New motion control machine elements representation for mechatronic education

The paper presents a new proposal for representing machine designs involving motion control. The new mechatronic approach for machine design is moving from a mechanic concept where mechanical transmissions, mechanical gears and coupling etc. are being implemented by electronic coupling, gears, etc. New concepts such as electronic virtual axis are also being employed very often. This brings that, in regards with machine design communication, mechanic elements represented in the past by mechanical drawings are being replaced by new electronic concepts. However, these new electronic motion control concepts should be also represented for a full understanding of the machine behaviors. Drawings are a fundamental tool to communicate preliminary designs, both in an academic and education environments as in professional ones. The new mechatronic elements graphical representation presented in the paper has the objective of bringing the gap between a pure mechanical machine design view and an automated one, including new electronic motion control concepts, and remarking the relevant “mechanic” information from the electronic motion control point of view. All this should facilitate the presentation and explanation of system-based mechatronic designs both in the classroom and at the professional level

Non-Linear Robust Observers For Systems With Non-Collocated Sensors And Actuators

Challenges in controlling highly nonlinear systems are not limited to the development of sophisticated control algorithms that are tolerant to significant modeling imprecision and external disturbances. Additional challenges stem from the implementation of the control algorithm such as the availability of the state variables needed for the computation of the control signals, and the adverse effects induced by non-collocated sensors and actuators. The present work investigates the adverse effects of non-collocated sensors and actuators on the phase characteristics of flexible structures and the ensuing implications on the performance of structural controllers. Two closed-loop systems are considered and their phase angle contours have been generated as functions of the normalized sensor location and the excitation frequency. These contours were instrumental in the development of remedial actions for rendering structural controllers immune to the detrimental effects of non-collocated sensors and actuators. Moreover, the current work has focused on providing experimental validation for the robust performances of a self-tuning observer and a sliding mode observer. The observers are designed based on the variable structure systems theory and the self-tuning fuzzy logic scheme. Their robustness and self-tuning characteristics allow one to use an imprecise model of the system and eliminate the need for the extensive tuning associated with a fixed rule-based expert fuzzy inference system. The first phase of the experimental work was conducted in a controlled environment on a flexible spherical robotic manipulator whose natural frequencies are configuration-dependent. Both controllers have yielded accurate estimates of the required state variables in spite of significant modeling imprecision. The observers were also tested under a completely uncontrolled environment, which involves a 16-ft boat operating in open-water under different sea states. Such an experimental work necessitates the development of a supervisory control algorithm to perform PTP tasks, prescribed throttle arm and steering tasks, surge speed and heading tracking tasks, or recovery maneuvers. This system has been implemented herein to perform prescribed throttle arm and steering control tasks based on estimated rather than measured state variables. These experiments served to validate the observers in a completely uncontrolled environment and proved their viability as reliable techniques for providing accurate estimates for the required state variables

Modelling and control of a variable-length flexible beam on inspection ground robot

Stabilising an inverted pendulum on a cart is a well-known control problem. This paper proposes the mechanical and control design for solving the oscillation problem of a variable-length flexible beam mounted on a mobile robot. The system under consideration is the robot PovRob, used at the European Organization for Nuclear Research (CERN) for visual and remote inspection tasks of particle accelerators. The flexible beam mounted on the robot houses cameras and sensors. The innovative aspect of the approach concerns the use of actuated masses mounted at the end of the rod, which induces an impulsive moment due to their inertia and angular acceleration. The modelling of the flexible rod has been suitably simplified in a lumped-parameter system, with dynamic parameters related to the rod’s flexibility. A linearisation of the dynamic model allows a linear-quadratic control to stabilise the system. Experimental results support the identification and the validation of the dynamic model, while simulation results evaluate the performances of the designed control law

Automated NDT inspection for large and complex geometries of composite materials

Large components with complex geometries, made of composite materials, have become very common in modern structures. To cope with future demand projections, it is necessary to overcome the current non-destructive testing (NDT) bottlenecks encountered during the inspection phase of manufacture. This thesis investigates several aspects of the introduction of automation within the inspection process of complex parts. The use of six-axis robots for product inspection and non-destructive testing systems is the central investigation of this thesis. The challenges embraced by the research include the development of a novel controlling approach for robotic manipulators and of novel path-planning strategies. The integration of robot manipulators and NDT data acquisition instruments is optimized. An effective and reliable way to encode the NDT data through the interpolated robot feedback positions is implemented. The viability of the new external control method is evaluated experimentally. The observed maximum position and orientation errors are respectively within 2mm and within 1 degree, over an operating envelope of 3m³. A new software toolbox (RoboNDT), aimed at NDT technicians, has been developed during this work. RoboNDT is intended to transform the robot path-planning problem into an easy step of the inspection process. The software incorporates the novel path-planning algorithms developed during this research and is shaped to overcome practical limitations of current OLP software. The software has been experimentally validated using scans on real high value aerospace components. RoboNDT delivers tool-path errors that are lower than the errors given by commercial off-line path-planning software. For example the variability of the standoff is within 10 mm for the tool-paths created with the commercial software and within 4.5 mm for the RoboNDT tool-paths, over a scanned area of 1.6m². The output of this research was used to support a 3-year industrial project, called IntACom and led by TWI on behalf of major aerospace sponsors. The result is a demonstrator system, currently in use at TWI Technology Centre, which is capable of inspecting complex geometries with high throughput. The IntACom system can scan real components 2.8 times faster than traditional 3-DoF scanners deploying phased-array inspection and 6.7 times faster than commercial gantry systems deploying traditional single-element inspection.Large components with complex geometries, made of composite materials, have become very common in modern structures. To cope with future demand projections, it is necessary to overcome the current non-destructive testing (NDT) bottlenecks encountered during the inspection phase of manufacture. This thesis investigates several aspects of the introduction of automation within the inspection process of complex parts. The use of six-axis robots for product inspection and non-destructive testing systems is the central investigation of this thesis. The challenges embraced by the research include the development of a novel controlling approach for robotic manipulators and of novel path-planning strategies. The integration of robot manipulators and NDT data acquisition instruments is optimized. An effective and reliable way to encode the NDT data through the interpolated robot feedback positions is implemented. The viability of the new external control method is evaluated experimentally. The observed maximum position and orientation errors are respectively within 2mm and within 1 degree, over an operating envelope of 3m³. A new software toolbox (RoboNDT), aimed at NDT technicians, has been developed during this work. RoboNDT is intended to transform the robot path-planning problem into an easy step of the inspection process. The software incorporates the novel path-planning algorithms developed during this research and is shaped to overcome practical limitations of current OLP software. The software has been experimentally validated using scans on real high value aerospace components. RoboNDT delivers tool-path errors that are lower than the errors given by commercial off-line path-planning software. For example the variability of the standoff is within 10 mm for the tool-paths created with the commercial software and within 4.5 mm for the RoboNDT tool-paths, over a scanned area of 1.6m². The output of this research was used to support a 3-year industrial project, called IntACom and led by TWI on behalf of major aerospace sponsors. The result is a demonstrator system, currently in use at TWI Technology Centre, which is capable of inspecting complex geometries with high throughput. The IntACom system can scan real components 2.8 times faster than traditional 3-DoF scanners deploying phased-array inspection and 6.7 times faster than commercial gantry systems deploying traditional single-element inspection

6G Radio Testbeds: Requirements, Trends, and Approaches

The proof of the pudding is in the eating - that is why 6G testbeds are essential in the progress towards the next generation of wireless networks. Theoretical research towards 6G wireless networks is proposing advanced technologies to serve new applications and drastically improve the energy performance of the network. Testbeds are indispensable to validate these new technologies under more realistic conditions. This paper clarifies the requirements for 6G radio testbeds, reveals trends, and introduces approaches towards their development

Information model to support PLCOpen Motion Control programming from Mechanical Design

The design of automated industrial machinery involves different areas of engineering, each of which employs its own and different information representation systems and software tools. The lack of a common information model to collect and organize the essential common data of each technology, prevents collaborative multidisciplinary engineering work, which complicates the use of a mechatronic approach. This article proposes the structure of an information model that allows to include geometric, kinematic and logical information related to the tools and objects that the machine manipulates, organized hierarchically according to the mechanical structure of the machine. This model complements an earlier development by the authors by calling MMCS “Mechanical and Motion Control Schematics”, which focuses on graphical representation. By combining them, the dynamic behavior can be visualized together

Design Considerations of Dedicated and Aerial 5G Networks for Enhanced Positioning Services

Dedicated and aerial fifth generation (5G) networks, here called 5G overlay networks, are envisaged to enhance existing positioning services, when combined with global navigation satellite systems (GNSS) and other sensors. There is a need for accurate and timely positioning in safety-critical automotive and aerial applications, such as advanced warning systems or in urban air mobility (UAM). Today, these high-accuracy demands can partially be satisfied by GNSS, though not in dense urban conditions or under GNSS threats (e.g. interference, jamming or spoofing). Temporary and on-demand 5G network deployments using ground and flying base stations (BSs) are indeed a novel solution to exploit hybrid GNSS, 5G and sensor algorithms for the provision of accurate three-dimensional (3D) position and motion information, especially for challenging urban and suburban scenarios. Thus, this paper first analyzes the positioning technologies available, including signals, positioning methods, algorithms and architectures. Then, design considerations of 5G overlay networks are discussed, by including simulation results on the 5G signal bandwidth, antenna array and network deployment.Peer reviewe

In-situ electron microscopy investigation of ferroelectric domain switching kinetics

Due to their ultra-high piezoelectricity, pyroelectric properties, mechanical/electrical hysteresis properties and their possessing of non-volatile polarization states, ferroelectric materials have been used in various electronic devices, including various sensors, actuators, transducers, micromotors, and non-volatile memories. The mechanical, electrical, electromechanical, and thermoelectric properties are crucial factors for device applications of ferroelectric materials. These properties are particularly sensitive to the change of the embedded microscopic structures. Therefore, the mechanical and electrical characterisation of ferroelectric materials and the observation of their microstructural evolution under external stimuli are necessary for understanding their unique properties. However, this is not an easy task because of the difficulty of mechanical and electrical testing of nano/microscale materials. Various techniques have been used to investigate the mechanical and electrical behaviours of ferroelectric materials, among which the in-situ transmission electron microscopy is one of the most effective techniques. This thesis aims to combine state-of-the-art in-situ transmission electron microscopy techniques, the scanning transmission electron microscopy high-angle annular dark-field imaging technique, and phase-field modelling to investigate microstructural evolution in ferroelectric materials under different external stimuli. One of the ultimate goals of this research is to improve the performance of non-volatile ferroelectric memory devices

Development and automation of a robotic welding cell Using machine vision in Halcon programming environment

The current Project is developed in ACRO, Automatisering Centrum Research en Opleiding. ACRO is a Research and project Group in the field of automation, it offers a complete package of trainings and services in automation. The project consists in the upgrade of a robotic welding cell into a complete automated application through the implementation of a visual recognition system. In order to achieve this big objective the total project have been segmented into three different task: 1. The installation and functionality of the robotic welding cell without machine vision. 2. Introduction, development and achievement of a vision solution that provides the position and orientation information of the recognised pieces to the industrial robot. 3. Encapsulation of the vision solution deployed into a visual basic environment to offer a friendly interface to the different users and operators. Following the technology used in the project it can be encompassed into three different systems (they will be extensively described in section 3 of this paper): Robotic System. Welding System. Vision System. The final objective piece to recognise and weld is a metal cylinder that will be fixed into a flat square piece. This piece has been selected attending to its welding and visual recognition challenges, which can represent an acceptable example of the potential of the final welding cell once the solution is properly developed. Actually, the current project isn´t an isolated development carried out by ACRO, it is also inside a bigger industrial project developed by different partners and it has the company Sirris as a main contractor. Sirris is the collective centre of the Belgian technological industry. They help companies in the implementation of technological innovations, enabling them to strengthen their competitive position over the long-term. Their employees visit companies on site, offer them technological advice, launch innovation paths, and provide guidance until they reach the implementation phase. It is their aim to find concrete solutions to the real challenges facing Belgian entrepreneurs. The project is called “Smart Factories. Towards the Factory of the Future”. It began in 2012 and it will finish in May of 2016. The goal of the project is support the manufacturing industry in Flanders by the development of intelligent factories increasing substantially the manufacturing production. The result is create a flexible production system able to produce small series with productivity in order to response to the current market trends. A list of concrete steps have been defined in order to achieve the purpose of the project. There are a total of seven technological phases: 1. Zero ramp-up: production of small test series or trial products to check that the specifications of the project are satisfied. 2. Safe human-robot interaction: safe human-robot work in order to the production remain accessible for operators. 3. Auto programming: challenge of achieve the automated programming of the robot according with the information captured by the vision system. 4. Intelligent automated quality control: integration and automation of quality control where the series are controlled 100 per cent. 5. Offline robot programming: development of the required software to ensure complex robot can be programmed remotely. 6. Remote monitoring production: generation of feed-back in order to achieve real-time monitoring. 7. To stand-alone to network manufacturing cells: cells created in the project doesn’t work as isolated islands there are communication with each other and with a Smart Factory. In that way as a final objective once the project is finished, we are focus on the achievement of a real robotic welding cell that presents small, flexible and functional characteristics for companies that does not have the necessarily incomes to invest in the expensive robotic welding solution already implemented in the market.Escuela Técnica Superior de Ingeniería IndustrialUniversidad Politécnica de Cartagen

Time-Optimal Trajectory Generation and Way-Point Sequencing for 5-Axis Laser Drilling

Laser drilling provides a highly productive method for producing arrays of holes on planar and freeform shaped components. Industrial applications include fuel injection nozzles, printed circuit boards (PCB’s), inkjet printer heads, pinholes and slits for scientific instrumentation, high-resolution circuitry, sensors, fiber-optic interconnects, medical devices, and gas turbine combustion chamber panels. This thesis deals with time-optimal trajectory planning for two mainstream laser drilling methods: on-the-fly drilling and percussion drilling, which are used in the aerospace industry. The research has been conducted in collaboration with the Canadian aero-engine producer, Pratt & Whitney Canada (P&WC). The algorithms developed have been tested in a target application involving the laser drilling of cooling hole arrays on gas turbine engine combustion chamber panels. On-the-fly drilling is an operation in which each hole receives one low powered shot at a time while the workpiece is in motion, and the beam focal point is continuously proceeding to the next hole location. The positioning sequence repeats itself until all holes are gradually opened up in small increments. Each hole location has ample time to cool down before the next shot is received. Thus, this process can yield favorable material properties in terms of preserving the desired crystal structure, and also hole quality in terms of dimensional (size) and form (shape) accuracy, due to the reduction of local thermal loading. However, there is no existing trajectory planner, in industry, or in literature, capable of generating time-optimized positioning trajectories for on-the-fly laser drilling. This thesis studies this problem and presents a new algorithm, capable of handling 5 degree-of-freedom (axis) positioning capability. The ability to generate spline-based smooth trajectories is integrated within a Traveling Salesman Problem (TSP) type sequencing algorithm. The sequencing algorithm optimizes both the order of the waypoints (i.e., hole locations) and also the timing levels in between, which affect the temporal (time-dependent) nature of the motions commanded to the laser drilling machine’s actuators. Furthermore, the duration between consecutive holes has to be an integer multiple of the laser pulsing period, considering a machine configuration in which the laser is firing at a constant frequency, and unused pulses are diverted away using a quick shutter. It is shown that the proposed algorithm is capable of generating 17-25% reduction in the beam positioning time spent during a manufacturing cycle, compared to some of the contemporary practices in industry. 17% reduction in the vibrations induced onto the laser optics is also observed, which helps prevent downtime due to the optics hardware gradually losing alignment. The second type of laser drilling operation for which optimized 5-axis trajectory planning has been developed is percussion drilling. In this process, a series of pulses are sent to each hole while the part is stationary. Once the hole is completely opened up, then positioning to the next hole proceeds. While percussion drilling is less advantageous in terms of local thermal loading and achievable part quality, it is used extensively in industry; due to its simplicity of automation compared to on-the-fly drilling. Thus, a TSP-style trajectory planning algorithm has also been developed for percussion laser drilling. The novelty, in this case, is concurrent planning of 5-axis time-optimal point-to-point movements within the sequencing algorithm, and direct minimization of the total travel time, rather than just distance (in two Cartesian axes); as is the method for which significant portion of TSP solvers and trajectory planners in literature have been developed. Compared to currently applied methods at P&WC, 32-36% reduction in the beam positioning time has been achieved. Also, 39-45% reduction in the peak magnitude of vibration has been realized. Limited benchmarking with state-of-the-art TSP solvers from combinatorial mathematics, considering only 2-axis Euclidean distance as the objective function, indicate that the proposed sequencing algorithm for percussion drilling is sub-optimal by 9-12%. Thus, it can still use further improvement in future research. Nevertheless, the two trajectory planners that have been developed in this thesis for on-the-fly drilling and percussion drilling have experimentally demonstrated very promising improvements in terms of motion time and smoothness. As more advanced Computer Numerical Control (CNC) systems and laser control electronics with deterministic execution and rapid synchronization capability become available, such algorithms are expected to facilitate significant production gains in laser drilling processes used in different industries