Sharif Digital Repository

Dynamic gait planning for humanoid robots encounters difficulties such as stability, speed, and smoothness. In most of previous studies, joints' trajectories are calculated in 3D Cartesian space, then, introducing boundary conditions and using polynomials, the first and second derivatives of the motion are ensured to be continuous. Then, the stability of the motion is guaranteed using Zero Moment Point (ZMP) stability criterion. In this study, a trajectory planner is presented using the semi-ellipse equations of the motion; the continuity of the derivatives is preserved. Stabilization of motion is attained through using ZMP criterion and 3d inverted pendulum equations in three slope... 

Humanoid robots have recently been the subject of many new and interesting fields both in robotics research and industry. The wide variety of their applications in civic and hostile environments demand developing approperiate theoretical models for analysis. A dynamical model was developed to study the human jumping process, and the effect of factors like joint speeds and hand motion in jumping. An experiment was designed and setup to compare the theoretical model with experimental observations. Time histories of vertical force, mass center velocity and driving torques were also obtained. Using dynamical equations, the effect of joint speeds on the maximum values of these quantities is... 

This paper presents the effect of robotics assisted language learning (RALL) on the vocabulary learning and retention of Iranian English as foreign language (EFL) junior high school students in Tehran, Iran. After taking a vocabulary pre-test, 46 beginner level female students at the age of 12, studying in their first year of junior-high participated in two groups of RALL (30 students) and non-RALL (16 students) in this study. The textbook used was the English book (Prospect-1) devised by the Iranian Ministry of Education for 7th graders, and the vocabulary taught and tested (pre-test and post-test) were taken from this book. Moreover, the treatment given by a teacher accompanied by a... 

Technology, as a source of instruction, has fulfilled various purposes in foreign language learning environments. During the last decade, Robot-Assisted Language Learning (RALL) has attracted teachers' and researchers' attention due to the look and feel of humanoid robots. However, in the field of pragmatics, studies highlighting the role of RALL have gone relatively unnoticed. To bridge this gap, this study sought to explore the effect of RALL on pragmatic features, including request and thanking speech acts by young Persian-speaking EFL learners. For this aim, 38 preschool children (3 to 6 year-old boys and girls) with no English learning experience were randomly assigned to the RALL (19... 

Autistic children are often impaired in initiating and responding to Joint Attention. In recent years, there has been an increase in the application of robots in diagnosis and treatment of autism. The purpose of the current research has been primarily to originate the proper therapeutic scenarios and to implement two interactive humanoid robots as therapy assistants in autism treatment in Iran. To this end, the humanoid robots were programmed and teleoperated via Microsoft Kinect Sensor and PhantomOmni Haptic Robot to elicit reactions consisting of imitation of humans by the humanoid robots and vice versa. In this paper, we elaborate on the therapeutic items that we have designed to improve... 

A passive bipedal walking robot can descend down a small slope without any exertion of external force and only by using the gravity force. By exerting a proper energy to a passive biped robot, its walking speed can be controlled and also it can be forced to walk on flat planes and ascending slopes. In this paper, the proper energy is applied to the robot in three different methods: applying a proper moment to the robot joints, applying a proper moment to the robot’s stance leg, and applying a proper movement to the robot’s upper body. It is found that the first method is not practical, but the second and third methods enhance the stability and speed regulation of the robot. Additionally, the... 

The understudy SURENA III humanoid robot was designed and fabricated at the Center of Advanced Systems and Technologies (CAST) located in the Universityof Tehran. In this paper, a full dynamic model of SURENA III in different walking phases including heel-offand 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 transmissionsystem is considered to be ideal. Afterward, system identification routine is adopted to model the dynamic behavior of the power transmission system. By... 

This study addresses optimal walking pattern generation for SURENA III humanoid robot in a stair-climbing scenario. To this end, the kinematic configuration of the 31-DOF humanoid robot is studied. Integrating the detailed dynamic properties of the robot, a comprehensive and precise dynamic model is developed for its lower-limb. In order to generate the optimal walking pattern for the considered humanoid robot, trajectories for feet and pelvis are first designed, and then joint angles are derived by means of inverse kinematics. Such a complete model provides the designer with the necessary tools to optimize the trajectory generation. Using two different types of objective functions, namely... 

The motivation of this work is to synthesize a kicking pattern for a humanoid robot with consideration of various objectives such as retaining its balance even after the kick is done and reducing the undesired angular momentum using both hands and torso. This kick pattern is designed so that a desirable ball velocity is achieved. In this paper, the law of conservation of angular momentum is used to generate a less energy consuming trajectory. Effectiveness of the proposed method is verified using computer simulation and is tested on Sharif CEDRA humanoid robot. Copyright © 2006 by ASME  

This paper presents the design characteristics of a new robot Assistant for Social Aims (RASA), being an upper-torso humanoid robot platform currently under final stages of development. This project addresses the need for developing affordable humanoid platforms designed to be utilized in new areas of social robotics research, primarily teaching Persian Sign Language (PSL) to children with hearing disabilities. RASA is characterized by three features which are hard to find at the same time in today’s humanoid robots: its dexterous hand-arm systems enabling it to perform sign language, low development cost, and easy maintenance. In this paper, design procedures and considerations are briefly... 

This study explores the effect of RALL (Robot Assisted Language Learning) on instructing greeting to young EFL (English as Foreign Language) students in Tehran, Iran. To this end, 38 preschool EFL children ranging from 3 to 6 years old were randomly assigned to the RALL (19 students) and game-based (19 students) groups, and the greeting sentences were extracted from the Functional Communication in English book [1] and ESL library website scenarios. In addition, the robot for the RALL group was used as an assistant to the teacher while for the game-based group the instruction was based on gaming methods such as command, mystery bag, and pass the ball. The instructional duration for both... 

In this paper, three pairs of children with autism include a pair of twins, two siblings, and two classmates were enrolled in a 12-session robot-assisted group-games program. As many environmental factors were for the most part the same for the siblings as well as genetic factors for the twins, we were able to observe/compare the effect of the designed games on the participants individually and in paired-groups. The results indicated that all participants’ autism severity decreased after the course of the program. Improvement in social skills, social participation/avoidance, and detrimental social behaviors were also observed in the participants with high-functioning autism with close to... 

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... 

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...