947 research outputs found
Force Controlled Knife-Grinding with Industrial Robot
This paper investigates the application of sharpening knives using a force controlled industrial robot, for an arbitrary knife shape and orientation. The problem is divided into different parts: calibration of the knife by identifying its unknown orientation, identification of the knife blade contour and estimation of its position in the robot frame through force control, and grinding of the knife, following the path defined by the earlier identified shape, while applying the desired contact force to the revolving grinding wheels. The experimental results show that the knives can be sharpened satisfactorily. An industrial application has also been developed and tested, and it has produced a sharpening quality equal or greater to that achieved manually
Force Controlled Grinding-The Cutting Edge
Sharpening knives by hand is both time-consuming and exhausting, and may still not always yield perfect results. This thesis investigates the possibility of sharpening knives with the use of a force-controlled industrial robot, regardless of the knifes shape. The procedure is performed by first identifying the shape of the knife, using Matlab Simulink to simulate the identifiation; two different types of force control are evaluated. Using an ABB IRB140B robot, the best performing controller is then used to identify a real knife. Based on the shape recorded by the robot, grinding experiments were successfully performed
Smart Knife: Integrated Intelligence for Robotic Meat Cutting
Automation is a key technology for a sustainable and secure meat sector in the future, both in terms of productivity and work environment. New robotic technologies, such as the so-called âmeat factory cell,â (MFC) aim to contribute to this goal, but they require new âsmartâ tools that provide sensor feedback, which enable robots to perform complex tasks. This article presents one such tool: the smart knife, which gives real-time feedback on its contact status with meat, as well as cutting depth. The tool and the system are described, and its operation evidenced via electromagnetic (EM) simulation using the Ansys High-Frequency Structure Simulator. Furthermore, the performance of the knife is validated using pork loin meat: in the worst case, knife is shown to have an error of 1.78% for contact detection, and a mean error of 7.66 mm (±1.45 mm) for depth detection. This article also presents brief discussion regarding eventual use of the knife as part of the MFC control system, in addition to future work to be performed.publishedVersio
Novel control of a high performance rotary wood planing machine
Rotary planing, and moulding, machining operations have been employed within the
woodworking industry for a number of years. Due to the rotational nature of the machining
process, cuttermarks, in the form of waves, are created on the machined timber surface. It is
the nature of these cuttermarks that determine the surface quality of the machined timber. It
has been established that cutting tool inaccuracies and vibrations are a prime factor in the
form of the cuttermarks on the timber surface. A principal aim of this thesis is to create a
control architecture that is suitable for the adaptive operation of a wood planing machine in
order to improve the surface quality of the machined timber.
In order to improve the surface quality, a thorough understanding of the principals of wood
planing is required. These principals are stated within this thesis and the ability to manipulate
the rotary wood planing process, in order to achieve a higher surface quality, is shown. An
existing test rig facility is utilised within this thesis, however upgrades to facilitate higher
cutting and feed speeds, as well as possible future implementations such as extended cutting
regimes, the test rig has been modified and enlarged. This test rig allows for the dynamic
positioning of the centre of rotation of the cutterhead during a cutting operation through the
use of piezo electric actuators, with a displacement range of ±15Όm.
A new controller for the system has been generated. Within this controller are a number of
tuneable parameters. It was found that these parameters were dependant on a high number
external factors, such as operating speeds and runâout of the cutting knives. A novel approach
to the generation of these parameters has been developed and implemented within the
overall system.
Both cutterhead inaccuracies and vibrations can be overcome, to some degree, by the vertical
displacement of the cutterhead. However a crucial information element is not known, the
particular displacement profile. Therefore a novel approach, consisting of a subtle change to
the displacement profile and then a pattern matching approach, has been implemented onto
the test rig.
Within the pattern matching approach the surface profiles are simplified to a basic form. This
basic form allows for a much simplified approach to the pattern matching whilst producing a
result suitable for the subtle change approach. In order to compress the data levels a Principal
Component Analysis was performed on the measured surface data. Patterns were found to be
present in the resultant data matrix and so investigations into defect classification techniques
have been carried out using both KâNearest Neighbour techniques and Neural Networks.
The application of these novel approaches has yielded a higher system performance, for no
additional cost to the mechanical components of the wood planing machine, both in terms of
wood throughput and machined timber surface quality
Dynamic Evaluation of Forces During Mastication
A reproduction of the human masticatory system is presented here to evaluate mechanical properties of foods, relevant design elements of the simulator, and the overall practicality of the system. The model incorporates a cam-driven linkage system providing realistic motion of the mandible, with reaction forces measured by strain gages on two axes to record real time changes in food structure. The experiment demonstrates that the construction of a mastication simulator is feasible and allows texture profiling and discrimination between similar foods
Control Strategies for Machining with Industrial Robots
This thesis presents methods for improving machining with industrial robots using control, with focus on increasing positioning accuracy and controlling feed rate. The strong process forces arising during high-speed machining operations, combined with the limited stiffness of industrial robots, have hampered the usage of industrial robots in high-end machining tasks. However, since such manipulators may offer flexible and cost-effective machining solutions compared to conventional machine tools, it is of interest to increase the achievable accuracy using industrial robots. In this thesis, several different methods to increase the machining accuracy are presented. Modeling and control of a piezo-actuated high-dynamic compensation mechanism for usage together with an industrial robot during a machining operation, such as milling in aluminium, is considered. Position control results from experiments are provided, as well as an experimental verification of the benefit of utilizing the online compensation scheme. It is shown that the milling surface accuracy achieved with the proposed compensation mechanism is increased by up to three times compared to the uncompensated case. Because of the limited workspace and the higher bandwidth of the compensator compared to the robot, a mid-ranging approach for control of the relative position between the robot and the compensator is proposed. An adaptive, model-based solution is presented, which is verified through simulations as well as experiments, where a close correspondence with the simulations was achieved. Comparing the IAE from experiments using the proposed controller to previously established methods, a performance increase of up to 56 % is obtained. Additionally, two different approaches to increasing the accuracy of the machining task are also presented in this thesis. The first method is based on identifying a stiffness model of the robot, and using online force measurements in order to modify the position of the robot to compensate for position deflections. The second approach uses online measurements from an optical tracking system to suppress position deviations. In milling experiments performed in aluminium, the absolute accuracy was increased by up to a factor of approximately 6 and 9, for the two approaches, respectively. Robotic machining is often performed using position feedback with a conservative feed rate, to avoid excessive process forces. By controlling the applied force, realized by adjusting the feed rate of the workpiece, precise control over the material removal can be exercised. This will in turn lead to maximization of the time-efficiency of the machining task, since the maximum amount of material can be removed per time unit. This thesis presents an adaptive force controller, based on a derived model of the machining process and an identified model of the Cartesian dynamics of the robot. The controller is evaluated in both simulation and an experimental setup
A flexible manufacturing system for lawnmower cutting cylinders
The thesis is concerned with the conception and design of a FLEXIBLE
MANUFACTURING SYSTEM (FMS) for the automation of the manufacture of
lawnmower cutting cylinders at Suffolk Lawnmowers Ltd. A review of FMS
definitions, planning methods and current systems is carried out for the
development of a suitable FMS configuration for the final stages of
manufacture of grass cutting cylinders having 21 different design
specifications. This involves examination of the capabilities of
robotics and microcontrollers to automate the technologies used in
cylinder production.
The company's current manual batch production system is analysed to
determine the suitable form and requirements of the FMS. This includes
analyses of annual volumes, throughputs, batch sizes, product and process
mixes. Long term objectives to automate the system are identified from
which short term objectives are derived. The FMS recommended for
immediate development encompasses the short term objectives for the
welding, hardening, grinding and transfer processes of 8 cutting cylinder
specifications.
It is shown that the MIG (Argon/C02) are welding, progressive flame
hardening and wide-face cylindrical grinding processes can be developed
successfully to automate cylinder production. The recommended system
integrates these processes into an FMS through the'automatic handling
of cylinders (through three process routes) by a robotic manipulator
utilising a double gripper. 'A robotic welding station, manually loaded,
is also recommended. ' The system is controlled overall by a 32K microcontroller
with the process machines individually controlled by programmahle
logic controllers with up to 6K of memory each.
The economic appraisal of the FMS indicates a 4.4 year payback based on
direct labour and material cost savings. The company's application for
grant aid to implement the FMS design has led to an offer of a Department
of Industry grant to cover 50% of all capital and revenue costs. The
grant of ÂŁ166,943 reduces the payback period to 2.3 years
Hum Factors Ergon Manuf
This paper reviews the experiences of 63 case studies of small businesses (< 250 employees) with manufacturing automation equipment acquired through a health/safety intervention grant program. The review scope included equipment technologies classified as industrial robots (n = 17), computer numerical control (CNC) machining (n = 29), or other programmable automation systems (n = 17). Descriptions of workers' compensation (WC) claim injuries and identified risk factors that motivated acquisition of the equipment were extracted from grant applications. Other aspects of the employer experiences, including qualitative and quantitative assessment of effects on risk factors for musculoskeletal disorders (MSD), effects on productivity, and employee acceptance of the intervention were summarized from the case study reports. Case studies associated with a combination of large reduction in risk factors, lower cost per affected employee, and reported increases in productivity were: CNC stone cutting system, CNC/vertical machining system, automated system for bottling, CNC/routing system for plastics products manufacturing, and a CNC/Cutting system for vinyl/carpet. Six case studies of industrial robots reported quantitative reductions in MSD risk factors in these diverse manufacturing industries: Snack Foods; Photographic Film, Paper, Plate, and Chemical; Machine Shops; Leather Good and Allied Products; Plastic Products; and Iron and Steel Forging. This review of health/safety intervention case studies indicates that advanced (programmable) manufacturing automation, including industrial robots, reduced workplace musculoskeletal risk factors and improved process productivity in most cases.CC999999/ImCDC/Intramural CDC HHSUnited States
Sensor-based navigating mobile robots for people with disabilities
People with severe physical disabilities need help with everyday tasks, such as getting dressed, eating, brushing their teeth, scratching themselves, drinking, etc. They also need support to be able to work. They are usually helped by one or more persona
Robotic processes to accelerate large optic fabrication
The manufacture of metre-scale optics for the next generation of extremely large
telescopes (and many other applications) poses a number of unique challenges. For the
primary mirror of the European Extremely Large Telescope, each of its 1.45 m
segments will need to be completed with nanometre scale accuracy. This demands an
unprecedented combination of hybrid fabricating technology to process nearly 1000
segments before the year 2024.
One important aspect in improving the current state-of-the-art manufacturing
developments is adding an efficient smoothing process that can achieve a faster, and
less expensive, manufacturing process-chain. The current process to finish a prototype
segment using CNC grinding and CNC polishing takes approximately 1-2 months, and a
significant contributing factor in this is the excessive processing times needed to correct
the local grinding marks. In this study, therefore, grolishing, an intermediate process
between grinding and polishing, is adopted to smooth the part and reduce the overall
manufacturing time.
This PhD work serves to advance the development of effective robotic grolishing
processes (RGP) by the following achievements: (1) to propose the specification and achieve the requirements; (2) to design tools and establish a mechanism for grolishing;
(3) to investigate and propose experimental methods to reduce process times while still
achieving high performance, reliability and quality surfaces; (4) to establish the RGP
and demonstrate that this process can smooth the errors from grinding and provide
superior surfaces for polishing to speed up the current process; (5) to develop prototype
metrology systems and algorithms to measure grolished surfaces; and, (6) to investigate
an innovative proposed method to control mid-spatial frequencies on complex surfaces
by using rotating rigid tools.
These novel achievements describe the newest fabrication technology, and anticipate
the evolution of the process-chain for future high-quality imaging systems for use in
astronomy, space-research and laser physics
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