Control of high precision roll-to-roll manufacturing systems

The flexible electronic industry has been growing rapidly over the past decade. One of the barriers to commercialization is the high cost of manufacturing micro- and nano-scale printed electronics using traditional methods. Roll-to-roll manufacturing has been identified as a method of achieving low cost and high throughput. A dynamic model of a roll-to-roll system is presented. In all roll-to-roll applications, tension and velocity must be accurately controlled to desired reference trajectories to ensure a quality finished product. Additionally, a registration error model is presented for the control design. Minimization of the registration is the primary objective for flexible electronics, but web tension and velocity cannot be neglected. The model is needed in order to formulate a methodology that can simultaneously control tension, velocity, and registration error in the presence of disturbances. Micro and nano-scale features are susceptible to damage from friction between the web and the roller. Therefore, tension estimation techniques is highly desired to eliminate load cells from the system. The reduced order observer, extended Kalman filter, and an unknown input observer is presented. Development of tension and velocity control strategies have historically revolved around decentralized SISO control schemes. In order to achieve higher precision, a centralized MIMO strategy is proposed and compared to decentralized SISO. The advantage of the MIMO controller improved handling of the tension velocity coupling in roll-to-roll systems. The tension observer is introduced to the control design and evaluated for overall effectiveness. In simulation, the centralized MIMO control with the unknown input observer demonstrated superior tension and velocity tracking as well as minimal registration error. Development of the proposed MIMO control strategy can enable flexible electronic fabrication using roll-to-roll manufacturing.Mechanical Engineerin

Decentralized Control Performances of an Experimental Web Handling System

Robust and good tracking control of the speed and the tension in web handling systems in spite of changes of set point is surely one of the important challenges in the web transport systems future development. In this paper, the authors experimentally demonstrate the real applicability of a decentralized robust control to a multi-span web transport system, which is composed of twelve guide rollers, four main sections mutually interconnected with each other. The overlapping methodology has been applied for the system decomposition. The experimental results carried out using the robust decentralized control show an excellent velocity and tension tracking in each controlled section of the system

UAV/UGV Autonomous Cooperation: UAV Assists UGV to Climb a Cliff by Attaching a Tether

This paper proposes a novel cooperative system for an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) which utilizes the UAV not only as a flying sensor but also as a tether attachment device. Two robots are connected with a tether, allowing the UAV to anchor the tether to a structure located at the top of a steep terrain, impossible to reach for UGVs. Thus, enhancing the poor traversability of the UGV by not only providing a wider range of scanning and mapping from the air, but also by allowing the UGV to climb steep terrains with the winding of the tether. In addition, we present an autonomous framework for the collaborative navigation and tether attachment in an unknown environment. The UAV employs visual inertial navigation with 3D voxel mapping and obstacle avoidance planning. The UGV makes use of the voxel map and generates an elevation map to execute path planning based on a traversability analysis. Furthermore, we compared the pros and cons of possible methods for the tether anchoring from multiple points of view. To increase the probability of successful anchoring, we evaluated the anchoring strategy with an experiment. Finally, the feasibility and capability of our proposed system were demonstrated by an autonomous mission experiment in the field with an obstacle and a cliff.Comment: 7 pages, 8 figures, accepted to 2019 International Conference on Robotics & Automation. Video: https://youtu.be/UzTT8Ckjz1

Resonant Frequencies in Web Lines and Filtering of Web Tension

A state space system model is proposed to predict the resonant frequencies of an idler system consisting of idler rollers and web spans between two driven rollers. A close match between the experimental results and the model simulations validate the correctness of the dynamic model. The relationship between system parameters and the system's minimum resonant frequency is investigated through analytical and numerical analyses. An analytical approximation of the minimum resonant frequency is developed for a special class of idler systems consisting of equal span lengths and any number of idle rollers. A Kalman filter is designed based on the web span tension dynamic model in terms of state errors. Extensive comparative experiments with and without the Kalman filter show improvement in the web tension signal when the Kalman filter is used.Mechanical & Aerospace Engineerin

A dynamic span model and associated control strategy for roll-transport systems used for sheet materials (Part II)

In this study, we propose a mathematical model that simulates the tension occurring at stands between rolls in a roll-transport system, and then we propose a method to estimate tension. The model is a lumped parameter system described by an ordinary differential equation (ODE). The ODE is derived on the basis of the tension of the stages between drive rolls on the stands. To build a realistic system, we utilized an estimation theory, which is the Kalman filter theory in a control theory. As a result, the proposed system is highly feasible

Observer-based tuning of two-inertia servo-drive systems with integrated SAW torque transducers

This paper proposes controller design and tuning methodologies that facilitate the rejection of periodic load-side disturbances applied to a torsional mechanical system while simultaneously compensating for the observer’s inherent phase delay. This facilitates the use of lower-bandwidth practically realizable disturbance observers. The merits of implementing full- and reduced-order observers are investigated, with the latter being implemented with a new low-cost servo-machine-integrated highband width torque-sensing device based on surface acoustic wave (SAW) technology. Specifically, the authors’ previous work based on proportional–integral–derivative (PID) and resonance ratio control (RRC) controllers (IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1226–1237, Aug. 2006) is augmented with observer disturbance feedback. It is shown that higher-bandwidth disturbance observers are required to maximize disturbance attenuation over the low-frequency band (as well as the desired rejection frequency), thereby attenuating a wide range of possible frequencies. In such cases, therefore, it is shown that the RRC controller is the preferred solution since it can employ significantly higher observer bandwidth, when compared to PID counterparts, by virtue of reduced noise sensitivity. Furthermore, it is demonstrated that the prototype servo-machine-integrated 20-N · mSAWtorque transducer is not unduly affected by machine-generated electromagnetic noise and exhibits similar dynamic behavior as a conventional instrument inline torque transducer

Auto-Tuning PI Controller Design Using Fuzzy Logic Controller for Web Tension Control in Roll Rewinder System

Paper has a very important role, because it increases the productivity of pulp and paper companies in Indonesia. The company's development in 2018 increased by 2.1%, this was indicated by increasing consumer demand. Therefore, paper becomes a necessity in everyday life. The criteria for the paper to be produced are paper with a flat surface and cannot be wrinkled. However, errors in paper production that often occur are a lot of wrinkles and uneven paper surfaces. This happens because of a discrepancy in the dynamics of paper tension with the standards that have been set. The paper record is caused by the dynamics of the web tension in the Rewinder Roll system. In order for the web tension to remain stable, a controller is needed. The controller used is Auto-Tuning PI controller using Fuzzy Logic Controller (FLC). The controller can be said to be successful when it is able to perform automatic tuning of setpoint changes. The results showed that the system was able to achieve setpoint values, overcome overshoot and steady-state error (Ess) with response time values, namely Tr=0.3151 seconds, Ts=0.3750, Td=0.0721, overshoot=0.0044%, and Ess=0 N.  Paper has a very important role, because it increases the productivity of pulp and paper companies in Indonesia. The company's development in 2018 increased by 2.1%, this was indicated by increasing consumer demand. Therefore, paper becomes a necessity in everyday life. The criteria for the paper to be produced are paper with a flat surface and cannot be wrinkled. However, errors in paper production that often occur are a lot of wrinkles and uneven paper surfaces. This happens because of a discrepancy in the dynamics of paper tension with the standards that have been set. The paper record is caused by the dynamics of the web tension in the Rewinder Roll system. In order for the web tension to remain stable, a controller is needed. The controller used is Auto-Tuning PI controller using Fuzzy Logic Controller (FLC). The controller can be said to be successful when it is able to perform automatic tuning of setpoint changes. The results showed that the system was able to achieve setpoint values, overcome overshoot and steady-state error (Ess) with response time values, namely Tr=0.3151 seconds, Ts=0.3750, Td=0.0721, overshoot=0.0044%, and Ess=0 N

Measuring and modelling towline responses using GPS aided inertial navigation

The offshore towage of large floating structures has been the broad subject of research since the 1960’s. The selection of a tug to engage in a tow is based on rules laid down by class and marine warranty surveyors derived from years of experience but a rigorous assessment of these rules based on a comprehensive real world datasets has not been possible. This is principally due to the nature of these tows, usually employing tugs chartered at short notice from the spot market, the long towline lengths when under tow and the high value of the tow itself. Given the commercial implications in being able to better match a suitable tug to any given tow, this research lays down the requirements of an ideal dataset, i.e. one that has a record of towline tensions, complete 6DOF of both the tug and tow all recorded to a universal timeline, along with the seastate experienced by the tow at any given point. It then reviews the historical restrictions in gathering this data and that the key issue has been gathering the motions of the unpowered tow and recording the towline tensions.A methodology is then developed which requires no interference with the towline and draws upon Kalman filters for optimal state estimation of the tug and tow’s position and attitude in 3D space driving a lumped mass simulation of the towline coded in MatLab. The stiffness properties of key elements of the towline are assessed by FEA and observations made on areas where normal industry practice’s may be lacking. Observations on advances in sensor technology as well as other areas for development are then made that provide fertile areas for further research. Finally the full code base for a MatLab, lumped mass simulator is presented in an appendix for future use.The offshore towage of large floating structures has been the broad subject of research since the 1960’s. The selection of a tug to engage in a tow is based on rules laid down by class and marine warranty surveyors derived from years of experience but a rigorous assessment of these rules based on a comprehensive real world datasets has not been possible. This is principally due to the nature of these tows, usually employing tugs chartered at short notice from the spot market, the long towline lengths when under tow and the high value of the tow itself. Given the commercial implications in being able to better match a suitable tug to any given tow, this research lays down the requirements of an ideal dataset, i.e. one that has a record of towline tensions, complete 6DOF of both the tug and tow all recorded to a universal timeline, along with the seastate experienced by the tow at any given point. It then reviews the historical restrictions in gathering this data and that the key issue has been gathering the motions of the unpowered tow and recording the towline tensions.A methodology is then developed which requires no interference with the towline and draws upon Kalman filters for optimal state estimation of the tug and tow’s position and attitude in 3D space driving a lumped mass simulation of the towline coded in MatLab. The stiffness properties of key elements of the towline are assessed by FEA and observations made on areas where normal industry practice’s may be lacking. Observations on advances in sensor technology as well as other areas for development are then made that provide fertile areas for further research. Finally the full code base for a MatLab, lumped mass simulator is presented in an appendix for future use

Accurate navigation applied to landing maneuvers on mobile platforms for unmanned aerial vehicles

Drones are quickly developing worldwide and in Europe in particular. They represent the future of a high percentage of operations that are currently carried out by manned aviation or satellites. Compared to fixed-wing UAVs, rotary wing UAVs have as advantages the hovering, agile maneuvering and vertical take-off and landing capabilities, so that they are currently the most used aerial robotic platforms. In operations from ships and boats, the final approach and the landing maneuver are the phases of the operation that involves a higher risk and where it is required a higher level of precision in the position and velocity estimation, along with a high level of robustness in the operation. In the framework of the EC-SAFEMOBIL and the REAL projects, this thesis is devoted to the development of a guidance and navigation system that allows completing an autonomous mission from the take-off to the landing phase of a rotary-wing UAV (RUAV). More specifically, this thesis is focused on the development of new strategies and algorithms that provide sufficiently accurate motion estimation during the autonomous landing on mobile platforms without using the GNSS constellations. In one hand, for the phases of the flights where it is not required a centimetric accuracy solution, here it is proposed a new navigation approach that extends the current estimation techniques by using the EGNOS integrity information in the sensor fusion filter. This approach allows improving the accuracy of the estimation solution and the safety of the overall system, and also helps the remote pilot to have a more complete awareness of the operation status while flying the UAV In the other hand, for those flight phases where the accuracy is a critical factor in the safety of the operation, this thesis presents a precise navigation system that allows rotary-wing UAVs to approach and land safely on moving platforms, without using GNSS at any stage of the landing maneuver, and with a centimeter-level accuracy and high level of robustness. This system implements a novel concept where the relative position and velocity between the aerial vehicle and the landing platform can be calculated from a radio-beacon system installed in both the UAV and the landing platform or through the angles of a cable that physically connects the UAV and the landing platform. The use of a cable also incorporates several extra benefits, like increasing the precision in the control of the UAV altitude. It also facilitates to center the UAV right on top of the expected landing position and increases the stability of the UAV just after contacting the landing platform. The proposed guidance and navigation systems have been implemented in an unmanned rotorcraft and a large number of tests have been carried out under different conditions for measuring the accuracy and the robustness of the proposed solution. Results showed that the developed system allows landing with centimeter accuracy by using only local sensors and that the UAV is able to follow a mobile landing platform in multiple trajectories at different velocities