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Synthesis of a Group of Mechanisms with Dual Function Depending on the Input Velocities
, M.Sc. Thesis Sharif University of Technology ; Fallah Rajabzadeh, Famida (Supervisor) ; Zohoor, Hassan (Supervisor)
Abstract
Compliant mechanisms are generally used in quasi-static condition and therefore system dynamics do not have a significant effect on their performance; But if the inertia of the links is high, the dynamics of the mechanism will affect its performance altogether. By cleverly designing the mechanism, these effects can be used to create new movement patterns. In this research, a family of compliant mechanisms is introduced whose movement patterns are a function of input speeds. This means that at low speeds, the flexibility of the mechanism does not have a significant effect on its performance, but when the speed exceeds a certain limit, this flexibility changes the configuration of the...
Distributed Optimal Control via Central Pattern Generator with Application to Biped Locomotion
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Saadat Foumani, Mahmood (Supervisor)
Abstract
Human walking is widely recognized as one of the most adaptable and robust forms of locomotion in nature, with intricate neural and biomechanical systems interacting to support this complex behavior. It is proposed that these systems are organized in a hierarchical structure, with the lower level comprising a complex distributed system consisting of muscles and the spinal cord, and the higher level being the brain cortex. The higher level is responsible for training and monitoring the output of the lower level, and intervening when the lower system fails to stabilize the system. To control the lower level, one popular model that has emerged is the central pattern generator (CPG). It is...
Robust Controller Design for Three-Dimensional Overhead Crane System with Variable Cable Length
, M.Sc. Thesis Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
The main goal of controlling overhead crane systems is to safely transfer the load to its desired position with maximum speed and accuracy, as well as to minimize or eliminate load oscillations. The overhead crane system is considered as an underactuated mechanical system in which the number of control inputs (actuators) is less than the number of degrees of freedom. In addition, overhead crane systems are generally associated with parametric or unmodeled uncertainties. Also, in these systems, external disturbances such as wind have a destructive effect on the system's performance. In addition, if the overhead crane has the hoisting mechanism and the length of the rope changes as the trolley...
Biped hopping control bazsed on spring loaded inverted pendulum model
, Article International Journal of Humanoid Robotics ; Volume 7, Issue 2 , 2010 , Pages 263-280 ; 02198436 (ISSN) ; Jafari, F ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
2010
Abstract
Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a...