Karl Stol - Academia.edu (original) (raw)
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Papers by Karl Stol
2016 IEEE 14th International Workshop on Advanced Motion Control (AMC), 2016
2016 International Conference on Unmanned Aircraft Systems (ICUAS), 2016
2015 IEEE International Conference on Mechatronics (ICM), 2015
International Journal of Advanced Robotic Systems, Sep 1, 2012
2000 ASME Wind Energy Symposium, 2000
Journal of Physics Conference Series
The use of individual pitch control (IPC) based on loads transformed into nonrotating coordinates... more The use of individual pitch control (IPC) based on loads transformed into nonrotating coordinates is explored on a range of wind turbines with ratings between 5MW and 15MW. Turbine models are generated using classical upscaling based on properties of the NREL 5MW reference wind turbine. The Ziegler-Nichols method is used with a low order linear model of each turbine to objectively tune a gain-scheduled, proportional-integral individual pitch controller. The performance of IPC is assessed by measuring reductions in blade and tower root damage equivalent loads from simulations at several wind speeds spanning Region 3. It is observed that the load reductions obtained with individual pitch control are maintained on upscaled turbines, with minimal impact on tower root loads, while actuator usage scales at a rate lower than expected with classical scaling.
This paper describes the dynamics and control of a two-wheeled robot (TWR) traversing a step. The... more This paper describes the dynamics and control of a two-wheeled robot (TWR) traversing a step. The TWR is able to navigate obstacles by shifting its centre of mass; however this comes at the cost of higher control requirements for stability. Equations of motion are derived for the system and a controller designed taking into account the initial conditions and possible reference trajectories. The TWR can be driven to any equilibrium position on the step by linearising the plant about that point and using state regulation. Analysis and simulation show that specific initial conditions are required for the TWR to avoid rolling back off the step. Limiting conditions of the developed controller are found, which include wheel slip, motor torque limit, and parameter uncertainty. The distance of the centre of mass of the TWR from the axle is the most sensitive to deviations from nominal. The current controller is able to traverse steps up to 5.7cm in height over any ascent time longer than 4.5s.
This paper presents a nonlinear feedback control framework for two-wheeled mobile robots. The app... more This paper presents a nonlinear feedback control framework for two-wheeled mobile robots. The approach uses a constructive Lyapunov function which allows the formulation of a control law with asymptotic stability of the equilibrium point of the system and a computable stability region. The dynamic equations are simplified through normalization and partial feedback linearization. The latter allows linearizing only the actuated coordinate. Description of the control law is complemented by the stability analysis of the closed loop dynamics of the system. The effectiveness of the method has been illustrated by its good performance and less control demand through simulations conducted for two control tasks: upright position stabilization and velocity tracking for a statically unstable two wheeled mobile robot.
20th 2001 ASME Wind Energy Symposium, 2001
2015 International Conference on Unmanned Aircraft Systems (ICUAS), 2015
2015 6th International Conference on Automation, Robotics and Applications (ICARA), 2015
42nd AIAA Aerospace Sciences Meeting and Exhibit, 2004
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
37th Aerospace Sciences Meeting and Exhibit, 1999
As the level of human interaction with robotic systems increases, robot mobility becomes more imp... more As the level of human interaction with robotic systems increases, robot mobility becomes more important. Two wheeled robots offer higher levels of mobility and manoeuvrability when compared to their four wheeled counterparts with the ability to turn on the spot and easily negotiate tight corners. Whilst the stabilisation of two wheeled platforms has been well studied, there is no published
Journal of Guidance, Control, and Dynamics, 2015
2016 IEEE 14th International Workshop on Advanced Motion Control (AMC), 2016
2016 International Conference on Unmanned Aircraft Systems (ICUAS), 2016
2015 IEEE International Conference on Mechatronics (ICM), 2015
International Journal of Advanced Robotic Systems, Sep 1, 2012
2000 ASME Wind Energy Symposium, 2000
Journal of Physics Conference Series
The use of individual pitch control (IPC) based on loads transformed into nonrotating coordinates... more The use of individual pitch control (IPC) based on loads transformed into nonrotating coordinates is explored on a range of wind turbines with ratings between 5MW and 15MW. Turbine models are generated using classical upscaling based on properties of the NREL 5MW reference wind turbine. The Ziegler-Nichols method is used with a low order linear model of each turbine to objectively tune a gain-scheduled, proportional-integral individual pitch controller. The performance of IPC is assessed by measuring reductions in blade and tower root damage equivalent loads from simulations at several wind speeds spanning Region 3. It is observed that the load reductions obtained with individual pitch control are maintained on upscaled turbines, with minimal impact on tower root loads, while actuator usage scales at a rate lower than expected with classical scaling.
This paper describes the dynamics and control of a two-wheeled robot (TWR) traversing a step. The... more This paper describes the dynamics and control of a two-wheeled robot (TWR) traversing a step. The TWR is able to navigate obstacles by shifting its centre of mass; however this comes at the cost of higher control requirements for stability. Equations of motion are derived for the system and a controller designed taking into account the initial conditions and possible reference trajectories. The TWR can be driven to any equilibrium position on the step by linearising the plant about that point and using state regulation. Analysis and simulation show that specific initial conditions are required for the TWR to avoid rolling back off the step. Limiting conditions of the developed controller are found, which include wheel slip, motor torque limit, and parameter uncertainty. The distance of the centre of mass of the TWR from the axle is the most sensitive to deviations from nominal. The current controller is able to traverse steps up to 5.7cm in height over any ascent time longer than 4.5s.
This paper presents a nonlinear feedback control framework for two-wheeled mobile robots. The app... more This paper presents a nonlinear feedback control framework for two-wheeled mobile robots. The approach uses a constructive Lyapunov function which allows the formulation of a control law with asymptotic stability of the equilibrium point of the system and a computable stability region. The dynamic equations are simplified through normalization and partial feedback linearization. The latter allows linearizing only the actuated coordinate. Description of the control law is complemented by the stability analysis of the closed loop dynamics of the system. The effectiveness of the method has been illustrated by its good performance and less control demand through simulations conducted for two control tasks: upright position stabilization and velocity tracking for a statically unstable two wheeled mobile robot.
20th 2001 ASME Wind Energy Symposium, 2001
2015 International Conference on Unmanned Aircraft Systems (ICUAS), 2015
2015 6th International Conference on Automation, Robotics and Applications (ICARA), 2015
42nd AIAA Aerospace Sciences Meeting and Exhibit, 2004
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
37th Aerospace Sciences Meeting and Exhibit, 1999
As the level of human interaction with robotic systems increases, robot mobility becomes more imp... more As the level of human interaction with robotic systems increases, robot mobility becomes more important. Two wheeled robots offer higher levels of mobility and manoeuvrability when compared to their four wheeled counterparts with the ability to turn on the spot and easily negotiate tight corners. Whilst the stabilisation of two wheeled platforms has been well studied, there is no published
Journal of Guidance, Control, and Dynamics, 2015