ABSTRACT A Humanoid Robot is a robot with its body shape built to resemble that of the human body. It is being developed to perform human task. In this paper, I have described the technical components of humanoid robot like sensors which are responsible to sense the environmental parameters and actuators which are responsible for the motion in the robot. In working and control mechanism, the theory of zero moment point explains the balance of humanoid robots during walking. Some humanoid robots like ASIMO and MYON which are developed to work in real-world environment.
ASIMO has the ability to recognize moving objects and surrounding environment which enables it to interact with the humans. MYON is the first humanoid robot in the world which can be disassembled into the parts. I. INTRODUCTION A Humanoid may be defined as something that resembles or looks like a human and having characteristics like opposable thumb, ability to walk in upright position, etc. Nowadays the concept of Humanoids is being widely implemented in Robotics and these robots are called Humanoid Robots or may be simply Humanoids.
In general, Humanoid Robots have a torso, a head, two arms, and two legs. Fig. 1 shows the ASIMO Humanoid Robot created by Honda which has the ability to walk or run on two feet at speeds up to 6 kilometer per hour. Fig. 1 ASIMO Humanoid Robot A Humanoid robot is fully automated as it can adapt to its surroundings and continue with its goals. Some humanoid robots may also have a face, with eyes and mouth. Androids are humanoid robots built to resemble a male human and Gynoids are humanoid robots built to resemble a human female.
II. NEED OF HUMANOID ROBOTS Humanoid robots are being developed to perform human tasks like personal assistance, where they should be able to assist the sick and elderly, and dirty or dangerous jobs. Humanoid robots are used as a research tool in several scientific areas and researchers need to understand the human body structure and behavior to build and study humanoid robots. Humanoid Robots can work in human environment without a need to adapt themselves or to change the environment.
It is easier for a human being to interact with a human-like being. III. TECHNICAL COMPONENTS The two most important components of Humanoid Robots are Sensors and Actuators. a. SENSORS Sensors are the devices which sense something like environmental parameters like heat, sound, light, temperature, etc, physical and physiological parameters like movement, orientation, etc. Sensors can be classified as: PROPRIOCEPTIVE SENSORS Proprioceptive sensors sense the position, the orientation and the speed of the humanoid’s body and joints.
Humanoid robots use accelerometers to measure the acceleration, from which velocity can be calculated by integration and tilt sensors to measure inclination. Force sensors which are placed in robot’s hands and feet are used to measure the contact force with environment and position sensor that indicate the actual position of the robot or even speed sensors. EXTEROCEPTIVE SENSORS Extroceptive sensors consist of arrays of tactels (touch receptors) which are used to provide data on what is being touched, forces and torques transferred between robots and other objects.
In humanoid robots vision is used to recognize objects and determine their properties. Vision sensors work most similarly to the eyes of human beings. Most humanoid robots use CCD cameras as vision sensors for capturing image information and microphones and speakers are used for sound reception and production respectively. b. ACTUATORS Actuators are the motors responsible for motion in the robot. Actuators are used to perform like joints and muscles. Mostly humanoid robots use rotator actuators to achieve the effects as human motion.
The actuators can be pneumatic, hydraulic, piezoelectric or ultrasonic. Pneumatic actuators operate on the basis of gas compressibility. As they are inflated, they expand along the axis, and as they deflate, they contract. If one end is fixed, the other will move in a linear trajectory. These actuators are intended for low speed and low/medium load applications. Hydraulic and electric actuators have a very rigid behavior and can only be made to act in a compliant manner through the use of relatively complex feedback control strategies.
While electric coreless motor actuators are better suited for high speed and low load applications, hydraulic ones operate well at low speed and high load applications. Piezoelectric actuators generate a small movement with a high force capability when voltage is applied. They can be used for ultra-precise positioning and for generating and handling high forces or pressures in static or dynamic situations. Ultrasonic actuators are designed to produce movements in a micrometer order at ultrasonic frequencies. They are useful for controlling vibration, ositioning applications and quick switching. IV. WORKING AND CONTROL MECHANISM The essential difference between humanoids and other kinds of robots is that the movement of the robot has to be human-like, using legged locomotion, especially biped gait. The ideal planning for humanoid movements during normal walking should result in minimum energy consumption, like it does in the human body. To maintain dynamic balance during the walk, the robot needs information about contact force and it’s current and desired motion.
The solution to this problem relies on a major concept, the Zero Moment Point (ZMP). ZERO MOMENT POINT It explains the dynamic balance of humanoids during walking which requires information about the contact forces and the current and desired direction of motion. As per the ZMP Theory, the pressure under supporting foot can be replaced by the appropriate reaction force acting at a certain point of the mechanism’s foot. Since the sum of all moments of active forces with respect to this point is equal to zero, it is termed as the Zero Moment Point (ZMP). Fig. Illustration of ZMP Gi = Gravitation force of the ith link acting at the mass center Ci Fi= inertial force of the ith link acting at the mass center Ci Mi= moment of the inertial force of the ith link for Ci Ri= the resultant ground reaction force R= Rv + Rf M= Mh + Mf where subscripts v, h and f denote vertical, horizontal and frictional components respectively. ZMP is the point on the walking ground surface at which the horizontal components of the resultant moment generated by active forces and moments acting on humanoid links are equal to zero.
It is the point on the floor at which the moments around x and y axes generated by reaction force and moment are zero. In addition to the concept of ZMP, several other planning and control mechanisms are used for self-collision detection, path planning and obstacle avoidance to allow humanoids to move in complex environments. V. SOME HUMANOIDS a. ASIMO (Advanced Step in Innovative Mobility) ASIMO is a humanoid robot created by Honda with a height of 130 cm and weight 54 kg. It was designed to operate in real-world environments with the ability to walk or run on two feet at speeds up to 6 kilometers per hour.
It looks like a human being and can do work just like human being does. ASIMO is capable of interpreting the postures and gestures of humans and can move independently in response. It can greet approaching people, follow them and move in the direction which they indicate. Fig. 3 shows how ASIMO humanoid robot interacts with the people. ASIMO is the world’s first humanoid robot to exhibit such a broad range of intelligent capabilities. Fig. 3 ASIMO interacting with the people FEATURES AND TECHNOLOGY The main features of ASIMO robot is that they are lightweight and of compact size.
They are advanced and flexible walking technology. They are expansive range of arm movement with simplified operation and also people friendly design. ASIMO has the ability to recognize moving objects, postures, gestures, its surrounding environment, sounds and faces, which enables it to interact with the humans. It can detect the movements of multiple objects by using visual information captured by two cameras i. e. eyes in its head and can also determine the distance and direction. This feature allows ASIMO to follow a person when approached near him.
ASIMO walks by prediction movement control and can predict the next move and shift the center of gravity accordingly. ASIMO is very stable even when moving suddenly. ASIMO can turns smoothly without pausing. ASIMO is powered by a 40V nickel metal hydride battery. It can operate for approximately 30 minutes on a single battery and four hours are required to completely recharge ASIMO’s battery, though the battery can be easily changed so ASIMO can continue to operate on fresh battery. ASIMO is equipped with two cameras in its head.
These camera eyes allow ASIMO and its operator to view the surrounding environment. These cameras also allow ASIMO to independently recognize unique faces that have been stored in its memory and to accurately judge distance from objects by using mathematical formulas and the stereoscopic nature of the cameras. ASIMO also has a camera mounted in its torso used to view markers on the floor and on stairs. These markers help ASIMO determine its relative position within its environment. ASIMO is controlled by a laptop computer or by a portable computer controller unit through a wireless network system.
This permits more direct and flexible operation. A single operator can easily and fully control ASIMO’s movements. ASIMO can comprehend and carry out tasks based on simple voice commands given in English that have been preprogrammed into its onboard memory. The number of commands that can be programmed is basically unlimited. Individual voices can also be registered to increase the performance of the voice recognition function. ASIMO’s intelligence lies in the technologies with which it is equipped, not in the ability to think or reason as a human.
ASIMO has a walking speed of 2. 7 kilometers per hour (1. 7 mph) and a running speed of 6 kilometers per hour (3. 7 mph). Its movements are determined by floor reaction control and target Zero Moment Point control, which enables the robot to keep a firm stance and maintain position. ASIMO can adjust the length of its steps, body position, speed and the direction in which it is stepping. Its arms, hands, legs, waist and neck also have varying degrees of movement. ASIMO has a total of 34 degrees of freedom.
The neck, shoulder, wrist and hip joints each have three degrees of freedom, while each hand has four fingers and a thumb that have two degrees of freedom. Each ankle has two degrees of freedom, and the waist, knees and elbows each have one degree of freedom. b. MYON MYON is a humanoid robot designed by the industrial design studio, Frackenpohl Poulheim and developed by the Neurorobotics Research Laboratory at Humboldt University in Berlin, Germany, which has the special ability to continue to operate even if some of its electronic components are damaged or separated.
It is also the first humanoid robot in the world that can be disassembled into parts while the parts which make it up continue to work steadily and autonomously. It has a robust skin made out of fiberglass. Fig. 4 shows the MYON robot. MYON is the world’s first humanoid robot whose body parts can completely be removed during operation and flange-mounted again. Fig. 4 MYON ROBOT MYON is one of five version of the Artificial Language Evolution on Autonomous Robots projects which are being used to study cognition and language acquisition and formation between robotic agents.
The six parts head, torso, arms and legs are truly modular in that each one has its own power supply, processing power and neural network that link up individually. The main feature of this modularity is that it can continue operating even if one or more of its parts fail. MYON robot is about 125 cm tall and weighs 15 kg and has 48 degrees of freedom with 35 torsional springs for biological movements and 192 sensors [4]. The robot has a built in touch screen on its chest. The skin is made up of bayer makrolon and a layer of glass fiber-stabilized polycarbonate to rotect him [5]. APPICATIONS Humanoid robots are being implemented in a wide range of industries. Currently the application of ASIMO in the United States is the ASIMO Technology Circuit, which is a travelling presentation about humanoid robotics designed to educate university students and the general public. Fig. 5 shows the application of humanoid robot in different fields.
In Japan, ASIMO works as a guide in science museums and is being used by a few high-tech companies to welcome guests to their facilities. Fig. Humanoid Robot applications Humanoid robots have the autonomous learning and self maintained. They have legged locomotion they avoid harmful situations to people, property and itself. They are also arm control and dexterous manipulation. Another characteristic of humanoid robots is that they move, gather information (using sensors) on the real world and interact with it. Humanoid robots include structures with variable flexibility, which provide safety and redundancy of movements. VI. A PEEP INTO THE FUTURE VIII. CONCLUSION
Humanoid robots have made the life of humans very simple in some extent and the technology is advanced much in the field of humanoid robotics but there are still several other problems which need more attention. Plenty of humans already who do not have jobs or good places to live, then why replace with the humanoids. According to me one day robots will become super intelligent and rule this world. The field of Humanoid Robotics is a very promising one and there are still a lot of changes needed to be brought in this technology.
