Implementation of automated assembly

Research has shown that about 60 - 80% wealth producing activities is related to manufacturing in major industrial countries. Increased competition in industry has resulted in a greater emphasis on using automation to improve productivity and quality and also to reduce cost. Most of the manufacturing works such as machining, painting, storage, retrieval, inspection and transportation have changed to automation successfully, except assembly. Manual assembly is predominant over automatic assembly techniques due to inherent assembly problem and the fact that the assembly machines lack the innate intelligence of human operator and lack sufficient flexibility to changeover when product designs and market demands change. With the advent of flexible manufacturing systems, which involve very large capital costs and complex interactions. For the reduction the risk of the investment and analyze the system, simulation is a valuable tool in planning the systems and in analyzing their behavior, and get the best use of them. This thesis applies animation techniques to simulate an automatic assembly system. In chapter 1 to 9, we cover some of the fundamental concepts and principles of automatic assembly and simulation. Some manufacturers put the subject of part orientation first on their list of priorities; but design for assembly (DFA) techniques have proven extremely valuable in developing better assembly techniques and ultimately, better products. We discuss DFA in chapter 1, part feeding and orientation in chapter 2. Chapter 3, 4 and 5 are concerned with assembly process, machines and control system, respectively. Annual sales for industrial robots have been growing at the rate of about 25 percent per year in major industrial countries, we review the robot application in chapter 6. The cost of material handling is a significant portion of the total cost of production, material storage uses valuable space and consumes investment, we cover these two topics in chapter 7 and 8. Chapter 9 is concerned with simulation. In chapter 10, 11,12 and 13, we implement a software package IGRIP to build a model of an automatic assembly system and analyze the result

Ground Robotic Hand Applications for the Space Program study (GRASP)

This document reports on a NASA-STDP effort to address research interests of the NASA Kennedy Space Center (KSC) through a study entitled, Ground Robotic-Hand Applications for the Space Program (GRASP). The primary objective of the GRASP study was to identify beneficial applications of specialized end-effectors and robotic hand devices for automating any ground operations which are performed at the Kennedy Space Center. Thus, operations for expendable vehicles, the Space Shuttle and its components, and all payloads were included in the study. Typical benefits of automating operations, or augmenting human operators performing physical tasks, include: reduced costs; enhanced safety and reliability; and reduced processing turnaround time

On disengaging a peg from a hole

In the field of manufacturing and remanufacturing, robots are employed in assembly tasks. Robotics researchers often use a cylindrical peg and a cylindrical hole as a model to understand high-precision insertion operations. During those operations, two main obstacles were identified, namely, jamming and wedging. Jamming occurs when the force is applied in the wrong direction and can be rectified easily by changing the direction. Wedging occurs when the peg appears to be stuck in the hole. The wedging of a peg is more complex than jamming, and it involves the deformation of the components. Many studies have been performed in the area of peg-hole assembly. Although researchers have mentioned the necessary conditions for wedging, the peg-hole jamming problem was the main focus. This thesis aims to better understand the peg-hole wedging problem to find methods to dislodge a wedged peg and to design a remote-centre-compliance (RCC) device to avoid the wedging and jamming of a peg that can be used in both assembly and disassembly. Using the definition and necessary conditions of peg-hole wedging, the systematic process of wedging a peg is analysed and illustrated. There are four steps to wedge a peg in a hole. First, the peg and hole must be in 2-point contact, and the two contact points must be within each other’s friction cone. A force or moment is then applied to deform the peg and hole, and the peg tilting angle increases. The force or moment is then released in the third step, and the peg tilting angle will be reduced by a small amount. Finally, when the peg tilting angle reduces, the reaction forces at the contact points will be collinear, and the peg is wedged. In the simulation and experiment in this research, the hole is divided into two sides, and a force-torque (FT) sensor is installed beneath each hole. The readings obtained from the sensors have shown that the hypothesis of the wedging process is correct, and when the peg is successfully wedged, the resultant force experienced by the FT sensors is balanced. The dislodging of a peg is also investigated in this thesis. To dislodge a wedged peg, intuitively, the peg is either shaken, twisted or knocked. Depending on the application, some would use a low force to dislodge the wedged peg to avoid damaging the components, while others would prefer a quicker disassembly process. In this investigation, the wedged peg is dislodged using different methods, such as applying a constant force and pulsating forces with different frequencies and magnitudes. The time needed to dislodge the peg is recorded to compare the effects of different combinations of parameters used. The result from the simulation shows that the peg can be dislodged at low impulses within a specific range of pulling force magnitudes. Adopting a pulsating force helps reduce the impulse required to dislodge the peg compared to using continuous force in the low magnitude region. However, in the lowest magnitude region, using a continuous force resulted in a lower impulse as the time for dislodging the peg was shorter compared to when a pulsating force was employed. Many techniques have been proposed and investigated to aid the peg-hole assembly process, and one of them is by using an RCC. At the University of Canterbury (New Zealand), researchers designed a passive compliant device, which was an inverted Gough-Whitehall-Stewart mechanism, to assist the peg-hole insertion process. This thesis analyses a modified version of that compliant device, where the legs do not meet in pairs at the platform but at points located remotely from it. This allows the device to have the features of an RCC mechanism, which has been proven by other researchers to be effective for precise peg-hole assembly tasks. This device is also suitable for both assembly and disassembly processes. Unlike the currently available RCC design, which can only withstand high compressive forces, the proposed compliant device can resist both compressive and tensile forces. The compliance matrix of the new design and the location at which it is diagonal are derived using small approximations, proving that the centre of compliance is situated away from the platform. The correctness of the small motion assumptions and the RCC properties of the new compliance device have been confirmed by performing the sensitivity analysis

Vibration as an aid in robotic peg-in-hole assembly

This dissertation presents an analytical and experimental investigation of vibration assisted engagement for parts mating. A dynamic model of assembly is established by using Lagrange\u27s equation for impact to derive impact equations for a robotic manipulator in peg-in-hole assembly. The model can be used to analyze part motion and contact force in the mating of parts by robots. The impact equations of a SCARA robot are derived using this model and utilized to investigate how robot configuration, insertion speed, chamfer angle, coefficient of restitution and other system parameters affect impulsive force and departure angle in the assembly of a peg with a chamfered hole in the presence of position errors. In the analytical investigation, how the vibration amplitude, vibration frequency, frequency ratio, phase angle, uncertainty and tolerance of the assembly system affect the engagement time is analyzed. An algorithm is developed to determine the required time for engagement given a set of assembly and vibration parameters. An intelligent force-based approach is used in conjunction with this algorithm to aid mating of parts and is implemented in experiments to verify analytical results

Flexible magazine operation and cellular techniques in automation systems

There is a strong current trend in automation towards These often systems that can handle small to medium batch sizes are also often associated with In prototyping situations. Batch numbers High complexity the application described Is for British Airways Heathrow Airport where the number of variations pattern of their meal trays Is large. The batch size the assembly variations Is also extremely variable. Catering at in assembly of each of This thesis describes the justification and design of anautomatic system to assemble these trays whilst retaining the flexibility Inherent In the current manual assembly arrangement.The work examines system layouts. Considering each possibility particularly from the flexibility and potential reliabilityaspects. This leads to the consideration of Industrial robots because of their Inherent flexibility. Consequently the variousconfigurations of robots are examined to assess the suitability of each In a cell arrangement the system which was chosen forIts potential reliability. The work continues by developing the Ideas and techniques of parts feeding to realise the maximumbenefits from a robotic cell system." The thesis describes novel magazining arrangements for handling each of the Items which make. up the tray assembly. Two major developments are described. one for the handling of stackable Items and the other for handling small discrete parts from bulk. Both systems are flexible to accomodate variations In part dimensions and possess ability to be quickly re-configured - to handle completely different parts. The equipment designed and constructed for British Airwaysuses Ideas that could also find use In many similar applications where the components have the same characteristics

Design and development of an automated pinning machine for the surface mount electronics industry

Thesis (M. Eng. in Manufacturing)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012."September 2012." Cataloged from PDF version of thesis.Includes bibliographical references (p. 97-99).This thesis describes the development of a concept for a pinning process and the associated machinery to handle odd-form pins specific to a company in the surface mount electronics industry. The developed pinning machine will reduce manual labor requirements, increase flexibility over current automated systems, and allow for greater part traceability. A brief history of industrial automation is presented to establish a background of the industry, followed by a more detailed look at robotic tooling. The design of the automated pinning machine is described in detail, as well as the design methodology behind the sub-systems and components themselves. Finally, the performance of the machine is documented in a testing chapter, comparing machine performance to the original design specifications. The final pinning machine is capable of processing pins with cycle times of 850ms, and has a mean time to failure of 0.24 hours.by Daniel J. Cook.M.Eng.in Manufacturin

The Role of the Central Nervous System in the Integration of Proprioceptive Information

The proprioceptive system provides feedback on human performance that makes it possible to learn and perform novel tasks. Proprioception predominately arises in the peripheral nervous system at the muscle spindle organ. Mechanical stimulus such as vibration has been implicated in altering muscle spindle afferent signals used as feedback. Researchers have utilized this understanding to document gross performance changes resulting from a muscle spindle disruption paradigm. Findings of this work have demonstrated that the altered proprioceptive feedback alters performance both during and after vibration exposure. This has also led many to postulate that altered proprioceptive feedback due to environmental working conditions may be responsible for many incidences of musculoskeletal injury, including low back pain. In order to more fully understand how proprioceptive feedback is integrated into a motor response it was required to investigate activity within the central nervous system, itself the target of the spindle afferent, both before and after receiving a modulate afferent. We developed a protocol based on measures of average velocity to test for this activity. Our investigation began we examining whether or not average velocity, in the form of seated sway velocity, would be sensitive to applied vibration. We found that while vibration was applied; mean sway speed increased significantly above pre vibration levels, regardless of feedback and task difficulty. A computer based pursuit task was then implemented in order to investigate performance relative to timing of vibration exposure. Our results revealed a significant decrease in pursuit velocity during vibration from pre-vibration velocity. Additionally, subjects demonstrated an equal magnitude but opposite increase in pursuit speed after vibration was removed. This protocol was then replicated in a functional-MRI to compare the gross motor pursuit task performance with the corresponding BOLD imaging data. We observed a similar decrease/increase pattern of joystick pursuit velocity. The corresponding cortical activity revealed patterns of inhibition consistent with cognitive inhibition. The current findings support proprioception as a central inhibitory control mechanism that shifts cortical networks dependent on available sensory stimulus

ISMCR 1994: Topical Workshop on Virtual Reality. Proceedings of the Fourth International Symposium on Measurement and Control in Robotics

This symposium on measurement and control in robotics included sessions on: (1) rendering, including tactile perception and applied virtual reality; (2) applications in simulated medical procedures and telerobotics; (3) tracking sensors in a virtual environment; (4) displays for virtual reality applications; (5) sensory feedback including a virtual environment application with partial gravity simulation; and (6) applications in education, entertainment, technical writing, and animation