Millions of cranes are used around the world. Because of their wide-spread use in construction industries, boom cranes are an important class of cranes whose performance should be optimized. One limitation of most boom cranes is they are usually attached to a stationary base or a mobile base that is only used for initial positioning and not during operation. This limits the workspace of the boom crane significantly. If a boom crane was attached to a mobile base that could be safely used during lifting operations, then the boom crane workspace could be extended significantly. The problem with using cranes, and in particular mobile cranes, is the large oscillations of the payload that are typically induced when moving the crane. One control strategy that has been used to control oscillation on other types of cranes is called Input Shaping, a command filtering technique that reduces motion-induced vibration in oscillatory systems. This thesis develops a dynamics model for a mobile boom crane and analyzes the difficulty of controlling payload oscillation on a boom crane. Input shaping will shown to be effective for controlling oscillation on boom cranes. A new method for operating a boom crane in Cartesian coordinates will also be shown. This thesis will also detail the design of a small-scale mobile boom crane for experimental and research purposes. A substantial part of this thesis will also focus on the development of new input-shaping methods for nonlinear drive systems commonly found on boom and other types of cranes. An example application of a control system featuring input shaping for an industrial bridge crane will also be discussed.

The rapid movement of machines is a challenging control problem because it often results in high levels of vibration. As a result, flexible machines are typically moved relatively slowly to avoid such vibration. Therefore, motion-induced vibration limits the operational speed of the system. Input shaping is one method that eliminates motion-induced vibrations by intelligently designing the reference command such that system vibration is cancelled. It has been successfully implemented on a number of systems, including bridge and tower cranes. The implementation of input shaping on cranes provides a substantial increase in the operational efficiency. Unfortunately, most cranes, once erected, have limited or no base mobility. This limits their workspace. The addition of base mobility could help extend the operational effectiveness of cranes and may also expand crane functionality. Mobile cranes may also be better suited for use in harsh and/or distant environments. Teleoperation of oscillatory systems, such as cranes, then becomes another avenue for advancement of crane functionality. Base mobility in cranes presents both additional control challenges and operational opportunities. A crane with base mobility is redundantly actuated (overactuated), such that multiple combinations of actuators can be used to move a payload from one location to another. This opens the possibility for the selection of a combination of actuation that provides both rapid motion and limited system vibration. The extension of input shaping into this operational domain will provide a method to maximize effective actuation combinations. Toward addressing these issues, new multi-input shaping methods were developed and applied to a mobile, portable tower crane. During this development, a firm understanding of robust input shaping techniques and the compromises inherent to input shaper design was formed. In addition, input shaping was compared to other command generation techniques, namely lowpass and notch filtering, and proven to be superior for vibration reduction in mechanical systems. Another, new class of input shapers was also introduced that limit the input shaper induced overshoot in human operated systems. Finally, a series of crane operator studies investigated the application of input shaping techniques to teleoperated cranes. These studies suggested that input shaping is able to dramatically improve remote crane operator performance.

Recent decades have been witness to explosive leaps in manufacturing productivity. Advances in communication technology, computing speed, control theory, and sensing technology have been significant contributors toward the increased productivity and efficiency that industry has exhibited. The continued growth of technological equipment and engineering knowledge challenges engineers to fully utilize these advancements in more sophisticated and useful automation systems. One such application involves enhancing bridge and gantry crane operation. These systems are used throughout the globe, and are critical aspects of industrial productivity. Consequently, improving the operational effectiveness of cranes can be extremely valuable. Effective control of cranes can be largely attributed to two distinct, but related aspects crane manipulation: 1) the expertise of operators, which are responsible for issuing commands to the structures, and 2) the dynamic properties of cranes, which influence how the structures respond to issued commands. Accordingly, the operational efficiency of cranes can be influenced by changing both the way that operators issue commands to cranes, and also how the crane responds to issued commands. This thesis is concerned with dynamic control theory of flexible machines, and human/machine interaction, especially as these areas relate to industrial crane control. In the area of dynamic control, this thesis investigates control strategies that are specifically suited for use on systems that possess common actuator nonlinearities, like saturation, rate limiting, dead-zone, backlash, and finite-state actuation. In the area of human/machine interaction, this thesis investigates the effects of different crane interface devices on the operational efficiency of cranes.

A helicopter can be used to transport a load hanging from a suspension cable. This technique is frequently used in construction, firefighting, and disaster relief operations, among other applications. Unfortunately, the suspended load swings, which makes load positioning difficult and can degrade control of the helicopter. This dissertation investigates the use of input shaping (a command-filtering technique for reducing vibration) to mitigate the load swing problem. The investigation is conducted using two different, but complementary, approaches. One approach studies manual tracking tasks, where a human attempts to make a cursor follow an unpredictably moving target. The second approach studies horizontal repositioning maneuvers on small-scale helicopter systems, including a novel testbed that limits the helicopter and suspended load to move in a vertical plane. Both approaches are used to study how input shaping affects control of a flexible element (the suspended load) and a driven base (the helicopter). In manual tracking experiments, conventional input shapers somewhat degraded control of the driven base but greatly improved control of the flexible element. New input shapers were designed to improve load control without negatively affecting base control. A method for adjusting the vibration-limiting aggressiveness of any input shaper between unshaped and fully shaped was also developed. Next, horizontal repositioning maneuvers were performed on the helicopter testbed using a human-pilot-like feedback controller from the literature, with parameter values scaled to match the fast dynamics of the model helicopter. It was found that some input shapers reduced settling time and peak load swing when applied to Attitude Command or Translational Rate Command response types. When the load was used as a position reference instead of the helicopter, the system was unstable without input shaping, and adding input shaping to a Translational Rate Command was able to stabilize the load-positioning system. These results show the potential to improve the safety and efficiency of helicopter suspended load operations.

Forests represent one of the biggest terrestrial ecosystems of Earth, that can produce important raw renewable materials such as wood with the help of sun, air and water. To efficiently extract these raw materials, the tree harvesting process is highly mechanized in developed countries, meaning that advanced forestry machines are continuously used to fell, to process and to transport the logs and biomass obtained from the forests. However, working with these machines is demanding both mentally and physically, which are known factors to negatively affect operator productivity. Mental fatigue is mostly due to the manual operation of the on-board knuckleboom crane, which requires advanced cognitive work with two joystick levers, while the most serious physical strains arise from cabin vibrations. These vibrations are generated from knuckleboom crane vibrations as a result of aggressive manual operation. To enhance operator workload, well-being, and to increase productivity of the logging process, semi-automation functions are suggested, which are supervised automatic executions of specific work elements. Some of the related issues are addressed in the current thesis. Therefore, the content is divided into: (1) the design and development of a semi-automation function focused only on the base joint actuator (slewing actuator) of a knuckleboom crane, and (2) active vibration damping solutions to treat crane structure vibrations induced by the main lift cylinder (inner boom actuator). The considered reference machine is a downsized knuckleboom crane of a forwarder machine, which is used to pick up log assortments from a harvesting site. The proposed semi-automation function presented in the first part could be beneficial for operators to use during log loading/unloading scenarios. It consists from a closed-loop position control architecture, to which smooth reference slewing trajectories are provided by a trajectory planner that is automated via operator commands. The used trajectory generation algorithms are taken from conventional robotics and adapted to semi-automation context with proposed modifications that can be customizable by operators. Further, the proposed active vibration damping solutions are aimed to reduce vibrations of the knuckleboom crane excited by the inner boom actuator due to aggressive manual commands. First, a popular input shaping control technique combined with a practical switching logic was investigated to deal with the excited payload oscillations. This technique proved to be useful with a fixed crane pose, however it did not provide much robustness in terms of different link configurations. To tackle this problem an H2-optimal controller is developed, which is active in the pressure feedback-loop and its solely purpose is to damp the same payload oscillations. During the design process, operator commands are treated and explained from input disturbance viewpoint. All of the hypothesis throughout this thesis were verified with extensive experimental studies using the reference machine.

VIBRATION AVOIDANCE, a technique to proactively remove unwanted or excessive vibrations in multi-joint industrial robots, has shown to be desired in various applications. A trade-off between vibration avoidance performance and path deviation has been thekey criteria for assessing the effectiveness and quality of an approach. The purpose of this thesis is to compare two proposed state-of-the-art vibration avoiding approaches: input shaping and extended flexible joint model combined with specialized compensation control and explore the fusion of them. Both approaches are first investigated and evaluated in simulation. A comparison is then conducted in the four presented baseline movements on a real robot. Among the two approaches, input shaping is less comprehensive but enables rapid identification, making it suitable for simple repetitive tasks. It is also found that joint-wise path generation used in input shaping causes a loss of path fidelity, but this problem is alleviated when using an extended flexible joint model combined with specialized compensation control. The latter approach preserves synchronicity across all joints and assures multi-input multi-output (MIMO)-path fidelity. The extended flexible joint model, which is identified through a nonlinear gray-box model, is also less susceptible to modeling errors. The performance comparison with two rudimentary digital filters exhibits promising results for both proposed solutions. Finally, a fusion of the two approaches is proposed as a final solution of this work. As a result, the collaborative approach is the closest to ideal vibration avoidance but suffers from greater path deviation. The extended flexible joint model combined with compensation results in the least deviation from the baseline trajectory among all tested approaches. / VIBRATIONSDÄMPNING, en teknik för att proaktivt undvika oönskade vibrationer i fleraxlade industrirobotar, har visat sig vara önskvärd i många olika applikationer. En avvägning mellan vibrationsdämpningens prestanda och avvikelser från rörelsebanan har varit viktiga kriterier för att bedöma effektiviteten och kvalitén av ett tillvägagångssätt. Syftet med denna avhandling är att jämföra två toppmoderna tillvägagångssätt för att undvika vibrationer: ingångsformning och utökad flexibel axelmodell kombinerad med specialiserad kompensationskontroll samt utforska sammanslagning av de två. Bägge tillvägagångssätt är först undersökta och utvärderade i en simulation. En jämförelsemellan de fyra standard robotrörelserna som är presenterade är sedan genomförd på en riktig robot. Mellan de två tillvägagångssätten är ingångsformning mindre förståeligt men möjliggör en snabb identifikation vilket gör den lämplig för simpla repetitiva uppgifter. Det fastställs även att axelvis generering av rörelsebanor som används med ingångsformning orsakar lägre noggrannhet och pålitlighet vad gäller avvikelser från rörelsebanan. Detta problem är inte lika påtagligt vid användning av utökad flexibel axelmodell kombinerad med specialiserad kompensationskontroll eftersom detta tillvägagångssätt bevarar synkroniciteten över samtliga axlar och garanterar multi-input multi-output (MIMO) följdriktighet. Den utökade flexibla axelmodellen, som identifieras med hjälp av en icke-linjär gray-box modell, är även mindre mottaglig för modelleringsfel. Prestandajämförelsen med två rudimentära digitala filter uppvisar lovande resultat för bägge föreslagna lösningar. Till sist, en sammanslagning av de två tillvägagångssätt är föreslagen som en slutgiltig lösning. Det sammanslagna tillvägagångssättet är närmast perfekt vibrationsdämpning men medför större avvikelser från rörelsebanan. Den utökade flexibla axelmodellen kombinerad med kompensation resulterar i minst avvikelse från rörelsebanan bland alla testade tillvägagångssätt.

This thesis project has been conducted during a five-month research exchange visit to the Space Structure Dynamics and Control research group at University College Dublin. This report presents the design, development, and validation of a nanosatellite attitude control testbed. The testbed was designed to replicate the microgravity conditions of space by utilising an air bearing, enabling single-axis rotational motion for a 1U CubeSat-sized nanosatellite. The novel aspect of this research is the inclusion of two-degree-of-freedom, lumped-mass flexible appendages on either side of the nanosatellite, emulating a lightweight, flexible space structure. These flexible appendages were designed based on the stiffness characteristics of a deployable CubeSat solar array system found in existing literature, with exaggerated motion to amplify the measurable effects of various control approaches. The central focus of this project was the development of an avionics stack closely resembling CubeSat attitude control boards. The stack uses an STM32 microcontroller as the primary attitude control computer, and a suite of off the shelf breakout boards for sensors and wireless telemetry systems. Power, serial and I2C buses connect the attitude control board and the onboard computer board. A reaction wheel actuator controls the Euler heading attitude. The testbed was designed as an experimental platform for validating control algorithms developed through a model-based approach. Integration with the Simulink Embedded Coder toolbox allows for the compilation of Simulink models into C code, facilitating direct execution on the testbed. The testbed’s physical construction involves 3D printed ABS components, with the inclusion of load cells to measure disturbance torques from the excited flexible appendages. Results from validation experiments show that a simple PID controller causes significant excitation in the flexible appendages during a slew manoeuvre. However, the introduction of an input shaped attitude profile tailored to the natural frequency of the appendages successfully reduced the measured appendage excitation by 50%. Conversely, the force impedance wave based control approach did not show a reduction in appendage excitation, but shows promise for further developments in future work. In conclusion, the testbed has successfully achieved its predefined project objectives, albeit requiring further refinement, particularly in the telemetry down-link system. It is recommended that future work focuses on enhancement of the telemetry system, and validation of a model based approach to controller design. / Detta examensarbete har utförts under ett fem månaders forskningsutbyte vid forskningsgruppen Space Structure Dynamics and Control vid University College Dublin. Denna rapport presenterar design, utveckling och validering av en testbädd för attitydstyrning av en nanosatellit. Testbädden utformades för att efterlikna mikrogravitationsförhållandena i rymden genom att använda ett luftbärande lager, vilket möjliggör rotationsrörelse kring en axel för en nanosatellit av storleken 1U CubeSat. En unik aspekt av detta arbete är inkluderingen av två-frihet-graders, sammansatta flexibla påhängen på vardera sidan av nanosatelliten, vilket efterliknar en lätt, flexibel rymdstruktur. Dessa flexibla påhängen utformades med utgångspunkt från styvhetsegenskaperna hos ett utskjutbart CubeSat-solcellssystem som finns i befintlig litteratur, med överdriven rörelse för att förstärka de mätbara effekterna av olika styrmetoder. Det centrala fokuset för detta projekt var utvecklingen av en avionikstack som nära liknar CubeSat-attitydregleringkort. Stacken använder en STM32-mikrokontroller som primär dator för attitydkontroll och ett urval färdiga breakout-kort för sensorer och trådlös telemetri. Strömförsörjning, serie- och I2C-bussar ansluter attitydregleringkortet och omborddatorn med en reaktionshjulsaktuator som styr Euler-attityd. Testbädden utformades som en experimentell plattform för att validera styralgoritmer som utvecklats med hjälp av en modellbaserad metod. Integration med Simulink Embedded Coder möjliggör kompilering av Simulink-modeller till C-kod, vilket underlättar direkt exekvering på testbädden. Testbäddens fysiska konstruktion innefattar 3D-utskrivna ABS-komponenter med inkludering av lastceller för att mäta störningsmoment från de exciterade flexibla påhängen. Resultaten från valideringsexperiment visar att en enkel PID-regulator orsakar betydande excitation i de flexibla påhängena under en vridningsmanöver. Dock lyckades en input-formad attitydprofil som anpassats till de flexibla påhängenas naturliga frekvens framgångsrikt minska den uppmätta excitationen med 50%. Omvänt visade den kraftimpedansvågbaserade styrmetoden inte någon minskning i excitation, men visar potential för vidare utvecklingar i framtida arbete. Sammanfattningsvis har testbädden framgångsrikt uppnått sina fördefinierade projektmål, om än med behov av ytterligare förfining, särskilt i telemetrisystemet. Det rekommenderas att framtida arbete fokuserar på förbättring av telemetrisystemet och validering av en modellbaserad ansats till styrdesign.