Humanoid Robots

For many years, the human being has been trying, in all ways, to recreate the complex mechanisms that form the human body. Such task is extremely complicated and the results are not totally satisfactory. However, with increasing technological advances based on theoretical and experimental researches, man gets, in a way, to copy or to imitate some systems of the human body. These researches not only intended to create humanoid robots, great part of them constituting autonomous systems, but also, in some way, to offer a higher knowledge of the systems that form the human body, objectifying possible applications in the technology of rehabilitation of human beings, gathering in a whole studies related not only to Robotics, but also to Biomechanics, Biomimmetics, Cybernetics, among other areas. This book presents a series of researches inspired by this ideal, carried through by various researchers worldwide, looking for to analyze and to discuss diverse subjects related to humanoid robots. The presented contributions explore aspects about robotic hands, learning, language, vision and locomotion

Climbing and Walking Robots

Nowadays robotics is one of the most dynamic fields of scientific researches. The shift of robotics researches from manufacturing to services applications is clear. During the last decades interest in studying climbing and walking robots has been increased. This increasing interest has been in many areas that most important ones of them are: mechanics, electronics, medical engineering, cybernetics, controls, and computers. Today’s climbing and walking robots are a combination of manipulative, perceptive, communicative, and cognitive abilities and they are capable of performing many tasks in industrial and non- industrial environments. Surveillance, planetary exploration, emergence rescue operations, reconnaissance, petrochemical applications, construction, entertainment, personal services, intervention in severe environments, transportation, medical and etc are some applications from a very diverse application fields of climbing and walking robots. By great progress in this area of robotics it is anticipated that next generation climbing and walking robots will enhance lives and will change the way the human works, thinks and makes decisions. This book presents the state of the art achievments, recent developments, applications and future challenges of climbing and walking robots. These are presented in 24 chapters by authors throughtot the world The book serves as a reference especially for the researchers who are interested in mobile robots. It also is useful for industrial engineers and graduate students in advanced study

Bipedal humanoid robot walking reference tuning by the use of evolutionary algorithms

Various aspects of humanoid robotics attracted the attention of researchers in the past four decades. One of the most challenging tasks in this area is the control of bipedal locomotion. The dynamics involved are highly nonlinear and hard to stabilize. A typical fullbody humanoid robot has more than twenty joints and the coupling effects between the links are significant. Reference generation plays a vital role for the success of the walking controller. Stability criteria including the Zero Moment Point (ZMP) criterion are extensively applied for this purpose. However, the stability criteria are usually applied on simplified models like the Linear Inverted Pendulum Model (LIPM) which only partially describes the equations of the motion of the robot. There are also trial and error based techniques and other ad-hoc reference generation techniques as well. This background of complicated dynamics and difficulties in reference generation makes automatic gait (step patterns of legged robots) tuning an interesting area of research. A natural command for a legged robot is the velocity of its locomotion. A number of walk parameters including temporal and spatial variables like stepping period and step size need to be set properly in order to obtain the desired speed. These problems, when considered from kinematics point of view, do not have a unique set of walking parameters as a solution. However, some of the solutions can be more suitable for a stable walk, whereas others may lead to instability and cause robot to fall. This thesis proposes a gait tuning method based on evolutionary methods. A velocity command is given as the input to the system. A ZMP based reference generation method is employed. Walking simulations are performed to assess the fitness of artificial populations. The fitness is measured by the amount of support the simulated bipedal robot received from torsional virtual springs and dampers opposing the changes in body orientation. Cross-over and mutation mechanisms generate new populations. A number of different walking parameters and fitness functions are tested to improve this tuning process. The walking parameters obtained in simulations are applied to the experimental humanoid platform SURALP (Sabanci University ReseArch Labaratory Platform). Experiments verify the merits of the proposed reference tuning method

Bipedal humanoid robot control by fuzzy adjustment of the reference walking plane

The two-legged humanoid structure has advantages for an assistive robot in the human living and working environment. A bipedal humanoid robot can avoid typical obstacles at homes and offices, reach consoles and appliances designed for human use and can be carried in human transport vehicles. Also, it is speculated that the absorption of robots in the human shape into the human society can be easier than that of other artificial forms. However, the control of bipedal walk is a challenge. Walking performance on solely even floor is not satisfactory. The complications of obtaining a balanced walk are dramatically more pronounced on uneven surfaces like inclined planes, which are quite commonly encountered in human surroundings. The difficulties lie in a variety of tasks ranging from sensor and data fusion to the design of adaptation systems which respond to changing surface conditions. This thesis presents a study on bipedal walk on inclined planes with changing slopes. A Zero Moment Point (ZMP) based gait synthesis technique is employed. The pitch angle reference for the foot sole plane −as expressed in a coordinate frame attached at the robot body − is adjusted online by a fuzzy logic system to adapt to different walking surface slopes. Average ankle pitch torques and the average value of the body pitch angle, computed over a history of a predetermined number of sampling instants, are used as the inputs to this system. The proposed control method is tested via walking experiments with the 29 degreesof- freedom (DOF) human-sized full-body humanoid robot SURALP (Sabanci University Robotics Research Laboratory Platform). Experiments are performed on even floor and inclined planes with different slopes. The results indicate that the approach presented is successful in enabling the robot to stably enter, ascend and leave inclined planes with 15 percent (8.5 degrees) grade. The thesis starts with a terminology section on bipedal walking and introduces a number of successful humanoid robot projects. A survey of control techniques for the walk on uneven surfaces is presented. The design and construction of the experimental robotic platform SURALP is discussed with the mechanical, electronic, walking reference generation and control aspects. The fuzzy reference adjustment system proposed for the walk on inclined planes is detailed and experimental results are presented

Humanoid robot omnidirectional walking trajectory generation and control

Walking humanoid machines, once only seen or read in science fiction, became reality with the intensive research of the last four decades. However, there is a long way to go in the direction of technical achievements before humanoid robots can be used widely as human assistants. The design of a controller which can achieve a steady and stable walk is central in humanoid robotics. This control cannot be achieved if the reference trajectories are not generated suitably. The Zero Moment Point (ZMP) is the most widely used stability criterion for trajectory generation. The Center of Mass (CoM) reference can be obtained from the ZMP reference in a number of ways. A natural ZMP reference trajectory and a Fourier series approximation based method for computing the CoM reference from it, was previously proposed and published for the Sabanci University Robotics ReseArch Laboratory Platform (SURALP), for a straight walk. This thesis improves these techniques by modifying the straight walk reference trajectory into an omnidirectional one. The second contribution of this thesis is controller designs in order to cope with the changing slopes of the walking surface. The proposed controllers employ the trunk link rotational motion to adapt to the ground surface. A virtual pelvis link is introduced for the robots which do not posses roll and pitch axis in pelvis link. The proposed reference generation and control algorithms are tested on the humanoid robot SURALP. The experiments indicate that these methods are successful under various floor conditions

Bipedal walking trajectory energy minimization through a learned hip height trajectory

This thesis describes methods used to optimize energy consumption of an offine bipedal walking trajectories through hip height control. The experiments were carried out on a miniature humanoid robot within the simulation environment Webots. Zero Moment Point (ZMP) preview control methods were implemented in Matlab to produce a stable walking trajectory for the robot with a fixed hip height. The hip height trajectory was then developed using an observation based Q-learning method that consider both stability and energy consumption. Through the Q-learning methods there was approximately a 9% decrease in the average energy consumption. Additionally, an increase in stability was observed.M.S., Mechanical Engineering and Mechanics -- Drexel University, 201

Running synthesis and control for monopods and bipeds with articulated

Bibliography: p. 179-20

ZMP based reference generation for a bipedal humanoid robot

Recent fifteen years witnessed fast improvements in the field of humanoid robotics. The human-like robot structure is more suitable to human environment with its supreme obstacle avoidance properties when compared with wheeled service robots. However, the walking control for bipedal robots is a challenging task due to their complex dynamics. Stable reference generation plays a very important role in control. Linear Inverted Pendulum Model (LIPM) and the Zero Moment Point (ZMP) criterion are applied in a number of studies for stable walking reference generation of biped walking robots. This thesis takes this main approach too. This thesis proposes a natural and continuous ZMP reference trajectory for a stable and human-like walk. Natural, human-like walking is obtained by ZMP trajectories which move forward under the sole of the support foot when the robot body is supported by a single leg. Robot center of mass trajectory is obtained from predefined ZMP reference trajectories by a Fourier series approximation method. The Gibbs phenomenon problem common with Fourier approximations of discontinuous functions is avoided by employing continuous ZMP references. Also, these ZMP reference trajectories, unlike many examples in the literature, possess pre-assigned single and double support phases, which are very useful in experimental tuning work. In this thesis, a method for generating a stepping sequence of finite number of steps is proposed too. The ZMP based reference generation strategy is applied on the full body humanoid robot SURALP designed at Sabanci University. Experimental results indicate that the proposed reference trajectory generation technique is successful