Material Handling Devices Research Articles

Pole Placement Approach to Crane Control Problem

Pole Placement Approach to Crane Control Problem The time and positioning accuracy of transportation operations realized by material handling systems are more and more significant problem in automated manufacturing processes, as well as the exploitation quality, safety and reliability, which can be met by implementing automation systems and improving control quality of material handling devices. The presented problem of anti-sway control system was solved using pole placement method employed to the time-discrete closed loop crane control system, which can be used in adaptive solutions. The proposed solution is based on the assumption, that crane nonlinear system is considered as a linear model with varying parameters.

Two-level manufacturing system performance analyser

Open queuing network is a commonly used analytical tool for modelling manufacturing systems. Parametric decomposition is a proven solution method for analysing open queuing networks and can estimate key performance measures such as work-in-process inventory, cycle time, and machine utilisation, fairly accurately. This paper presents a two-level hierarchical open queuing network model, which considers numerous features seen in a real manufacturing system including, machine set-up, material handling device setup (for example, loading and unloading operations), process as well as transfer batching, empty travel of the material handling device and machine or material handling device failures. The model first analyses a higher level open queuing network whose nodes are aggregations of a set of machines. The higher level network is solved via the parametric decomposition method and the results are then disaggregated to get lower level, e.g. machine specific, results. The motivation, algorithm and its relationship with the one-level model are discussed. Experimental results are provided to show that the two-level model provides comparable results with the one-level model in addition to its computational and managerial advantages. In addition, both are shown to provide better results than a recent method available in the literature that is based on the well-known queuing network analyser.

Workspace Supervising System for Material Handling Devices with Machine Vision Assistance

Workspace Supervising System for Material Handling Devices with Machine Vision AssistanceThe paper is focus on the possibility of the implementation machine vision system for the purposes supervising the transport device workspace interface including operation safety needs. The object of statement is structure of automatic supervising system built on the base material handling devices with open kinematic chain of the Cartesian type based on one CCD device.

Interoperable Approach to HMI and Supervisory Systems in Man-Machine Systems

Automation and higher level of control systems development cause that function of human in Man-Machine System (M-MS) is frequently moves to the function of supervisor. Observed evolution of M-MS systems accompanies development of Information and Communication Technologies (ICT) especially supervisory systems which are important aspects of interoperability in manufacturing systems. The higher and higher demands are put before those systems and more and more compound tasks are expected to realize especially connected with control, diagnostic, monitoring and managing. The main questions of supervisory systems evolution are inference mechanisms and so called intelligent systems (fuzzy logic, experts systems, artificial neural networks) which can be implemented to aid decision-making process, making faster and adequate diagnosis of occurrences and failures, formulating conclusions about symptoms-failures relationships and preventive or removing actions. In the paper example of HMI/SCADA system was presented which enables to implement and use in decision-making process interoperable heuristic knowledge of the user. Moreover the application which allows to realize fuzzy control system using user interface applied in HMI/SCADA system was shown. Presented examples were dedicated for material handling devices and has been tested on an overhead traveling crane example.

Optimal Scheduling of Material Handling Devices in a PCB Production Line: Problem Formulation and a Polynomial Algorithm

Modern automated production lines usually use one or multiple computer‐controlled robots or hoists for material handling between workstations. A typical application of such lines is an automated electroplating line for processing printed circuit boards (PCBs). In these systems, cyclic production policy is widely used due to large lot size and simplicity of implementation. This paper addresses cyclic scheduling of a multihoist electroplating line with constant processing times. The objective is to minimize the cycle time, or equivalently to maximize the production throughput, for a given number of hoists. We propose a mathematical model and a polynomial algorithm for this scheduling problem. Computational results on randomly generated instances are reported.

Modification of an EMG-assisted biomechanical model for pushing and pulling

Pushing and pulling tasks using carts and material handling devices have become more prevalent in occupational environments in an attempt to reduce the musculoskeletal risks associated with lifting. However, little change in low back disorder rates have been noted as tasks change from lifting to pushing and pulling indicating that we do not understand the mechanics of pushing and pulling well. Biomechanical assessments of pushing and pulling tasks using person-specific biologically assisted models offer a means to help understand how the spine is loaded under pushing and pulling conditions. However, critical components of these models must be adjusted so that they are sensitive to the different physiologic responses in the torso muscles expected during pushing and pulling compared to lifting tasks. The objective of this study was to modify an electromyography (EMG)-assisted biomechanical model designed to evaluate lifting tasks so that it can better represent the biomechanical forces expected during pushing and pulling tasks. Several key modifications were made. Based upon a literature review, changes in muscle cross-sectional area and muscle origins and insertions were made to better represent the geometry of the torso muscles. It was also necessary to adjust the length–force and velocity–force muscle relationships. Empirically derived length–force and velocity–force relationships were developed to independently represent the flexor and extensor musculature. These modifications were then systematically incorporated into the model. The model was exercised over several pushing and pulling conditions to assess the effect of these modifications on its ability to predict externally measured spinal moments. Results indicated that the alterations made to the preexisting EMG-assisted model resulted in acceptable model performance for pushing, pulling, and lifting activities. Relevance to industry The use of carts and material handling devices has become increasingly prevalent in industry, though little research has been done to examine the body's response. The modifications made to the biomechanical model would enable its use in the evaluation and design of material handling devices and pushing and pulling tasks.

Deadlock Resolution in Automated Manufacturing Systems With Robots

An automated manufacturing system (AMS) contains a number of versatile machines (or workstations), buffers, and an automated material handling system (MHS). The MHS can be an automated guide vehicle (AGV) system, and/or a system that consists of multiple robots. Deadlock resolution in AMS is an important issue. For the AMS with an AGV system as MHS, the problems of deadlock resolution for part processing process and AGV system as an integrated system has been studied. It is shown that AGVs can serve as both material handling devices and central buffers at the same time to help resolve deadlocks. For AMS with robots as MHS, the existing work treated the robots just as material handling devices and showed that the robots had contribution to deadlock. In this paper, such AMS is modeled by resource-oriented Petri nets. Contrary to the existing work, it is shown that the robots have no contribution to deadlock by adopting such nets to control AMS. More interestingly, they can be used to resolve deadlock by serving as temporary part storage devices. A new deadlock control policy is proposed by treating robots as both material handling devices and buffers. The new policy outperforms the existing ones.

Queueing network modelling of flexible manufacturing system using mean value analysis

In the present investigation, we develop queueing model for the performance prediction of flexible manufacturing systems (FMSs) with a multiple discrete material-handling devices (MHD). An iterative method has been suggested using mean value analysis (MVA) for the state-dependent routing. Two queueing network models are considered to determine the material-handling device interference. In the first one, we model the interference from the MHD by inflating the station service times but neglect queueing at the MHD. In another network, the queueing for the MHD is taken into consideration. The performance of FMS configuration is obtained by iterating between two networks. The suggested algorithms demonstrate better results than the algorithm used by earlier workers for single MHD. Some performance indices viz. throughput, mean service time, mean waiting time, etc. are obtained. Numerical results are provided to highlight the effect of the system parameters on performance indices, which are further evaluated by using neuro-fuzzy controller system to validate the tactability of soft computing approach.

Looking-Forward Scheduling Approach Applied in Pre-erection Area of a Shipyard

The major problem arises at a shipyard because of scarcity of space for arranging the building blocks of a ship under construction. A standardized erection sequence diagram is generally available to provide the prioritized erection sequence, and it serves as the framework. In order to make a timely erection of the blocks, a post plan has to be developed so that the blocks lie in the nearest possible vicinity of the material-handling devices while keeping the priority of erection, and the blocks are arranged in the pre-erection area. The genetic algorithm based solution procedure is developed to produce the optimal spatial arrangement. An innovative algorithm nicknamed ISBAS (Intelligent Spatial Block Arrangement Scheduler) has been developed and implemented using genetic algorithm, and a workable computer program has been developed using VC++. The detailed genetic operation is performed to run to meet the objectives of the critically complicated problem. Also, hand-in-hand algorithms such as knapsack problem, traveling salesmen problem, and weight assignment algorithms are used to segregate the better options. An indigenously developed looking-forward algorithm is also in place.

A two-stage simulated annealing procedure for block layout problems

Rules for setting simulated annealing control parameters are proposed for block layout problems where different material-handling devices are dynamically assigned to individual material movements as layout solutions are perturbed. Recognizing the high cost of computing materials-handling cost in this type of problem, the rules are based on adapting an existing two-stage simulated annealing procedure to accelerate convergence. Experimental results suggest that the application of these rules yields solution quality comparable with other single and two-stage simulated annealing algorithms but with significantly fewer re-evaluations of the objective function.

Design and Fabrication of a Robotic Arm for Material Handling

The commercial robots are expensive for use in the educational institutions. The operation of them will not leave room for experimentation, which is necessary in an educational institution. Further a large number of components that can be used for building a robot are readily available in the market. Hence this project has been taken up to allow us to build a working robot using as many of the off the shelf components to provide the necessary flexibility. This would make it a low cost robot with enough flexibility for the students to experiment the various functions of the robot.The mechanical component of the manipulator was built with three degrees of freedom, one revolute and two prismatic joints. This configuration is most common to be used as a material-handling device for machine tools. The revolute joint was achieved by making use of a pneumatic rotary table and one prismatic joint is realized by means of a pneumatic cylinder. The second prismatic joint in the Z-direction is achieved by the use of an AC servomotor with a ball screw and linear motion elements to provide for accurate positioning capability. The gripper had been designed for cylindrical components, since this robot was conceived as a material handling unit for a CNC turning center. All the necessary design calculations had been done and the finite element analysis was carried out for the main structure. The control system of the robot was one of the crucial elements. A PC is used as a controller. The motion control was carried out with the help of a motion control card DC2-PC100. It had the ability to control 2 servo and 2 stepper motors in addition to other digital and analogue controls. Several types of sensors and actuators were used for the robot to be fully automatic. The signal conditioning circuitry was designed in house for the interfacing between sensors, actuators and controllers. The control algorithm was developed with the necessary functioning to coordinate all the joint movement as well as gripper manipulation.

Multi-agent-based approach to solve part selection and task allocation problem in flexible manufacturing systems

Agent technology is currently being considered as an important approach for developing intelligent manufacturing systems. It offers a new way of thinking about many of the classical problems in manufacturing engineering. A multi-agent-based approach for solving the part allocation problems in flexible manufacturing systems (FMS) is presented that can easily cope with the dynamic environment. Four agents were involved in carrying out the tasks of allocating parts on different machines: communicator, machine, part and material handling device (MHD). Upon arrival in the manufacturing facility, the part informs the communicator agent about the task requirements. The communicator agent divides the task into subtasks and sends a call-for-bids message to the machine and MHD agents. Each machine responds in accordance with its process capabilities and buffer limit. This response may be for the whole task or for one or more subtasks and it contains the price and cost details for these subtasks along with the performance index and acceptance ratio of the machine. The final allocation is made based on the objective function that includes processing and transportation costs and time. An algorithm is presented that is used by the communicator agent for allocating parts to different machines. An illustrative example is given to solve the task allocation on five machines, with each machine having different performance index and acceptance ratio.

Minimizing cycle time in large robotic cells

We solve scheduling problems for a Texas-based company called FSI International Inc. that designs and manufactures robotic cells for semiconductor wafer fabrication companies. A robotic cell contains several processing stations served by a robot, repetitively producing a set of identical parts. Processing constraints define the cell to be an m-stage flowshop, i.e., each part is processed in it through an identical sequence of m processing stages. The robot acts as a material handling device transferring parts between stages. The objective is to find a robot moves sequence that minimizes the average time to produce a part. We study three robotic cell configurations that are used by FSI and other designers of robotic cells. It is shown that a well known cyclic solution, referred to as downhill permutation achieves optimal solutions for practically relevant problem instances of the simplest robotic cell configuration. For other configurations, we define a new class of cyclic schedule of robot moves called Least Common Multiple (LCM) cycles that are simple and easy to understand and implement. Metaheuristic algorithms are then devised to find the best LCM-cycle, where each cyclic schedule is evaluated through linear programming. These algorithms are considerably superior to the heuristic currently being used at FSI and improvements could amount to several million dollars per year for FSI's clients. We also establish theoretical lower bounds on the average time to produce a part. Subsequently, through extensive computational experiments, we show that the proposed metaheuristic solutions are very close to optimal solutions.

Forensic Engineering Analysis Of An Accident Caused By Inadequate Maintenance Of A Large Capacity Fork Lift Truck

Forklift Trucks Are The Single Most Versatile Industrial Material-Handling Device. This Versatility Is Created By The Ability Of The Flt To Move Loads In Three Dimensions, I.E., Forward, Laterally, And Vertically. This Freedom Of Movement Is Provided By The Rear Steer Front Wheel Drive Configuration Of Flts Permitting The Flt To Move Loads Into Tight Spaces And Also By The Mast Permitting The Forks To Raise And Lower Loads For Stacking. As Part Of The Stacking Operation The Masts Of Flts Have The Capability Of Tilting Fore And Aft, Which Permits The Forks To Get Under The Load And Then Once Placed On The Forks, For The Load To Be Raised And Then Cradled By The Forks By Tilting The Mast Backwards...A Case Study Is Presented Of A Fatality Accident Involving A Large Capacity Flt (52,000 Pound Capacity) Carrying 11 Sheets Of Steel Which Were 10 x 20 x 1/4 Each Weighing Approximately 1500 Pounds. The Operator Of The Flt Set The Load At About 1416 Above The Ground, Set The Spotting Brake, And Exited The Cab To Rearrange A Number Of Wooden Spacers Upon Which He Intended To Place The Sheets Of Steel. The Mast Drifted, Causing The Forks To Angle Down, Which In Turn Permitted The Sheets Of Steel To Slide Off The Forks (Much Like A Deck Of Cards) And Strike The Worker (Previously The Operator), Resulting In His Death.

Framework for designing a flexible cellular assembly system

Modern manufacturing companies have to face competition in a turbulent world market that requires them to improve their operating performances according to increasingly differentiated products with shorter life cycles, low volumes and reduced customer delivery times. The aim of the present paper is to develop a conceptual framework for the simultaneous design and control of a flexible, agile reconfigurable and robust assembly system in conjunction with the analysis and optimization of product, process, system structure, material-handling devices and plant layout. An effective solution for reconfigurability and agility in assembly to order and batch-type systems is a modular semi-automatic approach based on cellular flexible facilities: modularity, automation and human skills are combined to gain the advantages of mass production. Families of parts are produced in flexible cells, i.e. groups of various machines and resources that are physically close together and process one or more families of similar parts. The proposed approach is based on a multistage iterative procedure that integrates different supporting decision techniques and tools such as design for assembly, group technologies and cellular manufacturing. An application to the optimization of a semi-automatic flexible assembly system is illustrated: the system performances of example alternative solutions are presented and compared.

Coloured timed Petri net model for real-time control of automated guided vehicle systems

Automated guided vehicle systems (AGVS) are material-handling devices representing an efficient and flexible option for products management in automated manufacturing systems. In AGVS, vehicles follow a guide-path while controlled by a computer that assigns the route, tasks, velocity, etc. Moreover, the design of AGVS has to take into account some management problems such as collisions and deadlocks. The paper presents a novel control strategy to avoid deadlock and collisions in zone-controlled AGVS. In particular, the control scheme manages the assignments of new paths to vehicles and their acquisition of the next zone. Moreover, the use of coloured Petri nets is proposed to model the dynamics of AGVS and implement the control strategy stemming from the knowledge of the system state. Additionally, extending the coloured Petri net model with a time concept allows investigation of system performance. Several simulations of an AGVS with varying fleet size while measuring appropriate performance indices show the effectiveness of the proposed control strategy compared with an alternative policy previously presented.

A Practical Robotic End-Effector for Grasping Postal Sacks

This article describes a new class of end-effectors that can be used with robotic and material handling devices for grabbing and holding deformable objects with undefined shapes such as sacks and bags. These end-effectors can grab and hold filled sacks from any point on the sack and regardless of the sack orientation and position. The first prototype end-effector, designed for the U.S. Postal Service, has two rollers. The rollers are pushed toward each other by the force of a spring. When the rollers are powered to spin, the inward spinning of the rollers causes the sack material to be dragged in between the rollers due to the friction between the surfaces of the rollers and the sack material. The spring pushes the rollers toward each other with sufficient force to hold the sack material in place between the rollers. The end-effector described here has been evaluated and proven to be exceedingly effective in grabbing and holding postal sacks. This article describes the underlying principles of the design, grasp conditions and control of the end-effector.

Convertibility Measures for Manufacturing Systems

With increased consumer demands for a wider variety of products In changeable, unpredicted quantities, manufacturing system responsiveness has become increasingly Important for Industry competitiveness. Manufacturers need systems that can be rapidly adjusted with regard to both functionality and throughput capacity over the lifetime of the system. Convertibility is defined as the capability of a system to adjust production functionality, or change from one product to another. End-users of manufacturing systems are struggling with the Issue of how to measure and quantify convertibility. Metrics for convertibility are proposed in this paper so that different manufacturing systems can be compared with respect to this area of performance. These metrics are based on assessments of the configuration itself, and the system components such as machines and material handling devices. Metrics for quantifying convertibility are useful for comparing system configurations during the early phases of design, with out requiring detailed product or process plan Information.

Incorporating heterogeneous distance metrics within block layout design

This paper focuses on optimal design of block layouts when using more than one distance metric within a single facility. Previous work in block layout has assumed a single distance metric, usually the shortest rectilinear distance between department centroids, during the design step. However, most facilities have more than one method of material handling and alternative material handling systems can imply alternative distance metrics and cost structures. Specifically, up to three distance metrics within a single facility are considered--the shortest rectilinear distance between centroids (appropriate for automated guided vehicles and forklift trucks), the Tchebychev (maximum) distance (appropriate for overhead cranes) and the shortest Euclidean distance between centroids (appropriate for conveyor lines). Optimal block layouts using each of these distance metrics individually and then collectively are compared and contrasted. This approach can also be used to compare layouts when the choice of material handling system is not clear. It is argued that incorporating the distance metric that best reflects the planned material handling device is more realistic than previous formulations, avoids block layouts that are sub-optimal for the material handling systems installed, and is quite workable within a heuristic optimization framework.

Teleoperation of a Hydraulic Forklift from a Haptic Manipulator over the Internet

Remote operation of material handling equipment is of potential value when the proximity of the user is inconvenient or dangerous. Haptic feedback makes operation of this equipment more effective. The pervasive presence of the Internet makes it attractive to use it as a means of communication between the human operator and the remote device. This paper describes research underway to facilitate haptic feedback to the human operator in spite of the significant and variable delay of the Internet. An additional novelty of these experiments is the configuration of the remote device as a vehicle rather than a manipulator. The nature and role of the haptic interface, the material handling device and the wave variable treatment of the communication signal are summarized.