Department of Applied Mechanics (2017 - Present)
Mechanical Engineering
Mechanical Engineering, Tehran University, Tehran, Iran
Mechanical Engineering
Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Mechanical Engineering
Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran
Research field: Robotics, Artificial Intelligence, Mechatronics, Industrial Automation
Expert: Mahdi Alahdini
Phone: 82883996
Address: Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran.
Majid Sadedel received his B.S. degree from Amirkabir University of Technology, formerly called the Tehran Polytechnic, Tehran, Iran, in 2009, his M.S. degree from Sharif University of Technology, Tehran, Iran, in 2011, and his Ph.D. degree from Tehran University, Tehran, Iran, in 2016, all in Mechanical Engineering. Since 2017, he has been with the department of Mechanical Engineering at Tarbiat Modares University, Tehran, Iran, where he is currently an Assistant Professor. He is the founder and director of the Applied Mechatronics Innovation Center (amic) at Tarbiat Modares University. His research interests include robotics, artificial intelligence, mechatronics, and industrial automation.
The hexapod robot is one of the important classes in legged robots due to its great potential to operate in complex settings with high stability and flexibility. However, few researches have investigated the navigation and autonomous locomotion of this type of robot. This paper concerns with the behavior-based control and navigation of an autonomous hexapod robot utilizing a hybrid automaton. Switching between the distinct behaviors is based on the sensory data, and no representation of the environment is included. Since these systems are likely to rise chattering phenomenon, a sliding mode including clockwise and counter-clockwise boundary following behaviors are considered between the goal attraction and obstacle avoidance modes to modify
In this paper, a walking pattern optimization procedure is implemented to yield the optimal heel-strike and toe-off motions for different goal functions. To this end, first, a full dynamic model of a humanoid robot equipped with active toe joints is developed. This model consists of two parts: multi-body dynamics of the robot which is obtained by Lagrange and Kane methods and power transmission dynamic model which is developed using system identification approach. Then, a gait planning routine is presented and consistent parameters are specified. Several simulations and experimental tests are carried out on SURENA III humanoid robot which is designed and fabricated at the Center of Advanced Systems and Technologies located in the University
The main objective of this paper is to design a passive toe for Surena||| humanoid robot which is designed and fabricated at the center of advanced systems and technologies of the University of Tehran (CAST). To this end, a 2D model of robot has been adopted. The first step is to design the trajectory of joints neglecting the toe joints. The second step is to investigate the motion stability of the humanoid robot which has equipped with a passive toe using zero moment point criteria. For this purpose, angles of the passive toe during motion is needed which is obtained using vibrational equations. Afterward, the dynamic model of the robot is derived. Constraint-relaxation method is used to determine the reaction forces on the robot, then cal
In this article, an online adaptation algorithm for bipedal walking on uneven surfaces with height uncertainty is proposed. To generate walking patterns on flat terrains, the trajectories in the task space are planned to satisfy the dynamic balance and slippage avoidance constraints and also to guarantee smooth landing of the swing foot. To ensure smooth landing of the swing foot on surfaces with height uncertainty, the preplanned trajectories in the task space should be adapted. The proposed adaptation algorithm consists of two stages. In the first stage, once the swing foot reaches its maximum height, the supervisory control is initiated until the touch is detected. After the detection, the trajectories in the task space are modified to g
Adding active toe joints to a humanoid robot structure has lots of difficulties such as mounting a small motor and an encoder on the robot feet. Conversely, adding passive toe joints is simple, since it only consists of a spring and a damper. Due to lots of benefits of implementing passive toe joints, mentioned in the literature, the goal of this study is to add passive toe joints to the SURENA III humanoid robot which was designed and fabricated at the Center of Advanced Systems and Technologies (CAST), University of Tehran. To this end, a simple passive toe joint is designed and fabricated, at first. Then, stiffness and damping coefficients are calculated using a vision-based measurement. Afterwards, a gait planning routine for humanoid r
The understudy SURENA III humanoid robot was designed and fabricated at the Center of Advanced Systems and Technologies (CAST) located in the University of Tehran. In this paper, a full dynamic model of SURENA III in different walking phases including heel-off and heel-strike motions is presented. To this end, first a trajectory planning method based on robot kinematics is introduced. Then, the multi-body dynamics of the robot links are calculated using Lagrange and Kane approaches which are then verified. In this model, the power transmission system is considered to be ideal. Afterward, system identification routine is adopted to model the dynamic behavior of the power transmission system. By adding the calculated actuating
In this study, a gait optimization routine is developed to generate walking patterns which demand the lowest friction forces for implementation. The aim of this research is to fully address the question “which walking pattern demands the lowest coefficient of friction amongst all feasible patterns?”. To this end, first, the kinematic structure of the considered 31 DOF (Degrees of Freedom) humanoid robot is investigated and a closed-form dynamics model for its lower-body is developed. Then, the medium through which the walking pattern generation is conducted is presented. In this medium, after designing trajectories for the feet and the pelvis, the joint space variables are obtained, using the inverse kinematics. Finally, by employing a
In this paper, the main goal is to present an experimental comparison of the two prevailing contact modeling approaches of bipedal locomotion, ie rigid versus compliant contact model. To do this, first, an explicit dynamics model for the robot multibody with rigid model of contact for various phases of walking is developed. Then, in order to develop a model with compliant contact, a physically oriented software is exploited and using its tools the robot multibody is modeled. To model the unilateral contact in interaction points in this software, a nonlinear compliant contact model is proposed. Finally, the drive mechanism dynamics is modeled through a linear identification routine. By adding the drive system dynamics to both models, the pro
In this paper, the effects of the addition of an active toe joint on a 2D humanoid robot with heel-off and toe-off motions are studied. To this end, the trajectories of joints and links are designed firstly. After gait planning, the dynamic model of the humanoid robot in different phases of motion is derived using Kane and Lagrange methods. Then, the veracity of the derived dynamic model is demonstrated by two different methods. The under-study model, is in accordance with the features of SURENA III, which is a humanoid robot designed and fabricated at the Center of Advanced Systems and Technologies (CAST) located in University of Tehran. Afterward, the optimization procedure is done by selection of two different goal functions; one of them
The main objective of this article is to optimize the walking pattern of a 2D humanoid robot with heel-off and toe-off motions in order to minimize the energy consumption and maximize the stability margin. To this end, at first, a gait planning method is introduced based on the ankle and hip joint position trajectories. Then, using these trajectories and the inverse kinematics, the position trajectories of the knee joint and all joint angles are determined. Afterwards, the dynamic model of the 2D humanoid robot is derived using Lagrange and Kane methods. The dynamic model equations are obtained for different phases of motion and the unknowns, including ground reactions, and joint torques are also calculated. Next, the derived dynamic model
In this article, offline path planning for walking of a 2D humanoid robot with 6 Degrees of Freedom (DoF) is performed. This path planning is based on foot and hip trajectories. To make sure that walking cycle is stable, Zero Moment Point (ZMP) criterion is used. Full dynamic model of the humanoid robot in Single Support (SS) phase and Double Support (DS) phase are calculated by the use of Lagrange and Kane methods. By comparison of Lagrange and Kane methods, the dynamic model is verified. A Genetic Algorithm (GA) optimization of walking gait is proposed in which minimum energy consumption and maximum walking stability are two goal functions of this optimization. Finally the best stride length for each robot velocity is determined.
In this article, a general method for dynamics modeling of a humanoid robot which interacts with its environment is presented. This general method is based on developing equations assuming no interaction with its environment. Then, consistent constraints in different phases of motion are taken into account. In this method, each holonomic interaction constraint is considered as an unknown force/ moment which are then mapped into joint space of the robot, using transpose of jacobian matrices of interaction points. To this end, constrained dynamics model for the robot with broad-spectrum interaction with its environment in different phases of motion is encapsulated. In order to validate the proposed method, a dynamics model for a 21 DOF humano
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