By B. Preethi B. SriBhavana

8/14/2019 By B. Preethi B. SriBhavana

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By

B. Preethi

B. SriBhavana



Contents

Introduction

Purpose

Sensors

Actuators

Planning and Control

ConclusionReferences

http://en.wikipedia.org/wiki/Humanoid_robot#Sensors


http://en.wikipedia.org/wiki/Humanoid_robot#Actuators

http://en.wikipedia.org/wiki/Humanoid_robot











Introduction

A humanoid robot is an autonomous robot because it can adapt to changes in itsenvironment or itself and continue to reach its

goal. This is the main difference betweenhumanoids and other kinds of robots, likeindustrial robots which are used for performingtasks in highly structured environments.

In this context, some of the capacities of ahumanoid robot may include, among others:



self maintenance (recharge itself, swap batteries…)autonomous learning (learn or gain new capabilities

without outside assistance, adjust strategies based on

the surroundings and adapt to new situations)avoiding harmful situations to people, property and

itself

safe interacting with human beings and theenvironment.



A robot is an electro-mechanical device that can

perform autonomous or preprogrammed tasks.

A robot may act under the direct control of a

human or autonomously

under the control of a

programmed computer .

Honda's ASIMO, an example

of a humanoid robot



Purpose

Humanoid robots are used as a research tool inseveral scientific areas. Researchers need tounderstand the human body structure and behavior to build and study humanoid robots.

On the other side, the attempt to simulate thehuman body leads to a better understanding of it. Human cognition is a field of study which is

focused on how humans learn from sensoryinformation in order to acquire perceptual andmotor skills.



This knowledge is used to develop computational

models of human behaviour and it has been

improving over time.Although the initial aim of humanoid research

was to build better orthosis and prosthesis for

human beings, knowledge has been transferred between both disciplines.

Besides the research, humanoid robots are being

developed to perform human tasks like personalassistance, where they should be able to assist the

sick and elderly, and dirty or dangerous jobs.



Regular jobs like being a receptionist or a

worker of an automotive manufacturing line arealso suitable for humanoids.

In essence, since they can use tools and operate

equipment and vehicles designed for the humanform, humanoids could theoretically perform

any task a human being can, so long as they

have the proper software. However, the

complexity of doing so is deceptively great.



Diagram of the structurally variable monitoring

and control system.



Like other mechanical robots, humanoids refer to the following basic components too:

Sensing

Actuating andPlanning and Control.



Sensors

A sensor is a device that measures someattribute of the world. Being one of the three primitives of robotics (besides planning andcontrol), sensing plays an important role in

robotic paradigms.Sensors can be classifiedaccording to the physical process with whichthey work or according to the type of measurement information that they give asoutput. In this case, the second approach wasused.



Most sensors operate via electrical or electronic

signals, although other types of sensors exist.

Basically, a sensor is a type of transducer. Sensorsare either direct indicating (e.g. a mercury

thermometer or electrical meter) or are paired with

an indicator (perhaps indirectly through an analog to

digital converter, a computer and a display) so that

the value sensed becomes human readable.



Proprioceptive Sensors

Proprioceptive sensors sense the position, the

orientation and the speed of the humanoid’s

body and joints.

In human beings inner ears are used to

maintain balance and orientation.



Humanoid robots use accelerometers to

measure the acceleration, from which velocity

can be calculated by integration; tilt sensors to

measure inclination; force sensors placed in

robot’s hands and feet to measure contactforce with environment; position sensors, that

indicate the actual position of the robot (from

which the velocity can be calculated byderivation) or even speed sensors.



Exteroceptive Sensors

Exteroceptive sensors give the robotinformation about the surrounding

environment, which is the real world in

case of humanoid robots. That informationallows the robot to interact with the world.

The exteroceptive sensors are classified

according to their functionality. Proximitysensors are used to measure the relative

distance (range) between the sensor and

objects in the environment.



They perform the same task that vision and tactile

sensing do in human beings. For that, humanoidrobots can use sonars, infrared sensors or tactile

sensors like bump sensors, whiskers (or feelers),

capacitive or piezoresistive sensors.Tactile sensors also provide information about

forces and torques transferred between the robot and

the objects.



There are other kinds of proximity

measurements like laser ranging, the usage of stereo cameras or projecting a colored line,

grid or pattern of dots on the environment and

observe how the pattern is distorted .Vision refers to processing data from any

modality which uses the electromagnetic

spectrum to produce an image.



In humanoid robots context it is used to

recognize objects and determine their

properties.Vision sensors work similarly to the eyes of

the human beings.

Most humanoid robots use CCD cameras asvision sensors .They can also capture a scene

with the CCD cameras installed in its head &

can transmit the video signals which can beseen on a remote monitor .





Actuators

Actuator is the name given to each one of the motorswhich move the robot, a humanoid robot in this case.

Humanoid robots are constructed in such a way that

they mimic human body, so they have actuators that perform like muscles and joints, although with a

different structure.

To achieve the same effect as human actuators

humanoids use mainly rotary actuators.



The actuators are all wired to an electrical circuit.

The circuit powers electrical motors and solenoidsdirectly, and it activates the hydraulic system by

manipulating electrical valves.

The valves determine the pressurized fluid's paththrough the machine.

To move a hydraulic leg, for example, the robot's

controller would open the valve leading from the

fluid pump to a piston cylinder attached to that leg.



The pressurized fluid would extend the piston,

swiveling the leg forward.

Typically, in order to move their segments in

two directions, robots use pistons that can push

both ways.



Planning and Control

In planning and control the essential difference

between humanoids and other kinds of robots

(like industrial ones) is that the movement of

the robot has to be human-like, using leggedlocomotion, especially biped gait (A gait is a

particular way or manner of moving on foot:

walking and running are the two basic humangaits). ;). energy consumption, like it happens

in the human body.



For this reason, studies on dynamics and control

of these kinds of structures become more and

more important.A controller manipulates the inputs to a system to

obtain the desired effect on the output of the

system.To maintain dynamic balance during the walk, a

robot needs information about contact force and

its current and desired motion. The solution tothis problem relies on a major concept, the Zero

Moment Point (ZMP).



Zero Moment Point

is a concept related withdynamics and control of legged locomotion, e.g.,

for humanoid robots.

It specifies the point with respect to which

dynamic reaction force at the contact of the foot

with the ground does not produce any moment,

i.e. the point where total inertia force equals 0

(zero).



Another characteristic about humanoid robots is

that they move, gather information (usingsensors) on the “real world” and interact with it,

they don’t stay still like factory manipulators and

other robots that work in highly structured

environments.

Planning and Control have to focus about self-

collision detection, path planning and obstacle

avoidance to allow humanoids to move in

complex environments.



There are features in the human body that can’t

be found in humanoids yet. They include

structures with variable flexibility, which providesafety (to the robot itself and to the people), and

redundancy of movements, i.e., more

degree of freedom and therefore wide task availability.

Although these characteristics are desirable to

humanoid robots, they will bring morecomplexity and new problems to planning and

control.



The humanoid robots developed until now are

mostly very heavy and hence there exists adanger that even injure their operators.

To overcome, they have developed a

humanoid robot closer to the size of a human being but very light in weight with a high level

of flexibility and versatility and able to

execute self-supported action.



Research Issues

Roboticist Rodney Brooks has long arguedthat our view of how we think and act istainted with subjectivity. We cannot whollytranscend our biased perspective.

The best we can do is to neutralize its effect by bringing humanoid bodies in line with our own.

Most likely, we will never fully understand,much less recreate everything that it means to be human.

A th f ti f lf d t di d



As the frontiers of our self-understanding expand,

humanoid robots may simply follow (and, at

times, propel) our

continuouslychanging conception

of what we are.

Robot developed which imitateshuman actions and observes

with a camera

equivalent to the humaneye.



Conclusion

We can conclude that ,using robots we have

both advantages as well as disadvantages .

The disadvantages is that they may fall over

and be damaged ,and this is one of the fatal

barriers to practical applications of humanoid

robots.

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By B. Preethi B. SriBhavana