WELCOME

TO

SEMINAR-1

ON

INSECT WALKING AND ROBOTICS

CONTENT

Introduction

Mechanism of leg movement

Coordination between legs

Sensory system of the leg and its role in walking

Brain control of insect walking

Importance of hexapod robots

Insect walking as a model of robots

Hexapod robot body architecture

Case studies

conclusion

INTRODUCTION

Mechanism of leg movement in walking arthropods

The cyclic movement of a walking leg consists of two

parts

Stance phase :

The leg is retracted

It moves backwards relative to the body, with the foot on the

ground

Propelling the body forwards

Swing phase :

The leg is protracted

So that it swings forwards with the foot off the ground

At low speed metachronal wave and at high speeds alternate

tripod

Crusie, 1990

Ripple gait

DIFFERENT WALKING PATTRENS

Huges, 1952

Stepping patterns of the legs

Central pattern generators : networks of neurons capable of

generating & alternating contractions of antagonistic muscles,

controls the stepping movements of individual legs present in

most of insects except stick insects

Interactions between the CPG's and sensory feedback from

the moving legs

Peripheral feedback provide information about leg load,

position, velocity, and acceleration, joint angles and foot

contact

Delcomyn, 1999

Coordination of legs

CPG's that control insect locomotion are not as well known

Some of the neurons are nonspiking

During leg movement, the nonspiking neurons alternately excite

and inhibit the motor neurons that control leg muscles

How the legs are coordinated with one another is still less well

understood

Experiments with crayfish, insects, and vertebrates suggest that

interneurons that run between adjacent ganglia provide

coordinating information

Delcomyn, 1980

Proprioreceptors : The position of the leg

segment &stance of the insect

Hair plates : Gravitational sense

Mechanoreceptors and chemoreceptors : Perception of environment

stimuli

Feedback from sense organs in the moving legs is critical to a properly

coordinated sequence of steps, during slow walking

Fast moving insects essentially ignore sensory input during fast running

The sensilla in different areas of the leg converge to separate

interneurons so that spatial information is maintained in the central

nervous system

Sensory system of legs and their role in walking

Cruse, 1979

Found on all six legs, especially near the joints

Typically arranged in compact fields consisting of 10 or more

individual cs.

Oriented in more or less the same direction, giving the entire

field a directional selectivity

Primarily responsible for adjustments in muscle activity

Campaniform sensilla

Delcomyn, 2008

SEM of campaniform sensilla

Brain Control of Insect Walking

Zill, et al., 2010

The brain not micromanage the movements but directs patterns of

activity

Rapid running can also guided by sensory inputs from the head

e.g. cockroaches that are startled by a puff of air to the abdominal

cerci will rapidly turn and run

It receives inputs from the from other multimodal sensory

interneuron's & influence motor by descending interneuron's

e.g. electrical stimulation of focal brain regions can initiate walking in

quiescent insects or cause turning in one direction or another

Experiments concluding that for walking promote mechanism

located in the subesophageal ganglion

Whereas centers that inhibit walking are located in the

supraesophageal ganglion

Experiments in brain structure disruption have yielded two

types of effects on walking

1) differences in the duration in episodes of walking

2) changes in the coordination of right and left sides

It is mainly due to disruption to the mushroom body

Most neurons recorded in the central complex changed when

animals ran or walked rapidly

The firing frequencies of more than half of the neurons were

correlated with the rate of walking

Bender et al., 2007

Two excitatory motor neurons control extension of the coxa–

trochanter (ctr) joint

Another two motor neurons slow motor neuron and fast motor

neuron control extension of the femur–tibia (fti) joint

The slow motor neuron is responsible for slower leg cycles

As the insect runs faster, the slow motor neurons are activated

at higher frequencies and in shorter bursts

The fast neurons not active in stationary insect

Pearson et al., 1971

Neurons involved in control of leg movement

At very fast running speeds, fast motor neurons are recruited.

Making the transition from stance to swing significantly shorter

Local control rules for each leg are coupled by a series of

“influences.”

For example, the controller for a middle leg would “influence”

all adjacent legs not to enter into swing while the middle leg is

in its swing phase.

Watson and Ritzmann, 1998

Damage to legs and its effect on locomotion

Slow-moving insects: If both middle legs are removed, the

insects immediately change their gaits

The front and rear legs now move alternately rather than

together hence maintaining mechanical stability.

Why it is happening ?

The loss of support by the middle legs

The most likely cause of the switch is the altered input

delivered to the central nervous system by the cs in the legs

Fast-moving insects :

If most of both middle legs are removed, the insects do behave

same at slow walk behave differently as their speeds increase

The front and rear legs begin to move more and more in

synchrony

Their legs are moved forward and back quickly enough that the

insect does not have time to fall over when the legs are lifted

Why it is so happening ?

The ability of the central nervous system to modulate the

strength of a sensory signal during high-speed walking

A robot is an automatic, servo-controlled, freely

programmable, multi-purpose manipulator with several

degrees of freedom. Variably programmed operations make

possible execution of a multiplicity of tasks.

‘‘ROBOT’’

ISO DEFINITION

Robots needs to be stability

There are two kinds of stability:

Static

Dynamic

A statically stable robot can stand still without falling over.

This is a useful feature, but a difficult one to achieve

It requires that there be enough legs/wheels on the robot to

provide sufficient static points of support.

IMPORTANT CONSIDERATIONS FOR ROBOT

• For example, people are not statically stable

• In order to stand up, which appears effortless to us, we are

actually using active control of our balance

• Achieved through nerves and muscles and tendons

• This balancing is largely unconscious

• It must be learned

• So that's why it takes babies take time learnt it

Locomotion mechanisms found in nature

Types of Locomotion in robots

Legs (for walking/crawling/climbing/jumping/hopping)

Wheels (for rolling)

Arms (for swinging/crawling/climbing)

Flippers (for swimming)

Many kinds of effectors and actuators can be used to move

a robot around

Legged locomotion is a very difficult robotic problem,

especially when compared to wheeled locomotion

Insects walking as model for walking robots

Insect walking exhibits three features

Autonomy : Present method of choosing the path by robots ?

alternative method ?

An insect can select a suitable path to traverse any terrain, no

matter how complex, using only its own sensory receptors and

nervous system.

Complete autonomy of action can be desirable in a walking

robot so that no human guidance is required for path selection

Delcomyn, 2014

Agility : How insects achieved so agile in walking ?

Insects walk with agility over any rough or rugged surface, no

matter how large or small the particles, or how steep the surface

insect walking is extraordinarily robust by using sensory system

Robustness : How insect are compensating damage to legs ?

Insect can sustain considerable physical damage, even lose

several legs, without impairing its ability to walking by using

remaining sense organs

Robot, especially one that is expected to operate in remote

places far from human contact it is most desirable

Why Chosen Legs?

Better handling of rough terrain.

Less energy loss

Potentially less weight

Legs do less damage to terrain

Potentially more maneuverability

Omni directionality

Can easily walk on a slope ,stairs, over obstacles and sandy

terrain

Body rotations without changing its footprints

Walking Robots Body Architecture

There are two basic architectures of hexapod robots

Rectangular :

Six legs distributed symmetrically along two sides, each

side having three legs

Hexagonal :

Legs distributed axi-symmetrically around the body, in a

hexagonal or circular shape

Require a special gait for turning action

Need four steps in order to realize a turning action

Depends on the application

Factors like terrain form, workspace, payload

Different leg types employed for hexapod walking robots.

All have advantages and disadvantages

Kinematic Architectures of the legged robots

perpendicular

to the

advancement

of the legs

position

parallel to

the robot

legs

move in any

direction

Electric rotating motors: the majority of hexapods is

actuated by this type

They are relatively cheap, easy to control

Pneumatics actuators

Hydraulics actuators: able to supply very high force

Heavy weight will added to engine suitable for larger sized

hexapod robots

Actuator Types for walking robots

Walking Algorithm of hexapod robot

Step 1

– legs 1,4,and 5 down,

legs 2,3 and 6 up.

Step 2

– rotate torso 7 and 9

counter-clockwise,

torso 8 clockwise.

Step 3

– legs 1,4 and 5 up,

– legs 2,3, and 6 down.

Step 4

– rotate torso 7 and 9

clockwise, torso 8

counter-clockwise.

Go to step 1

CASE STUDIES

Robot name Year of

manufacture

Total DF Purpose

Ambler 1989 12 Planetary

exploration

ASV 1989 15 Navigate on

uneven terrains

Tum 1989 19 Hexapod

following

biological

principles

Hannibal 1989 19 Planetary

exploration

Biobot 2000 18 Locomotion on

rough terrain

Hamlet 2001 18 Testing force

&position

control

Sprawlita,

Gregor I

2002&2006 12,16 Robots inspired

by cockroach

Overview of development hexapod robots

Tedeschi and carbone, 2014

Athlete 2006 36 Navigate on the

rough soil of the

moon

Aqua II 2010 6 Under water

hexapod robot

Comet IV 2011 24 Multitasks on

outdoor

environment

CR200 2013 18 Walk on the land

or underwater in

the turbelent surf

zone

Mantis 2013 18 Entertainment

RiSE is the first legged machine capable of locomotion on both

the ground and a variety of vertical buildings at speeds up to 4

cm/s

Interlocking solutions claws or spines generate a combination

of pull in &propulsive forces against gravity e.g. Cats and bears

Bonding mechanisms generate adhesion via suction, chemicals,

capillary forces, or vanderwaal forces e.g. Lizards, frogs, and

insects

RiSE uses both interlocking mechanisms and is thus capable

of climbing both rough and smooth surfaces

Spenko et al., 2008

Biologically Inspired Climbing with Hexapedal Robot- RiSE

DYLEMA: Using walking robots for landmine detection and location

Gonzalez, et al., 2005

Mobile platform

Manipulator

GPS antenna

Magnetic compass

Sensor head

Goldschmidt, et al., 2013

AMOS II hexapod robot

Body flexion

Com elevation

Local Leg Reflexes

Reactive Backbone Joint Control (BJC)

Leg Reflex Control (LRC)

Neural Locomotion Control (NLC)

AMOS II negotiated obstacles with a height up to 13 cm 75% of

its leg length with a success rate of 100 per cent

LAURON is biologically-inspired by the stick insect

Because of the flexible behavior based Control system, LAURON

is capable of adapting to unknown situations very well

Roennau, et al., 2014

Lauron V

A series of hexapods named LIMBED EXCURSION MECHANICAL

UTILITY ROBOT

using for robots repair and maintenance in near-zero gravity on

the surface of spacecraft

Kennedy, 2005

LEMUR

This capable of walking in any direction without turning i.e. perform

manipulation tasks with its six feet including typing on a computer

keyboard

It is suited for space and could do inspection and maintenance tasks

in zero-gravity

Sticky, gecko-like technology on its feet would keeps it anchored

Showlater, 2009

MARS (MULTI APPENDAGE ROBOTIC SYSTEM)

(All terrain hex limbed extra terrestrial explorer)

Ability to roll rapidly over flat smooth terrain and walk carefully

& on fixed wheels over irregular and steep terrain.

Useful for unloading bulky cargo from stationary landers and for

transporting it long distances.

NASA

ATHLETE

AQUA

An amphibious hexapod robot developed with six

independently-controlled leg Actuators.

Able to switch from walking to swimming gaits when it is

moving from a sand beach or surf-zone to deep water

Georgiades, 2005

Can climb in rock fields, mud, sand, and vegetation, across

railroad tracks, up telephone poles, slopes, and stairways.

Controlled remotely at distances up to 700 meters, and ir

cameras and illuminators provide front and rear views from the

robot

Using for

military service

Inspired by the

cockroach

Sarnli, et al ., 2001

RHex

Forest Walker Hexapod

Mantis is a hexapod robot hydraulic powered

It stands nearly 3 m tall and weighs about 2 tons; at present, it is

one of the biggest hexapod robots in the world

It is operated by piloted or wifi enable

HECTOR (Hexapod Cognitive autonomously Operating Robot)

The robot developed by inspiring stick insect walking

algorithms

HECTOR uses a new type of bioinspired, self-contained,

elastic joint drive exoskeleton made of carbon fiber reinforced

plastic

Which makes up only around 13 percent of the robot's body

weight, but allows it to carry loads many times

Hector the ability to learn and plan ahead, which will enable

it to make its way through unfamiliar territory and carry out

exploration tasks autonomously.

Schneider, et al., 2012

Swarm robotics

Biologically inspired by social insects

Emergent complex behaviour from simple agents

Swarm Intelligence Principles:

Autonomous control

Simple agents

Fast and flexible responses

Local communication

Decentralised

applications :

Cleaning up toxic waste

Exploring an unknown planet

Surveillance

Military application

Tiny Robots, Swarms

STRIDE II, which uses footpads for high lift, stability

This robot uses the repulsive surface tension force on its

footpads as the dominant lift principle

The robot propel quickly and power efficiently on the water

surface by the sculling motion of their two side-legs, which

never break the water surface completely

could be used in water surface monitoring, cleaning and

analysis in lakes, dams, rivers and the sea

STRIDE II: A Water Strider-inspired Miniature Robot

Ozcan, et al., 2014

CONCLUSION

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