During the uniform locomotion of legged robots with compliant legs, the body of the robot exhibits quasi-periodic oscillations that have a disturbing eect on dierent onboard sensors. Of particular interest is the camera sensor which suers from image degradation in the form of motion-blur as a result of this camera motion. The eect of angular disturbances on the camera are pronounced due to the perspective projection property of the camera. The thesis focuses on the particular problem of legged robots exhibiting angular body motions and attempts to analyze and overcome the resulting disturbances on a camera carrying platform (head). Although the full problem is in 3D with three independent axes of rotation, a planar analysis provides signicant insight into the problem and is the approach taken in the thesis. A carefully modeled planar version of an actual camera platform with realistic mechanical and actuator selections is presented. Passive (ltering) and active (controller) approaches are discussed to compensate/cancel motion generated disturbances. We consider and comparatively evaluate PID and LQR based active control. Since PID has the limitation of controlling only one output, PID-PID control is considered to iv control two states of the model. Due to its state-space formulation and the capability of controlling an arbitrary number of states, LQR is considered. In addition to standard reference signals, Gyroscope measured disturbance signals are collected from the actual robot platform to analyze the bandwidth and test the performance of the controllers. Inverted pendulum control performance is evaluated both on a Matlab-Simulink as well as a precise electro-mechanical test setup. Since construction of the planar head test setup is in progress, tests are conducted on simulation.

This thesis presents an innovative approach to enhance the stability of floating offshore wind turbine (FOWT) platform through mooring actuation. First, an OC3- Hywind spar-buoy floating platform is modeled utilizing the Control-oriented, Reconfigurable, and Acausal Floating Turbine Simulator (CRAFTS) with a specific focus on predicting hydrodynamic and mooring line loads while intentionally excluding consideration of aerodynamic forces. The accuracy of this model is validated against the industry standard OpenFAST simulator through various test cases. The central objective of this study revolves around achieving robust stabilization of the spar buoy platform, primarily focusing on X-Z symmetric planar motions, including surge, pitch, and heave degrees of freedom (DOFs). To accomplish this, two linearization techniques are employed: one transforms the inherently complex nonlinear model from CRAFTS into a linear Mass-Spring-Damper (MSD) system, particularly targeting surge and pitch motions, while the other method involves the conversion of the nonlinear model from CRAFTS into the Functional Mockup Interface (FMI) within MATLAB/Simulink for linearization. The analysis utilizing Bode plots derived from these lin- earized models yields crucial insights into the system's response to mooring actuation. Notably, it emphasizes the inherent challenge in pitch control, characterized by lower gain compared to surge at relevant frequencies, necessitating substantial mooring actuation or cable length modifications for effective pitch stabilization. Then, a Linear Quadratic Regulator (LQR) controller is designed to mitigate surge and pitch motions. Numerical simulations conducted across diverse scenarios reveal the inherent challenge in simultaneously mitigating surge and pitch motions using the original platform configuration. To address this challenge, a control co-design strategy is proposed, leading to the development of an optimized mooring line configuration that effectively stabilizes both motions with minimal adjustments. In summary, this thesis introduces a control-oriented modeling approach and an innovative control strategy to enhance the stability of the floating wind turbine platform through mooring actuation. The results emphasize the potential for broader application of this approach to various floating platforms for FOWTs and the extension of stabilization efforts to address all six DOFs in future research, where aerodynamic loads are also incorporated.

In this thesis work construction of the angular acceleration signal of a 2-DOF gimbal platform and use of this signal for improving the stabilization performance is aimed. This topic can be divided into two subtopics, first being the construction of angular acceleration and the second being the use of this information in a way to improve system performance. Both problems should be tackled in order to get satisfactory results. The most important output of this work is defined as the demonstration of the improvements obtained both theoretically and on experimental setup. Although the system to be studied is a two axis gimbal platform, the results obtained can be applied to other servo control problems. It is possible to define different performance criteria for a servo control problem and different techniques will be addressed with different control objectives. For this thesis work, the performance criterion is defined as the stabilization performance of the platform. As a result, disturbance rejection characteristics of the controller emerges as the main topic and methods for rejecting these disturbances such as the friction torques and externally applied moments are focused on throughout the studies. As expected, remarkable improvement is achieved as a result of the use of acceleration feedback.