introductionofbipedrobots (1)

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CHAPTER-1 INTRODUCTION 1.1 Aim of the Project Locomotion, the ability of a body to move from one place to another, is a defining characteristic of animal life. It is accomplished by manipulating the body with respect to the environment. In the case of environments with discontinuous ground support, such as a rocky slope, a flight of stairs, or the rungs of a ladder, it is arguable that the most appropriate and versatile means for locomotion is legs. Legs enable the avoidance of support discontinuities in the environment stepping over them. The main aim of this project is to build a bipedal robot with a total of 6 DOF (degrees of freedom). This enables the bipedal robot to mimic the human way of walking to most extent, thereby making the robot to move in all kinds of terrains and also eliminating the need for a special environment for the biped to work. The biped robot can adapt to the normal conditions of transportation 1

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Page 1: INTRODUCTIONOFBIPEDROBOTS (1)

CHAPTER-1

INTRODUCTION

1.1 Aim of the Project

Locomotion, the ability of a body to move from one place to another, is a defining

characteristic of animal life. It is accomplished by manipulating the body with respect to

the environment. In the case of environments with discontinuous ground support, such as a

rocky slope, a flight of stairs, or the rungs of a ladder, it is arguable that the most

appropriate and versatile means for locomotion is legs. Legs enable the avoidance of

support discontinuities in the environment stepping over them. The main aim of this project

is to build a bipedal robot with a total of 6 DOF (degrees of freedom). This enables the

bipedal robot to mimic the human way of walking to most extent, thereby making the robot

to move in all kinds of terrains and also eliminating the need for a special environment for

the biped to work. The biped robot can adapt to the normal conditions of transportation

which have been designed for human beings and this enables the biped robot to be exposed

to a wide variety of applications. The control of the biped i.e the Gait to be performed by

the biped is instructed to itself by means of on-hands manipulation, backed by reverse

mapping.

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1.2 Scope of the Project

The attention of the robotics community has been drawn more and more on humanoid

robots in the last years. This interest is not only motivated by the trend of designing robots

with human appearance, but also for the implications of their use in human environments.

They must be able to perform a wide range of different tasks in partially or completely

unknown environments. And, what is most interesting, they must able to cooperate and

probably communicate with humans in a variety of modes. The development of such

amount of different capabilities represents and ambitious and attractive research field for

many scientists. The mechanical design of a humanoid robot must be anthropomorphic not

only in their appearance but also in their capabilities. And this often implies that the

different parts must be light-weighted and highly versatile, that is, with a high number of

degrees of freedom. In addition, the development of humanoid robots results in the research

fields that otherwise would have a smaller area of application. An example of these, is the

development of anthropomorphic arm and hands, the development of stereo heads, and the

research on biped robots.

Probably the most exciting interest of humanoid robots is their intense interaction with

humans and their appropriateness for tasks in human-centered environments, due both to

their friendly appearance an their anthropomorphic design. But the exploitation of these

capabilities requires the development of novel control strategies, and, more interestingly,

more advanced human-robot cooperation and communication skills. Examples of the last

are learning by imitation, language acquisition, and gesture recognition, among others.

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Biped robots represent a very interesting research subject, with several particularities and

scope topics, such as: mechanical design, gait simulation, patterns generation, kinematics,

dynamics, equilibrium, stability, kinds of control, adaptability, biomechanics, cybernetics,

and rehabilitation technologies. We have diverse problems related to these topics, making

the study of biped robots a very complex subject, and many times the results of researches

are not totally satisfactory. However, with scientific and technological advances, based on

theoretical and experimental works, many researchers have collaborated in the evolution of

the biped robots design, looking for to develop autonomous systems, as well as to help in

rehabilitation technologies of human beings.

1.3 Literature Survey

During the past three decades research and development in robotics has expanded

from traditional industrial robot manipulators to include autonomous and animal-like or

humanoid robots. Over the past two decades, the field of humanoid robotics has witnessed

significant advances. This development has been driven by improvements in actuator,

computer and other enabling technologies and guided by the vision of building machines

with (some) human-like capabilities. A machine with human-like appearance and

capabilities would be able to operate in all environments designed for humans, such as

factories, offices and homes. Also, interacting with humans using natural language and

gestures both simplifies the interaction for the human and decreases the psychological

barrier for the use of such machines in service applications. All this makes service robotics

one of the most promising application areas for humanoids, while the entertainment

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industry is also exploring the potential of such machines. Even without high-level

intelligence, biped robots are potentially superior to wheeled or tracked vehicles in complex

and cluttered environments, since they can climb stairs or step onto or over large obstacles.

Building truly humanoid robots will require significant advances in areas including, among

others, high-level cognition, computer vision, speech synthesis, speech recognition,

manipulation and biped locomotion. Recent interest in humanoid robotics has spawned a

large number of research projects focusing either on individual problems or on systems

integration.

In the natural setting, locomotion takes on many forms, whether it’s the swimming

of amoebas, flying of birds, or walking of humans. The diversity of animal locomotion is

truly astounding and surprisingly complex.

The same is true in objects crafted by man: airplanes have wings that create lift for

flight, tanks have tracks for traversing uneven terrain, automobiles have wheels for rolling

efficiently—and robots are now walking on their own two legs! Moreover, legs are an

obvious choice for locomotion in environments designed for human walking, running, and

climbing.

To the extent that a machine equipped with two legs may imitate a human’s gait,

bipedal robots are biomimetic. The appeal to biomimetic largely stops here. This is because

the material and components available to an engineer for creating a bipedal robot are quite

different from those provided by biology. For example, the engineer has at his disposal

metal instead of bones, motors instead of muscles, wires instead of nerves, and

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microprocessors instead of a brain. In addition, there are differences in what quantities can

be sensed and the speed and accuracy with which they can be sensed. Just as important, the

operational expectations are different. Whereas we are accustomed to many years of

training required for a human to acquire a high degree of skill in locomotion related

activities (consider a baby learning to walk), and we expect ability to vary greatly from one

human to another (consider the sprinter Michael Johnson versus the average runner), we

expect that the functioning of machines be exactly reproducible and correct from the

moment they are turned on. We would be greatly disappointed in a car, for example, if the

automatic transmission’s control system took many trials “to learn” how to smoothly shift

gears or to maximize the vehicle’s intended performance, whether that be speed of

acceleration or fuel economy. Similarly, we are disappointed in a legged robot whose

control system cannot deliver gaits that utilize the full capabilities of the machine, in terms

of elegance, speed, energy economy, and of course, stability.

Robotic Arms vs. Robotic Walkers

Many high performance robotic arms and hands have been developed for use in factories,

space, and research. It might seem to an outside observer that these technologies could be

exploited for use in a legged robot. Most of the time this is not the case. There are several

reasons why.

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Fixed vs. Floating Reference

Robotic arms are generally fixed to an inertial reference frame (factory) or a body whose

mass is large enough that it can be considered fixed (spacecraft). A walking robot is not

fixed to any reference frame and has a limited set of torques which it can apply due to its

limited contact with the world.

On-board vs. Off-board

Robot arms can often place their heavy motors at their fixed end. Then the motors are only

responsible for moving the frame of the arm and not themselves. Because a walking robot

must carry all its components, the motors support themselves as well as the structure of the

robot. Carrying power is also an issue for walking robots although most are tethered due to

battery limitations

Environmental Awareness

Robot arms are not usually expected to perform in unknown situations. They generally are

designed for specific working conditions and their ability to handle unexpected

disturbances is limited. Ideally, walking robots are supposed to handle rough and unknown

terrain.

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Success Metrics

Robotic arms are often judged on their ability to position their end effectors precisely.

Robotic walkers are usually not judged on their ability to position precisely but rather on

their ability to get from Point A to Point B without falling down.

Impacts

Most robot arms are not designed to handle impacts. Walking, however, has an impact at

every touchdown.

Why Bipedal Robots

Bipedal robots form a subclass of legged robots. On the practical side, the study of

mechanical legged locomotion has been motivated by its potential use as a means of

locomotion in rough terrain, or environments with discontinuous supports, such as the

rungs of a ladder. It must also be acknowledged that much of the current interest in legged

robots stems from the appeal of machines that operate in anthropomorphic or animal-like

ways (we have in mind several well-known biped and quadruped toys). The motivation for

studying bipedal robots in particular arises from diverse sociological and commercial

interests, ranging from the desire to replace humans in hazardous occupations (de-mining,

nuclear power plant inspection, military interventions, etc.), to the restoration of motion in

the disabled (dynamically controlled lower-limb prostheses, rehabilitation robotics, and

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functional neural stimulation).As a result, only slow motions may be achieved. Truly

dynamic motions, such as balancing, running or fast walking, are excluded with these

approaches.

1.4 Organisation of the project

The presented project is organised with 9 main chapters. Chapter 1 gives an

overview of the aim of the project, scope of the project, literature survey and the

organisation of the project thesis. Chapter 2 deals with the Biped terminology, walking

phases and strategies. Chapter 3 gives the detailed description on the design parameters.

Chapter 4 deals with the Modelling methodology of the Biped where Gait and the walking

cycle are explained. Chapter 5 gives the information on the specifications the mechanical

parts and electronics used in this project. Chapter 6 deals with the process of assembling

the Biped robot. Chapter 7 describes the software programming and operation of the biped.

Chapter 8 discusses the applications of Bipedal robots in different fields. Chapter 9 gives

the conclusion. Chapter 10 gives a brief overview of the future scope of the Biped robots.

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CHAPTER-2

BIPED TERMINOLOGY

2.1 Terminology

Biped is a very interesting area of robotics where the various attributes of the

mechanism are influenced from the human behaviour of walking. Many aspects of modern

life involve the use of intelligent machines capable of operating under dynamic interaction

with their environment. Bipedal are Hyper DOF system (>20) with Complex Kinematics

and Dynamics which are also complex real-time control architecture. Complexity limits the

trajectory tracking of ease. Conventional control algorithms for humanoid robots can run

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into some problems related to Mathematical tractability, Optimisation, Limited

extendibility, Limited biological plausibility.

Generally the movement on the land so far has been achieved in three ways-the

legs, wheels, tracks. Though there are various advantages like speed to the transport by

wheels and tracks they prove to be disadvantageous in the rough terrain and when they

meet the obstacles. When they meet an obstacle the axle should be at least a little high than

the height of the obstacles and in case where the wheeled vehicles are supposed to go uphill

their movement is restricted by the max torque capacity of the vehicle. In the above cases

the only way of overcoming these is the movement through legs. Tracks are said to have

greater balance in rough terrain too but their ability to turn at greater speeds Is considerably

less. Therefore, a new generation of robots called the bipeds have come into usage which

use the advantages of wheeled movement of having great speed and the use of legs to easily

overcome the obstacles.

Bipeds however, caught the eye of the specialists in the military research.

Considering the situations that are frequently met in military and defence operations the

vehicles or the medium of transport for the military equipment comes into picture. As result

many such vehicles are designed and implemented but all those necessaries are met at a

price of either sacrificing the speed or balancing itself. This problem has been solved by the

implementing the two technologies into a single robot called biped. Besides, having high

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stability it also believed to achieve farther speeds with more advancements in the

technology.

Biped robot dynamics are mainly categorized into two divisions. First being the

static stabilization and the other being the dynamic stabilization. Static stabilization is

achieved through the COG based stabilization strategy whereas the dynamic stabilization is

achieved through the internal stabilization strategy.

2.1.1 Static Walking

In Static Walking the biped is made to walk very slowly so that the dynamics can be

ignored. The bipeds projected center of gravity should be within the supporting area. If the

above mentioned criteria is not followed or the biped modelling is not made in a correct

way where the bipedal robot center of gravity is not within the foot area of the planted foot

which is on the ground at that instant of the walking motion of the bipedal robot then the

biped will not have correct balance. Since, the walking motion of the bipedal robot is very

slow the impact of balance when on one foot is very critical and careful design has to be

made. However, if the design fails to follow them, then the biped will fall to the ground.

The main idea in designing a bipedal robot with static walking is by using the Center of

Gravity method.

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Many studies on biped walking robots have been performed since 1970. During

that period, biped walking robots have transformed into biped humanoid robots through the

technological development. Furthermore, the biped humanoid robot has become a one of

representative research topics in the intelligent robot research society. Many researchers

anticipate that the humanoid robot industry will be the industry leader of the 21st century

and we eventually enter an era of one robot in every home. The strong focus on biped

humanoid robots stems from a long-standing desire for human-like robots. Furthermore, a

human-like appearance is desirable for coexistence in a human-robot society. However,

while it is not hard to develop a human-like biped robot platform, the realization of stable

biped robot walking poses a considerable challenge. This is because of a lack of

understanding on how humans walk stably. Furthermore, biped walking is an unstable

successive motion of a single support phase. Early biped walking of robots involved static

walking with a very low walking speed. The step time was over 10 seconds per step and the

balance control strategy was performed through the use of COG (Center Of Gravity).

Hereby the projected point of COG onto the ground always falls within the supporting

polygon that is made by two feet. During the static walking, the robot can stop the walking

motion any time without falling down. The disadvantage of static walking is that the

motion is too slow and wide for shifting the COG.

2.1.2 Dynamic Walking

In Dynamic Walking the biped can be moved at very high speeds and the dynamics are

taken into consideration. Unlike the static walking where the slow motion of the biped are

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taken into consideration where modelling has to be done by taking the center of gravity of

the robot and then maintaining it in the required positions the dynamics of a bipedal robot

however do not take into account the center of gravity rather it takes the methodology of

the internal stabilizations where a feedback control loop is designed to give the information

about the bipeds position at every instant of the walking motion and the feeding it back to

the controller so that the controller then corrects its walking motion and maintains the

stability of the robot even in high speed conditions. This type of considerations requires

considerable mechanics and inverse kinematics to get the desired equations that can solve

the dynamics of the biped motion with high speed walking. Further, different kinds of

sensors can be accommodated with the bipedal robot to make it more compatible and

reliable like using the ultrasonic sensors to avoid obstacles etc.

Bipeds became an interesting topic and few applications of it are to use them as the

artificial legs for humans. Hence, this integration of different aspects of technology the

bipeds are most likely to find a huge number of applications in many diverse fields and also

in the evolution of multi-legged such as four legged robots which can work as a dog, six

legged robots to simulating the spider movements with much more dexterity and dynamic

stability.

Researchers thus began to focus on dynamic walking of biped robots. It is fast

walking with a speed of less than 1 second per step. If the dynamic balance can be

maintained, dynamic walking is smoother and more active even when using small body

motions. However, if the inertial forces generated from the acceleration of the robot body

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are not suitably controlled, a biped robot easily falls down. In addition, during dynamic

walking, a biped robot may falls down from disturbances and cannot stop the walking

motion suddenly. Hence, the notion of ZMP (Zero Moment Point) was introduced in order

to control inertial forces . In the stable single support phase, the ZMP is equal to the COP

(Center of Pressure) on the sole. The advantage of the ZMP is that it is a point where the

center of gravity is projected onto the ground in the static state and a point where the total

inertial force composed of the gravitational force and inertial force of mass goes through

the ground in the dynamic state. If the ZMP strictly exists within the supporting polygon

made by the feet, the robot never falls down. Most research groups have used the ZMP as a

walking stability criterion of dynamic biped walking. To this end, the robot is controlled

such that the ZMP is maintained within the supporting polygon.

2.2 Walking Strategies

In general, the walking control strategies using the ZMP can be divided into two

approaches. First, the robot can be modeled by considering many point masses, the

locations of the point masses and the mass moments of inertia of the linkages. The walking

pattern is then calculated by solving ZMP dynamics derived from the robot model with a

desired ZMP trajectory. During walking, sensory feedback is used to control the robot.

Second, the robot is modeled by a simple mathematical model such as an inverted

pendulum system, and then the walking pattern is designed based on the limited

information of a simple model and experimental hand tuning. During walking, many kinds

of online controllers are activated to compensate the walking motion through the use of

various sensory feedback data including the ZMP. The first approach can derive a precise

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walking pattern that satisfies the desired ZMP trajectory, but it is hard to generate the

walking pattern in real-time due to the large calculation burden. Further, if the

mathematical model is different from the real robot, the performance is diminished. On the

contrary, the second approach can easily generate the walking pattern online. However,

many kinds of online controllers are needed to compensate the walking pattern in real-time,

because the prescribed walking pattern cannot satisfy the desired ZMP trajectory. In

addition, this method depends strongly on the sensory feedback, and hence the walking

ability is limited to the sensor’s performance and requires considerable experimental hand

tuning. To date, most biped humanoid robots have performed stable dynamic walking on

the well prepared flat floors. Studies involving walking on the uneven and inclined floors

are still in the early stage. Dynamic walking on an uneven surface is hard to realize because

most biped humanoid robots perform hard position control of the joints by using motors

and reduction gears and the response times of the actuators and sensors are low due to the

reduction gear and sensor noise. Accordingly, it is impossible for the robot to measure the

ground conditions instantaneously and it is also impossible for the robot to appropriately

respond even if it measures the ground conditions rapidly. On the contrary, the human

ankle can rapidly adapt to changing ground conditions. Furthermore, human muscles can

contract or relax quickly with smooth motions.

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Fig.2.1 (a): Cop on foot balanced, (b) cop shifted forwards.

The ZMP (Zero Moment Point) criterion in a nutshell. Idealize a robot with one leg

in contact with the ground as a planar inverted pendulum that is attached to a base

consisting of a foot with torque applied at the ankle, and assume all other joints are

independently actuated. In addition, assume adequate friction so that the foot is not sliding.

In (a), the robot’s nominal trajectory has been planned so that the center of pressure of the

forces on the foot, P, remains strictly within the interior of the footprint. In this case, the

foot will not rotate (i.e, the foot is acting as a base, as in a normal robotic manipulator) and

the system is therefore fully actuated. It follows that small deviations from the planned

trajectory can be attenuated via feedback control, proving stabilizability of the walking

motion. In case (b), however, the center of pressure (Cop) has moved to the toe, allowing

the foot to rotate. The system is now under actuated (two degrees of freedom and one

actuator), and designing a stabilizing controller is non trivial, especially when impact

events are taken into account. The ZMP principle says to design trajectories so that case (a)

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holds; i.e., walk flat footed. Humans, even with prosthetic legs, use foot rotation to decrease

energy loss at impact.

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Fig 2.2 Model biped robot

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2.3 Support Phases

A biped is an open kinematic chain consisting of two sub chains called legs and,

often, a sub chain called the torso, all connected at a common point called the hip. One or

both of the legs may be in contact with the ground. When only one leg is in contact with the

ground, the contacting leg is called the stance leg and the other is called the swing leg. The

end of a leg, whether it has links constituting a foot or not, will sometimes be referred to as

a foot. The single support or swing phase is defined to be the phase of locomotion where

only one foot is on the ground. Conversely, double support is the phase where both feet are

on the ground. Walking is then defined as alternating phases of single and double support,

with the requirement that the displacement of the horizontal component of the robot’s

center of mass (COM) is strictly monotonic.2 Implicit in this description is the assumption

that the feet are not slipping when in w contact with the ground. Running is defined as

sequential phases of single support, flight, and (single-legged) impact, with the additional

provision that impacts occur on alternating legs. Below figure give a brief explanation of

how the bipedal robot walks and what are the two phases look like when the bipedal robot

is in motion. The figure shows the various joints and links. The dots representing the the

joints where the servos will be mounted and give the actuation and the lines represent the

bars or links of robot legs. When only one foot is on the ground it is the single support

phase and when both the feet are on the ground it is said to be double support phase.

However, the double support phases is the most balanced state of a walking bipedal robot

because it has both the feet on the ground and is highly stable. Hence, the center of gravity

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of the robot is maintained exactly at the center of the two supporting legs while in the

double support stage.

Fig:2.3 Phases of bipedal walking with point feet. In (a), the single support or swing phase,

and in (b), the double support phase.

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CHAPTER-3

THE DESIGN

3.1 MECHANICAL DESIGN

The Mechanical design forms the basis for developing this type of walking robots. The

mechanical design is divided into four phases:

1. Determining the Mechanical constraints.

2. Conceptual Design

3. Specification.

3.1.1 Determining the Mechanical Constraints

There are various design considerations when designing a Bipedal robot. Among

them, the major factors that have to be considered are:-

A) Robot Size Selection:

Robot size plays a major role. Based on this the Cost of the Project, Materials required for

fabrication and the no of actuators required can be determined. In this project miniature size

of the robot is preferred so a height not more than 40 cm is decided which includes

mounting of the control circuits. This small size of the robot enables us to carry out the

dynamic equations very easily and also to eliminate the unnecessary modal analysis and

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stress analysis. Depending upon the size of the robot the foot of the robot is also chosen. If

the biped height is too big then relatively the biped foot gets bigger and bigger because the

assumption on which the present biped is being built is that, it is a static walking biped.

B) Degrees of Freedom

Human leg has got Six Degrees of freedom (Hip – 3 D.O.F, Knee – 1 D.O.F, Ankle – 2

D.O.F), but implementing all the Six D.O.F is difficult due to increase in the complexity

and cost of the project. Placing 3 actuators in hip itself makes it difficult to frame the body

structure of the biped and several control issues are faced when the biped is set into motion.

While so in this project reduced degrees of freedom is aimed so 3 D.O.F per leg has been

finalized (Hip – 1 D.O.F, Knee – 1 D.O.F, Ankle – 1 D.O.F). This type of system

formulated makes a pair of set with two different dynamic centers for motion in each set

and thus six degrees of freedom can be mimicked. By using this kind of mechanism the

bipedal robot can be used to mimic the human walking more realistically. Had there been

any actuators in the waist socket too it would take turns more like humans. and the need to

make the foot straight when walking would be eliminated to a certain degree and would be

used in more applications but as said earlier the more the degrees of freedom, more is the

complexity of programming all the servos.

C) Link Design

In this project U-shaped bracket like arrangement called servo frames and flat brackets

called servo clamps are used for various joints and connecting servos to the leg parts

wherever needed. Servo frames used are of various lengths according to the various lengths

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of the different parts of the leg whereas the servo flat brackets will join the servo motors to

the different joints.

By using the U-shaped bracket the servos can be mounted easily and the actuation is

relatively very easy when compared to the conventional design of any typical robot which

consists of bars as links between different actuators. When such type of links are used,

special kind of equipment should be used to accommodate all the different types of the

motions that are required and the positioning of those actuators would also be difficult

because there could be a possibility of requiring more than one actuator at a particular joint

to perform motion in more than one axis. For example, just as in the care of a wrist or a

robot arm.

D) Stability

With Biped mechanism, only two points will be in contact with the ground surface. In

order to achieve effective balance, actuator will be made to rotate in sequence and the robot

structure will try to balance. If the balancing is not proper, in order to maintain the Center

of Mass, dead weight would be placed in inverted pendulum configuration with 1 D.O.F.

This dead weight will be shifted from one side to the other according to the balance

requirement. But in this project no such configuration is used.

E) Foot Pad Design

The stability of the robot is determined by the foot pad. Generally there is a concept that

over sized and heavy foot pad will have more stability due to more contact area. But there

is a disadvantage in using the oversized and heavy foot pad, because more material will be

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required leading to increased costs and no significant contribution to the stability of the

system. This will also force the servo motors to apply more torque for lifting the various leg

parts.

3.1.2 Conceptual Design

Initially the Bipedal robot was conceived with ten degrees of freedom. Due to constraints

faced in controlling greater number degrees of freedom we, a new design was arrived with

the knowledge gathered from developing previous Bipedal models. The new design has got

Six degrees of freedom with three degrees of freedom per leg. Optimal distance was

maintained between the legs to ensure that legs don’t hit each other while walking.

fig 3.1 CAD model of biped

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3.1.3 Specifications

Material Required

ITEM ILLUSTRATION QUANTITY SPECIFICATIONS

Aluminum

Main U-shape

Bracket

1 Aluminum Main U-shape Bracket forlinking robot electronic moduleswith its leg parts

Aluminum

Foot Plate

2 For connecting with servo-side bracket to fit the ankle servo

Aluminum

Servo-side

Bracket

2 For connecting with the ankle servoand the foot bracket

Aluminum U-

shape

Bracket

6 Provides connection with the servoround horn and movement space of the Servo; It also provides connection with two U-shape brackets fordifferent applications.

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Aluminum U-shape Bracket

4 Provides connection with the servocase; It also provides connection with two U-shape Brackets fordifferent applications.

NANO Shield 1 The NANO Shield board is used toconnect the Arduino NANO board andTT Linker Mini signal conversionboard, include two used to indicatethe LED1 and LED2, two input buttonsS1 and S2.

Arduino Nano 1 The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply

TT Linker Mini 1 TTLinker Mini is a signal conversionboard, connect to Arduino Nano TX1and RX0 two digital serial ports

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Battery 12.4V,NiMh,900mAh

.

SC Servo

(SCS15)

6 SC Servo is meaning that Smart Control Servo. SC Servo can work at servo mode and wheel mode, has a unique ID number to identify on BUSnetwork, have kinds of baud rate available, and can feedback thevalue of Position, Temperature,Load, Speed and Input Voltage

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Screws and other accessories

ITEM ILLUSTRATION QUANTITY SPECIFICATIONS

Screw 1 10 ISOP 3 x 10 mm

Screw 2 30 ISOP 3 x 6 mm

Screw 3 50 ISOP 3 x 4 mm

Screw 4 40 TP1P 2 x 6 mm

Screw 5 10 ISOF 3 x 6 mm

Nut 40 3 x 5 mm

Servo Cable 6 5264 connecter100mm *4150mm *2

Breadboard Jumper Cables

8 Male to Female type

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CHAPTER 4

BIPED MODELLING METHODOLOGY

4.1 Gait of Biped

Gait is the pattern of movement of the limbs of animals, including humans, during

locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based

on speed, terrain, the need to manoeuvre, and energetic efficiency. While gaits can be

classified by footfall, new work involving whole-body kinematics and force-plate records

has given rise to an alternative classification scheme, based on the mechanics of the

movement. In this scheme, movements are divided into walking and running. Walking gaits

are all characterized by a 'vaulting' movement of the body over the legs, frequently

described as in inverted pendulum (displaying fluctuations in kinetic and potential energy

which are perfectly out of phase). In running, the kinetic and potential energy fluctuate in-

phase, and the energy change is passed on to muscles, bones, tendons and ligaments acting

as springs (thus it is described by the spring-mass model), as in case of animals and

humans. In case of a Bi pedal robot the energy changes are passed on to the physical leg

structure comprising of Servo frames, clamps, Footpads, Servomotors, and other minor

components which should be designed and assembled to give maximum durability and

control while walking.

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Designing a simple gait involves an active relationship between hardware and

software. To illustrate, it can be easily appreciated that the more degrees of freedom a biped

robot has, the more complicated the control program and electronic controller will have to

be. In many applications, increase in the degree of freedom may outweigh the benefits,

such as seen in biped robots with 10 degrees of freedom and more. With respect to software

design, biped gaits describe the control of balance. Balance involves an autonomous biped

robot maintaining a stable equilibrium while progressing along a surface. A way to achieve

such a balance can be done by using the walking state methodology. The method uses static

balance poses to define points of tending to balance during a gait. The point that a biped

robot tends to balance is called a state. The walking states are chosen as the maximum and

minimum tending to balance stance equilibrium positions where little or no torque needs to

be applied to maintain the state. Other methods that can be used include simulations, zero

point method, and trial, and error.

4.2 Autonomous Biped Gait

Autonomous biped gait algorithm can be achieved by considering a marching gait.

For a conceptual marching gait with two steps, left and right, we will assume that there are

five states where the robot tends to either balance or tend to topple. When marching gait is

considered with two steps the biped center of mass tends to shift to one side completely

when it is walking and is in the single support stage where only one foot is planted on the

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ground.In this stage the biped tends to topple because most of the weight is shifted onto one

side.

The programming of biped walking consists the two steps which are discussed

further below.

4.3 Walking Cycle

Generally walking cycle consists of two steps namely Initialization and Walking: These are

explained below in detail.

4.3.1 Initialization

In the Initialization step the robot will be in balanced condition and in this step the

servomotors are made to return to home position. This will certainly help the robot to

advance into the next step.

4.3.2 Walking

Walking step is further classified into six phases.

Phase 1 – Double Support:

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In this phase both the legs are in same line and the center of mass is maintained

between the two legs.

Phase 2 – Single Support (Pre-Swing):

In this phase both the ankle joints are in actuated in roll orientation which shifts the

center of mass towards the left leg and the right leg will be lifted up from the

ground.

Phase 3 – Single Support (Swing):

In this phase, the right leg is lifted further and made to swing in the air. Hip and

knee joints are actuated in pitch orientation so that right leg is moved forward.

Phase 4 – Post Swing:

In this phase the lifted leg is placed down with the actuation of ankle joints. After

the stage 5 stage 1 continues.

Fig 4.1 Walking phases

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These stages are used for the modelling of the bipedal robot. However, considering

the ZMP which shifts its position very rapidly in the case of the humans the same

methodology cannot be adapted by the bipedal robot as of now, because of the

height constraints and the number of the degrees of freedom the biped motion is

very limited. This makes the biped to walk very slowly and the COG should not

cross the area where the landed foot is present on the ground during the single

support phase.

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CHAPTER 5

ELECTRONICS AND CHASSIS

5.1 Electronics

The major electronic components comprise of Arduino Nano, which is the

processing unit and the and also the program memory is vested on the arduino board.The

Arduino is seated upon the Arduino Nano Shield for designed for smart serial control of

servos. The output from the Nano Shield goes to the TT Linker Mini which processes its

input and manipulates it to control both the legs using two different UART serial channels

connecting the Servo at Hip to the Servo at Ankle via Servo at Knee.

5.2 Arduino

Arduino is a tool for making computers that can sense and control more of the physical

world than your desktop computer. It's an open-source physical computing platform based on a

simple microcontroller board, and a development environment for writing software for the board.

Arduino can be used to develop interactive objects, taking inputs from a variety of switches

or sensors, and controlling a variety of lights, motors, and other physical outputs. Arduino projects

can be stand-alone, or they can communicate with software running on your computer

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Advantages of Arduino

Simple, clear programming environment - The Arduino programming environment is easy-

to-use for beginners, yet flexible enough for advanced users to take advantage of as well.

For teachers, it's conveniently based on the Processing programming environment, so

students learning to program in that environment will be familiar with the look and feel of

Arduino

Open source and extensible software- The Arduino software is published as open source tools,

available for extension by experienced programmers. The language can be expanded

through C++ libraries, and people wanting to understand the technical details can make the

leap from Arduino to the AVR C programming language on which it's based. Similarly, you

can add AVR-C code directly into your Arduino programs if you want to.

Cross-platform - The Arduino software runs on Windows, Macintosh OSX, and Linux

operating systems. Most microcontroller systems are limited to Windows.

Inexpensive - Arduino boards are relatively inexpensive compared to other microcontroller

platforms. The least expensive version of the Arduino module can be assembled by hand,

and even the pre-assembled Arduino modules cost less.

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5.3 Arduino Nano

The Arduino Nano is a small, complete, and breadboard-friendly board based on the

ATmega328 (Arduino Nano 3.x) or ATmega168 (Arduino Nano 2.x). It has more or less the same

functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power

jack, and works with a Mini-B USB cable instead of a standard one. The Nano was designed and is

being produced by Gravitech.

Fig 5.1 Arduino Nano Front and Rear view

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5.3.1 Power

The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated

external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source

is automatically selected to the highest voltage source.

5.3.2 Memory

The ATmega168 has 16 KB of flash memory for storing code (of which 2 KB is used for

the bootloader); the ATmega328has 32 KB, (also with 2 KB used for the bootloader). The

ATmega168 has 1 KB of SRAM and 512 bytes of EEPROM (which can be read and written with

the EEPROM library); the ATmega328 has 2 KB of SRAM and 1 KB of EEPROM.

5.3.3 Input and Output

Each of the 14 digital pins on the Nano can be used as an input or output, using

pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin

can provide or receive a maximum of 40 mA and has an internal pull-up resistor

(disconnected by default) of 20-50 kOhms.

5.4 Smart Servo Control Shield

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Shields are boards that can be plugged on top of the Arduino PCB extending its

capabilities. The purpose of a shield is to provide new plug-and-play functionality to the

host microcontroller, so as to control the actuation of Smart Control Servo’s. Here in the

use of Arduino Nano shield in the electronics of Bipedal Robot is to mutate the number of

inputs according to the servos. The wiring schema of the Biped is such that all the SC

Servo’s of one leg are connected in series i.e Servo at the Hip to the Servo at the Ankle via

Servo at Knee. So to actuate each servo simultaneously which a Arduino can't do by itself

the Arduino Nano Shield is used. With this smart servo shield and Smart Control series

servos, It's quite easy to drive multi servos with daisy chain connection to Arduino

processor and build a biped, robotic dog, hexapod with powerful servos.

5.4.1 TT Linker Mini

The NANO Shield board is used to connect the Arduino NANO board and TT Linker Mini

signal conversion board, include two used to indicate the LED1 and LED2, two input

buttons S1 and S2.Two LEDs corresponding connection Arduino Nano D2 and D4 digital

port, two buttons correspond to connect the Arduino Nano A1 and A2 Analog

port.TTLinker_mini connect to Arduino Nano TX1 and RX0 two digital serial ports and

convert the Arduino Nano control signals into a single bus to control SC Servo.

5.5 SC Servo

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SC Servo is meaning that Smart Control Servo. SC Servo can work at servo mode and

wheel mode, has a unique ID number to identify on BUS network, have kinds of baud rate

available, and can feedback the value of Position, Temperature, Load, Speed and Input

Voltage. SC Servo is easy to be controlled by Arduino.

5.6 Actuators selection

Electric motors are used to “actuate” something in robots: its wheels, legs, tracks,

arms, fingers, sensor turrets, or weapon systems. There are literally dozens of types of

electric motors (and many more if we count gasoline and other fuelled engines), but for

amateur robotics, the choice comes down to these three: dc motor , stepper motor ,servos.

Though all the three of these actuators are considered to be well suited only one of them is

most efficient for our current bipedal robot. The choice of selection of actuator of these

bipedal robots is supported by the following.

5.6.1 DC Motor

In a continuous DC motor, application of power causes the shaft to rotate

continually. The shaft stops only when the power is removed, of if the motor is stalled

because it can no longer drive the load attached to it.

5.6.2 Stepper motor

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In a stepping motor, applying power causes the shaft to rotate a few degrees, then

stop. Continuous rotation of the shaft requires that the power be pulsed to the motor. As

with continuous DC motors, there are sub-types of stepping motors. Permanent magnet

steppers are the ones you’ll likely encounter, and they are also the easiest to use.

5.6.3 Servo motor

A special “subset” of continuous motors is the servo motor, which in typical cases

combines a continuous DC motor with a “feedback loop” to ensure accurate positioning.

There are many, many types of servo motors; a common form is the kind used in model

and hobby radio-controlled cars and planes.

Motor Type Pros Cons

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Continuous DC ● Wide selection available,

both new and used.- Easy

to control via computer

with relays or electronic

switches.

● With gearbox, larger DC

motors can power a 200

pound robot.

● Requires gear reduction to

provide torques needed for most

robotic applications.

● Poor standards in sizing and

mounting arrangements.

Stepper ● Does not require gear

reduction to power at low

speeds.

● Low cost when purchased

on the surplus market.

● Dynamic braking effect

achieved by leaving coils

of stepper motor

energized (motor will not

turn, but will lock in

place).

● Poor performance under varying

loads. Not great for robot

locomotion over uneven

surfaces.

● Consumes high current.

● Needs special driving circuit to

provide stepping rotation.

R/C servo ● Least expensive non-

surplus source for gear

● Requires modification for

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motors.

● Can be used for precise

angular control, or for

continuous rotation (the

latter requires

modification).

● Available in several

standard sizes, with

standard mounting holes.

continuous rotation.

● Requires special driving circuit.

● Though more powerful servos

are available, practical weight

limit for powering a robot is

about 10 pounds.

Upon careful research and on the basis of the above mentioned reasons Servos are being

selected for the actuation of the biped robot joints because of their precise angular control

which can mimic the human walking pretty much with ease.

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5.7 Mechanical components:

5.7.1 Material selection:

While there are almost dozens of materials to choose from to make the chassis of

the biped. Aluminium has been selected finally as the optimal material after careful

research to use for this current bipedal robot project. The benefits of using the aluminium

material are given below. Some of the main reasons for choosing aluminium body is

because of its light weight and good durability and ease of availability. More of the features

and benefits are as follows:

● It has the precision of manufacture,

● It has long-time stability of dimensions (they do not change their shape like PVC

due to heating up),

● It has high mechanical endurance (resistance to impact),

● The aluminium structures do not require surface maintenance, such as wooden ones,

and their cleaning is fast and easy,

● The aluminium structures are very durable, resistant to weather conditions and

wear,

● It has a wide selection of appearance in the form of high quality finishing (RAL,

anode and wood colour veneering),

● The elegant profile of aluminium structures guarantees maximum access to light

and aesthetic appearance,

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● It has a very good thermal insulation provided by a complex structure and various

types of fill (aluminium profile enable a structure with a thermal insulation

coefficient of U=1.2 W/(m2*K) with a glass coefficient of U=1.0 W/(m2*K) ),

● It has various styles and opening systems, as well as compatibility with other

aluminium systems,

● It is available fire systems, classes from EI15 to EI60, and a burglar alarm,

● It has a high acoustic insulation and a possibility of individual product preparation

for an appropriate design,

5.7.2 Aluminium C shaped brackets

These C brackets typically make the whole body of our biped. These brackets are

used to fix the servos and hold them at their respective points. These C shaped brackets

accommodate the servos very easily and perfectly giving the robot a smooth and hassle free

motion. Also using these C shaped brackets the robot is very flexible and can turn and bend

easily. Upon impacts, the potential damage endangered will be reduced to zero since all the

links are c brackets and they bend because of the actuators present at their joints.

Fig 5.2. C-bracket joints

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5.7.3 Main U-shaped brackets

The U shaped aluminium bracket is used to hold the two legs together. This bracket

is placed on top of the two legs and is fixed to the two legs using few screws and nuts.

Besides, holding the two legs together, it also serves as the platform or base to mount the

servo shield and the Arduino nano.

Fig 5.3 U shaped bracket

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CHAPTER 6

ASSEMBLY

6.1 Assembling the biped robot

The biped assembly is done in various stages. Each stage is being discussed below

and represented pictorially.

6.1.1 Footpad and Servo side bracket

Initially the foot bracket is taken and the servo side bracket is placed on top of it.

The purpose of placing a servo side bracket is to hold the servos. Having 3 servos fixed in

each leg one of the three servos is placed on the foot to give it the tilting motion. In order to

fix the servo onto the foot simple screws cannot be used. Hence, by initially fixing a servo

side bracket the servo on the foot gets a base support and this servo side bracket is then

fixed onto the foot plate.

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Fig 6.1. servo side bracket on foot plate.

6.1.2 C shaped brackets

The C shape brackets make the complete robot links which means the whole body is

made up of C shaped brackets. The C shaped brackets accommodate the servos and then are

fixed together end to end. The other side of the servos also contain C shaped brackets

which are then fixed to the U shaped bracket on top.

(a)

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(b)

Fig: 6.2 (a) C shaped brackets (b) assembled brackets

6.1.3 Main U shaped bracket

Finally, the U shaped bracket is being mounted on top of the two legs to give it

support and also to provide a base for the arduino and the ttlinker. With this the whole

biped body is assembled. The arduino and the ttlinker can also be screwed to the u shaped

bracket so that twist and bend positions it does not fall off the body.

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Fig 6.3 Assembled Biped.

CHAPTER 7

SOFTWARE PROGRAMING AND OPERATION

7.1 Methodology

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The main idea of the project is to make in-Hand manipulating Biped Robot. In-

Hand Manipulation, often called as Dexterous manipulation or Object manipulation is a

process of performing the actions to be done robot by the operator and simultaneously

feeding the same into the memory of the program chip. Then upon call for operation the

robot mimics the same actions fed to itself by the operator. This is achieved by the process

of Reverse mapping.

7.2 In-Hand Manipulation

“In-hand manipulation” is the ability to reposition an object in the hand, for

example when adjusting the grasp of a hammer before hammering a nail. The common

approach to in-hand manipulation with robotic hands, known as dexterous manipulation, is

to hold an object within the fingertips of the hand and wiggle the fingers, or walk them

along the object’s surface. Dexterous manipulation, however, is just one of the many

techniques available to the robot. The robot can also roll the object in the hand by using

gravity, or adjust the object’s pose by pressing it against a surface, or if fast enough, it can

even toss the object in the air and catch it in a different pose. All these techniques have one

thing in common: they rely on resources extrinsic to the hand, either gravity, external

contacts or dynamic arm motions. We refer to them as “extrinsic dexterity”.

Upon using the Dexterous Manipulation Technology, the movement given to the

boy of the biped generates electrical impulses in the Smart control Servo motors and then

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the impulses are backed to the Arduino Shield via TT Linker where the shield

communicates with the Arduino board and Arduino writes the movements as motion with

set of delays as command to servo motors. As this is an extrinsic effect the arduino is

programmed to receive the impulses and negate the impulses to create the intrinsic effect

and stores the program to its flash memory. Thus when on operation the previously stored

movements are performed by the biped.

7.3 Reverse Mapping

Reverse mapping is the backend process of In-hand manipulation. It is the process

where all the geometric configurations performed upon the robot are reversely mapped on

the memory as a program to implement the same actions intrinsically. This is the crux

technology behind the In-Hand manipulation methodology. Reverse mapping technology

allows to feed programs simply without coding, by self-generating the program when the

movements are performed upon the robot extrinsically.

7.4 Advantages

The advantages of this process is that hefty coding schedules can be discarded for

each type of motion/geometric configuration to be performed by the biped. Only a one time

program should be coded so as to perform the movements fed to the biped. This system

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eliminates the program changeover time and program development time. a person with high

programming skills isn't needed every time to create the set of codes for each type of

movement, rather a lay man can feed the movement by physical manipulation of required

movement.

The program and the header files required to code the Biped are shown further.

7.5 Header file for the program

/* * SCServo.h * Series Control Servo

* Created on: 2015.04.06 * Author: Hareen,Jonny,Surya|Project Biped|

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*/#ifndef _SCSERVO_h_#define _SCSERVO_h_

#if defined(ARDUINO) && ARDUINO >= 100#include "Arduino.h"#else#include "WProgram.h"#endif

#define s8 char#define u8 unsigned char#define u16 unsigned short#define s16 short#define u32 unsigned long#define s32 long

class SCServo{public:

SCServo();u8 EnableTorque(u8 ID, u8 Enable, u8

ReturnLevel=2);u8 WritePos(u8 ID, s16 position, s16 velocity, u8

ReturnLevel=2);u8 RegWritePos(u8 ID, s16 position, s16 velocity,

u8 ReturnLevel=2);s16 ReadPos(u8 ID);s16 ReadVoltage(u8 ID);s16 ReadTemper(u8 ID);void RegWriteAction();void SyncWritePos(u8 ID[], u8 IDN, s16 position,

s16 velocity);u8 WriteID(u8 oldID, u8 newID, u8 ReturnLevel=2);u8 WriteLimitAngle(u8 ID, u16 MinAngel, u16

MaxAngle, u8 ReturnLevel=2);u8 WriteLimitTroque(u8 ID, u16 MaxTroque, u8

ReturnLevel=2);u8 WritePunch(u8 ID, u16 Punch, u8 ReturnLevel=2);u8 WriteBaund(u8 ID, u8 Baund, u8 ReturnLevel=2);u8 WriteComplianceMrgin(u8 ID, u8 CCW, u8 CW, u8

ReturnLevel=2);u8 WritePID(u8 ID, u8 P, u8 I, u8 D, u8

ReturnLevel=2);u8 WriteSpe(u8 ID, s16 velocity, u8 ReturnLevel=2);

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u8 LockEprom(u8 ID, u8 Enable, u8 ReturnLevel=2);private:

u8 ReadBuf(u8 len, u8 *buf=NULL);#define startByte 0xFF#define TIMEOUT 2000//TIMEOUT 2000

#define B_1M 0#define B_0_5M 1#define B_250K 2#define B_128K 3#define B_115200 4#define B_76800 5#define B_57600 6#define B_38400 7

//register Address#define P_MODEL_NUMBER_L 0#define P_MODEL_NUMBER_H 1#define P_VERSION_L 3#define P_VERSION_H 4#define P_ID 5#define P_BAUD_RATE 6#define P_RETURN_DELAY_TIME 7#define P_RETURN_LEVEL 8#define P_MIN_ANGLE_LIMIT_L 9#define P_MIN_ANGLE_LIMIT_H 10#define P_MAX_ANGLE_LIMIT_L 11#define P_MAX_ANGLE_LIMIT_H 12#define P_LIMIT_TEMPERATURE 13#define P_MAX_LIMIT_VOLTAGE 14#define P_MIN_LIMIT_VOLTAGE 15#define P_MAX_TORQUE_L 16#define P_MAX_TORQUE_H 17#define P_ALARM_LED 18#define P_ALARM_SHUTDOWN 19#define P_COMPLIANCE_P 21#define P_COMPLIANCE_D 22#define P_COMPLIANCE_I 23#define P_PUNCH_L 24#define P_PUNCH_H 25#define P_CW_COMPLIANCE_MARGIN 26#define P_CCW_COMPLIANCE_MARGIN 27

#define P_TORQUE_ENABLE (31)

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#define P_LED (32)#define P_GOAL_POSITION_L (33)#define P_GOAL_POSITION_H (34)#define P_GOAL_SPEED_L (35)#define P_GOAL_SPEED_H (36)#define P_LOCK (37)

#define P_PRESENT_POSITION_L (41)#define P_PRESENT_POSITION_H (42)#define P_PRESENT_SPEED_L (43)#define P_PRESENT_SPEED_H (44)#define P_PRESENT_LOAD_L (45)#define P_PRESENT_LOAD_H (46)#define P_PRESENT_VOLTAGE (47)#define P_PRESENT_TEMPERATURE (48)#define P_REGISTERED_INSTRUCTION (49)#define P_ERROR (50)#define P_MOVING (51)

//Instruction:#define INST_PING 0x01#define INST_READ 0x02#define INST_WRITE 0x03#define INST_REG_WRITE 0x04#define INST_ACTION 0x05#define INST_RESET 0x06#define INST_SYNC_WRITE 0x83

};#endif

7.6 Program

/* * Series Robot Control v1.0 * Created on: 2015.04.07 * Author: Hareen,Jonny,Surya

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*/#include <SCServo.h>#include <EEPROM.h>SCServo SERVO;int addr = 0;int maxaddr = 12;int LED1 = 4;int LED2 = 2;int motion_t = 900; int T = 1000; #define But_1 A1 // define an button for select Program mode or Control mode#define But_2 A2 // define an button to confirm input

void ProgramStartMotion(){ int bot2 = analogRead(But_2); // if(bot2<20) { digitalWrite(LED2,HIGH); // delay(500); digitalWrite(LED2,LOW); for(int y=0; y<=960;y++) { for(int i = 1; i <= 6; i++) { s16 pos = SERVO.ReadPos(i);//read Servo ID i position byte posL = pos&0xff; EEPROM.write(y, posL); byte posH = pos>>8; y = y + 1; EEPROM.write(y, posH); y = y + 1; } } EEPROM.write(12, 0xff); EEPROM.write(13, 0xff); }}

void ProgramMotion(){

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int back_loop = 1; while(back_loop) { SERVO.EnableTorque(0xfe, 0); delay(200); digitalWrite(LED1,LOW); // delay(200); digitalWrite(LED1,HIGH); // int bot1 = analogRead(But_1); // if(bot1 < 20)//exit program motion { addr = 0;//perform start at address 0 back_loop = 0; digitalWrite(LED1,LOW); // delay(500); } int bot2 = analogRead(But_2); // if(bot2 < 20) { digitalWrite(LED2,HIGH); // delay(500); digitalWrite(LED2,LOW); // for(int i = 1; i <= 6; i++) { s16 pos = SERVO.ReadPos(i);//read Servo ID i position byte posL = pos&0xff; EEPROM.write(addr, posL); byte posH = pos>>8; addr = addr + 1; EEPROM.write(addr, posH); addr = addr + 1; // advance to the next address. there are 1k bytes in // the EEPROM, so go back to 0 when we hit 1k. if (addr == 960) { addr = 0; delay(100); } } if(addr>maxaddr) {

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maxaddr=addr; EEPROM.write(addr, 0xff); EEPROM.write(addr+1, 0xff); } digitalWrite(LED2,HIGH); // delay(500); digitalWrite(LED2,LOW); // } }}

void PerformMotion(){ SERVO.EnableTorque(0xfe, 1); // read a byte from the current address of the EEPROM for(int i = 1; i <= 6; i++) { byte posL = EEPROM.read(addr); addr = addr + 1; byte posH = EEPROM.read(addr); addr = addr + 1; s16 pos =posH<<8; pos = pos | posL; s16 current_pos = SERVO.ReadPos(i);//read Servo ID:1 position if(pos!=-1) { s16 pos_error = abs( pos - current_pos) ; s16 s = motion_t * 10; //s *=100; s16 velocity = s / pos_error; //SERVO.WritePos(i, pos, velocity); SERVO.RegWritePos(i, pos, velocity); } if (addr == 960) { addr = 0; delay(100); } } if(EEPROM.read(addr)==0xff && EEPROM.read(addr+1)==0xff) { addr = 0;//read end flat perform start at address 0 }

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SERVO.RegWriteAction(); delay(T);}

void setup(){ Serial.begin(1000000);//init Serial baudrate delay(500); pinMode(LED1,OUTPUT); pinMode(LED2,OUTPUT); SERVO.EnableTorque(0xfe, 0);// ProgramStartMotion();}

void loop(){ int bot1 = analogRead(But_1); // digitalWrite(LED2,LOW); // if(bot1<20) { digitalWrite(LED1,HIGH); // delay(100); ProgramMotion(); } else { digitalWrite(LED1,LOW); // digitalWrite(LED2,HIGH); // PerformMotion(); } int bot2 = analogRead(But_2); // if(bot2<20) { digitalWrite(LED2,LOW); // motion_t = motion_t - 100; if(motion_t < 100) { motion_t = 1000; } delay(500); } }

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7.7 Operation:

For initially setting the robot to a reference position or to reset the robots position the S2

button is pressed. This button is also used for deleting all the previously saved motion and

bringing it back to the original position. This should be pressed initially after power on.

Another method of resetting is to press the reset button for 1 second until the LED2 flashes

for one time.

The period of the on time for LED2 will be used by the biped to keep its position to set up

its initial motion.LED2 normally on means that the initial setup is complete. If after power

is on, no reset button is pressed or S2 is pressed this will skip the initial setting.

When LED2 normally on, pressing the S1 button to let LED2 off and LED1 flashing, this

time can be used to set biped robot motion by hand, all SC Servo torque output will be off,

and the arbitrary flipping in biped robot’s degree of freedom by hand to set up the position

desired can be done.

In order to let the continuity of action, the movement angle should not be too big

between the joints of the robot.

CHAPTER 8

APPLICATIONS

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• Bipedal robots have become the ones to attract scientists, researchers,

industrialists, educational institutions. Their use have been foreseen in many diverse fields.

The current artificial environment is designed for humans. For example, the width of a

corridor is determined by the size of humans, and the height of steps on stairs by the length

of a human leg. Therefore, a robot can move in the current environment without re-

investment to the environment when the kinematics of the robot is compatible with that of

humans.

• Industrial plants can be run without a break if tele-operated robots are able to

maintain them, including hazardous areas. Besides, we can expect that the plants do not

need remodelling when the maintenance robots are humanoid robots.

• Bipeds can be used for assisting the physically challenged people in walking.

• Bipeds can be used for Guarding the home and office.

• Bipeds can be used to replace some of the human tedious works such as carrying loads.

• Bipeds can be used to develop Polypedal robots which could be more stable.

• Bipeds are a very useful means of transportation in rough or uneven terrains or slippery

terrains.

• Bipeds can be used in military where medical supplies have to be transported to a remote

base.

• The robot can move in the environment that is designed for humans.

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CHAPTER 9

CONCLUSION

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In the present day world where technological advancements play a major role in

every field, the whole world is running towards achieving a better tomorrow where almost

all the present day processes will be automated and would require less or no human

intervention at all. With the technology advancing in leaps and bounds, the usage and

application of the humanoid robots are ever increasing attracting the industries, educational

institutions, medical departments, defence etc., globally. It is true that humanoid robots

need more time to be applied in real society on a large scale, but it started approaching the

goal with a rapid speed. We believe that biped humanoid robots have a good chance of

being the largest product of this century.

CHAPTER 10

FUTURE ADVANCEMENTS

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These BI-PED legs can further be aimed into creating a full humanoid. First the hands can

be added enabling it to walk and pick up things, punch obstacles and other functions. Then

a head can also be attached enabling it to recognize colours through image processing.

More human like functions can be assigned to the robot leading it to become something

bigger than only a pair of bipedal legs. A controller can also be made to manually handle

the bot and make it perform tasks.

REFERENCES

• M. Vukobratovi c, B. Borovac, D. Surla, and D. Stoki' c,Biped Locomotion. Dynamics, Stability,

Control and Application.Springer, 1990.

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• S. Kajita and K. Tani, "Experimental Study of Biped Dynamic Walking," in 1995 IEEE Int. Conf. on

Robotics and Automation,pp. 13.

• W. T. Miller, "Real-Time Neural Network Control of a Biped Walking Robot," IEEE Control

Systems Magazine, pp. 41-48, February. 1994.

• K. Hashimoto, Y. Sugahara, H. 0. Lim, A. Takanishi.: Realization of stable walking on public road

with new biped foot system adaptable to uneven terrain. Paper presented at the IEEE/RAS-EMBS

international conference on biomedical robotics and biomechatronics, 20-22 Feb. 2006.

• J. H. Kim, J. H. Oh.: Walking control of the humanoid platform KHR-1 based on torque feedback

control. Paper presented at the IEEE international conference on robotics and automation, New

Orieans, LA, 26 April -1 May 2004

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