Browsing by Author "Kuru, Alihan"

Now showing 1 - 3 of 3

Metadata only
Design and development of a torsion-based series elastic actuator with nested encoders for a wearable exoskeleton robot
(IEEE, 2022) Kuru, Alihan; Uğurlu, Regaip Barkan; Bebek, Özkan; Mechanical Engineering; UĞURLU, Regaip Barkan; BEBEK, Özkan; Kuru, Alihan
This paper presents the design of a high torque-to-mass ratio series elastic actuator (SEA) for wearable powered exoskeletons. Nonbackdrivable actuators are ideal for applications that require high torque. Commonly, active exoskeleton robots are powered by actuators that are nonbackdrivable. Due to the high gear ratio, the output mechanical impedance of these actuators is quiet high which renders their force/torque control challenging. To provide torque controllability a custom torsional spring has been produced and placed at the output side of the series elastic actuator. In addition, the measurement of the angular displacement of this elastic element is challenging in terms of mechanical design. To prevent this design challenge a double shaft mechanism was proposed. In this mechanism, the first shaft, which connects the spring and the spring encoder, goes through the second shaft, which is connected to the motor and the motor encoder. This way both encoders are placed on a the same side of the SEA. In addition to explaining this compact spring shaft mechanism, this article presents the results of the cascaded PID controller with a disturbance observer (DoB) applied on the actuator.
Metadata only
Design and development of torsion spring based series elastic actuator with nested encoders for wearable exoskeleton robot
Kuru, Alihan; Bebek, Özkan; Bebek, Özkan; Başol, Altuğ Melik; Topaloğlu, N.; Department of Mechanical Engineering; Kuru, Alihan
his thesis proposes a series elastic actuator design to power an assistive exoskele ton for the paraplegic or stroke patient whom incapable to walk or provide any motion at lower extremity portion of the body. Commonly, active exoskeleton robots are powered with the rigid actuators which do not provide torque control lability any physiological compliance and physical elasticity with the patient. Physical elasticity in the actuator can be used to compensate the environmen tal external forces during motion of the exoskeleton. Therefore, controlling the torque generated at the joints of the exoskeleton would provide safer human-robot interaction. Series elastic actuators are able to provide advanced control and high fidelity control with the elastic element located between the motor and the me chanical output of the series elastic actuator. The main goal of this thesis is to develop a series elastic actuator for a powered exoskeleton to provide torque mea surement and control during locomotion and optimizing the elastic element of the actuator for high fidelity control. To provide torque controllability a custom torsional spring has been produced and placed at the output side of the series elastic actuator. Especially developed SEA modules are designed to be modular, lightweight and have a high torque-to mass ratio. In addition, measurement of the angular displacement of the elastic element is challenging in terms of mechanical design. To circumvent this design problem, a double shaft mechanism was proposed. In this mechanism, the first shaft, which connects the spring and the spring encoder, goes through the second shaft, which is connected to the motor and the motor encoder. This way both encoders are placed on the same side of the SEA. In addition to design, results of the cascaded proportional integral derivative (PID) controller with a disturbance observer (DoB) applied on the actuator is presented.
Metadata only
Simulation-based design and locomotion control implementation for a lower body exoskeleton
(IEEE, 2022) Derman, Mustafa; Soliman, Ahmed Fahmy; Kuru, Alihan; Çevik, Süleyman Can; Ünal, Ramazan; Bebek, Özkan; Uğurlu, Regaip Barkan; Mechanical Engineering; ÜNAL, Ramazan; BEBEK, Özkan; UĞURLU, Regaip Barkan; Derman, Mustafa; Soliman, Ahmed Fahmy; Kuru, Alihan; Çevik, Süleyman Can
This paper proposes a simulation-based design and locomotion control methodology for an exoskeleton that is aimed at providing assistance to users with ambulatory difficulties. To increase the power-to-weight ratio while satisfying design constraints, we made use of simulation tools to recursively update the initial mechanical design for a finer solution. To this end, a coupled human-exoskeleton model was constructed in MSC ADAMS environment using an average human model and the initial design of the robot. Following this step, dynamic walking control simulations were carried out to determine actuator torques and loading. Using the loading data obtained via simulation experiments, certain mechanical links were optimized such that the portions with no stress concentration were removed without violating safety. Finally, two distinct control implementations were conducted: i) stand-to-sit motion, ii) dynamic walking. As a result, we obtained dynamically consistent motion behavior for both cases, adequately validating the proposed methodology.