A unique Unmanned Aerial Manipulator (UAM), also termed an aerial robot, is the subject of this thesis. A UAM is composed of a floating base attached to a manipulator that enables it to interact physically with the environment. The floating base is an Unmanned Aerial Vehicle (UAV) and the manipulator is defined as a two-cable underactuated Cable Driven Parallel Robot (CDPR). This specific design of a UAM is, to the author’s best knowledge, a novel concept. The thesis is done in collaboration with Airforestry, a company currently developing a solution for aerial forest thinning aiming to provide a more sustainable and efficient way to thin forests. Forest thinning today involves using heavy ground equipment that can cause damage to the surrounding environment and climate. The solution includes a UAV hovering over a chosen tree and attaching a tool (the manipulator) to it, cutting it, lifting it, and then transporting it. The thesis presents a planar model, control method, and simulation of the UAM system. The kinematic and dynamic models of the UAM are derived. A Proportional-Derivative (PD) controller is implemented for flying the UAV and another for controlling the cables. The model is simulated and examined by commanding the UAM to specific set-points under different circumstances such as comparing the UAV flying with and without the tool, changing the length of the cables, and changing the placement of the manipulators Center of Mass (CoM). Overall, the degree project provides a solid model foundation for the specific UAM which can be built upon and further improved. / En specifik Obemannad Flygande Manipulator (UAM), även kallad en flygande robot, är ämnet för denna avhandling. En UAM består av en flytande bas som är fäst vid en manipulator, vilket gör det möjligt för den att interagera med omgivningen. Den flytande basen är ett Obemannat Flygfordon (UAV) och manipulatorn definieras som en tvåkabel-aktuerad kabeldriven parallellrobot (CDPR). Denna specifika design av en UAM är, enligt författarens bästa kunskap, ett nytt koncept. Avhandlingen utförs i samarbete med Airforestry, ett företag som för närvarande utvecklar en lösning för skogsavverkning från luften i syfte att erbjuda ett mer hållbart och effektivt sätt att tunna ut skogar. Skogsavverkning idag innebär användning av tunga markmaskiner som kan skada den omgivande miljön och klimatet. Lösningen inkluderar en UAV som svävar över ett valt träd och fäster ett verktyg (manipulatorn) på det, skär det, lyfter det och transporterar det sedan bort. Avhandlingen presenterar en planarmodell, kontrollmetod och simulering av UAM-systemet. De kinematiska och dynamiska modellerna för UAM härleds. En proportionell-derivativ (PD) kontroller implementeras för att styra UAV:n och en annan för att kontrollera kablarna. Modellen simuleras och undersöks genom att styra UAM:n till specifika målpunkter under olika omständigheter, såsom att jämföra UAV-flygning med och utan verktyget, ändra längden på kablarna och ändra placeringen av manipulatorns masscentrum (CoM).svis ger examensarbetet en stabil modellgrund för den specifika UAM:n, som kan byggas vidare och förbättras.

Researchers have offered a variety of solutions for overcoming the old and challenging problem of undesired vibrations. The optimum vibration-control solution that can be a passive, semi-active or active solution, is chosen based on the desired level of vibration-control, the budget and the nature of the vibration source. Mechanical vibration-control systems, which work based on variable stiffness control, are categorized as semi-active solutions. They are advantageous for applications with multiple excitation frequencies, such as seismic applications. The available mechanical variable stiffness systems that are used for vibration-control, however, are slow and usually big, and their slowness and size have limited their application. A new semi-active variable stiffness solution is introduced and developed in this thesis to address these challenges by providing a faster vibration-control system with a feasible size. The new solution proposed in this thesis is a semi-active variable stiffness mount/isolator called the antagonistic Variable Stiffness Mount (VSM), which uses a variable stiffness spring called the Antagonistic Variable stiffness Spring (AVS). The AVS is a kinematically singular prestressable mechanism. Its stiffness can be changed by controlling the prestress of the mechanisms links. The AVS provides additional stiffness for a VSM when such stiffness is needed and remains inactive when it is not needed. The damping of the VSM is constant and an additional constant stiffness in the VSM supports the deadweight. Two cable-mechanisms - kinematically singular cable-driven mechanisms and Prism Tensegrities - are developed as AVSs in this thesis. Their optimal configurations are identified and a general formulation for their prestress stiffness is provided by using the notion of infinitesimal mechanism. The feasibility and practicality of the AVS and VSM are demonstrated through a case study of a typical engine mount by simulation of the mathematical models and by extensive experimental analysis. A VSM with an adjustable design, a piezo-actuation mechanism and a simple on-off controller is fabricated and tested for performance evaluation. The performance is measured based on four criteria: (1) how much the VSM controls the displacement near the resonance, (2) how well the VSM isolates the vibration at high frequencies, (3) how well the VSM controls the motion caused by shock, and (4) how fast the VSM reacts to control the vibration. For this evaluation, first the stiffness of the VSM was characterized through static and dynamic tests. Then performance of the VSM was evaluated and compared with an equivalent passive mount in two main areas of transmissibility and shock absorption. The response time of the VSM is also measured in a realistic scenario.

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