Design of an adaptive force and stiffness controlled compliant device for robotic polishing

Polishing is a repetitive task done in an unhealthy environment. Often more than half of the manufacturing time is required to polish a die. The manual polishing process is a tedious work actively rely on a skilled human worker. Industrial Robot has replaced the human in performing these tasks. For robotic polishing to control the polishing force, an active compliant device is used. Due to the compressibility of air, a pneumatic system is preferred as the actuator of the device. The force of the actuator is controlled by regulating air pressure in both chambers of the cylinder. However, to improve productivity, a constant polishing force alone is not sufficient, the stiffness is also considered. The current work involved a new adaptive approach to model and control of the force and stiffness of an active compliant device. The device can adaptively control the compliance and force in real time compensating the gravitational effect due to the mass, gravity, and orientation of the tool. The designed single axis controller consists of a dual acting pneumatic cylinder attached to the end effector of an industrial robot. The effectiveness of the force and stiffness controlled polishing system was proved through experiments --Abstract, page iii

Modification of the rotary machining process to improve surface form

Planing and moulding operations carried out within the woodworking industry make extensive use of rotary machining. Cutter-marks are produced on the timber surface which are generally accepted as unavoidable. More noticeable surface defects may be produced by such factors as cutter-head imbalance, and until recently most research has concentrated on removing these defects. When a high quality finish is required, a further machining operation, such as sanding, is often required to remove cutter-marks. What is required, is a modified machining process which combines a surface closer to the ideal fixed knife finish, whilst retaining the flexibility, practicality and cost effectiveness of rotary machining. [Continues.

Development of an Electro-Hydraulic Floating Double-Disc Valve.

There is a need for low-cost switching and proportional electro-hydraulic valves with low contamination sensitivity and good reliability. In an attempt to meet this need, a novel electro-hydraulic floating double-disc valve has been developed to the stage where it can be used to control hydraulic cylinders or motors directly. As the valve is significantly underlapped, problems still remain in achieving adequate hydraulic stiffness in the proportional mode of operation. The valve operation, which relies on the complex interaction between fluid and electro-magnetic forces acting on the valve discs, is described and a theoretical model of the fluid and electro-magnetic characteristics of the valve is presented. The theory shows satisfactory agreement with experimental data. A pre-production version of the double-disc valve has been designed and manufactured and it incorporates ideas for manufacturing cost reduction while at the same time conforming to CETOP 3 international valve port standards. This valve has been successfully tested as a switching or proportional device when controlling two different cylinders. Proportional control of the valve is achieved using Pulse-Width-Modulation technique. British Technology Group and University of Surrey have applied for a patent on the valve. The patented floating-disc valve has the following features: (a) 3 way or 4 way 2-position or proportional action with minor changes to produce the two types of action, (b) cartridge construction with interchangeable components, (c) low contamination sensitivity, (d) few critical dimensions, (e) no sliding surfaces, (f) CETOP valve port configuration and (g) potentially capable of operating with corrosive or non-lubricating fluids

Master of Science

thesisTechnological advancements have created a demand for ever more complex components with extremely small features, high aspect ratios, and tight tolerances. Components are also being made from harder materials, which are more difficult to produce with traditional machining methods. Electric discharge machining (EDM) offers a manufacturing method that addresses these issues. Micro electric discharge milling is a powerful method that rotates the electrode and enables the cutting of complex 3-D pockets with standard electrodes. In order to meet some of the challenges in the micro manufacturing industry, an micro electric discharge milling spindle has been designed. This design uses a standard industrial collet, is capable of loading a large variety of electrode sizes and shapes, and incorporates optimal dielectric flushing. The spindle design offers injection flushing through the electrode and side flushing for the use of solid electrodes. This spindle design also offers the unique feature of variable flushing pressure. The spindle varies the injection pressure automatically to maintain a constant flow rate of dielectric fluid through the electrode as the electrode becomes shorter. The spindle is also capable of automatically feeding and fixturing the electrode as it wears down. The addition of a C-axis gives the spindle the unique ability to rotationally orient the tool. When the C-axis ability of the spindle is used in conjunction with wire electric discharge grinding, the machine is given the ability to produce a large variety of electrode shapes with extremely high aspect ratios and small features. This spindle design offers an economical versatile and compact solution to micro-electric discharge milling and can be easily placed into a CNC machine platform for accurate creation of complex features. The electrode fixturing range, variable dielectric pressure, and C-axis capabilities of this design are unique to this design and are not offered on the current market

Modeling and performance of a Pneumatic/Hydraulic hybrid actuator with tunable mechanical impedance

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Bibliography: leaves 125-127.by Mark Alan Kleidon.M.S

Volume 2 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 1 | 2: Digital systems Group 3: Novel displacement machines Group 4: Industrial applications Group 5: Components Group 6: Predictive maintenance Group 7: Electro-hydraulic actuatorsDer Download des Gesamtbandes wird erst nach der Konferenz ab 15. Oktober 2020 möglich sein.:Group 1 | 2: Digital systems Group 3: Novel displacement machines Group 4: Industrial applications Group 5: Components Group 6: Predictive maintenance Group 7: Electro-hydraulic actuator

Experimental Studies of Interfacial Behavior of Contact System During Liquid Mediated Rough Surfaces Separation

In the applications related to liquid-solid interface, their operation could be affected by the properties of the interface especially the applications that have infinitesimal interaction force at the interface surface and high interaction velocity. This study provides real time dynamic force measurement in separation process along with the real time image acquisition to explain the deviation between theoretical and experimental methods. The experimental design, setup and initial conditions for experiment are described in detail for further study related to liquid separating force. The simulation model is created to apply the theoretical model in prediction of meniscus force for different initial conditions. The characteristics of solid liquid interface in static and dynamic state are showed in the study with visual demonstration, and how they can affect the experimental results is presented. The experiments showed that, in the static state, the evaporation will change the geometric parameters such as the contact angle, the vertical radius or the horizontal radius of liquid bridge, and the change of geometric parameters lead to the change of meniscus force. The analytical or models also showed that the change of maximum separation force caused by volume mass deviation and minimum distance deviation is more significant than that caused by contact angle deviation for the liquid with receding contact angle under 40 degree. The deviation of maximum separation force was not observed in the experiments with different roughness. In the experiments of different liquid with the same volume, the maximum separation force reduces with the reduction of surface tension if the receding contact angle is similar. The experiment can be conducted with the same liquid on different surface coating (non-wetting coating, nano-textured surfaces) to investigate the effect of hydrophobic contact to meniscus force

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

Investigation of Novel Displacement-Controlled Hydraulic Architectures for Railway Construction and Maintenance Machines

This dissertation aims at showing how to transform hydraulic systems of railway multi-actuator machinery characterized by inefficient state-of-the-art systems into the 21st Century. Designing machines that are highly efficient, productive, reliable, and cost affordable represents the target of this research. In this regard, migrating from valve-controlled architectures to displacement-controlled layouts is the proper answer. Displacement-controlled systems remove the losses generated by flow throttling typical of conventional circuits, allow an easy implementation of energy recovery (e.g. during regenerative braking), and create the possibility for the use of hybrid systems capable of maximizing the downsizing of the combustion engine. One portion of the dissertation focuses on efficient propulsion systems suitable for railway construction and maintenance machines. Two non-hybrid architectures are first proposed, i.e. a novel layout grounded on two independent hydrostatic transmissions (HSTs) and two secondary controlled hydraulic motors (SCHMs) connected in parallel. Three suitable control strategies are developed according to the specific requirements for railway machines and dedicated controllers are implemented. Detailed analyses are conducted via high-fidelity virtual simulations involving accurate modeling of the rail/wheel interface. The performance of the propulsion systems is proven by acceptable velocity tracking, accurate stopping position, achieving regenerative braking, and the expected behavior of the slip coefficients on both axles. Energy efficiency is the main emphasis during representative working cycles, which shows that the independent HSTs are more efficient. They consume 6.6% less energy than the SCHMs working with variable-pressure and 12.8% less energy than the SCHMs controlled with constant-pressure. Additionally, two alternative hybrid propulsion systems are proposed and investigated. These architectures enable a 35% reduction of the baseline machine’s rated engine power without modifying the working hydraulics. Concerning the working hydraulics, the focus is to extend displacement-controlled technology to specific functions on railway construction and maintenance machines. Two specific examples of complete hydraulic circuits for the next generation tamper-liners are proposed. In particular, an innovative approach used to drive displacement-controlled dual function squeeze actuators is presented, implemented, and experimentally validated. This approach combines two functions into a unique actuator, namely squeezing the ballast and vibrating the tamping tools of the work-heads. This results in many advantages, such as variable amplitude and variable frequency of the tamping tools’ vibration, improved reliability of the tamping process, and energy efficient actuation. A motion of the squeeze actuator characterized by a vibration up to 45 Hz, i.e. the frequency used in state-of-the-art systems, is experimentally confirmed. In conclusion, this dissertation demonstrates that displacement-controlled actuation represents the correct solution for next-generation railway construction and maintenance machines