. This paper describes a remanufacturing cell for the automated rework of fine pitch components that is under development at the Center for Integrated Electronics and Electronics Manufacturing (CIEEM) at Rensselaer.

Fuel Cell ASAP: Two Iterations of an Automated Stack Assembly Process and Ramifications for Fuel Cell Design-for-Manufacture Considerations

Polymer-electrode membrane (PEM) fuel cell technology, a low-emissions power source receiving much attention for its efficiency, will need to progress from low-volume production to high-volume within the course of the next decade. To successfully achieve this transition, significant research progress has already been made towards developing a fully-functional fuel cell automatic stack assembly robotic station. Lessons can be drawn from this research with regards to design-for-manufacture (DFM) and design-for-assembly (DFA) considerations of fuel cells; however, more work still remains to be done. This document outlines both iterations of the robotic fuel cell assembly stations, other work to date, DFM and DFA lessons learned, and the anticipated future progression of automatic fuel cell stack assembly stations. A literature search reveals numerous patents pertaining to equipment and processes for fuel cell assembly as well as a great number of patents pertaining to fuel cell stack features to aid in manufacture or assembly. However, most of this is focused upon proper compression of the membrane material, with little thought given to overall assembly and throughput. Journal articles have begun to consider real-world manufacturing considerations pertinent to production scale-up, but much remains to be done. Therefore, there is a need for more contributions to stack manufacture and assembly. Work already completed (by the authors and their lab) towards the manufacturing workcell specifically includes the design and construction of two individual robotic fuel cell assembly stations, including custom-built end effectors and parts feeders. The second station incorporated numerous improvements, including overlapping work envelopes, elimination of a shuttle cart, software synchronization, fewer axes, and a better end effector. Consequentially, the second workcell achieved a four-fold improvement in cycle time over the previous iteration. Future improvements will focus in part upon improving the reliability of the overall system. Close study of the manufacturing workcell indicated that stack component design features are key for production and scale-up of fuel cell stack manufacturing processes. Critical features are discussed in this article, as well as their ramifications for the overall stack design. As the stack assembly workcell continues to improve, research will focus upon the ramifications and interplay of tolerances, stack failure modes, sealing, reliability, and the potential for component redesign specifically to optimize fuel cell manufacturing throughput.Copyright

Automation issues of SMD automated rework cell

The 1990s has become the decade of electronics manufacturing. Never before has electronics been a major element of nearly every product sector. Surface mount components have become the choice of industry to solve problems met at the circuit boards. New components using increased lead count of the surface mount technology (SMT) components, and also the increasing compactness of the SMT assemblies has demanded the creation of newer rework tools as an essential part of electronics manufacturing. It therefore becomes essential to have a well-controlled process to assure that rework is not only possible but that is consistent and flawless. Automation is the common answer to achieve both efficiency and quality. This paper describes a system for the automated rework of fine pitch components that is under development as part of the Electronics Manufacturing Programme at Rensselaer.

Designed experiments to analyze the solder joint quality output of a SMD remanufacturing system

A robotic remanufacturing cell system developed at Rensselaer is used to replace a surface mounted component on a populated Printed Circuit Board (PCB). The performance goal is to estimate the high quality solder joint output to measure the cell systems throughput. Maximizing the number of the reliably reworked components by the cell system is not chosen as a goal for measuring the systems performance. This is because rework is a low volume process and the cell being used is an experimental prototype system. The purpose of this paper is to present the steps, factors, and levels for obtaining a good solder joint with the rework cell developed here.

An algorithm for CAD-based generation of collision-free robot paths

Generating efficient collision-free paths interactively through computer simulation is one of the main goals of offline programming. These paths can be difficult to create, especially for redundant robots. In addition, the efficiency of the path is dependent upon the expertise of the programmer. Automatic path planning is an attractive option for eliminating these problems.

Distributed control of a track based multi‐head robot

A novel closed loop track based multi‐head robot has been developed to increase the material handing throughput. This robot allows waves of autonomous robot heads to move materials in to the working path by eliminating the traditional return path. Two distributed control architectures were developed using a system comprising of desktop, embedded and single board PCs some linked by wireless communications. This paper discusses the design and impact of such control architectures, and looks at some performance boundaries.