W W W . R O B O T I X . I N

Classes

• Innovative Mechanisms and its implementation.

• Autonomous robotics – Basics and Advanced.

• Programming in C for Autonomous robotics.

Hands – On

• Sensor circuits and motor driver.

• Line follower/Object detection/Light follower.

• Microcontrollers.

WELCOME TO KRAIG

•Wire Stripper

•63-37 Solder

•Pencil tip soldering iron

•Desoldering wick

•Multimeter

•Basic Bread board

•Single strand wires

•Tweezers

•Screw driver set

•Heat shrink tube(10mm/5mm/2mm/1mm)

•Matchbox

•Glue-fevikwik

•Insulation Tape

MATERIALS REQUIRED

• Gears are the most common form of torque increment devices, found in almost all mechanical machines.

• The concept of reducing the rotation speed to increase torque is known as ‘Gear Reduction’.

• A high speed motor with low torque is used to drive heavier loads at lower speeds.

• They have much more efficiency than pulleys

• The maximum torque capability is not limited by friction but material strength.

GEARED SYSTEMS

• ‘Gear Reduction’ to increase torque / decrease speed of

rotation.

• Alter the direction of rotation axis.

• Synchronization to two axes.

• Reversal of direction of rotation.

USES OF GEAR SYSTEMS

• Spur Gears

• Helical Gears

• Bevel Gears

• Worm Gears

• Rack and Pinion Gears

TYPES OF GEARS

SPUR GEARS

• Very common kind

of Gear.

• Used primarily for

gear reduction.

• Reduction ratio is

the ratio of teeth in

the driver gear and

the driven gear.

WORM WHEEL MECHANISM

• Used for very high gear

reduction

• The wheel is driven by

the worm screw.

• One rotation of the

worm causes the wheel

to advance one tooth

RACK & PINION MECHANISM

Used for converting

rotational motion into

linear motion

• Velocity of contact point and power transferred from one gear to other remains constant.

• V=r . w, Power=Torque x w

• Consider r1 and r2. r1w1=r2w2 and T1 x w1=T2 x w2.

• The gear with larger radius will have lower w and larger torque.

GEARS THEORY

RACK AND PINION

• A rack and pinion is a type

of linear actuator that

comprises a pair of gears which

convert rotational motion into

linear motion.

• The circular pinion engages teeth

on a linear "gear" bar.

• The rack. Rotational motion

applied to the pinion will cause

the rack to move to the side, up

to the limit of its travel.

GRIPPING MECHANISMS

• The most important thing

that is to be taken care of

in order to properly stack

objects, is the gripper. For

this type of gripper we

can have one part of the

gripper as stationary and

actuate the other.

GRIPPING MECHANISMS

DEMO

SOME GRIPPING MECHANISM

• Another option with the grippers can

be to move both the parts

simultaneously using gears or wires

and spool..

• The picture below shows how to

accomplish this mechanism using

gears.

• When motor moves the driving gear

the driven gear automatically moves

in the opposite sense due to the

meshing.

• This is used to move the gripping

pads closer or farther from one

another.

GEARS

Walking Mechanisms• Most living creatures on this planet use limbs as a mode of

locomotion. So it must probably be the most easiest way of

locomotion. But then why do we go on using wheels?

• It turns out that making a walking robot is far more difficult than

making a wheeled or tracked one. Even the most basic walker requires

more actuators.

• More degrees of freedom i.e. more moving parts.

There are basically three ways in which to move a

robotic limb:

1. Linear actuators(hydraulic, pneumatic, electrical etc)

2. Rotary actuators

3. Cable driven

BASICS OF A WALKER

LINEAR ACTUATORS

http://www.youtube.com/watch?v=ue

wMphsBamk

• These are the most elegant sort of actuators as they are the

simplest to use.

• The only problem with these is that they make the joints of

the limb very bulky as they have to be directly attached at

the limb for best performance.

• Some of the most commonly used of these actuators are

servo motors and stepper motors. A normal DC motor of

low rpm can also be used to this extend.

ROTARY ACTUATORS

ROTARY ACTUATORS -

SERVO MOTORS

http://www.youtube.com/watch?v=RCgOCfaWShc

Now imagine implementing these methods of actuation

into a structure like the one shown below.

• A relay is an electrically operated switch.

• Relays use an electromagnet to operate a switching mechanism

mechanically.

RELAYS

• Each relay has two mechanical parts inside.

• The first one is the contact(s) of the relay. The contacts operates

similarly to the contacts of a simple switch or pushbutton.

• You should consider the contacts as a pair of metals like the

following diagram.

BASIC DESIGN AND OPERATION

BASIC DESIGN AND

OPERATION

• The two terminals operates as a switch. When the contacts are 'in contact' then the current flows

from Terminal 1 to Terminal 2. There are two types of contacts: the NO and the NC.

• NO stands for Normal Open contact, while NC stands for Normal Closed contact. The Normal

Open is a contact like the one showed in the previous illustration.

• When the contact is still, then no current flows through it (because it is an OPEN circuit). On the

other hand, a Normal Closed contact allows the current to flow when the contact is still. Below is

illustrate both of these contacts:

DEMO

BASIC DESIGN AND

OPERATION

• A relay may have a combination of the above contacts. Look at the

following illustration:

• In this case, there is a 3rd terminal called "COMMON". The NO and

NC contacts are referred to the COMMON terminal. Between the NC

and the NO contact, there is no contact at any time! The following

animation shows how this pair operates:

DEMO

BASIC DESIGN AND

OPERATION

• This is the last part of the relay operation.

• The device that forces the terminal to move, is actually an electromagnet!

A coil is placed right under the contact.

• When current is flown through this coil, a magnetism is created.

• This magnetism can overcome the force of the spring and can pull the

contact towards it, thus it changes it's position!

DEMO